Marion S. Buckwalter, MD, PhD

All Publications

• Evidence of aberrant anti-epstein-barr virus antibody response, though no viral reactivation, in people with post-stroke fatigue. Journal of inflammation (London, England) Mouat, I. C., Zhu, L., Aslan, A., McColl, B. W., Allan, S. M., Smith, C. J., Buckwalter, M. S., McCulloch, L. 2024; 21 (1): 30

  Abstract

  Fatigue is a common complication of stroke that has a significant impact on quality of life. The biological mechanisms that underly post-stroke fatigue are currently unclear, however, reactivation of latent viruses and their impact on systemic immune function have been increasingly reported in other conditions where fatigue is a predominant symptom. Epstein-Barr virus (EBV) in particular has been associated with fatigue, including in long-COVID and myalgic encephalomyelitis/chronic fatigue syndrome, but has not yet been explored within the context of stroke.We performed an exploratory analysis to determine if there is evidence of a relationship between EBV reactivation and post-stroke fatigue.In a chronic ischemic stroke cohort (> 5 months post-stroke), we assayed circulating EBV by qPCR and measured the titres of anti-EBV antibodies by ELISA in patients with high fatigue (FACIT-F < 40) and low fatigue (FACIT-F > 41). Statistical analysis between two-groups were performed by t-test when normally distributed according to the Shapiro-Wilk test, by Mann-Whitney test when the data was not normally distributed, and by Fisher's exact test for categorical data.We observed a similar incidence of viral reactivation between people with low versus high levels of post-stroke fatigue (5 of 22 participants (24%) versus 6 of 22 participants (27%)). Although the amount of circulating EBV was similar, we observed an altered circulating anti-EBV antibody profile in participants with high fatigue, with reduced IgM against the Viral Capsid Antigen (2.244 ± 0.926 vs. 3.334 ± 2.68; P = 0.031). Total IgM levels were not different between groups indicating this effect was specific to anti-EBV antibodies (3.23 × 105 ± 4.44 × 104 high fatigue versus 4.60 × 105 ± 9.28 × 104 low fatigue; P = 0.288).These data indicate that EBV is not more prone to reactivation during chronic stroke recovery in those with post-stroke fatigue. However, the dysregulated antibody response to EBV may be suggestive of viral reactivation at an earlier stage after stroke.

  View details for DOI 10.1186/s12950-024-00402-0

  View details for PubMedID 39135051

  View details for PubMedCentralID 8926410

• Joint and Individual Mitochondrial DNA Variation and Cognitive Outcomes in Black and White Older Adults. The journals of gerontology. Series A, Biological sciences and medical sciences Odden, M. C., Li, Y., Jotwani, V., Dobrota, S., Tan, A., Cummings, S. R., Shlipak, M. G., Scherzer, R., Ix, J. H., Buckwalter, M., Tranah, G. J. 2024

  Abstract

  BACKGROUND: Mitochondrial dysfunction manifests in neurodegenerative diseases and other age-associated disorders. In this study, we examined variation in inherited mitochondrial DNA (mtDNA) sequences in Black and White participants from two large aging studies to identify variants related to cognitive function.METHODS: Participants included self-reported Black and White adults aged ≥ 70 years in the Lifestyle Interventions and Independence for Elders (LIFE; N=1319) and Health Aging and Body Composition (Health ABC; N=7888) studies. Cognitive function was measured by the digit-symbol substitution test (DSST), and the Modified Mini-Mental State Exam (3MSE) at baseline and over follow-up in LIFE (3.6 years) and Health ABC (10 years). We examined joint effects of multiple variants across 16 functional mitochondrial regions with cognitive function using a sequence kernel association test. Based on these results, we prioritized meta-analysis of common variants in Black and White participants using mixed effects models. A Bonferroni adjusted p-value of <0.05 was considered statistically significant.RESULTS: Joint variation in subunits ND1, ND2, and ND5 of Complex I, 12S RNA, and hypervariable region (HVR) were significantly associated with DSST and 3MSE at baseline. In meta-analyses among Black participants, variant m.4216T>C, ND1 was associated with a faster decline in 3MSE, and variant m.462C>T in the HVR was associated with a slower decline in DSST. Variant m.5460G>C, ND2 was associated with slower and m.182C>T in the HVR was associated with faster decline in 3MSE in White participants.CONCLUSION: Among Black and White adults, oxidative phosphorylation Complex I variants were associated with cognitive function.

  View details for DOI 10.1093/gerona/glae170

  View details for PubMedID 39007867

• The effect of robot-assisted versus standard training on motor function following subacute rehabilitation after ischemic stroke - protocol for a randomised controlled trial nested in a prospective cohort (RoboRehab). BMC neurology Skovgaard Jensen, J., Sorensen, A. S., Kruuse, C., Nielsen, H. H., Skov, C. D., Jensen, H. B., Buckwalter, M. S., Bojsen-Moller, J., Lambertsen, K. L., Holsgaard-Larsen, A. 2024; 24 (1): 233

  Abstract

  BACKGROUND: Body weight unloaded treadmill training has shown limited efficacy in further improving functional capacity after subacute rehabilitation of ischemic stroke patients. Dynamic robot assisted bodyweight unloading is a novel technology that may provide superior training stimuli and continued functional improvements in individuals with residual impairments in the chronic phase after the ischemic insult. The aim of the present study is to investigate the effect of dynamic robot-assisted versus standard training, initiated 6months post-stroke, on motor function, physical function, fatigue, and quality of life in stroke-affected individuals still suffering from moderate-to-severe disabilities after subacute rehabilitation.METHODS: Stroke-affected individuals with moderate tosevere disabilities will be recruited into a prospective cohort with measurements at 3-, 6-, 12- and 18-months post-stroke. A randomised controlled trial (RCT) will be nested in the prospective cohort with measurements pre-intervention (Pre), post-intervention (Post) and at follow-up 6months following post-intervention testing. The present RCT will be conducted as a multicentre parallel-group superiority of intervention study with assessor-blinding and a stratified block randomisation design. Following pre-intervention testing, participants in the RCT study will be randomised into robot-assisted training (intervention) or standard training (active control). Participants in both groups will train 1:1 with a physiotherapist two times a week for 6months (groups are matched for time allocated to training). The primary outcome is the between-group difference in change score of Fugl-Meyer Lower Extremity Assessment from pre-post intervention on the intention-to-treat population. A per-protocol analysis will be conducted analysing the differences in change scores of the participants demonstrating acceptable adherence. A priori sample size calculation allowing the detection of the minimally clinically important between-group difference of 6 points in the primary outcome (standard deviation 6 point, alpha=5% and beta=80%) resulted in 34 study participants. Allowing for dropout the study will include 40 participants in total.DISCUSSION: For stroke-affected individuals still suffering from moderate tosevere disabilities following subacute standard rehabilitation, training interventions based on dynamic robot-assisted body weight unloading may facilitate an appropriate intensity, volume and task-specificity in training leading to superior functional recovery compared to training without the use of body weight unloading.TRIAL REGISTRATION: ClinicalTrials.gov. NCT06273475.TRIAL STATUS: Recruiting. Trial identifier: NCT06273475. Registry name: ClinicalTrials.gov. Date of registration on ClinicalTrials.gov: 22/02/2024.

  View details for DOI 10.1186/s12883-024-03734-9

  View details for PubMedID 38965499

• TREM1 disrupts myeloid bioenergetics and cognitive function in aging and Alzheimer disease mouse models. Nature neuroscience Wilson, E. N., Wang, C., Swarovski, M. S., Zera, K. A., Ennerfelt, H. E., Wang, Q., Chaney, A., Gauba, E., Ramos Benitez, J. A., Le Guen, Y., Minhas, P. S., Panchal, M., Tan, Y. J., Blacher, E., A Iweka, C., Cropper, H., Jain, P., Liu, Q., Mehta, S. S., Zuckerman, A. J., Xin, M., Umans, J., Huang, J., Durairaj, A. S., Serrano, G. E., Beach, T. G., Greicius, M. D., James, M. L., Buckwalter, M. S., McReynolds, M. R., Rabinowitz, J. D., Andreasson, K. I. 2024

  Abstract

  Human genetics implicate defective myeloid responses in the development of late-onset Alzheimer disease. A decline in peripheral and brain myeloid metabolism, triggering maladaptive immune responses, is a feature of aging. The role of TREM1, a pro-inflammatory factor, in neurodegenerative diseases is unclear. Here we show that Trem1 deficiency prevents age-dependent changes in myeloid metabolism, inflammation and hippocampal memory function in mice. Trem1 deficiency rescues age-associated declines in ribose 5-phosphate. In vitro, Trem1-deficient microglia are resistant to amyloid-β42 oligomer-induced bioenergetic changes, suggesting that amyloid-β42 oligomer stimulation disrupts homeostatic microglial metabolism and immune function via TREM1. In the 5XFAD mouse model, Trem1 haploinsufficiency prevents spatial memory loss, preserves homeostatic microglial morphology, and reduces neuritic dystrophy and changes in the disease-associated microglial transcriptomic signature. In aging APPSwe mice, Trem1 deficiency prevents hippocampal memory decline while restoring synaptic mitochondrial function and cerebral glucose uptake. In postmortem Alzheimer disease brain, TREM1 colocalizes with Iba1+ cells around amyloid plaques and its expression is associated with Alzheimer disease clinical and neuropathological severity. Our results suggest that TREM1 promotes cognitive decline in aging and in the context of amyloid pathology.

  View details for DOI 10.1038/s41593-024-01610-w

  View details for PubMedID 38539014

  View details for PubMedCentralID 4369837

• Blocking Formation of Neurotoxic Reactive Astrocytes is Beneficial Following Stroke. bioRxiv : the preprint server for biology Prescott, K., Munch, A. E., Brahms, E., Weigel, M. M., Inoue, K., Buckwalter, M. S., Liddelow, S. A., Peterson, T. C. 2023

  Abstract

  Microglia and astrocytes play an important role in the neuroinflammatory response and contribute to both the destruction of neighboring tissue as well as the resolution of inflammation following stroke. These reactive glial cells are highly heterogeneous at both the transcriptomic and functional level. Depending upon the stimulus, microglia and astrocytes mount a complex, and specific response composed of distinct microglial and astrocyte substates. These substates ultimately drive the landscape of the initiation and recovery from the adverse stimulus. In one state, inflammation- and damage-induced microglia release tumor necrosis factor (TNF), interleukin 1alpha (IL1alpha), and complement component 1q (C1q), together 'TIC'. This cocktail of cytokines drives astrocytes into a neurotoxic reactive astrocyte (nRA) substate. This nRA substate is associated with loss of many physiological astrocyte functions (e.g., synapse formation and maturation, phagocytosis, among others), as well as a gain-of-function release of neurotoxic long-chain fatty acids which kill neighboring cells. Here we report that transgenic removal of TIC led to reduction of gliosis, infarct expansion, and worsened functional deficits in the acute and delayed stages following stroke. Our results suggest that TIC cytokines, and likely nRAs play an important role that may maintain neuroinflammation and inhibit functional motor recovery after ischemic stroke. This is the first report that this paradigm is relevant in stroke and that therapies against nRAs may be a novel means to treat patients. Since nRAs are evolutionarily conserved from rodents to humans and present in multiple neurodegenerative diseases and injuries, further identification of mechanistic role of nRAs will lead to a better understanding of the neuroinflammatory response and the development of new therapies.

  View details for DOI 10.1101/2023.10.11.561918

  View details for PubMedID 37905154

• Ipsilesional Hippocampal GABA Is Elevated and Correlates With Cognitive Impairment and Maladaptive Neurogenesis After Cortical Stroke in Mice. Stroke Torres-López, C., Cuartero, M. I., García-Culebras, A., de la Parra, J., Fernández-Valle, M. E., Benito, M., Vázquez-Reyes, S., Jareño-Flores, T., de Castro-Millán, F. J., Hurtado, O., Buckwalter, M. S., García-Segura, J. M., Lizasoain, I., Moro, M. A. 2023

  Abstract

  Cognitive dysfunction is a frequent stroke sequela, but its pathogenesis and treatment remain unresolved. Involvement of aberrant hippocampal neurogenesis and maladaptive circuitry remodeling has been proposed, but their mechanisms are unknown. Our aim was to evaluate potential underlying molecular/cellular events implicated.Stroke was induced by permanent occlusion of the middle cerebral artery occlusion in 2-month-old C57BL/6 male mice. Hippocampal metabolites/neurotransmitters were analyzed longitudinally by in vivo magnetic resonance spectroscopy. Cognitive function was evaluated with the contextual fear conditioning test. Microglia, astrocytes, neuroblasts, interneurons, γ-aminobutyric acid (GABA), and c-fos were analyzed by immunofluorescence.Approximately 50% of mice exhibited progressive post-middle cerebral artery occlusion cognitive impairment. Notably, immature hippocampal neurons in the impaired group displayed more severe aberrant phenotypes than those from the nonimpaired group. Using magnetic resonance spectroscopy, significant bilateral changes in hippocampal metabolites, such as myo-inositol or N-acetylaspartic acid, were found that correlated, respectively, with numbers of glia and immature neuroblasts in the ischemic group. Importantly, some metabolites were specifically altered in the ipsilateral hippocampus suggesting its involvement in aberrant hippocampal neurogenesis and remodeling processes. Specifically, middle cerebral artery occlusion animals with higher hippocampal GABA levels displayed worse cognitive outcome. Implication of GABA in this setting was supported by the amelioration of ischemia-induced memory deficits and aberrant hippocampal neurogenesis after blocking pharmacologically GABAergic neurotransmission, an intervention which was ineffective when neurogenesis was inhibited. These data suggest that GABA exerts its detrimental effect, at least partly, by affecting morphology and integration of newborn neurons into the hippocampal circuits.Hippocampal GABAergic neurotransmission could be considered a novel diagnostic and therapeutic target for poststroke cognitive impairment.

  View details for DOI 10.1161/STROKEAHA.123.043516

  View details for PubMedID 37694402

• Machine learning models of plasma proteomic data predict mood in chronic stroke and tie it to aberrant peripheral immune responses. Brain, behavior, and immunity Bidoki, N. H., Zera, K. A., Nassar, H., Drag, L. L., Mlynash, M., Osborn, E., Musabbir, M., Eun K Kim, D., Paula Mendez, M., Lansberg, M. G., Aghaeepour, N., Buckwalter, M. S. 2023

  Abstract

  Post-stroke depression is common, long-lasting and associated with severe morbidity and death, but mechanisms are not well-understood. We used a broad proteomics panel and developed a machine learning algorithm to determine whether plasma protein data can predict mood in people with chronic stroke, and to identify proteins and pathways associated with mood. We used Olink to measure 1,196 plasma proteins in 85 participants aged 25 and older who were between 5 months and 9 years after ischemic stroke. Mood was assessed with the Stroke Impact Scale mood questionnaire (SIS3). Machine learning multivariable regression models were constructed to estimate SIS3 using proteomics data, age, and time since stroke. We also dichotomized participants into better mood (SIS3 > 63) or worse mood (SIS3 ≤ 63) and analyzed candidate proteins. Machine learning models verified that there is indeed a relationship between plasma proteomic data and mood in chronic stroke, with the most accurate prediction of mood occurring when we add age and time since stroke. At the individual protein level, no single protein or set of proteins predicts mood. But by using univariate analyses of the proteins most highly associated with mood we produced a model of chronic post-stroke depression. We utilized the fact that this list contained many proteins that are also implicated in major depression. Also, over 80% of immune proteins that correlate with mood were higher with worse mood, implicating a broadly overactive immune system in chronic post-stroke depression. Finally, we used a comprehensive literature review of major depression and acute post-stroke depression. We propose that in chronic post-stroke depression there is over-activation of the immune response that then triggers changes in serotonin activity and neuronal plasticity leading to depressed mood.

  View details for DOI 10.1016/j.bbi.2023.08.002

  View details for PubMedID 37557961

• Translatome analysis reveals microglia and astrocytes to be distinct regulators of inflammation in the hyperacute and acute phases after stroke. Glia Hernandez, V. G., Lechtenberg, K. J., Peterson, T. C., Zhu, L., Lucas, T. A., Bradshaw, K. P., Owah, J. O., Dorsey, A. I., Gentles, A. J., Buckwalter, M. S. 2023

  Abstract

  Neuroinflammation is a hallmark of ischemic stroke, which is a leading cause of death and long-term disability. Understanding the exact cellular signaling pathways that initiate and propagate neuroinflammation after stroke will be critical for developing immunomodulatory stroke therapies. In particular, the precise mechanisms of inflammatory signaling in the clinically relevant hyperacute period, hours after stroke, have not been elucidated. We used the RiboTag technique to obtain microglia and astrocyte-derived mRNA transcripts in a hyperacute (4 h) and acute (3 days) period after stroke, as these two cell types are key modulators of acute neuroinflammation. Microglia initiated a rapid response to stroke at 4 h by adopting an inflammatory profile associated with the recruitment of immune cells. The hyperacute astrocyte profile was marked by stress response genes and transcription factors, such as Fos and Jun, involved in pro-inflammatory pathways such as TNF-α. By 3 days, microglia shift to a proliferative state and astrocytes strengthen their inflammatory response. The astrocyte pro-inflammatory response at 3 days is partially driven by the upregulation of the transcription factors C/EBPβ, Spi1, and Rel, which comprise 25% of upregulated transcription factor-target interactions. Surprisingly, few sex differences across all groups were observed. Expression and log2 fold data for all sequenced genes are available on a user-friendly website for researchers to examine gene changes and generate hypotheses for stroke targets. Taken together, our data comprehensively describe the microglia and astrocyte-specific translatome response in the hyperacute and acute period after stroke and identify pathways critical for initiating neuroinflammation.

  View details for DOI 10.1002/glia.24377

  View details for PubMedID 37067534

• Translatome analysis reveals microglia and astrocytes to be distinct regulators of inflammation in the hyperacute and acute phases after stroke. bioRxiv : the preprint server for biology Hernandez, V. G., Lechtenberg, K. J., Peterson, T. C., Zhu, L., Lucas, T. A., Owah, J. O., Dorsey, A. I., Gentles, A. J., Buckwalter, M. S. 2023

  Abstract

  Neuroinflammation is a hallmark of ischemic stroke, which is a leading cause of death and long-term disability. Understanding the exact cellular signaling pathways that initiate and propagate neuroinflammation after stroke will be critical for developing immunomodulatory stroke therapies. In particular, the precise mechanisms of inflammatory signaling in the clinically relevant hyperacute period, hours after stroke, have not been elucidated. We used the RiboTag technique to obtain astrocyte and microglia-derived mRNA transcripts in a hyperacute (4 hours) and acute (3 days) period after stroke, as these two cell types are key modulators of acute neuroinflammation. Microglia initiated a rapid response to stroke at 4 hours by adopting an inflammatory profile associated with the recruitment of immune cells. The hyperacute astrocyte profile was marked by stress response genes and transcription factors, such as Fos and Jun , involved in pro-inflammatory pathways such as TNF-alpha. By 3 days, microglia shift to a proliferative state and astrocytes strengthen their inflammatory response. The astrocyte pro-inflammatory response at 3 days is partially driven by the upregulation of the transcription factors C/EBPbeta, Spi1 , and Rel , which comprise 25% of upregulated transcription factor-target interactions. Surprisingly, few sex differences across all groups were observed. Expression and log 2 fold data for all sequenced genes are available on a user-friendly website for researchers to examine gene changes and generate hypotheses for stroke targets. Taken together our data comprehensively describe the astrocyte and microglia-specific translatome response in the hyperacute and acute period after stroke and identify pathways critical for initiating neuroinflammation.

  View details for DOI 10.1101/2023.02.14.520351

  View details for PubMedID 36824949

• Blocking of microglia-astrocyte proinflammatory signaling is beneficial following stroke. Frontiers in molecular neuroscience Prescott, K., Münch, A. E., Brahms, E., Weigel, M. K., Inoue, K., Buckwalter, M. S., Liddelow, S. A., Peterson, T. C. 2023; 16: 1305949

  Abstract

  Microglia and astrocytes play an important role in the neuroinflammatory response and contribute to both the destruction of neighboring tissue as well as the resolution of inflammation following stroke. These reactive glial cells are highly heterogeneous at both the transcriptomic and functional level. Depending upon the stimulus, microglia and astrocytes mount a complex, and specific response composed of distinct microglial and astrocyte substates. These substates ultimately drive the landscape of the initiation and recovery from the adverse stimulus. In one state, inflammation- and damage-induced microglia release tumor necrosis factor (TNF), interleukin 1α (IL1α), and complement component 1q (C1q), together "TIC." This cocktail of cytokines drives astrocytes into a neurotoxic reactive astrocyte (nRA) substate. This nRA substate is associated with loss of many physiological astrocyte functions (e.g., synapse formation and maturation, phagocytosis, among others), as well as a gain-of-function release of neurotoxic long-chain fatty acids which kill neighboring cells. Here we report that transgenic removal of TIC led to reduction of gliosis, infarct expansion, and worsened functional deficits in the acute and delayed stages following stroke. Our results suggest that TIC cytokines, and likely nRAs play an important role that may maintain neuroinflammation and inhibit functional motor recovery after ischemic stroke. This is the first report that this paradigm is relevant in stroke and that therapies against nRAs may be a novel means to treat patients. Since nRAs are evolutionarily conserved from rodents to humans and present in multiple neurodegenerative diseases and injuries, further identification of mechanistic role of nRAs will lead to a better understanding of the neuroinflammatory response and the development of new therapies.

  View details for DOI 10.3389/fnmol.2023.1305949

  View details for PubMedID 38240014

  View details for PubMedCentralID PMC10794541

• The 2022 FASEB virtual Catalyst Conference on B Cells in Injury and Regeneration, March 30, 2022. FASEB journal : official publication of the Federation of American Societies for Experimental Biology Dwyer, L. J., Stowe, A. M., Doyle, K., Popovich, P., Engler-Chiurazzi, E., LeGuern, C., Buckwalter, M. S., Poznansky, M. C., Sirbulescu, R. F. 2022; 36 (8): e22459

  View details for DOI 10.1096/fj.202201027

  View details for PubMedID 35857314

• An RNA-sequencing transcriptome of the rodent Schwann cell response to peripheral nerve injury. Journal of neuroinflammation Brosius Lutz, A., Lucas, T. A., Carson, G. A., Caneda, C., Zhou, L., Barres, B. A., Buckwalter, M. S., Sloan, S. A. 2022; 19 (1): 105

  Abstract

  BACKGROUND: The important contribution of glia to mechanisms of injury and repair of the nervous system is increasingly recognized. In stark contrast to the central nervous system (CNS), the peripheral nervous system (PNS) has a remarkable capacity for regeneration after injury. Schwann cells are recognized as key contributors to PNS regeneration, but the molecular underpinnings of the Schwann cell response to injury and how they interact with the inflammatory response remain incompletely understood.METHODS: We completed bulk RNA-sequencing of Schwann cells purified acutely using immunopanning from the naive and injured rodent sciatic nerve at 3, 5, and 7days post-injury. We used qRT-PCR and in situ hybridization to assess cell purity and probe dataset integrity. Finally, we used bioinformatic analysis to probe Schwann cell-specific injury-induced modulation of cellular pathways.RESULTS: Our data confirm Schwann cell purity and validate RNAseq dataset integrity. Bioinformatic analysis identifies discrete modules of genes that follow distinct patterns of regulation in the 1st days after injury and their corresponding molecular pathways. These findings enable improved differentiation of myeloid and glial components of neuroinflammation after peripheral nerve injury and highlight novel molecular aspects of the Schwann cell injury response such as acute downregulation of the AGE/RAGE pathway and of secreted molecules Sparcl1 and Sema5a.CONCLUSIONS: We provide a helpful resource for further deciphering the Schwann cell injury response and a depth of transcriptional data that can complement the findings of recent single cell sequencing approaches. As more data become available on the response of CNS glia to injury, we anticipate that this dataset will provide a valuable platform for understanding key differences in the PNS and CNS glial responses to injury and for designing approaches to ameliorate CNS regeneration.

  View details for DOI 10.1186/s12974-022-02462-6

  View details for PubMedID 35501870

• Immune Pathways in Etiology, Acute Phase, and Chronic Sequelae of Ischemic Stroke. Circulation research Endres, M., Moro, M. A., Nolte, C. H., Dames, C., Buckwalter, M. S., Meisel, A. 2022; 130 (8): 1167-1186

  Abstract

  Inflammation and immune mechanisms are crucially involved in the pathophysiology of the development, acute damage cascades, and chronic course after ischemic stroke. Atherosclerosis is an inflammatory disease, and, in addition to classical risk factors, maladaptive immune mechanisms lead to an increased risk of stroke. Accordingly, individuals with signs of inflammation or corresponding biomarkers have an increased risk of stroke. Anti-inflammatory drugs, such as IL (interleukin)-1beta blockers, methotrexate, or colchicine, represent attractive treatment strategies to prevent vascular events and stroke. Lately, the COVID-19 pandemic shows a clear association between SARS-CoV2 infections and increased risk of cerebrovascular events. Furthermore, mechanisms of both innate and adaptive immune systems influence cerebral damage cascades after ischemic stroke. Neutrophils, monocytes, and microglia, as well as T and B lymphocytes each play complex interdependent roles that synergize to remove dead tissue but also can cause bystander injury to intact brain cells and generate maladaptive chronic inflammation. Chronic systemic inflammation and comorbid infections may unfavorably influence both outcome after stroke and recurrence risk for further stroke. In addition, stroke triggers specific immune depression, which in turn can promote infections. Recent research is now increasingly addressing the question of the extent to which immune mechanisms may influence long-term outcome after stroke and, in particular, cause specific complications such as poststroke dementia or even poststroke depression.

  View details for DOI 10.1161/CIRCRESAHA.121.319994

  View details for PubMedID 35420915

• Prognostication of ICU Patients by Providers with and without Neurocritical Care Training. Neurocritical care Finley Caulfield, A., Mlynash, M., Eyngorn, I., Lansberg, M. G., Afjei, A., Venkatasubramanian, C., Buckwalter, M. S., Hirsch, K. G. 2022

  Abstract

  BACKGROUND: Predictions of functional outcome in neurocritical care (NCC) patients impact care decisions. This study compared the predictive values (PVs) of good and poor functional outcome among health care providers with and without NCC training.METHODS: Consecutive patients who were intubated for≥72h with primary neurological illness or neurological complications were prospectively enrolled and followed for 6-month functional outcome. Medical intensive care unit (MICU) attendings, NCC attendings, residents (RES), and nurses (RN) predicted 6-month functional outcome on the modified Rankin scale (mRS). The primary objective was to compare these four groups' PVs of a good (mRS score 0-3) and a poor (mRS score 4-6) outcome prediction.RESULTS: Two hundred eighty-nine patients were enrolled. One hundred seventy-six had mRS scores predicted by a provider from each group and were included in the primary outcome analysis. At 6months, 54 (31%) patients had good outcome and 122 (69%) had poor outcome. Compared with other providers, NCC attendings expected better outcomes (p<0.001). Consequently, the PV of a poor outcome prediction by NCC attendings was higher (96%[95% confidence interval [CI] 89-99%]) than that by MICU attendings (88% [95% CI 80-93%]), RES (82% [95% CI 74-88%]), and RN (85% [95% CI 77-91%]) (p=0.047, 0.002, and 0.012, respectively). When patients who had withdrawal of life-sustaining therapy (n=67) were excluded, NCC attendings remained better at predicting poor outcome (NCC 90% [95% CI 75-97%] vs. MICU 73% [95% CI 59-84%], p=0.064). The PV of a good outcome prediction was similar among groups (MICU 65% [95% CI 52-76%], NCC 63% [95% CI 51-73%], RES 71% [95% CI 55-84%], and RN 64% [95% CI 50-76%]).CONCLUSIONS: Neurointensivists expected better outcomes than other providers and were better at predicting poor functional outcomes. The PV of a good outcome prediction was modest among all providers.

  View details for DOI 10.1007/s12028-022-01467-6

  View details for PubMedID 35314970

• Self-report Does Not Align With Objective Assessments Of Memory And Fine Motor Functioning In Stroke Survivors Mendez, M. P., Drag, L. L., Mlynash, M., Musabbir, M., Kim, D. K., Lansberg, M. G., Buckwalter, M. S. LIPPINCOTT WILLIAMS & WILKINS. 2022

  View details for DOI 10.1161/str.53.suppl_1.TP15

  View details for Web of Science ID 000788100600303

• Depression And Not Cognitive Ability Is Most Strongly Associated With Long-term Functional Outcomes Following Stroke. Drag, L. L., Musabbir, M., Mlynash, M., Mendez, M. P., Kim, D. K., Aghaeepour, N., Lansberg, M. G., Buckwalter, M. S. LIPPINCOTT WILLIAMS & WILKINS. 2022

  View details for DOI 10.1161/str.53.suppl_1.TP9

  View details for Web of Science ID 000788100600297

• Higher White Blood Cell Count In The First Week After Stroke Predicts Worse Cognitive Outcomes In A Population With Smaller Ischemic Strokes Musabbir, M., Kim, D., Drag, L., Mlynash, M., Mendez, M., Lansberg, M. G., Smith, C. J., Buckwalter, M. S. LIPPINCOTT WILLIAMS & WILKINS. 2022

  View details for DOI 10.1161/str.53.suppl_1.TP59

  View details for Web of Science ID 000788100600345

• Targeting VCAM1 to reduce neuroinflammation in ischemia-triggered vascular dementia. Alzheimer's & dementia : the journal of the Alzheimer's Association Zera, K. A., Peterson, T., Yousef, H., Lee, D., Wyss-Coray, T., Buckwalter, M. S. 1800; 17 Suppl 3: e053849

  Abstract

  BACKGROUND: Ischemia is a well-established contributor to vascular dementia. Indeed, the most common pathology in people with dementia is mixed, and over half of patients diagnosed with AD have demonstrable vascular pathologies. Ischemia induces an immune response which triggers secondary neurodegeneration remote to the initial lesion, and consequent cognitive decline. Ischemia-triggered vascular dementia is dependent on B-lymphocytes driving chronic neuroinflammation in adult mice. However, vascular dementia is most common in the aged, and there are key differences in inflammatory responses with age. Vascular cell adhesion molecule 1 (VCAM1) is an endothelial protein that facilitates vascular-immune crosstalk via interaction with very late antigen-4 (VLA-4). Soluble VCAM1 is elevated in stroke, vascular dementia, and normal aging in both people and mice. In aging mice, anti-VCAM1 ameliorates age-induced neuroinflammation and cognitive impairment. Although the mechanism is unclear, this is likely mediated via changes in endothelial cell activation and secretion of pro-inflammatory mediators. Therefore, we hypothesized that acute anti-VCAM1 treatment would reduce microgliosis and astrogliosis, while delayed treatment would reduce B and T lymphocyte infiltration in a mouse model of ischemia-triggered vascular dementia.METHOD: Adult (3-month-old) or aged (10-month-old) C57BL/6J mice (n=10-15/group) underwent permanent distal middle cerebral artery occlusion. Mice were dosed with anti-VCAM1 antibody either 4 hours or 4 days post-ischemia, and then sacrificed at 72 hours, 3 weeks or 6 weeks post-ischemia. Microgliosis and astrogliosis were quantified as percent area immunostained in the lesion border by CD68 and GFAP, respectively. B and T cell infiltration were quantified as percent lesion immunostained by B220, and CD3+ cells in the ischemic lesion, respectively.RESULT: Acute treatment reduced microgliosis 30% (p=0.0476) and astrogliosis 39% (p<0.03). In adults, delayed anti-VCAM1 significantly reduced B and T cell infiltration approximately 25% (p=0.0015) and 50% (p=0.0192), respectively. Similarly, in aged mice, delayed anti-VCAM1 significantly reduced B and T cell infiltration approximately 50% (p=0.0037) and 30% (p=0.0036), respectively. In contrast, early anti-VCAM1 had little or no effect on B or T cell infiltration.CONCLUSION: Together, these findings establish VCAM1 as a possible therapeutic target to ameliorate ischemia-induced neuroinflammation and consequent cognitive decline in a mouse model of vascular dementia.

  View details for DOI 10.1002/alz.053849

  View details for PubMedID 35108898

• Brain profiling in murine colitis and human epilepsy reveals neutrophils and TNFalpha as mediators of neuronal hyperexcitability. Journal of neuroinflammation Barnes, S. E., Zera, K. A., Ivison, G. T., Buckwalter, M. S., Engleman, E. G. 2021; 18 (1): 199

  Abstract

  BACKGROUND: Patients with chronic inflammatory disorders such as inflammatory bowel disease frequently experience neurological complications including epilepsy, depression, attention deficit disorders, migraines, and dementia. However, the mechanistic basis for these associations is unknown. Given that many patients are unresponsive to existing medications or experience debilitating side effects, novel therapeutics that target the underlying pathophysiology of these conditions are urgently needed.METHODS: Because intestinal disorders such as inflammatory bowel disease are robustly associated with neurological symptoms, we used three different mouse models of colitis to investigate the impact of peripheral inflammatory disease on the brain. We assessed neuronal hyperexcitability, which is associated with many neurological symptoms, by measuring seizure threshold in healthy and colitic mice. We profiled the neuroinflammatory phenotype of colitic mice and used depletion and neutralization assays to identify the specific mediators responsible for colitis-induced neuronal hyperexcitability. To determine whether our findings in murine models overlapped with a human phenotype, we performed gene expression profiling, pathway analysis, and deconvolution on microarray data from hyperexcitable human brain tissue from patients with epilepsy.RESULTS: We observed that murine colitis induces neuroinflammation characterized by increased pro-inflammatory cytokine production, decreased tight junction protein expression, and infiltration of monocytes and neutrophils into the brain. We also observed sustained neuronal hyperexcitability in colitic mice. Colitis-induced neuronal hyperexcitability was ameliorated by neutrophil depletion or TNFalpha blockade. Gene expression profiling of hyperexcitable brain tissue resected from patients with epilepsy also revealed a remarkably similar pathology to that seen in the brains of colitic mice, including neutrophil infiltration and high TNFalpha expression.CONCLUSIONS: Our results reveal neutrophils and TNFalpha as central regulators of neuronal hyperexcitability of diverse etiology. Thus, there is a strong rationale for evaluating anti-inflammatory agents, including clinically approved TNFalpha inhibitors, for the treatment of neurological and psychiatric symptoms present in, and potentially independent of, a diagnosed inflammatory disorder.

  View details for DOI 10.1186/s12974-021-02262-4

  View details for PubMedID 34511110

• T cells direct microglial repair of white matter after stroke. Trends in neurosciences Zera, K. A., Buckwalter, M. S. 2021

  Abstract

  A recent paper by Shi et al. defines the role of regulatory T cells (Tregs) in white matter recovery after ischemic stroke. This study elucidates the mechanisms by which Tregs direct microglia to alter their phenotype to support oligodendrogenesis, thereby improving white matter integrity and functional recovery after stroke in mice.

  View details for DOI 10.1016/j.tins.2021.07.005

  View details for PubMedID 34332802

• Spleen glia are a transcriptionally unique glial subtype interposed between immune cells and sympathetic axons. Glia Lucas, T. A., Zhu, L., Buckwalter, M. S. 2021

  Abstract

  Glia are known to play important roles in the brain, the gut, and around the sciatic nerve. While the gut has its own specialized nervous system, other viscera are innervated solely by autonomic nerves. The functions of glia that accompany autonomic innervation are not well known, even though they are one of the most abundant cell types in the peripheral nervous system. Here, we focused on non-myelinating Schwann cells in the spleen, spleen glia. The spleen is a major immune organ innervated by the sympathetic nervous system, which modulates immune function. This interaction is known as neuroimmune communication. We establish that spleen glia can be visualized using both immunohistochemistry for S100B and GFAP and with a reporter mouse. Spleen glia ensheath sympathetic axons and are localized to the lymphocyte-rich white pulp areas of the spleen. We sequenced the spleen glia transcriptome and identified genes that are likely involved in axonal ensheathment and communication with both nerves and immune cells. Spleen glia express receptors for neurotransmitters made by sympathetic axons (adrenergic, purinergic, and Neuropeptide Y), and also cytokines, chemokines, and their receptors that may communicate with immune cells in the spleen. We also established similarities and differences between spleen glia and other glial types. While all glia share many genes in common, spleen glia differentially express genes associated with immune responses, including genes involved in cytokine-cytokine receptor interactions, phagocytosis, and the complement cascade. Thus, spleen glia are a unique glial type, physically and transcriptionally poised to participate in neuroimmune communication in the spleen.

  View details for DOI 10.1002/glia.23993

  View details for PubMedID 33710690

• Mapping causal circuit dynamics in stroke using simultaneous electroencephalography and transcranial magnetic stimulation. BMC neurology Rolle, C. E., Baumer, F. M., Jordan, J. T., Berry, K., Garcia, M., Monusko, K., Trivedi, H., Wu, W., Toll, R., Buckwalter, M. S., Lansberg, M., Etkin, A. 2021; 21 (1): 280

  Abstract

  Motor impairment after stroke is due not only to direct tissue loss but also to disrupted connectivity within the motor network. Mixed results from studies attempting to enhance motor recovery with Transcranial Magnetic Stimulation (TMS) highlight the need for a better understanding of both connectivity after stroke and the impact of TMS on this connectivity. This study used TMS-EEG to map the causal information flow in the motor network of healthy adult subjects and define how stroke alters these circuits.Fourteen stroke patients and 12 controls received TMS to two sites (bilateral primary motor cortices) during two motor tasks (paretic/dominant hand movement vs. rest) while EEG measured the cortical response to TMS pulses. TMS-EEG based connectivity measurements were derived for each hemisphere and the change in connectivity (ΔC) between the two motor tasks was calculated. We analyzed if ΔC for each hemisphere differed between the stroke and control groups or across TMS sites, and whether ΔC correlated with arm function in stroke patients.Right hand movement increased connectivity in the left compared to the right hemisphere in controls, while hand movement did not significantly change connectivity in either hemisphere in stroke. Stroke patients with the largest increase in healthy hemisphere connectivity during paretic hand movement had the best arm function.TMS-EEG measurements are sensitive to movement-induced changes in brain connectivity. These measurements may characterize clinically meaningful changes in circuit dynamics after stroke, thus providing specific targets for trials of TMS in post-stroke rehabilitation.

  View details for DOI 10.1186/s12883-021-02319-0

  View details for PubMedID 34271872

• B and T Lymphocyte Densities Remain Stable With Age in Human Cortex. ASN neuro Berry, K., Farias-Itao, D. S., Grinberg, L. T., Plowey, E. D., Schneider, J. A., Rodriguez, R. D., Suemoto, C. K., Buckwalter, M. S. 2021; 13: 17590914211018117

  Abstract

  One hallmark of human aging is increased brain inflammation represented by glial activation. With age, there is also diminished function of the adaptive immune system, and modest decreases in circulating B- and T-lymphocytes. Lymphocytes traffic through the human brain and reside there in small numbers, but it is unknown how this changes with age. Thus we investigated whether B- and T-lymphocyte numbers change with age in the normal human brain. We examined 16 human subjects in a pilot study and then 40 human subjects from a single brain bank, ranging in age from 44-96years old, using rigorous criteria for defining neuropathological changes due to age alone. We immunostained post-mortem cortical tissue for B- and T-lymphocytes using antibodies to CD20 and CD3, respectively. We quantified cell density and made a qualitative assessment of cell location in cortical brain sections, and reviewed prior studies. We report that density and location of both B- and T-lymphocytes do not change with age in the normal human cortex. Solitary B-lymphocytes were found equally in intravascular, perivascular, and parenchymal locations, while T-lymphocytes appeared primarily in perivascular clusters. Thus, any change in number or location of lymphocytes in an aging brain may indicate disease rather than normal aging.

  View details for DOI 10.1177/17590914211018117

  View details for PubMedID 34056948

• Home-based Virtual Reality Therapy for Hand Recovery After Stroke. PM & R : the journal of injury, function, and rehabilitation Lansberg, M. G., Legault, C. n., MacLellan, A. n., Parikh, A. n., Muccini, J. n., Mlynash, M. n., Kemp, S. n., Buckwalter, M. S., Flavin, K. n. 2021

  Abstract

  Many stroke survivors suffer from arm and hand weakness, but there are only limited efficacious options for arm therapy available.To assess the feasibility of unsupervised home-based use of a virtual reality device (Smart Glove) for hand rehabilitation post stroke.Prospective single-arm study consisting of a 2-week run-in phase with no device use followed by an 8-week intervention period.Participants were recruited at the Stanford Neuroscience Outpatient Clinic.Twenty chronic stroke patients with upper extremity impairment.Participants were instructed to use the Smart Glove 50 minutes per day, 5 days per week for 8 weeks.We measured (1) compliance, (2) patients' impression of the intervention, and (3) efficacy measures including the upper extremity Fugl-Meyer (UE-FM), the Jebsen-Taylor hand function test (JTHFT) and the Stroke Impact Scale (SIS).Of 20 subjects, 7 (35%) met target compliance of 40 days use, and 6 (30%) used the device for 20-39 days. Eighty-five percent of subjects were satisfied with the therapy, with 80% reporting improvement in hand function. During the run-in phase there were no improvements in hand function. During the intervention, patients improved by a mean of 26.6 ± 48.8 seconds on the JTHFT (P = 0.03), by 16.1 ± 15.3 points on the hand-domain of the SIS (P < 0.01) and there was a trend towards improvement on the UE-FM (2.2 ± 5.5 points, P = 0.10).Unsupervised use of the Smart Glove in the home environment may improve hand/arm function in subacute/chronic stroke patients. A randomized controlled trial is needed to confirm these results. This article is protected by copyright. All rights reserved.

  View details for DOI 10.1002/pmrj.12598

  View details for PubMedID 33773059

• New Mechanistic Insights, Novel Treatment Paradigms, and Clinical Progress in Cerebrovascular Diseases. Frontiers in aging neuroscience Boltze, J., Aronowski, J. A., Badaut, J., Buckwalter, M. S., Caleo, M., Chopp, M., Dave, K. R., Didwischus, N., Dijkhuizen, R. M., Doeppner, T. R., Dreier, J. P., Fouad, K., Gelderblom, M., Gertz, K., Golubczyk, D., Gregson, B. A., Hamel, E., Hanley, D. F., Hartig, W., Hummel, F. C., Ikhsan, M., Janowski, M., Jolkkonen, J., Karuppagounder, S. S., Keep, R. F., Koerte, I. K., Kokaia, Z., Li, P., Liu, F., Lizasoain, I., Ludewig, P., Metz, G. A., Montagne, A., Obenaus, A., Palumbo, A., Pearl, M., Perez-Pinzon, M., Planas, A. M., Plesnila, N., Raval, A. P., Rueger, M. A., Sansing, L. H., Sohrabji, F., Stagg, C. J., Stetler, R. A., Stowe, A. M., Sun, D., Taguchi, A., Tanter, M., Vay, S. U., Vemuganti, R., Vivien, D., Walczak, P., Wang, J., Xiong, Y., Zille, M. 2021; 13: 623751

  Abstract

  The past decade has brought tremendous progress in diagnostic and therapeutic options for cerebrovascular diseases as exemplified by the advent of thrombectomy in ischemic stroke, benefitting a steeply increasing number of stroke patients and potentially paving the way for a renaissance of neuroprotectants. Progress in basic science has been equally impressive. Based on a deeper understanding of pathomechanisms underlying cerebrovascular diseases, new therapeutic targets have been identified and novel treatment strategies such as pre- and post-conditioning methods were developed. Moreover, translationally relevant aspects are increasingly recognized in basic science studies, which is believed to increase their predictive value and the relevance of obtained findings for clinical application.This review reports key results from some of the most remarkable and encouraging achievements in neurovascular research that have been reported at the 10th International Symposium on Neuroprotection and Neurorepair. Basic science topics discussed herein focus on aspects such as neuroinflammation, extracellular vesicles, and the role of sex and age on stroke recovery. Translational reports highlighted endovascular techniques and targeted delivery methods, neurorehabilitation, advanced functional testing approaches for experimental studies, pre-and post-conditioning approaches as well as novel imaging and treatment strategies. Beyond ischemic stroke, particular emphasis was given on activities in the fields of traumatic brain injury and cerebral hemorrhage in which promising preclinical and clinical results have been reported. Although the number of neutral outcomes in clinical trials is still remarkably high when targeting cerebrovascular diseases, we begin to evidence stepwise but continuous progress towards novel treatment options. Advances in preclinical and translational research as reported herein are believed to have formed a solid foundation for this progress.

  View details for DOI 10.3389/fnagi.2021.623751

  View details for PubMedID 33584250

• Immune responses to stroke: mechanisms, modulation, and therapeutic potential. The Journal of clinical investigation Iadecola, C., Buckwalter, M. S., Anrather, J. 2020

  Abstract

  Stroke is the second leading cause of death worldwide and a leading cause of disability. Most strokes are caused by occlusion of a major cerebral artery, and substantial advances have been made in elucidating how ischemia damages the brain. In particular, increasing evidence points to a double-edged role of the immune system in stroke pathophysiology. In the acute phase, innate immune cells invade brain and meninges and contribute to ischemic damage, but may also be protective. At the same time, danger signals released into the circulation by damaged brain cells lead to activation of systemic immunity, followed by profound immunodepression that promotes life-threatening infections. In the chronic phase, antigen presentation initiates an adaptive immune response targeted to the brain, which may underlie neuropsychiatric sequelae, a considerable cause of poststroke morbidity. Here, we briefly review these pathogenic processes and assess the potential therapeutic value of targeting immunity in human stroke.

  View details for DOI 10.1172/JCI135530

  View details for PubMedID 32391806

• Home-Based Virtual Reality Therapy for Hand Recovery After Stroke MacLellan, A., Legault, C., Parikh, A., Lugo, L., Kemp, S., Mlynash, M., Buckwalter, M., Flavin, K., Lansberg, M. LIPPINCOTT WILLIAMS & WILKINS. 2020

  View details for Web of Science ID 000590040201420

• Development of a Comprehensive Neuropsychological Battery to Assess Post-Stroke Cognitive Functioning Drag, L., Aghaeepour, N., Mlynash, M., Osborn, E., Rah, E., Buckwalter, M., Lansberg, M. LIPPINCOTT WILLIAMS & WILKINS. 2020

  View details for Web of Science ID 000590040201406

• Obesity Drives Delayed Infarct Expansion, Inflammation, and Distinct Gene Networks in a Mouse Stroke Model. Translational stroke research Peterson, T. C., Lechtenberg, K. J., Piening, B. D., Lucas, T. A., Wei, E. n., Chaib, H. n., Dowdell, A. K., Snyder, M. n., Buckwalter, M. S. 2020

  Abstract

  Obesity is associated with chronic peripheral inflammation, is a risk factor for stroke, and causes increased infarct sizes. To characterize how obesity increases infarct size, we fed a high-fat diet to wild-type C57BL/6J mice for either 6 weeks or 15 weeks and then induced distal middle cerebral artery strokes. We found that infarct expansion happened late after stroke. There were no differences in cortical neuroinflammation (astrogliosis, microgliosis, or pro-inflammatory cytokines) either prior to or 10 h after stroke, and also no differences in stroke size at 10 h. However, by 3 days after stroke, animals fed a high-fat diet had a dramatic increase in microgliosis and astrogliosis that was associated with larger strokes and worsened functional recovery. RNA sequencing revealed a dramatic increase in inflammatory genes in the high-fat diet-fed animals 3 days after stroke that were not present prior to stroke. Genetic pathways unique to diet-induced obesity were primarily related to adaptive immunity, extracellular matrix components, cell migration, and vasculogenesis. The late appearance of neuroinflammation and infarct expansion indicates that there may be a therapeutic window between 10 and 36 h after stroke where inflammation and obesity-specific transcriptional programs could be targeted to improve outcomes in people with obesity and stroke.

  View details for DOI 10.1007/s12975-020-00826-9

  View details for PubMedID 32588199

• A longitudinal study of the post-stroke immune response and cognitive functioning: the StrokeCog study protocol. BMC neurology Drag, L. L., Mlynash, M. n., Nassar, H. n., Osborn, E. n., Kim, D. E., Angst, M. S., Aghaeepour, N. n., Buckwalter, M. n., Lansberg, M. G. 2020; 20 (1): 313

  Abstract

  Stroke increases the risk of cognitive impairment even several years after the stroke event. The exact mechanisms of post-stroke cognitive decline are unclear, but the immunological response to stroke might play a role. The aims of the StrokeCog study are to examine the associations between immunological responses and long-term post-stroke cognitive trajectories in individuals with ischemic stroke.StrokeCog is a single-center, prospective, observational, cohort study. Starting 6-12 months after stroke, comprehensive neuropsychological assessment, plasma and serum, and psychosocial variables will be collected at up to 4 annual visits. Single cell sequencing of peripheral blood monocytes and plasma proteomics will be conducted. The primary outcome will be the change in global and domain-specific neuropsychological performance across annual evaluations. To explain the differences in cognitive change amongst participants, we will examine the relationships between comprehensive immunological measures and these cognitive trajectories. It is anticipated that 210 participants will be enrolled during the first 3 years of this 4-year study. Accounting for attrition, an anticipated final sample size of 158 participants with an average of 3 annual study visits will be available at the completion of the study. Power analyses indicate that this sample size will provide 90% power to detect an average cognitive change of at least 0.23 standard deviations in either direction.StrokeCog will provide novel insight into the relationships between immune events and cognitive change late after stroke.

  View details for DOI 10.1186/s12883-020-01897-9

  View details for PubMedID 32847540

• Development of a CD19 PET tracer for detecting B cells in a mouse model of multiple sclerosis. Journal of neuroinflammation Stevens, M. Y., Cropper, H. C., Lucot, K. L., Chaney, A. M., Lechtenberg, K. J., Jackson, I. M., Buckwalter, M. S., James, M. L. 2020; 17 (1): 275

  Abstract

  B cells play a central role in multiple sclerosis (MS) through production of injurious antibodies, secretion of pro-inflammatory cytokines, and antigen presentation. The therapeutic success of monoclonal antibodies (mAbs) targeting B cells in some but not all individuals suffering from MS highlights the need for a method to stratify patients and monitor response to treatments in real-time. Herein, we describe the development of the first CD19 positron emission tomography (PET) tracer, and its evaluation in a rodent model of MS, experimental autoimmune encephalomyelitis (EAE).Female C57BL/6 J mice were induced with EAE through immunization with myelin oligodendrocyte glycoprotein (MOG1-125). PET imaging of naïve and EAE mice was performed 19 h after administration of [64Cu]CD19-mAb. Thereafter, radioactivity in organs of interest was determined by gamma counting, followed by ex vivo autoradiography of central nervous system (CNS) tissues. Anti-CD45R (B220) immunostaining of brain tissue from EAE and naïve mice was also conducted.Radiolabelling of DOTA-conjugated CD19-mAb with 64Cu was achieved with a radiochemical purity of 99% and molar activity of 2 GBq/μmol. Quantitation of CD19 PET images revealed significantly higher tracer binding in whole brain of EAE compared to naïve mice (2.02 ± 0.092 vs. 1.68 ± 0.06 percentage of injected dose per gram, % ID/g, p = 0.0173). PET findings were confirmed by ex vivo gamma counting of perfused brain tissue (0.22 ± 0.020 vs. 0.12 ± 0.003 % ID/g, p = 0.0010). Moreover, ex vivo autoradiography of brain sections corresponded with PET imaging results and the spatial distribution of B cells observed in B220 immunohistochemistry-providing further evidence that [64Cu]CD19-mAb enables visualization of B cell infiltration into the CNS of EAE mice.CD19-PET imaging can be used to detect elevated levels of B cells in the CNS of EAE mice, and has the potential to impact the way we study, monitor, and treat clinical MS.

  View details for DOI 10.1186/s12974-020-01880-8

  View details for PubMedID 32948198

• Infection as a Stroke Risk Factor and Determinant of Outcome After Stroke. Stroke Elkind, M. S., Boehme, A. K., Smith, C. J., Meisel, A. n., Buckwalter, M. S. 2020: STROKEAHA120030429

  Abstract

  Understanding the relationship between infection and stroke has taken on new urgency in the era of the coronavirus disease 2019 (COVID-19) pandemic. This association is not a new concept, as several infections have long been recognized to contribute to stroke risk. The association of infection and stroke is also bidirectional. Although infection can lead to stroke, stroke also induces immune suppression which increases risk of infection. Apart from their short-term effects, emerging evidence suggests that poststroke immune changes may also adversely affect long-term cognitive outcomes in patients with stroke, increasing the risk of poststroke neurodegeneration and dementia. Infections at the time of stroke may also increase immune dysregulation after the stroke, further exacerbating the risk of cognitive decline. This review will cover the role of acute infections, including respiratory infections such as COVID-19, as a trigger for stroke; the role of infectious burden, or the cumulative number of infections throughout life, as a contributor to long-term risk of atherosclerotic disease and stroke; immune dysregulation after stroke and its effect on the risk of stroke-associated infection; and the impact of infection at the time of a stroke on the immune reaction to brain injury and subsequent long-term cognitive and functional outcomes. Finally, we will present a model to conceptualize the many relationships among chronic and acute infections and their short- and long-term neurological consequences. This model will suggest several directions for future research.

  View details for DOI 10.1161/STROKEAHA.120.030429

  View details for PubMedID 32897811

• The Local and Peripheral Immune Responses to Stroke: Implications for Therapeutic Development. Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics Zera, K. A., Buckwalter, M. S. 2020

  Abstract

  The immune response to stroke is an exciting target for future stroke therapies. Stroke is a leading cause of morbidity and mortality worldwide, and clot removal (mechanical or pharmacological) to achieve tissue reperfusion is the only therapy currently approved for patient use. Due to a short therapeutic window and incomplete effectiveness, however, many patients are left with infarcted tissue that stimulates inflammation. Although this is critical to promote repair, it can also damage surrounding healthy brain tissue. In addition, acute immunodepression and subsequent infections are common and are associated with worse patient outcomes. Thus, the acute immune response is a major focus of researchers attempting to identify ways to amplify its benefits and suppress its negative effects to improve short-term recovery of patients. Here we review what is known about this powerful process. This includes the role of brain resident cells such as microglia, peripherally activated cells such as macrophages and neutrophils, and activated endothelium. The role of systemic immune activation and subsequent immunodepression in the days after stroke is also discussed, as is the chronic immune responses and its effects on cognitive function. The biphasic role of inflammation, as well as complex timelines of cell production, differentiation, and trafficking, suggests that the relationship between the acute and chronic phases of stroke recovery is complex. Gaining a more complete understanding of this intricate process by which inflammation is initiated, propagated, and terminated may potentially lead to therapeutics that can treat a larger population of stroke patients than what is currently available. The immune response plays a critical role in patient recovery in both the acute and chronic phases after stroke. In patients, the immune response can be beneficial by promoting repair and recovery, and also detrimental by propagating a pro-inflammatory microenvironment. Thus, it is critical to understand the mechanisms of immune activation following stroke in order to successfully design therapeutics.

  View details for DOI 10.1007/s13311-020-00844-3

  View details for PubMedID 32193840

• Immunological mechanisms in poststroke dementia. Current opinion in neurology Doyle, K. P., Buckwalter, M. S. 2019

  Abstract

  PURPOSE OF REVIEW: To review new evidence on links between poststroke dementia and inflammation.RECENT FINDINGS: Although there are still no treatments for poststroke dementia, recent evidence has improved our understanding that stroke increases the risk of incident dementia and worsens cognitive trajectory for at least a decade afterwards. Within approximately the first year dementia onset is associated with stroke severity and location, whereas later absolute risk is associated with more traditional dementia risk factors, such as age and imaging findings. The molecular mechanisms that underlie increased risk of incident dementia in stroke survivors remain unproven; however new data in both human and animal studies suggests links between cognitive decline and inflammation. These point to a model where chronic brain inflammation, provoked by inefficient clearance of myelin debris and a prolonged innate and adaptive immune response, causes poststroke dementia. These localized immune events in the brain may themselves be influenced by the peripheral immune state at key times after stroke.SUMMARY: This review recaps clinical evidence on poststroke dementia, new mechanistic links between the chronic inflammatory response to stroke and poststroke dementia, and proposes a model of immune-mediated neurodegeneration after stroke.

  View details for DOI 10.1097/WCO.0000000000000783

  View details for PubMedID 31789707

• A YEAR-LONG IMMUNE PROFILE OF THE SYSTEMIC RESPONSE IN ACUTE STROKE SURVIVORS Tsai, A., Berry, K., Beneyto, M. M., Gaudilliere, D., Ganio, E. A., Culos, A., Ghaemi, M. S., Choisy, B., Djebali, K., Einhaus, J. F., Bertrand, B., Tanada, A., Stanley, N., Fallahzadeh, R., Baca, Q., Quach, L. N., Osborn, E., Drag, L., Lansberg, M., Angst, M., Gaudilliere, B., Buckwalter, M. S., Aghaeepour, N. LIPPINCOTT WILLIAMS & WILKINS. 2019: 155

  View details for Web of Science ID 000480793600335

• Aged blood impairs hippocampal neural precursor activity and activates microglia via brain endothelial cell VCAM1 NATURE MEDICINE Yousef, H., Czupalla, C. J., Lee, D., Chen, M. B., Burke, A. N., Zera, K. A., Zandstra, J., Berber, E., Lehallier, B., Mathur, V., Nair, R. V., Bonanno, L. N., Yang, A. C., Peterson, T., Hadeiba, H., Merkel, T., Koerbelin, J., Schwaninger, M., Buckwalter, M. S., Quake, S. R., Butcher, E. C., Wyss-Coray, T. 2019; 25 (6): 988-+

  View details for DOI 10.1038/s41591-019-0440-4

  View details for Web of Science ID 000470844400031

• Augmented beta2-adrenergic signaling dampens the neuroinflammatory response following ischemic stroke and increases stroke size. Journal of neuroinflammation Lechtenberg, K. J., Meyer, S. T., Doyle, J. B., Peterson, T. C., Buckwalter, M. S. 2019; 16 (1): 112

  Abstract

  BACKGROUND: Ischemic stroke provokes a neuroinflammatory response and simultaneously promotes release of epinephrine and norepinephrine by the sympathetic nervous system. This increased sympathetic outflow can act on beta2-adrenergic receptors expressed by immune cells such as brain-resident microglia and monocyte-derived macrophages (MDMs), but the effect on post-stroke neuroinflammation is unknown. Thus, we investigated how changes in beta2-adrenergic signaling after stroke onset influence the microglia/MDM stroke response, and the specific importance of microglia/MDM beta2-adrenergic receptors to post-stroke neuroinflammation.METHODS: To investigate the effects of beta2-adrenergic receptor manipulation on post-stroke neuroinflammation, we administered the beta2-adrenergic receptor agonist clenbuterol to mice 3h after the onset of photothrombotic stroke. We immunostained to quantify microglia/MDM numbers and proliferation and to assess morphology and activation 3days later. We assessed stroke outcomes by measuring infarct volume and functional motor recovery and analyzed gene expression levels of neuroinflammatory molecules. Finally, we evaluated changes in cytokine expression and microglia/MDM response in brains of mice with selective knockout of the beta2-adrenergic receptor from microglia and monocyte-lineage cells.RESULTS: We report that clenbuterol treatment after stroke onset causes enlarged microglia/MDMs and impairs their proliferation, resulting in reduced numbers of these cells in the peri-infarct cortex by 1.7-fold at 3days after stroke. These changes in microglia/MDMs were associated with increased infarct volume in clenbuterol-treated animals. In mice that had the beta2-adrenergic receptor specifically knocked out of microglia/MDMs, there was no change in morphology or numbers of these cells after stroke. However, knockdown of beta2-adrenergic receptors in microglia and MDMs resulted in increased expression of TNFalpha and IL-10 in peri-infarct tissue, while stimulation of beta2-adrenergic receptors with clenbuterol had the opposite effect, suppressing TNFalpha and IL-10 expression.CONCLUSIONS: We identified beta2-adrenergic receptor signaling as an important regulator of the neuroimmune response after ischemic stroke. Increased beta2-adrenergic signaling after stroke onset generally suppressed the microglia/MDM response, reducing upregulation of both pro- and anti-inflammatory cytokines, and increasing stroke size. In contrast, diminished beta2-adrenergic signaling in microglia/MDMs augmented both pro- and anti-inflammatory cytokine expression after stroke. The beta2-adrenergic receptor may therefore present a therapeutic target for improving the post-stroke neuroinflammatory and repair process.

  View details for DOI 10.1186/s12974-019-1506-4

  View details for PubMedID 31138227

• Radiolabeling and pre-clinical evaluation of a first-in-class CD19 PET Tracer for imaging B cells in multiple sclerosis Stevens, M., Cropper, H., Jackson, I., Chaney, A., Lechtenberg, K., Buckwalter, M., James, M. L. SOC NUCLEAR MEDICINE INC. 2019

  View details for Web of Science ID 000473116800129

• A year-long immune profile of the systemic response in acute stroke survivors. Brain : a journal of neurology Tsai, A. S., Berry, K., Beneyto, M. M., Gaudilliere, D., Ganio, E. A., Culos, A., Ghaemi, M. S., Choisy, B., Djebali, K., Einhaus, J. F., Bertrand, B., Tanada, A., Stanley, N., Fallahzadeh, R., Baca, Q., Quach, L. N., Osborn, E., Drag, L., Lansberg, M. G., Angst, M. S., Gaudilliere, B., Buckwalter, M. S., Aghaeepour, N. 2019

  Abstract

  Stroke is a leading cause of cognitive impairment and dementia, but the mechanisms that underlie post-stroke cognitive decline are not well understood. Stroke produces profound local and systemic immune responses that engage all major innate and adaptive immune compartments. However, whether the systemic immune response to stroke contributes to long-term disability remains ill-defined. We used a single-cell mass cytometry approach to comprehensively and functionally characterize the systemic immune response to stroke in longitudinal blood samples from 24 patients over the course of 1 year and correlated the immune response with changes in cognitive functioning between 90 and 365 days post-stroke. Using elastic net regularized regression modelling, we identified key elements of a robust and prolonged systemic immune response to ischaemic stroke that occurs in three phases: an acute phase (Day 2) characterized by increased signal transducer and activator of transcription 3 (STAT3) signalling responses in innate immune cell types, an intermediate phase (Day 5) characterized by increased cAMP response element-binding protein (CREB) signalling responses in adaptive immune cell types, and a late phase (Day 90) by persistent elevation of neutrophils, and immunoglobulin M+ (IgM+) B cells. By Day 365 there was no detectable difference between these samples and those from an age- and gender-matched patient cohort without stroke. When regressed against the change in the Montreal Cognitive Assessment scores between Days 90 and 365 after stroke, the acute inflammatory phase Elastic Net model correlated with post-stroke cognitive trajectories (r = -0.692, Bonferroni-corrected P = 0.039). The results demonstrate the utility of a deep immune profiling approach with mass cytometry for the identification of clinically relevant immune correlates of long-term cognitive trajectories.

  View details for DOI 10.1093/brain/awz022

  View details for PubMedID 30860258

• Deep Immune Profiling of the Post-Stroke Peripheral Immune Response Reveals Tri-phasic Response and Correlations With Long-Term Cognitive Outcomes Tsai, A. S., Berry, K., Beneyto, M. M., Gaudilliere, D., Ganio, E. A., Choisy, B., Djebali, K., Baca, Q., Quach, L., Drag, L., Lansberg, M. G., Angst, M. S., Gaudilliere, B., Buckwalter, M. S., Aghaeepour, N. LIPPINCOTT WILLIAMS & WILKINS. 2019

  View details for Web of Science ID 000478733402484

• Feasibility and Utility of Home-Based Gait Analysis Using Body-Worn Sensors Huang, E., Sharp, M. T., Osborn, E., MacLellan, A., Mlynash, M., Kemp, S., Buckwalter, M. S., Lansberg, M. G. LIPPINCOTT WILLIAMS & WILKINS. 2019

  View details for Web of Science ID 000478733400393

• C-11-DPA-713 Versus F-18-GE-180: A Preclinical Comparison of Translocator Protein 18 kDa PET Tracers to Visualize Acute and Chronic Neuroinflammation in a Mouse Model of Ischemic Stroke JOURNAL OF NUCLEAR MEDICINE Chaney, A., Cropper, H. C., Johnson, E. M., Lechtenberg, K. J., Peterson, T. C., Stevens, M. Y., Buckwalter, M. S., James, M. L. 2019; 60 (1): 122–28

  View details for DOI 10.2967/jnumed.118.209155

  View details for Web of Science ID 000454687800024

• Aged blood impairs hippocampal neural precursor activity and activates microglia via brain endothelial cell VCAM1. Nature medicine Yousef, H. n., Czupalla, C. J., Lee, D. n., Chen, M. B., Burke, A. N., Zera, K. A., Zandstra, J. n., Berber, E. n., Lehallier, B. n., Mathur, V. n., Nair, R. V., Bonanno, L. N., Yang, A. C., Peterson, T. n., Hadeiba, H. n., Merkel, T. n., Körbelin, J. n., Schwaninger, M. n., Buckwalter, M. S., Quake, S. R., Butcher, E. C., Wyss-Coray, T. n. 2019

  Abstract

  An aged circulatory environment can activate microglia, reduce neural precursor cell activity and impair cognition in mice. We hypothesized that brain endothelial cells (BECs) mediate at least some of these effects. We observe that BECs in the aged mouse hippocampus express an inflammatory transcriptional profile with focal upregulation of vascular cell adhesion molecule 1 (VCAM1), a protein that facilitates vascular-immune cell interactions. Concomitantly, levels of the shed, soluble form of VCAM1 are prominently increased in the plasma of aged humans and mice, and their plasma is sufficient to increase VCAM1 expression in cultured BECs and the hippocampi of young mice. Systemic administration of anti-VCAM1 antibody or genetic ablation of Vcam1 in BECs counteracts the detrimental effects of plasma from aged individuals on young brains and reverses aging aspects, including microglial reactivity and cognitive deficits, in the brains of aged mice. Together, these findings establish brain endothelial VCAM1 at the blood-brain barrier as a possible target to treat age-related neurodegeneration.

  View details for PubMedID 31086348

• 11C-DPA-713 versus 18F-GE-180: A preclinical comparison of TSPO-PET tracers to visualize acute and chronic neuroinflammation in a mouse model of ischemic stroke. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Chaney, A. n., Cropper, H. C., Johnson, E. M., Lechtenberg, K. J., Peterson, T. C., Stevens, M. Y., Buckwalter, M. S., James, M. L. 2018

  Abstract

  Neuroinflammation plays a key role in neuronal injury following ischemic stroke. Positron emission tomography (PET) imaging of translocator protein 18 kDa (TSPO) permits longitudinal, non-invasive visualization of neuroinflammation in both pre-clinical and clinical settings. Many TSPO tracers have been developed, however it is unclear which tracer is the most sensitive and accurate for monitoring the in vivo spatiotemporal dynamics of neuroinflammation across applications. Hence, there is a need for head-to-head comparisons of promising TSPO-PET tracers across different disease states. Accordingly, the aim of this study was to directly compare two promising second-generation TSPO tracers; 11C-DPA-713 and 18F-GE-180, for the first time at acute and chronic time-points following ischemic stroke. Methods: Following distal middle cerebral artery occlusion (dMCAO) or sham surgery, mice underwent consecutive PET/CT imaging with 11C-DPA-713 and 18F-GE-180 at 2, 6, and 28 days after stroke. T2-weighted magnetic resonance (MR) images were acquired to enable delineation of ipsilateral (infarct) and contralateral brain regions of interest (ROIs). PET images were analyzed by calculating % injected dose per gram (%ID/g) in MR-guided ROIs. Standardized uptake value ratios were determined using the contralateral thalamus as a pseudo-reference region (SUVTh). Ex vivo autoradiography and immunohistochemistry were performed to verify in vivo findings. Results: Significantly increased tracer uptake was observed in the ipsilateral compared to contralateral ROI (SUVTh, 50-60 min summed data) at acute and chronic time-points using 11C-DPA-713 and 18F-GE-180. Ex vivo autoradiography confirmed in vivo findings demonstrating increased TSPO-tracer uptake in infarcted versus contralateral brain tissue. Importantly, a significant correlation was identified between microglial/macrophage activation (CD68 immunostaining) and 11C-DPA-713-PET signal, that was not evident with 18F-GE-180. No significant correlations were observed between TSPO-PET and activated astrocytes (GFAP immunostaining). Conclusion: Both 11C-DPA-713 and 18F-GE-180-PET enable detection of neuroinflammation at early and chronic time-points following cerebral ischemia in mice. 11C-DPA-713-PET reflects the extent of microglial activation in infarcted dMCAO mouse brain tissue more accurately compared to 18F-GE-180, and appears to be slightly more sensitive. These results highlight the potential of 11C-DPA-713 for tracking microglial activation in vivo after stroke, and warrants further investigation in both pre-clinical and clinical settings.

  View details for PubMedID 29976695

• Clopidogrel and Aspirin in Acute Ischemic Stroke and High-Risk TIA. The New England journal of medicine Johnston, S. C., Easton, J. D., Farrant, M. n., Barsan, W. n., Conwit, R. A., Elm, J. J., Kim, A. S., Lindblad, A. S., Palesch, Y. Y. 2018

  Abstract

  Background Combination antiplatelet therapy with clopidogrel and aspirin may reduce the rate of recurrent stroke during the first 3 months after a minor ischemic stroke or transient ischemic attack (TIA). A trial of combination antiplatelet therapy in a Chinese population has shown a reduction in the risk of recurrent stroke. We tested this combination in an international population. Methods In a randomized trial, we assigned patients with minor ischemic stroke or high-risk TIA to receive either clopidogrel at a loading dose of 600 mg on day 1, followed by 75 mg per day, plus aspirin (at a dose of 50 to 325 mg per day) or the same range of doses of aspirin alone. The dose of aspirin in each group was selected by the site investigator. The primary efficacy outcome in a time-to-event analysis was the risk of a composite of major ischemic events, which was defined as ischemic stroke, myocardial infarction, or death from an ischemic vascular event, at 90 days. Results A total of 4881 patients were enrolled at 269 international sites. The trial was halted after 84% of the anticipated number of patients had been enrolled because the data and safety monitoring board had determined that the combination of clopidogrel and aspirin was associated with both a lower risk of major ischemic events and a higher risk of major hemorrhage than aspirin alone at 90 days. Major ischemic events occurred in 121 of 2432 patients (5.0%) receiving clopidogrel plus aspirin and in 160 of 2449 patients (6.5%) receiving aspirin plus placebo (hazard ratio, 0.75; 95% confidence interval [CI], 0.59 to 0.95; P=0.02), with most events occurring during the first week after the initial event. Major hemorrhage occurred in 23 patients (0.9%) receiving clopidogrel plus aspirin and in 10 patients (0.4%) receiving aspirin plus placebo (hazard ratio, 2.32; 95% CI, 1.10 to 4.87; P=0.02). Conclusions In patients with minor ischemic stroke or high-risk TIA, those who received a combination of clopidogrel and aspirin had a lower risk of major ischemic events but a higher risk of major hemorrhage at 90 days than those who received aspirin alone. (Funded by the National Institute of Neurological Disorders and Stroke; POINT ClinicalTrials.gov number, NCT00991029 .).

  View details for PubMedID 29766750

• Depression one year after hemorrhagic stroke is associated with late worsening of outcomes. NeuroRehabilitation Stern-Nezer, S., Eyngorn, I., Mlynash, M., Snider, R. W., Venkatsubramanian, C., Wijman, C. A., Buckwalter, M. S. 2017

  Abstract

  Poststroke depression is the most common psychiatric sequelae of stroke, and it's independently associated with increased morbidity and mortality. Few studies have examined depression after intracranial hemorrhage (ICH).To investigate the relationship between depression, ICH and outcomes.A substudy of the prospective Diagnostic Accuracy of MRI in Spontaneous Intracerebral Hemorrhage (DASH) study, we included 89 subjects assessed for depression 1 year after hemorrhage. A Hamilton Depression Rating Scale score >10 defined depression. Univariate, multivariable, and trend analyses evaluated relationships between depression, clinical, radiographic, and inflammatory factors and modified Rankin score (mRS) at 90 days and one year.Prevalence of depression at one year was 15%. Depression was not associated with hematoma volumes, presence of IVH or admission NIHSS, nor with demographic factors. Despite this, depressed patients had worse 1-year outcomes (p = 0.004) and were less likely to improve between 3 and 12 months, and more likely to worsen (p = 0.042).This is the first study to investigate depression one year after ICH. Post-ICH depression was common and associated with late worsening of disability unrelated to initial hemorrhage severity. Further research is needed to understand whether depression is caused by worsened disability, or whether the converse is true.

  View details for DOI 10.3233/NRE-171470

  View details for PubMedID 28505996

• Neurotoxic reactive astrocytes are induced by activated microglia. Nature Liddelow, S. A., Guttenplan, K. A., Clarke, L. E., Bennett, F. C., Bohlen, C. J., Schirmer, L., Bennett, M. L., Münch, A. E., Chung, W., Peterson, T. C., Wilton, D. K., Frouin, A., Napier, B. A., Panicker, N., Kumar, M., Buckwalter, M. S., Rowitch, D. H., Dawson, V. L., Dawson, T. M., Stevens, B., Barres, B. A. 2017; 541 (7638): 481-487

  Abstract

  Reactive astrocytes are strongly induced by central nervous system (CNS) injury and disease, but their role is poorly understood. Here we show that a subtype of reactive astrocytes, which we termed A1, is induced by classically activated neuroinflammatory microglia. We show that activated microglia induce A1 astrocytes by secreting Il-1α, TNF and C1q, and that these cytokines together are necessary and sufficient to induce A1 astrocytes. A1 astrocytes lose the ability to promote neuronal survival, outgrowth, synaptogenesis and phagocytosis, and induce the death of neurons and oligodendrocytes. Death of axotomized CNS neurons in vivo is prevented when the formation of A1 astrocytes is blocked. Finally, we show that A1 astrocytes are abundant in various human neurodegenerative diseases including Alzheimer's, Huntington's and Parkinson's disease, amyotrophic lateral sclerosis and multiple sclerosis. Taken together these findings help to explain why CNS neurons die after axotomy, strongly suggest that A1 astrocytes contribute to the death of neurons and oligodendrocytes in neurodegenerative disorders, and provide opportunities for the development of new treatments for these diseases.

  View details for DOI 10.1038/nature21029

  View details for PubMedID 28099414

• Imaging B cells in a mouse model of multiple sclerosis using (64)Cu-Rituximab-PET. Journal of nuclear medicine : official publication, Society of Nuclear Medicine James, M. L., Hoehne, A. n., Mayer, A. T., Lechtenberg, K. n., Moreno, M. n., Gowrishankar, G. n., Ilovich, O. n., Natarajan, A. n., Johnson, E. M., Nguyen, J. n., Quach, L. n., Han, M. n., Buckwalter, M. n., Chandra, S. n., Gambhir, S. S. 2017

  Abstract

  B lymphocytes are a key pathological feature of multiple sclerosis (MS), and are becoming an important therapeutic target for this condition. Currently, there is no approved technique to non-invasively visualize B cells in the central nervous system (CNS) to monitor MS disease progression and response to therapies. Here we evaluated (64)Cu-Rituximab, a radiolabeled antibody specifically targeting the human B cell marker CD20, for its ability to image B cells in a mouse model of MS using positron emission tomography (PET). Methods: To model CNS infiltration by B cells, experimental autoimmune encephalomyelitis (EAE) was induced in transgenic mice that express human CD20 on B cells. EAE mice were given subcutaneous injections of Myelin Oligodendrocyte Glycoprotein fragment1-125 (MOG1-125) emulsified in complete Freund's adjuvant. Control mice received complete Freund's adjuvant alone. PET imaging of EAE and control mice was performed 1, 4, and 19h following (64)Cu-Rituximab administration. Mice were perfused and sacrificed after final PET scan, and radioactivity in dissected tissues was measured with a gamma-counter. CNS tissues from these mice were immunostained to quantify B cells or further analyzed via digital autoradiography. Results: Lumbar spinal cord PET signal was significantly higher in EAE mice compared to controls at all evaluated time points (e.g., 1h post-injection: 5.44 ± 0.37 vs. 3.33 ± 0.20 %ID/g, p<0.05). (64)Cu-Rituximab-PET signal in brain regions ranged between 1.74 ± 0.11 and 2.93 ± 0.15 %ID/g for EAE mice compared to 1.25±0.08 and 2.24±0.11%ID/g for controls, p<0.05 for all regions except striatum and thalamus at 1h post-injection. Similarly, ex vivo biodistribution results revealed notably higher (64)Cu-Rituximab uptake in brain and spinal cord of huCD20tg EAE, and B220 immunostaining verified that increased (64)Cu-Rituximab uptake in CNS tissues corresponded with elevated B cells. Conclusion: B cells can be detected in the CNS of EAE mice using (64)Cu-Rituximab-PET. Results from these studies warrant further investigation of (64)Cu-Rituximab in EAE models and consideration of use in MS patients to evaluate its potential for detecting and monitoring B cells in the progression and treatment of this disease. These results represent an initial step toward generating a platform to evaluate B cell-targeted therapeutics en route to the clinic.

  View details for PubMedID 28687602

• Astrocytes: Integrative Regulators of Neuroinflammation in Stroke and Other Neurological Diseases. Neurotherapeutics Cekanaviciute, E., Buckwalter, M. S. 2016; 13 (4): 685-701

  Abstract

  Astrocytes regulate neuroinflammatory responses after stroke and in other neurological diseases. Although not all astrocytic responses reduce inflammation, their predominant function is to protect the brain by driving the system back to homeostasis after injury. They receive multidimensional signals within the central nervous system and between the brain and the systemic circulation. Processing this information allows astrocytes to regulate synapse formation and maintenance, cerebral blood flow, and blood-brain barrier integrity. Similarly, in response to stroke and other central nervous system disorders, astrocytes detect and integrate signals of neuronal damage and inflammation to regulate the neuroinflammatory response. Two direct regulatory mechanisms in the astrocyte arsenal are the ability to form both physical and molecular barriers that seal the injury site and localize the neuroinflammatory response. Astrocytes also indirectly regulate the inflammatory response by affecting neuronal health during the acute injury and axonal regrowth. This ability to regulate the location and degree of neuroinflammation after injury, combined with the long time course of neuroinflammation, makes astrocytic signaling pathways promising targets for therapies.

  View details for PubMedID 27677607

  View details for PubMedCentralID PMC5081110

• Stroke, Inflammation and the Immune Response: Dawn of a New Era NEUROTHERAPEUTICS Becker, K. J., Buckwalter, M. 2016; 13 (4): 659–60

  View details for PubMedID 27677606

  View details for PubMedCentralID PMC5081111

• Does B lymphocyte-mediated autoimmunity contribute to post-stroke dementia? Brain, behavior, and immunity Doyle, K. P., Buckwalter, M. S. 2016

  Abstract

  Post-stroke cognitive decline and dementia pose a significant public health problem, with 30% of stroke survivors suffering from dementia. The reason for this high prevalence is not well understood. Pathogenic B cell responses to the damaged CNS are one possible contributing factor. B-lymphocytes and antibodies are present in and around the stroke core of some human subjects who die with stroke and dementia, and mice that develop delayed cognitive dysfunction after stroke have clusters of B-lymphocytes in the stroke lesion, and antibody infiltration in the stroked hemisphere. The ablation of B-lymphocytes prevents post-stroke cognitive impairment in mice. Multiple drugs that target B cells are FDA approved, and so if pathogenic B cell responses are occurring in a subset of stroke patients, this is potentially treatable. However, it has also been demonstrated that regulatory B cells can be beneficial in mouse models of stroke. Consequently, it is important to understand the relative contribution of B-lymphocytes to recovery versus pathogenicity, and if this balance is heterogeneous in different individuals. Therefore, the purpose of this review is to summarize the current state of knowledge with regard to the role of B-lymphocytes in the etiology of post-stroke dementia.

  View details for DOI 10.1016/j.bbi.2016.08.009

  View details for PubMedID 27531189

• Antibodies to myelin basic protein are associated with cognitive decline after stroke. Journal of neuroimmunology Becker, K. J., Tanzi, P., Zierath, D., Buckwalter, M. S. 2016; 295-296: 9-11

  Abstract

  B lymphocytes cause post-stroke cognitive decline in mice. We therefore evaluated the association between autoantibodies and post-stroke cognitive decline in a prospectively collected human cohort. The mini-mental state exam (MMSE) was administered 30, 90, 180, and 365days after stroke. Antibody titers to myelin basic protein (MBP), proteolipid protein, and several non-specific proteins were determined. Among 58 subjects with initial MMSE≥20 and at least 2 MMSE examinations in the year after stroke, cognitive decline (MMSE decrease ≥2) occurred in 10 (17%) subjects. In multivariate analysis, MBP antibody titers were the only independent predictor of cognitive decline (OR=9.02 [1.18, 68.90]; P=0.03).

  View details for DOI 10.1016/j.jneuroim.2016.04.001

  View details for PubMedID 27235342

• Antibodies to myelin basic protein are associated with cognitive decline after stroke JOURNAL OF NEUROIMMUNOLOGY Becker, K. J., Tanzi, P., Zierath, D., Buckwalter, M. S. 2016; 295: 9-11

  Abstract

  B lymphocytes cause post-stroke cognitive decline in mice. We therefore evaluated the association between autoantibodies and post-stroke cognitive decline in a prospectively collected human cohort. The mini-mental state exam (MMSE) was administered 30, 90, 180, and 365days after stroke. Antibody titers to myelin basic protein (MBP), proteolipid protein, and several non-specific proteins were determined. Among 58 subjects with initial MMSE≥20 and at least 2 MMSE examinations in the year after stroke, cognitive decline (MMSE decrease ≥2) occurred in 10 (17%) subjects. In multivariate analysis, MBP antibody titers were the only independent predictor of cognitive decline (OR=9.02 [1.18, 68.90]; P=0.03).

  View details for DOI 10.1016/j.jneuroim.2016.04.001

  View details for Web of Science ID 000377822000002

  View details for PubMedCentralID PMC4884610

• Glial Fibrillary Acidic Protein-Expressing Glia in the Mouse Lung ASN NEURO Suarez-Mier, G. B., Buckwalter, M. S. 2015; 7 (5)

  Abstract

  Autonomic nerves regulate important functions in visceral organs, including the lung. The postganglionic portion of these nerves is ensheathed by glial cells known as non-myelinating Schwann cells. In the brain, glia play important functional roles in neurotransmission, neuroinflammation, and maintenance of the blood brain barrier. Similarly, enteric glia are now known to have analogous roles in gastrointestinal neurotransmission, inflammatory response, and barrier formation. In contrast to this, very little is known about the function of glia in other visceral organs. Like the gut, the lung forms a barrier between airborne pathogens and the bloodstream, and autonomic lung innervation is known to affect pulmonary inflammation and lung function. Lung glia are described as non-myelinating Schwann cells but their function is not known, and indeed no transgenic tools have been validated to study them in vivo. The primary goal of this research was, therefore, to investigate the relationship between non-myelinating Schwann cells and pulmonary nerves in the airways and vasculature and to validate existing transgenic mouse tools that would be useful for studying their function. We focused on the glial fibrillary acidic protein promoter, which is a cognate marker of astrocytes that is expressed by enteric glia and non-myelinating Schwann cells. We describe the morphology of non-myelinating Schwann cells in the lung and verify that they express glial fibrillary acidic protein and S100, a classic glial marker. Furthermore, we characterize the relationship of non-myelinating Schwann cells to pulmonary nerves. Finally, we report tools for studying their function, including a commercially available transgenic mouse line.

  View details for DOI 10.1177/1759091415601636

  View details for Web of Science ID 000364740200001

  View details for PubMedID 26442852

  View details for PubMedCentralID PMC4601129

• Metronidazole-Induced Encephalopathy: Not Always a Reversible Situation NEUROCRITICAL CARE Hobbs, K., Stern-Nezer, S., Buckwalter, M. S., Fischbein, N., Caulfield, A. F. 2015; 22 (3): 429-436

  Abstract

  Metronidazole is a nitroimidazole antimicrobial drug prescribed to treat infections caused by anaerobic bacteria and protozoa. Uncommonly, it causes central nervous system (CNS) toxicity manifesting as metronidazole-induced encephalopathy (MIE).Case report.A 65-year-old woman with hepatitis B cirrhosis (Child-Pugh class C, MELD 21) developed progressive encephalopathy to GCS 4 during a 3-week course of metronidazole for cholecystitis. Initial MRI was consistent with CNS metronidazole toxicity, with symmetrical T2 hyperintensity and generally restricted diffusion in bilateral dentate nuclei, corpus callosum, midbrain, superior cerebellar peduncles, internal capsules, and cerebral white matter. Laboratory values did not demonstrate significant electrolyte shifts, and continuous EEG was without seizure. High-dose thiamine was empirically administered. Lumbar puncture was not performed due to coagulopathy and thrombocytopenia. Despite discontinuation of metronidazole and keeping ammonia levels near normal, the patient did not improve. MRI was repeated 1 week after discontinuation of metronidazole. Although there was decreased DWI hyperintensity in the dentate nuclei, diffuse T2 hyperintensity persisted and even progressed in the brainstem, basal ganglia, and subcortical white matter. Petechial hemorrhages developed in bilateral corticospinal tracts and subcortical white matter. T1 hypointensity appeared in the corpus callosum. She was transitioned to comfort measures only and died 12 days later.MIE is an uncommon adverse effect of treatment with metronidazole that characteristically affects the dentate nuclei but may also involve the brainstem, corpus callosum, subcortical white matter, and basal ganglia. While the clinical symptoms and neuroimaging changes are usually reversible, persistent encephalopathy with poor outcome may occur.

  View details for DOI 10.1007/s12028-014-0102-9

  View details for PubMedID 25561434

• Albumin induces excitatory synaptogenesis through astrocytic TGF-beta/ALK5 signaling in a model of acquired epilepsy following blood-brain barrier dysfunction NEUROBIOLOGY OF DISEASE Weissberg, I., Wood, L., Kamintsky, L., Vazquez, O., Milikovsky, D. Z., Alexander, A., Oppenheim, H., Ardizzone, C., Becker, A., Frigerio, F., Vezzani, A., Buckwalter, M. S., Huguenard, J. R., Friedman, A., Kaufer, D. 2015; 78: 115-125

  Abstract

  Post injury epilepsy (PIE) is a common complication following brain insults, including ischemic and traumatic brain injuries. At present there are no means to identify the patients at-risk to develop PIE or to prevent its development. Seizures can occur months or years after the insult, do not respond to anti-seizure medications in over third of the patients, and are often associated with significant neuropsychiatric morbidities. We have previously established the critical role of blood-brain barrier dysfunction in PIE, demonstrating that exposure of brain tissue to extravasated serum albumin induces activation of inflammatory transforming growth factor beta (TGF-β) signaling in astrocytes and eventually seizures. However, the link between the acute astrocytic inflammatory responses and reorganization of neural networks that underlie recurrent spontaneous seizures, remains unknown. Here we demonstrate in-vitro and in-vivo that activation of the astrocytic ALK5/TGF-β-pathway induces excitatory, but not inhibitory, synaptogenesis that precedes the appearance of seizures. Moreover, we show that treatment with SJN2511, a specific ALK5/TGF-β inhibitor, prevents synaptogenesis and epilepsy. Our findings point to astrocyte-mediated synaptogenesis as a key epileptogenic process, and highlight manipulation of the TGF-β-pathway as a potential strategy for the prevention of PIE.

  View details for DOI 10.1016/j.nbd.2015.02.029

  View details for PubMedID 25836421

• B-Lymphocyte-Mediated Delayed Cognitive Impairment following Stroke. journal of neuroscience Doyle, K. P., Quach, L. N., Solé, M., Axtell, R. C., Nguyen, T. V., Soler-Llavina, G. J., Jurado, S., Han, J., Steinman, L., Longo, F. M., Schneider, J. A., Malenka, R. C., Buckwalter, M. S. 2015; 35 (5): 2133-2145

  Abstract

  Each year, 10 million people worldwide survive the neurologic injury associated with a stroke. Importantly, stroke survivors have more than twice the risk of subsequently developing dementia compared with people who have never had a stroke. The link between stroke and the later development of dementia is not understood. There are reports of oligoclonal bands in the CSF of stroke patients, suggesting that in some people a B-lymphocyte response to stroke may occur in the CNS. Therefore, we tested the hypothesis that a B-lymphocyte response to stroke could contribute to the onset of dementia. We discovered that, in mouse models, activated B-lymphocytes infiltrate infarcted tissue in the weeks after stroke. B-lymphocytes undergo isotype switching, and IgM, IgG, and IgA antibodies are found in the neuropil adjacent to the lesion. Concurrently, mice develop delayed deficits in LTP and cognition. Genetic deficiency, and the pharmacologic ablation of B-lymphocytes using an anti-CD20 antibody, prevents the appearance of delayed cognitive deficits. Furthermore, immunostaining of human postmortem tissue revealed that a B-lymphocyte response to stroke also occurs in the brain of some people with stroke and dementia. These data suggest that some stroke patients may develop a B-lymphocyte response to stroke that contributes to dementia, and is potentially treatable with FDA-approved drugs that target B cells.

  View details for DOI 10.1523/JNEUROSCI.4098-14.2015

  View details for PubMedID 25653369

• Ferumoxytol administration does not alter infarct volume or the inflammatory response to stroke in mice. Neuroscience letters Doyle, K. P., Quach, L. N., Arceuil, H. E., Buckwalter, M. S. 2015; 584: 236-240

  Abstract

  Ferumoxytol is an ultrasmall superparamagnetic iron oxide (USPIO) nanoparticle that is FDA-approved as an intravenous iron replacement therapy for the treatment of iron deficiency anemia in patients with chronic kidney disease. Ferumoxytol has also been used as a contrast agent for cerebral blood volume mapping by magnetic resonance imaging (MRI), which suggests it could be used for imaging hemodynamic abnormalities after stroke. However, circulating macrophages can internalize USPIOs, and recent data indicate that the accumulation of iron in macrophages can lead them to adopt the M1 pro-inflammatory phenotype. Therefore, the uptake of intravenously administered iron particles by circulating macrophages that home to the stroke core could potentially alter the inflammatory response to stroke. To test this possibility in vivo we administered a dose of ferumoxytol previously used to obtain cerebral blood volume maps in healthy humans by steady-state susceptibility contrast (SSC) MRI to BALB/cJ mice 48h after stroke and examined cytokine levels, microglial/macrophage activation, and lesion volume in the brain 5 days later. Treatment with ferumoxytol did not lead to any differences in these parameters. These data indicate that the use of ferumoxytol as a contrast agent for brain imaging after stroke does not alter the inflammatory response to stroke in mice, and is therefore unlikely to do so in human subjects.

  View details for DOI 10.1016/j.neulet.2014.10.041

  View details for PubMedID 25449870

• Astrocytic transforming growth factor-beta signaling reduces subacute neuroinflammation after stroke in mice. Glia Cekanaviciute, E., Fathali, N., Doyle, K. P., Williams, A. M., Han, J., Buckwalter, M. S. 2014; 62 (8): 1227-1240

  Abstract

  Astrocytes limit inflammation after CNS injury, at least partially by physically containing it within an astrocytic scar at the injury border. We report here that astrocytic transforming growth factor-beta (TGFβ) signaling is a second, distinct mechanism that astrocytes utilize to limit neuroinflammation. TGFβs are anti-inflammatory and neuroprotective cytokines that are upregulated subacutely after stroke, during a clinically accessible time window. We have previously demonstrated that TGFβs signal to astrocytes, neurons and microglia in the stroke border days after stroke. To investigate whether TGFβ affects astrocyte immunoregulatory functions, we engineered "Ast-Tbr2DN" mice where TGFβ signaling is inhibited specifically in astrocytes. Despite having a similar infarct size to wildtype controls, Ast-Tbr2DN mice exhibited significantly more neuroinflammation during the subacute period after distal middle cerebral occlusion (dMCAO) stroke. The peri-infarct cortex of Ast-Tbr2DN mice contained over 60% more activated CD11b(+) monocytic cells and twice as much immunostaining for the activated microglia and macrophage marker CD68 than controls. Astrocytic scarring was not altered in Ast-Tbr2DN mice. However, Ast-Tbr2DN mice were unable to upregulate TGF-β1 and its activator thrombospondin-1 2 days after dMCAO. As a result, the normal upregulation of peri-infarct TGFβ signaling was blunted in Ast-Tbr2DN mice. In this setting of lower TGFβ signaling and excessive neuroinflammation, we observed worse motor outcomes and late infarct expansion after photothrombotic motor cortex stroke. Taken together, these data demonstrate that TGFβ signaling is a molecular mechanism by which astrocytes limit neuroinflammation, activate TGFβ in the peri-infarct cortex and preserve brain function during the subacute period after stroke.

  View details for DOI 10.1002/glia.22675

  View details for PubMedID 24733756

• Astrocytic TGF-ß signaling limits inflammation and reduces neuronal damage during central nervous system Toxoplasma infection. Journal of immunology Cekanaviciute, E., Dietrich, H. K., Axtell, R. C., Williams, A. M., Egusquiza, R., Wai, K. M., Koshy, A. A., Buckwalter, M. S. 2014; 193 (1): 139-149

  Abstract

  The balance between controlling infection and limiting inflammation is particularly precarious in the brain because of its unique vulnerability to the toxic effects of inflammation. Astrocytes have been implicated as key regulators of neuroinflammation in CNS infections, including infection with Toxoplasma gondii, a protozoan parasite that naturally establishes a chronic CNS infection in mice and humans. In CNS toxoplasmosis, astrocytes are critical to controlling parasite growth. They secrete proinflammatory cytokines and physically encircle parasites. However, the molecular mechanisms used by astrocytes to limit neuroinflammation during toxoplasmic encephalitis have not yet been identified. TGF-β signaling in astrocytes is of particular interest because TGF-β is universally upregulated during CNS infection and serves master regulatory and primarily anti-inflammatory functions. We report in this study that TGF-β signaling is activated in astrocytes during toxoplasmic encephalitis and that inhibition of astrocytic TGF-β signaling increases immune cell infiltration, uncouples proinflammatory cytokine and chemokine production from CNS parasite burden, and increases neuronal injury. Remarkably, we show that the effects of inhibiting astrocytic TGF-β signaling are independent of parasite burden and the ability of GFAP(+) astrocytes to physically encircle parasites.

  View details for DOI 10.4049/jimmunol.1303284

  View details for PubMedID 24860191

• A mouse model of permanent focal ischemia: distal middle cerebral artery occlusion. Methods in molecular biology (Clifton, N.J.) Doyle, K. P., Buckwalter, M. S. 2014; 1135: 103-110

  Abstract

  Here we provide a standardized protocol for performing distal middle cerebral artery occlusion (DMCAO) in mice. DMCAO is a method of inducing permanent focal ischemia that is commonly used as a rodent stroke model. To perform DMCAO a temporal craniotomy is performed, and the middle cerebral artery (MCA) is permanently ligated at a point downstream of the lenticulostriate branches. The size of the lesion produced by this surgery is strain dependent. In C57BL/6J mice, DMCAO produces an infarct predominantly restricted to the barrel region of the somatosensory cortex, but in BALB/cJ mice, DMCAO generates a much larger lesion that incorporates more of the somatosensory cortex and part of the M1 region of the motor cortex. The larger lesion produced by DMCAO in BALB/cJ mice produces a clearer sensorimotor deficit, which is useful for investigating recovery from stroke. We also describe how to modify DMCAO in C57BL/6J mice with the application of hypoxia to generate a lesion and sensorimotor deficit that are similar in size to those produced by DMCAO alone in BALB/cJ mice. This is extremely useful for stroke experiments that require a robust sensorimotor deficit in transgenic mice created on a C57BL/6J background.

  View details for DOI 10.1007/978-1-4939-0320-7_9

  View details for PubMedID 24510858

• Chronic Over-Expression of TGF beta 1 Alters Hippocampal Structure and Causes Learning Deficits HIPPOCAMPUS Martinez-Canabal, A., Wheeler, A. L., Sarkis, D., Lerch, J. P., Lu, W., Buckwalter, M. S., Wyss-Coray, T., Josselyn, S. A., Frankland, P. W. 2013; 23 (12): 1198-1211

  Abstract

  The cytokine Transforming Growth Factor β1 (TGFβ1) is chronically upregulated in several neurodegenerative conditions, including Alzheimer's disease, Parkinson's disease, Creutzfeldt-Jacob disease, amyotrophic lateral sclerosis and multiple sclerosis, and following stroke. While previous studies have shown that TGFβ1 may be neuroprotective, chronic exposure to elevated levels of this cytokine may contribute to disease pathology on its own. In order to study the effects of chronic exposure to TGFβ1 in isolation we used transgenic mice that over-express a constitutively active porcine TGFβ1 in astrocytes. We found that TGFβ1 over-expression altered brain structure, with the most pronounced volumetric increases localized to the hippocampus. Within the dentate gyrus (DG) of the hippocampus, increases in granule cell number and astrocyte size were responsible for volumetric expansion, with the increased granule cell number primarily related to a marked reduction in death of new granule cells generated in adulthood. Finally, these cumulative changes in DG micro- and macrostructure were associated with the age-dependent emergence of spatial learning deficits in TGFβ1 over-expressing mice. Together, our data indicate that chronic upregulation of TGFβ1 negatively impacts hippocampal structure and, even in the absence of disease, impairs hippocampus-dependent learning. © 2013 Wiley Periodicals, Inc.

  View details for DOI 10.1002/hipo.22159

  View details for Web of Science ID 000327157200007

  View details for PubMedID 23804429

• Suppression of Inflammation with Conditional Deletion of the Prostaglandin E-2 EP2 Receptor in Macrophages and Brain Microglia JOURNAL OF NEUROSCIENCE Johansson, J. U., Pradhan, S., Lokteva, L. A., Woodling, N. S., Ko, N., Brown, H. D., Wang, Q., Loh, C., Cekanaviciute, E., Buckwalter, M., Manning-Bog, A. B., Andreasson, K. I. 2013; 33 (40): 16016-16032

  Abstract

  Prostaglandin E2 (PGE2), a potent lipid signaling molecule, modulates inflammatory responses through activation of downstream G-protein coupled EP(1-4) receptors. Here, we investigated the cell-specific in vivo function of PGE2 signaling through its E-prostanoid 2 (EP2) receptor in murine innate immune responses systemically and in the CNS. In vivo, systemic administration of lipopolysaccharide (LPS) resulted in a broad induction of cytokines and chemokines in plasma that was significantly attenuated in EP2-deficient mice. Ex vivo stimulation of peritoneal macrophages with LPS elicited proinflammatory responses that were dependent on EP2 signaling and that overlapped with in vivo plasma findings, suggesting that myeloid-lineage EP2 signaling is a major effector of innate immune responses. Conditional deletion of the EP2 receptor in myeloid lineage cells in Cd11bCre;EP2(lox/lox) mice attenuated plasma inflammatory responses and transmission of systemic inflammation to the brain was inhibited, with decreased hippocampal inflammatory gene expression and cerebral cortical levels of IL-6. Conditional deletion of EP2 significantly blunted microglial and astrocytic inflammatory responses to the neurotoxin MPTP and reduced striatal dopamine turnover. Suppression of microglial EP2 signaling also increased numbers of dopaminergic (DA) neurons in the substantia nigra independent of MPTP treatment, suggesting that microglial EP2 may influence development or survival of DA neurons. Unbiased microarray analysis of microglia isolated from adult Cd11bCre;EP2(lox/lox) and control mice demonstrated a broad downregulation of inflammatory pathways with ablation of microglial EP2 receptor. Together, these data identify a cell-specific proinflammatory role for macrophage/microglial EP2 signaling in innate immune responses systemically and in brain.

  View details for DOI 10.1523/JNEUROSCI.2203-13.2013

  View details for PubMedID 24089506

• Serum Neuron-Specific Enolase Levels from the Same Patients Differ Between Laboratories: Assessment of a Prospective Post-cardiac Arrest Cohort. Neurocritical care Mlynash, M., Buckwalter, M. S., Okada, A., Caulfield, A. F., Venkatasubramanian, C., Eyngorn, I., Verbeek, M. M., Wijman, C. A. 2013; 19 (2): 161-166

  Abstract

  In comatose post-cardiac arrest patients, a serum neuron-specific enolase (NSE) level of >33 μg/L within 72 h was identified as a reliable marker for poor outcome in a large Dutch study (PROPAC), and this level was subsequently adopted in an American Academy of Neurology practice parameter. Later studies reported that NSE >33 μg/L is not a reliable predictor of poor prognosis. To test whether different clinical laboratories contribute to this variability, we compared NSE levels from the laboratory used in the PROPAC study (DLM-Nijmegen) with those of our hospital's laboratory (ARUP) using paired blood samples.We prospectively enrolled cardiac arrest patients who remained comatose after resuscitation. During the first 3 days, paired blood samples for serum NSE were drawn at a median of 10 min apart. After standard preparation for each lab, one sample was sent to ARUP laboratories and the other to DLM-Nijmegen.Fifty-four paired serum samples from 33 patients were included. Although the serum NSE measurements correlated well between laboratories (R = 0.91), the results from ARUP were approximately 30 % lower than those from DLM-Nijmegen. Therapeutic hypothermia did not affect this relationship. Two patients had favorable outcomes after hypothermia despite NSE levels measured by DLM-Nijmegen as >33 μg/L.Absolute serum NSE levels of comatose cardiac arrest patients differ between laboratories. Any specific absolute cut-off levels proposed to prognosticate poor outcome should not be used without detailed data on how neurologic outcomes correspond to a particular laboratory's method, and even then only in conjunction with other prognostic variables.

  View details for DOI 10.1007/s12028-013-9867-5

  View details for PubMedID 23839710

• A small molecule p75(NTR) ligand prevents cognitive deficits and neurite degeneration in an Alzheimer's mouse model. Neurobiology of aging Knowles, J. K., Simmons, D. A., Nguyen, T. V., Vander Griend, L., Xie, Y., Zhang, H., Yang, T., Pollak, J., Chang, T., Arancio, O., Buckwalter, M. S., Wyss-Coray, T., Massa, S. M., Longo, F. M. 2013; 34 (8): 2052-2063

  Abstract

  The p75 neurotrophin receptor (p75(NTR)) is associated with multiple mechanisms linked to Alzheimer's disease (AD); hence, modulating its function might confer therapeutic effects. In previous in vitro work, we developed small molecule p75(NTR) ligands that inhibited amyloid-β-induced degenerative signaling and prevented neurite degeneration. In the present study, a prototype p75(NTR) ligand, LM11A-31, was administered orally to the Thy-1 hAPP(Lond/Swe) (APP(L/S)) AD mouse model. LM11A-31 reached brain concentrations known to inhibit degenerative signaling without toxicity or induction of hyperalgesia. It prevented deficits in novel object recognition after 2.5 months and, in a separate cohort, deficits in Y-maze performance after 3 months of treatment. Stereology studies found that the number and size of basal forebrain cholinergic neurons, which are normal in APP(L/S) mice, were unaffected. Neuritic dystrophy, however, was readily apparent in the basal forebrain, hippocampus and cortex, and was significantly reduced by LM11A-31, with no effect on amyloid levels. These studies reveal that p75(NTR) is an important and tractable in vivo drug target for AD, with LM11A-31 representing a novel class of therapeutic candidates.

  View details for DOI 10.1016/j.neurobiolaging.2013.02.015

  View details for PubMedID 23545424

• Blood-brain barrier dysfunction-induced inflammatory signaling in brain pathology and epileptogenesis EPILEPSIA Kim, S. Y., Buckwalter, M., Soreq, H., Vezzani, A., Kaufer, D. 2012; 53: 37-44

  Abstract

  The protection of the brain from blood-borne toxins, proteins, and cells is critical to the brain's normal function. Accordingly, a compromise in the blood-brain barrier (BBB) function accompanies many neurologic disorders, and is tightly associated with brain inflammatory processes initiated by both infiltrating leukocytes from the blood, and activation of glial cells. Those inflammatory processes contribute to determining the severity and prognosis of numerous neurologic disorders, and can both cause, and result from BBB dysfunction. In this review we examine the role of BBB and inflammatory responses, in particular activation of transforming grown factor β (TGFβ) signaling, in epilepsy, stroke, and Parkinson's disease.

  View details for DOI 10.1111/j.1528-1167.2012.03701.x

  View details for Web of Science ID 000310797400006

  View details for PubMedID 23134494

  View details for PubMedCentralID PMC3703535

• Stratification substantially reduces behavioral variability in the hypoxic-ischemic stroke model. Brain and behavior Pollak, J., Doyle, K. P., Mamer, L., Shamloo, M., Buckwalter, M. S. 2012; 2 (5): 698-706

  Abstract

  Stroke is the most common cause of long-term disability, and there are no known drug therapies to improve recovery after stroke. To understand how successful recovery occurs, dissect candidate molecular pathways, and test new therapies, there is a need for multiple distinct mouse stroke models, in which the parameters of recovery after stroke are well defined. Hypoxic-ischemic stroke is a well-established stroke model, but behavioral recovery in this model is not well described. We therefore examined a panel of behavioral tests to see whether they could be used to quantify functional recovery after hypoxic-ischemic stroke. We found that in C57BL/6J mice this stroke model produces high mortality (approximately one-third) and variable stroke sizes, but is fast and easy to perform on a large number of mice. Horizontal ladder test performance on day 1 after stroke was highly and reproducibly correlated with stroke size (P < 0.0001, R(2) = 0.7652), and allowed for functional stratification of mice into a group with >18% foot faults and 2.1-fold larger strokes. This group exhibited significant functional deficits for as long as 3 weeks on the horizontal ladder test and through the last day of testing on automated gait analysis (33 days), rotarod (30 days), and elevated body swing test (EBST) (36 days). No deficits were observed in an automated activity chamber. We conclude that stratification by horizontal ladder test performance on day 1 identifies a subset of mice in which functional recovery from hypoxic-ischemic stroke can be studied.

  View details for DOI 10.1002/brb3.77

  View details for PubMedID 23139913

  View details for PubMedCentralID PMC3489820

• Stratification substantially reduces behavioral variability in the hypoxic-ischemic stroke model BRAIN AND BEHAVIOR Pollak, J., Doyle, K. P., Mamer, L., Shamloo, M., Buckwalter, M. S. 2012; 2 (5): 698-706

  Abstract

  Stroke is the most common cause of long-term disability, and there are no known drug therapies to improve recovery after stroke. To understand how successful recovery occurs, dissect candidate molecular pathways, and test new therapies, there is a need for multiple distinct mouse stroke models, in which the parameters of recovery after stroke are well defined. Hypoxic-ischemic stroke is a well-established stroke model, but behavioral recovery in this model is not well described. We therefore examined a panel of behavioral tests to see whether they could be used to quantify functional recovery after hypoxic-ischemic stroke. We found that in C57BL/6J mice this stroke model produces high mortality (approximately one-third) and variable stroke sizes, but is fast and easy to perform on a large number of mice. Horizontal ladder test performance on day 1 after stroke was highly and reproducibly correlated with stroke size (P < 0.0001, R(2) = 0.7652), and allowed for functional stratification of mice into a group with >18% foot faults and 2.1-fold larger strokes. This group exhibited significant functional deficits for as long as 3 weeks on the horizontal ladder test and through the last day of testing on automated gait analysis (33 days), rotarod (30 days), and elevated body swing test (EBST) (36 days). No deficits were observed in an automated activity chamber. We conclude that stratification by horizontal ladder test performance on day 1 identifies a subset of mice in which functional recovery from hypoxic-ischemic stroke can be studied.

  View details for DOI 10.1002/brb3.77

  View details for Web of Science ID 000209174200016

  View details for PubMedCentralID PMC3489820

• Delayed Administration of a Small Molecule Tropomyosin-Related Kinase B Ligand Promotes Recovery After Hypoxic-Ischemic Stroke STROKE Han, J., Pollak, J., Yang, T., Siddiqui, M. R., Doyle, K. P., Taravosh-Lahn, K., Cekanaviciute, E., Han, A., Goodman, J. Z., Jones, B., Jing, D., Massa, S. M., Longo, F. M., Buckwalter, M. S. 2012; 43 (7): 1918-1924

  Abstract

  Stroke is the leading cause of long-term disability in the United States, yet no drugs are available that are proven to improve recovery. Brain-derived neurotrophic factor stimulates neurogenesis and plasticity, processes that are implicated in stroke recovery. It binds to both the tropomyosin-related kinase B and p75 neurotrophin receptors. However, brain-derived neurotrophic factor is not a feasible therapeutic agent, and no small molecule exists that can reproduce its binding to both receptors. We tested the hypothesis that a small molecule (LM22A-4) that selectively targets tropomyosin-related kinase B would promote neurogenesis and functional recovery after stroke.Four-month-old mice were trained on motor tasks before stroke. After stroke, functional test results were used to randomize mice into 2 equally, and severely, impaired groups. Beginning 3 days after stroke, mice received LM22A-4 or saline vehicle daily for 10 weeks.LM22A-4 treatment significantly improved limb swing speed and accelerated the return to normal gait accuracy after stroke. LM22A-4 treatment also doubled both the number of new mature neurons and immature neurons adjacent to the stroke. Drug-induced differences were not observed in angiogenesis, dendritic arborization, axonal sprouting, glial scar formation, or neuroinflammation.A small molecule agonist of tropomyosin-related kinase B improves functional recovery from stroke and increases neurogenesis when administered beginning 3 days after stroke. These findings provide proof-of-concept that targeting of tropomyosin-related kinase B alone is capable of promoting one or more mechanisms relevant to stroke recovery. LM22A-4 or its derivatives might therefore serve as "pro-recovery" therapeutic agents for stroke.

  View details for DOI 10.1161/STROKEAHA.111.641878

  View details for PubMedID 22535263

• The double-edged sword of inflammation after stroke: What sharpens each edge? ANNALS OF NEUROLOGY Doyle, K. P., Buckwalter, M. S. 2012; 71 (6): 729-731

  View details for DOI 10.1002/ana.23579

  View details for Web of Science ID 000305506300004

  View details for PubMedID 22718541

• Distal hypoxic stroke: A new mouse model of stroke with high throughput, low variability and a quantifiable functional deficit JOURNAL OF NEUROSCIENCE METHODS Doyle, K. P., Fathali, N., Siddiqui, M. R., Buckwalter, M. S. 2012; 207 (1): 31-40

  Abstract

  C57BL/6J are the most commonly used strain of mouse for stroke experiments but vascular anatomy of the Circle of Willis within this strain is extremely variable and the cortex has extensive collateralization. This causes large variability in stroke models that target the middle cerebral artery proximally and confers resistance to ischemia in those that target it distally. We tested the hypothesis that by combining distal middle cerebral artery occlusion with 1h of hypoxia, we could generate a large lesion that causes a behavioral deficit with low variability. We found that this new distal hypoxic (DH) model of stroke generates a lesion with a volume of 25% of the ipsilateral hemisphere, extends to the motor cortex and causes a behavioral deficit. It also has a very clear border, exceptionally low variability, and can be performed by a single surgeon on up to 30 animals a day. Moreover, survivability is 100% in young adult animals, the model can be performed on old animals, and therapeutic intervention can reduce infarct volume. Therefore DH stroke is an excellent complement to existing stroke models and could be used for preclinical studies in C57BL/6J mice.

  View details for DOI 10.1016/j.jneumeth.2012.03.003

  View details for PubMedID 22465679

• A comparison of cooling techniques to treat cardiac arrest patients with hypothermia. Stroke research and treatment Finley Caulfield, A., Rachabattula, S., Eyngorn, I., Hamilton, S. A., Kalimuthu, R., Hsia, A. W., Lansberg, M. G., Venkatasubramanian, C., BAUMANN, J. J., Buckwalter, M. S., Kumar, M. A., Castle, J. S., Wijman, C. A. 2011; 2011: 690506-?

  Abstract

  Introduction. We sought to compare the performance of endovascular cooling to conventional surface cooling after cardiac arrest. Methods. Patients in coma following cardiopulmonary resuscitation were cooled with an endovascular cooling catheter or with ice bags and cold-water-circulating cooling blankets to a target temperature of 32.0-34.0°C for 24 hours. Performance of cooling techniques was compared by (1) number of hourly recordings in target temperature range, (2) time elapsed from the written order to initiate cooling and target temperature, and (3) adverse events during the first week. Results. Median time in target temperature range was 19 hours (interquartile range (IQR), 16-20) in the endovascular group versus. 10 hours (IQR, 7-15) in the surface group (P = .001). Median time to target temperature was 4 (IQR, 2.8-6.2) and 4.5 (IQR, 3-6.5) hours, respectively (P = .67). Adverse events were similar. Conclusion. Endovascular cooling maintains target temperatures better than conventional surface cooling.

  View details for DOI 10.4061/2011/690506

  View details for PubMedID 21822470

• A Comparison of Cooling Techniques to Treat Cardiac Arrest Patients with Hypothermia STROKE RESEARCH AND TREATMENT Caulfield, A., Rachabattula, S., Eyngorn, I., Hamilton, S. A., Kalimuthu, R., Hsia, A. W., Lansberg, M. G., Venkatasubramanian, C., Baumann, J. J., Buckwalter, M. S., Kumar, M. A., Castle, J. S., Wijman, C. C. 2011

  View details for DOI 10.4061/2011/690506

  View details for Web of Science ID 000214672300038

• TGF beta signaling in the brain increases with aging and signals to astrocytes and innate immune cells in the weeks after stroke JOURNAL OF NEUROINFLAMMATION Doyle, K. P., Cekanaviciute, E., Mamer, L. E., Buckwalter, M. S. 2010; 7

  Abstract

  TGFβ is both neuroprotective and a key immune system modulator and is likely to be an important target for future stroke therapy. The precise function of increased TGF-β1 after stroke is unknown and its pleiotropic nature means that it may convey a neuroprotective signal, orchestrate glial scarring or function as an important immune system regulator. We therefore investigated the time course and cell-specificity of TGFβ signaling after stroke, and whether its signaling pattern is altered by gender and aging.We performed distal middle cerebral artery occlusion strokes on 5 and 18 month old TGFβ reporter mice to get a readout of TGFβ responses after stroke in real time. To determine which cell type is the source of increased TGFβ production after stroke, brain sections were stained with an anti-TGFβ antibody, colocalized with markers for reactive astrocytes, neurons, and activated microglia. To determine which cells are responding to TGFβ after stroke, brain sections were double-labelled with anti-pSmad2, a marker of TGFβ signaling, and markers of neurons, oligodendrocytes, endothelial cells, astrocytes and microglia.TGFβ signaling increased 2 fold after stroke, beginning on day 1 and peaking on day 7. This pattern of increase was preserved in old animals and absolute TGFβ signaling in the brain increased with age. Activated microglia and macrophages were the predominant source of increased TGFβ after stroke and astrocytes and activated microglia and macrophages demonstrated dramatic upregulation of TGFβ signaling after stroke. TGFβ signaling in neurons and oligodendrocytes did not undergo marked changes.We found that TGFβ signaling increases with age and that astrocytes and activated microglia and macrophages are the main cell types that undergo increased TGFβ signaling in response to post-stroke increases in TGFβ. Therefore increased TGFβ after stroke likely regulates glial scar formation and the immune response to stroke.

  View details for DOI 10.1186/1742-2094-7-62

  View details for PubMedID 20937129

• Intravenous Thrombolysis Plus Hypothermia for Acute Treatment of Ischemic Stroke (ICTuS-L) Final Results STROKE Hemmen, T. M., Raman, R., Guluma, K. Z., Meyer, B. C., Gomes, J. A., Cruz-Flores, S., Wijman, C. A., Rapp, K. S., Grotta, J. C., Lyden, P. D. 2010; 41 (10): 2265-2270

  Abstract

  Induced hypothermia is a promising neuroprotective therapy. We studied the feasibility and safety of hypothermia and thrombolysis after acute ischemic stroke.Intravenous Thrombolysis Plus Hypothermia for Acute Treatment of Ischemic Stroke (ICTuS-L) was a randomized, multicenter trial of hypothermia and intravenous tissue plasminogen activator in patients treated within 6 hours after ischemic stroke. Enrollment was stratified to the treatment time windows 0 to 3 and 3 to 6 hours. Patients presenting within 3 hours of symptom onset received standard dose intravenous alteplase and were randomized to undergo 24 hours of endovascular cooling to 33°C followed by 12 hours of controlled rewarming or normothermia treatment. Patients presenting between 3 and 6 hours were randomized twice: to receive tissue plasminogen activator or not and to receive hypothermia or not. Results- In total, 59 patients were enrolled. One patient was enrolled but not treated when pneumonia was discovered just before treatment. All 44 patients enrolled within 3 hours and 4 of 14 patients enrolled between 3 to 6 hours received tissue plasminogen activator. Overall, 28 patients randomized to receive hypothermia (HY) and 30 to normothermia (NT). Baseline demographics and risk factors were similar between groups. Mean age was 65.5±12.1 years and baseline National Institutes of Health Stroke Scale score was 14.0±5.0; 32 (55%) were male. Cooling was achieved in all patients except 2 in whom there were technical difficulties. The median time to target temperature after catheter placement was 67 minutes (Quartile 1 57.3 to Quartile 3 99.4). At 3 months, 18% of patients treated with hypothermia had a modified Rankin Scale score of 0 or 1 versus 24% in the normothermia groups (nonsignificant). Symptomatic intracranial hemorrhage occurred in 4 patients (68); all were treated with tissue plasminogen activator <3 hours (1 received hypothermia). Six patients in the hypothermia and 5 in the normothermia groups died within 90 days (nonsignificant). Pneumonia occurred in 14 patients in the hypothermia and in 3 of the normothermia groups (P=0.001). The pneumonia rate did not significantly adversely affect 3 month modified Rankin Scale score (P=0.32).This study demonstrates the feasibility and preliminary safety of combining endovascular hypothermia after stroke with intravenous thrombolysis. Pneumonia was more frequent after hypothermia, but further studies are needed to determine its effect on patient outcome and whether it can be prevented. A definitive efficacy trial is necessary to evaluate the efficacy of therapeutic hypothermia for acute stroke.

  View details for DOI 10.1161/STROKEAHA.110.592295

  View details for Web of Science ID 000282221700036

  View details for PubMedID 20724711

  View details for PubMedCentralID PMC2947593

• Outcome prediction in mechanically ventilated neurologic patients by junior neurointensivists NEUROLOGY Caulfield, A. F., GABLER, L., Lansberg, M. G., Eyngorn, I., Mlynash, M., Buckwalter, M. S., Venkatasubramanian, C., Wijman, C. A. 2010; 74 (14): 1096-1101

  Abstract

  Physician prediction of outcome in critically ill neurologic patients impacts treatment decisions and goals of care. In this observational study, we prospectively compared predictions by neurointensivists to patient outcomes at 6 months.Consecutive neurologic patients requiring mechanical ventilation for 72 hours or more were enrolled. The attending neurointensivist was asked to predict 6-month 1) functional outcome (modified Rankin scale [mRS]), 2) quality of life (QOL), and 3) whether supportive care should be withdrawn. Six-month functional outcome was determined by telephone interviews and dichotomized to good (mRS 0-3) and poor outcome (mRS 4-6).Of 187 eligible patients, 144 were enrolled. Neurointensivists correctly predicted 6-month functional outcome in 80% (95% confidence interval [CI], 72%-86%) of patients. Accuracy for a predicted good outcome was 63% (95% CI, 50%-74%) and for poor outcome 94% (95% CI, 85%-98%). Excluding patients who had life support withdrawn, accuracy for good outcome was 73% (95% CI, 60%-84%) and for poor outcome 87% (95% CI, 74%-94%). Accuracy for exact agreement between neurointensivists' mRS predictions and actual 6-month mRS was only 43% (95% CI, 35%-52%). Predicted accuracy for QOL was 58% (95% CI, 39%-74%) for good/excellent and 67% (95% CI, 46%-83%) for poor/fair. Of 27 patients for whom withdrawal of care was recommended, 1 patient survived in a vegetative state.Prediction of long-term functional outcomes in critically ill neurologic patients is challenging. Our neurointensivists were more accurate in predicting poor outcome than good outcome in patients requiring mechanical ventilation >or=72 hours.

  View details for Web of Science ID 000276354400005

  View details for PubMedID 20368630

• Diagnostic Accuracy of MRI in Spontaneous Intra-cerebral Hemorrhage (DASH): Initial Results International Stroke Conference Wijman, C. A., Snider, R. W., Venkatasubramanian, C., Caulfield, A. F., Buckwalter, M., Eyngorn, I., Fischbein, N., Gean, A., Schwartz, N., Lansberg, M., Mlynash, M., Kemp, S., Thai, D., Narayana, R. K., Marks, M., Bammer, R., Moseley, M., Albers, G. W. LIPPINCOTT WILLIAMS & WILKINS. 2010: E210–E211

  View details for Web of Science ID 000276106100102

• Accuracy of Serum NSE and S-100 Protein in Predicting Outcome After Cardiac Arrest Mlynash, M., Caulfield, A., Eyngorn, I., Buckwalter, M. S., Wijman, C. A. LIPPINCOTT WILLIAMS & WILKINS. 2010: E307

  View details for Web of Science ID 000276106100455

• Diagnostic Yield of CT Angiography in Addition to MRI/MRA in Spontaneous Intracerebral Hemorrhage Snider, R. W., Thai, D., Narayana, R. K., Mlynash, M., Caulfield, A., Venkatasubramanian, C., Buckwalter, M., Fischbein, N., Wijman, C. A. LIPPINCOTT WILLIAMS & WILKINS. 2010: E310

  View details for Web of Science ID 000276106100470

• Prognostic Accuracy of Serum Neuron-Specific Enolase Levels in Comatose Post-Cardiac Arrest Patients Mlynash, M., Caulfield, A., Eyngorn, I., Buckwalter, M. S., Wijman, C. A. LIPPINCOTT WILLIAMS & WILKINS. 2009: E146–E147

  View details for Web of Science ID 000264709500258

• A Mouse Model for Studying Functional Recovery from Stroke Pollak, J., Debsi, B., Mamer, L. E., Liu, S., Doyle, K. P., Jones, B., Shamloo, M., Buckwalter, M. LIPPINCOTT WILLIAMS & WILKINS. 2009: E214

  View details for Web of Science ID 000264709500531

• TGF-beta Production And Signaling After Stroke. Doyle, K. P., Mamer, L. E., Buckwalter, M. S. LIPPINCOTT WILLIAMS & WILKINS. 2009: E174

  View details for Web of Science ID 000264709500368

• Real-time Imaging of molecular signaling after stroke - Novel reporter mice for dissection of in vivo responses to TGF-beta 33rd International Stroke Conference Buckwalter, M. S., Luo, J., Debsi, B., Wyss-Coray, T. LIPPINCOTT WILLIAMS & WILKINS. 2008: 659–59

  View details for Web of Science ID 000252726100580

• Glia-dependent TGF-beta signaling, acting independently of the TH17 pathway, is critical for initiation of murine autoimmune encephalomyelitis JOURNAL OF CLINICAL INVESTIGATION Luo, J., Ho, P. P., Buckwalter, M. S., Hsu, T., Lee, L. Y., Zhang, H., Kim, D., Kim, S., Gambhir, S. S., Steinman, L., Wyss-Coray, T. 2007; 117 (11): 3306-3315

  Abstract

  Autoimmune encephalomyelitis, a mouse model for multiple sclerosis, is characterized by the activation of immune cells, demyelination of axons in the CNS, and paralysis. We found that TGF-beta1 synthesis in glial cells and TGF-beta-induced signaling in the CNS were activated several days before the onset of paralysis in mice with autoimmune encephalomyelitis. While early production of TGF-beta1 was observed in glial cells TGF-beta signaling was activated in neurons and later in infiltrating T cells in inflammatory lesions. Systemic treatment with a pharmacological inhibitor of TGF-beta signaling ameliorated the paralytic disease and reduced the accumulation of pathogenic T cells and expression of IL-6 in the CNS. Priming of peripheral T cells was not altered, nor was the generation of TH17 cells, indicating that this effect was directed within the brain, yet affected the immune system. These results suggest that early production of TGF-beta1 in the CNS creates a permissive and dangerous environment for the initiation of autoimmune inflammation, providing a rare example of the brain modulating the immune system. Importantly, inhibition of TGF-beta signaling may have benefits in the treatment of the acute phase of autoimmune CNS inflammation.

  View details for DOI 10.1172/JCI31763

  View details for PubMedID 17965773

• Immune Regulation of Regenerative Responses to Stroke: TGF-b1 and Neurogencsis Buckwalter, M. S., Yamane, M., Wyss-Coray, T. WILEY-LISS. 2007: 532

  View details for Web of Science ID 000251383300022

• Increased T cell recruitment to the CNS after amyloid beta(1-42) immunization in Alzheimer's mice overproducing transforming growth factor-beta 1 JOURNAL OF NEUROSCIENCE Buckwalter, M. S., Coleman, B. S., Buttini, M., Barbour, R., Schenk, D., Games, D., Seubert, P., Wyss-Coray, T. 2006; 26 (44): 11437-11441

  Abstract

  Immunotherapy targeting the amyloid beta (Abeta) peptide is a novel therapy under investigation for the treatment of Alzheimer's disease (AD). A clinical trial using Abeta(1-42) (AN1792) as the immunogen was halted as a result of development of meningoencephalitis in a small number of patients. The cytokine TGF-beta1 is a key modulator of immune responses that is increased in the brain in AD. We show here that local overexpression of TGF-beta1 in the brain increases both meningeal and parenchymal T lymphocyte number. Furthermore, TGF-beta1 overexpression in a mouse model for AD [amyloid precursor protein (APP) mice] leads to development of additional T cell infiltrates when mice were immunized at a young but not old age with AN1792. Notably, only mice overproducing both Abeta (APP mice) and TGF-beta1 experienced a rise in T lymphocyte number after immunization. One-third of infiltrating T cells were CD4 positive. We did not observe significant differences in B lymphocyte numbers in any of the genotypes or treatment groups. These results demonstrate that TGF-beta1 overproduction in the brain can promote T cell infiltration, in particular after Abeta(1-42) immunization. Likewise, levels of TGF-beta1 or other immune factors in brains of AD patients may influence the response to Abeta(1-42) immunization.

  View details for DOI 10.1523/JNEUROSCI.2436-06.2006

  View details for PubMedID 17079673

• Chronically increased transforming growth factor-beta 1 strongly inhibits hippocampal neurogenesis in aged mice AMERICAN JOURNAL OF PATHOLOGY Buckwalter, M. S., Yamane, M., Coleman, B. S., Ormerod, B. K., Chin, J. T., Palmer, T., Wyss-Coray, T. 2006; 169 (1): 154-164

  Abstract

  There is increasing evidence that hippocampal learning correlates strongly with neurogenesis in the adult brain. Increases in neurogenesis after brain injury also correlate with improved outcomes. With aging the capacity to generate new neurons decreases dramatically, both under normal conditions and after injury. How this decrease occurs is not fully understood, but we hypothesized that transforming growth factor (TGF)-beta1, a cell cycle regulator that rapidly increases after injury and with age, might play a role. We found that chronic overproduction of TGF-beta1 from astrocytes almost completely blocked the generation of new neurons in aged transgenic mice. Even young adult TGF-beta1 mice had 60% fewer immature, doublecortin-positive, hippocampal neurons than wild-type littermate controls. Bromodeoxyuridine labeling of dividing cells in 2-month-old TGF-beta1 mice confirmed this decrease in neuro-genesis and revealed a similar decrease in astrogenesis. Treatment of early neural progenitor cells with TGF-beta1 inhibited their proliferation. This strongly suggests that TGF-beta1 directly affects these cells before their differentiation into neurons and astrocytes. Together, these data show that TGF-beta1 is a potent inhibitor of hippocampal neural progenitor cell proliferation in adult mice and suggest that it plays a key role in limiting injury and age-related neurogenesis.

  View details for DOI 10.2353/ajpath.2006.051272

  View details for PubMedID 16816369

• Modelling neuroinflammatory phenotypes in vivo. Journal of neuroinflammation Buckwalter, M. S., Wyss-Coray, T. 2004; 1 (1): 10

  Abstract

  Inflammation of the central nervous system is an important but poorly understood part of neurological disease. After acute brain injury or infection there is a complex inflammatory response that involves activation of microglia and astrocytes and increased production of cytokines, chemokines, acute phase proteins, and complement factors. Antibodies and T lymphocytes may be involved in the response as well. In neurodegenerative disease, where injury is more subtle but consistent, the inflammatory response is continuous. The purpose of this prolonged response is unclear, but it is likely that some of its components are beneficial and others are harmful. Animal models of neurological disease can be used to dissect the specific role of individual mediators of the inflammatory response and assess their potential benefit. To illustrate this approach, we discuss how mutant mice expressing different levels of the cytokine transforming growth factor beta-1 (TGF-beta1), a major modulator of inflammation, produce important neuroinflammatory phenotypes. We then demonstrate how crosses of TGF-beta1 mutant mice with mouse models of Alzheimer's disease (AD) produced important new information on the role of inflammation in AD and on the expression of different neuropathological phenotypes that characterize this disease.

  View details for DOI 10.1186/1742-2094-1-10

  View details for PubMedID 15285805

  View details for PubMedCentralID PMC500895

• Chronically increased brain TGF beta-1 leads to hippocampal microgliosis and decreased hippocampal neurogenesis in adult mice Buckwalter, M. S., Yamane, M., Lee, S., Palmer, T. D., Wyss-Coray, T. ELSEVIER SCIENCE INC. 2004: S168

  View details for DOI 10.1016/S0197-4580(04)80566-9

  View details for Web of Science ID 000223058700564

• Modelling neuroinflammatory phenotypes in vivo JOURNAL OF NEUROINFLAMMATION Buckwalter, M. S., Wyss-Coray, T. 2004; 1

  Abstract

  Inflammation of the central nervous system is an important but poorly understood part of neurological disease. After acute brain injury or infection there is a complex inflammatory response that involves activation of microglia and astrocytes and increased production of cytokines, chemokines, acute phase proteins, and complement factors. Antibodies and T lymphocytes may be involved in the response as well. In neurodegenerative disease, where injury is more subtle but consistent, the inflammatory response is continuous. The purpose of this prolonged response is unclear, but it is likely that some of its components are beneficial and others are harmful. Animal models of neurological disease can be used to dissect the specific role of individual mediators of the inflammatory response and assess their potential benefit. To illustrate this approach, we discuss how mutant mice expressing different levels of the cytokine transforming growth factor beta-1 (TGF-beta1), a major modulator of inflammation, produce important neuroinflammatory phenotypes. We then demonstrate how crosses of TGF-beta1 mutant mice with mouse models of Alzheimer's disease (AD) produced important new information on the role of inflammation in AD and on the expression of different neuropathological phenotypes that characterize this disease.

  View details for DOI 10.1186/1742-2094-1-10

  View details for Web of Science ID 000208759200010

  View details for PubMedCentralID PMC500895

• Molecular and functional dissection of TGF-beta 1-induced cerebrovascular abnormalities in transgenic mice 3rd World Congress on Vascular Factors in Alzheimers Disease Buckwalter, M., Pepper, J. P., Gaertner, R. F., Von Euw, D., Lacombe, P., Wyss-Coray, T. NEW YORK ACAD SCIENCES. 2002: 87–95

  Abstract

  Cerebrovascular abnormalities, such as reduced blood flow, microvascular fibrosis, and cerebrovascular amyloid angiopathy, are prominent in Alzheimer's disease (AD). However, their etiology is poorly understood and it is unclear whether cerebrovascular changes contribute to functional impairments in the absence of neurodegeneration. In humans with AD, transforming growth factor-beta1 (TGF-beta1) mRNA levels in the midfrontal gyrus correlate positively with the relative degree of cerebrovascular amyloid deposition in that brain region, suggesting a possible role for TGF-beta1 in human cerebrovascular abnormalities. Transgenic mice overexpressing TGF-beta1 in astrocytes develop AD-like cerebrovascular abnormalities, including perivascular astrocytosis, microvascular basement membrane thickening, and accumulation of thioflavin S-positive amyloid in the absence of parenchymal degeneration. Mice overexpressing TGF-beta1 alone or in addition to human amyloid precursor protein (hAPP) show selective accumulation of human beta-amyloid (Abeta) in blood vessels and develop cerebral hemorrhages in old age. In 9-month-old TGF-beta1 transgenic mice, cerebral blood flow (CBF) in the limbic system was significantly less than in nontransgenic littermate controls. Aged TGF-beta1 mice also showed overall reduced cerebral glucose uptake (CGU) as a measure of brain activity. Thus, chronic overproduction of TGF-beta1 in the brain results in structural and functional impairments reminiscent of those in AD cases with amyloid angiopathy.

  View details for Web of Science ID 000179767000009

  View details for PubMedID 12480736

• Construction of a 3-Mb contig and partial transcript map of the central region of mouse chromosome 11 GENOMICS WATKINSCHOW, D. E., Douglas, K. R., Buckwalter, M. S., Probst, F. J., Camper, S. A. 1997; 45 (1): 147-157

  Abstract

  We report the establishment of a high-resolution genetic map, a physical map, and a partial transcript map of the Ames dwarf critical region on mouse chromosome 11. A contig of 24 YACs and 13 P1 clones has been assembled and spans approximately 3 Mb from Flt4 to Tcf7. A library of approximately 1000 putative transcript clones from the region was prepared using exon amplification and pituitary cDNA selection. Ten novel transcripts were partially characterized, including a member of the olfactory receptor family, an alpha-tubulin-related sequence, and a novel member of the cdc2/CDC28-like kinase family, Clk4. The location of Prop1, the gene responsible for Ames dwarfism, has been localized within the contig. This contig spans a region of mouse chromosome 11 that exhibits linkage conservation with human chromosome 5q23-q35. The strength of the genetic map and genomic resources for this region suggest that comparative DNA sequencing of this region could reveal the genes responsible for other mouse mutants and human genetic diseases.

  View details for Web of Science ID A1997YA72100018

  View details for PubMedID 9339371

• Genetic mapping of 21 genes on mouse chromosome 11 reveals disruptions in linkage conservation with human chromosome 5 GENOMICS WATKINSCHOW, D. E., Buckwalter, M. S., Newhouse, M. M., Lossie, A. C., Brinkmeier, M. L., Camper, S. A. 1997; 40 (1): 114-122

  Abstract

  We report a high-resolution genetic map of 21 genes on the central region of mouse Chr 11. These genes were mapped by segregation analysis of more than 1650 meioses from three interspecific backcrosses. The order of these genes in mouse was compared to the previously established gene order in human. Eighteen of the 21 genes map to human Chr 5, and 2 of the genes define a proximal border for the region of homology between mouse Chr 11 and human Chr 17. Our results indicate a minimum of four rearrangements within the 10-cM region of synteny homology between mouse Chr 11 and human Chr 5. In addition, the linkage conservation is disrupted by groups of genes that map to mouse Chrs 13 and 18. These data demonstrate that large regions of conserved linkage can contain numerous chromosomal microrearrangements that have occurred since the divergence of mouse and human ancestors. Comparison of the mouse and human maps with data for other species provides an emerging picture of mammalian chromosome evolution.

  View details for Web of Science ID A1997WJ33600015

  View details for PubMedID 9070927

• A FRAMESHIFT MUTATION IN THE MOUSE ALPHA(1) GLYCINE RECEPTOR GENE (GLRA1) RESULTS IN PROGRESSIVE NEUROLOGICAL SYMPTOMS AND JUVENILE DEATH HUMAN MOLECULAR GENETICS Buckwalter, M. S., Cook, S. A., Davisson, M. T., White, W. F., Camper, S. A. 1994; 3 (11): 2025-2030

  Abstract

  The neurologic mutant mouse, oscillator, is characterized by a fine motor tremor and muscle spasms that begin at 2 weeks of age and progressively worsen, resulting in death by 3 weeks of age. We report the localization of the oscillator mutation to the central region of mouse Chr 11, and demonstrate its allelism with spasmodic, a recessive viable neurological mutation which displays excessive startle. Oscillator is caused by a microdeletion in the gene coding for the alpha 1 subunit of the adult glycine receptor (Glra1). Glra1 assembles into a pentameric complex with the beta subunit of the glycine receptor (3 alpha (1)2 beta 5) to form a glycine-gated chloride channel. This receptor is the major adult glycine receptor, and the site of action of the poison strychnine. The oscillator deletion causes a frameshift resulting in loss of the highly conserved third cytoplasmic loop and fourth transmembrane domain of the protein. Membranes isolated from oscillator homozygote spinal cords display a 90% reduction in glycine-displaceable strychnine binding. This lack of ligand binding function confirms that oscillator is a complete loss of function allele. The oscillator mutation provides evidence that although at least four different alpha subunits exist for the glycine receptor, none of the other subunits can compensate for the loss of alpha 1 function. Mutations which impair GLRA1 function in humans have been shown to cause dominant familial startle disease. The identification of the oscillator mutation suggests that severe loss of function alleles in humans would result in prenatal or neonatal lethality.

  View details for Web of Science ID A1994PT23100017

  View details for PubMedID 7874121

• A MISSENSE MUTATION IN THE GENE ENCODING THE ALPHA(1) SUBUNIT OF THE INHIBITORY GLYCINE RECEPTOR IN THE SPASMODIC MOUSE NATURE GENETICS Ryan, S. G., Buckwalter, M. S., LYNCH, J. W., Handford, C. A., Segura, L., Shiang, R., Wasmuth, J. J., Camper, S. A., Schofield, P., OCONNELL, P. 1994; 7 (2): 131-135

  Abstract

  Hereditary hyperekplexia, an autosomal dominant neurologic disorder characterized by an exaggerated startle reflex and neonatal hypertonia, can be caused by mutations in the gene encoding the alpha 1 subunit of the inhibitory glycine receptor (GLRA1). Spasmodic (spd), a recessive neurologic mouse mutant, resembles hyperekplexia phenotypically, and the two disease loci map to homologous chromosomal regions. Here we describe a Glra1 missense mutation in spd that results in reduced agonist sensitivity in glycine receptors expressed in vitro. We conclude that spd is a murine homologue of hyperekplexia and that mutations in GLRA1/Glra1 can produce syndromes with different inheritance patterns.

  View details for Web of Science ID A1994NQ03700010

  View details for PubMedID 7920629

• GENETIC-MAPPING AND EVALUATION OF CANDIDATE GENES FOR SPASMODIC, A NEUROLOGICAL MOUSE MUTATION WITH ABNORMAL STARTLE RESPONSE GENOMICS Buckwalter, M. S., Testa, C. M., Noebels, J. L., Camper, S. A. 1993; 17 (2): 279-286

  Abstract

  Spasmodic (spd) is a recessive mouse mutation characterized by a prolonged righting reflex, fine motor tremor, leg clasping, and stiffness. Using an intersubspecific backcross that segregates spd, we placed spd on Chr 11 with the following gene order: Adra-1-3.8 +/- 2.1 cM-Pad-1-6.3 +/- 2.7-(spd, Anx-6, Csfgm, Glr-1, Il-3, Il-4, Il-5, Sparc)-9.1 +/- 2.4-D11 Mit5-2.2 +/- 1.5-Asgr-1. This localization eliminated the alpha 1-adrenergic receptor (Adra-1) and the alpha 1 and gamma 2 subunits of the GABAA receptor as candidate genes. Two other promising candidate genes, annexin VI (Anx-6) and a glutamate receptor (Glr-1), were mapped to within 2.1 cM of the spd locus. Although no recombination was observed between spd and Anx-6 or Glr-1, no evidence was obtained for a lesion in either gene. The presence of normal Anx-6 and Glr-1 mRNA transcripts was confirmed by Northern blot analysis, in situ hybridization, and DNA sequence analysis. The localization of Anx-6 and Glr-1 extends the known synteny homology between human chromosome 5q21-q31 and mouse Chr 11 and reveals the probable chromosomal location of the human counterpart to spd. Synteny homology and phenotypic similarities suggest that spasmodic mice may be a genetic model for the inherited human startle disease, hyperekplexia (STHE).

  View details for Web of Science ID A1993LP81500002

  View details for PubMedID 8406478

• LYSYL OXIDASE (LOX) MAPS BETWEEN GRL-1 AND ADRB-2 ON MOUSE CHROMOSOME-18 MAMMALIAN GENOME Lossie, A. C., Buckwalter, M. S., Camper, S. A. 1993; 4 (3): 177-178

  View details for Web of Science ID A1993KP76000007

  View details for PubMedID 8094989

• LOCALIZATION OF THE HUMAN CHROMOSOME-5Q GENES GABRA-1, GABRG-2, IL-4, IL-5, AND IRF-1 ON MOUSE CHROMOSOME-11 MAMMALIAN GENOME Buckwalter, M. S., Lossie, A. C., SCARLETT, L. M., Camper, S. A. 1992; 3 (10): 604-607

  View details for Web of Science ID A1992KX50600012

  View details for PubMedID 1358285

• MOUSE CHROMOSOME-11 6TH INTERNATIONAL WORKSHOP ON MOUSE GENOME MAPPING BUCHBERG, A. M., Buckwalter, M. S., Camper, S. A. SPRINGER VERLAG. 1992: S162–S181

  View details for Web of Science ID A1992JT43900011

  View details for PubMedID 1498430

• LOCALIZATION OF THE PANHYPOPITUITARY DWARF MUTATION (DF) ON MOUSE CHROMOSOME-11 IN AN INTERSUBSPECIFIC BACKCROSS GENOMICS Buckwalter, M. S., Katz, R. W., Camper, S. A. 1991; 10 (3): 515-526

  Abstract

  Ames dwarf (df) is an autosomal recessive mutation characterized by severe dwarfism and infertility. This mutation provides a mouse model for panhypopituitarism. The dwarf phenotype results from failure in the differentiation of the cells which produce growth hormone, prolactin, and thyroid stimulating hormone. Using the backcross (DF/B-df/df X CASA/Rk) X DF/B-df/df, we confirmed the assignment of df to mouse chromosome 11 and demonstrated recombination between df and the growth hormone gene. This backcross is an invaluable resource for screening candidate genes for the df mutation. The df locus maps to less than 1 cM distal to Pad-1 (0.85 +/- 0.85 cM). Two new genes localized on mouse chromosome 11, Rpo2-1, and Edp-1, map to a region of conserved synteny with human chromosome 17. The localization of the alpha 1 adrenergic receptor, Adra-1, extends a known region of synteny conservation between mouse chromosome 11 and human chromosome 5, and suggests that a human counterpart to df would map to human chromosome 5.

  View details for Web of Science ID A1991FQ64000001

  View details for PubMedID 1889803

• Mouse chromosome 11. Mammalian genome BUCHBERG, A. M., Moskow, J. J., Buckwalter, M. S., Camper, S. A. 1991; 1: S158-91

  View details for PubMedID 1799798

• BACTERIOPHAGE-MU SITES REQUIRED FOR TRANSPOSITION IMMUNITY PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Darzins, A., KENT, N. E., Buckwalter, M. S., CASADABAN, M. J. 1988; 85 (18): 6826-6830

  Abstract

  Plasmids with bacteriophage Mu sequences receive additional Mu insertions 20-700 times less frequently than plasmids without Mu sequences. The Mu sites required for this transposition immunity were mapped near each end, either of which was sufficient. The left site was between 127 and 203 base pairs from the left end, and the right site was between 22 and 93 base pairs from the right end. These sequences include the innermost but not the outermost of the three binding sites for the Mu A transposition protein at each end of Mu. Transposition immunity was cis-acting and independent of its location on a target plasmid. An additional copy of an immunity site reduced transposition a factor of 10 further. Transposition immunity was seen both during full phage lytic growth, with all the bacteriophage Mu genes, and during normal cellular growth, with a mini-Mu element containing only the Mu c and ner regulatory and A and B transposition genes.

  View details for Web of Science ID A1988Q138700053

  View details for PubMedID 2842794

  View details for PubMedCentralID PMC282071