- Anatomic Pathology
- Molecular Pathology
Education & Certifications
Board Certification: Molecular Genetic Pathology, American Board of Pathology (2013)
Fellowship:Stanford University School of Medicine (2013) CA
Fellowship:Stanford Hospital and Clinics (2012) CA
Residency:Stanford Hospital and Clinics (2011) CA
Medical Education:Stanford University School of Medicine (2009) CA
Board Certification: Anatomic Pathology, American Board of Pathology (2012)
Next-Generation Molecular Testing of Newborn Dried Blood Spots for Cystic Fibrosis
JOURNAL OF MOLECULAR DIAGNOSTICS
2016; 18 (2): 267-282
Newborn screening for cystic fibrosis enables early detection and management of this debilitating genetic disease. Implementing comprehensive CFTR analysis using Sanger sequencing as a component of confirmatory testing of all screen-positive newborns has remained impractical due to relatively lengthy turnaround times and high cost. Here, we describe CFseq, a highly sensitive, specific, rapid (<3 days), and cost-effective assay for comprehensive CFTR gene analysis from dried blood spots, the common newborn screening specimen. The unique design of CFseq integrates optimized dried blood spot sample processing, a novel multiplex amplification method from as little as 1 ng of genomic DNA, and multiplex next-generation sequencing of 96 samples in a single run to detect all relevant CFTR mutation types. Sequence data analysis utilizes publicly available software supplemented by an expert-curated compendium of >2000 CFTR variants. Validation studies across 190 dried blood spots demonstrated 100% sensitivity and a positive predictive value of 100% for single-nucleotide variants and insertions and deletions and complete concordance across the polymorphic poly-TG and consecutive poly-T tracts. Additionally, we accurately detected both a known exon 2,3 deletion and a previously undetected exon 22,23 deletion. CFseq is thus able to replace all existing CFTR molecular assays with a single robust, definitive assay at significant cost and time savings and could be adapted to high-throughput screening of other inherited conditions.
View details for DOI 10.1016/j.jmoldx.2015.11.005
View details for Web of Science ID 000370997200013
View details for PubMedID 26847993
Rapid, High-Quality, Cost-Effective, Comprehensive and Expandable Targeted Next-Generation Sequencing Assay for Inherited Heart Diseases
2015; 117 (7): 603-611
Thousands of mutations across more than 50 genes have been implicated in inherited cardiomyopathies. However, options for sequencing this rapidly evolving gene set are limited as many sequencing services and off-the-shelf kits suffer from slow turnaround, inefficient capture of genomic DNA, and/or high cost. Furthermore, customization of these assays to cover emerging targets and to suit individual needs is often expensive and time-consuming.We sought to develop a custom high throughput, clinical-grade next generation sequencing (NGS) assay for detecting cardiac disease gene mutations with improved accuracy, flexibility, turnaround, and cost.We employed double-stranded probes (complementary long "padlock" probes (cLPPs)), an inexpensive and customizable capture technology, to efficiently capture and amplify the entire coding region and flanking intronic and regulatory sequences of 88 genes and 40 microRNAs (miRNA) associated with inherited cardiomyopathies, congenital heart disease (CHD), and cardiac development. Multiplexing 11 samples per sequencing run resulted in a mean base coverage of 420, of which 97% had >20X coverage and >99% were concordant with known heterozygous single nucleotide polymorphisms (SNPs). The assay correctly detected germline variants in 24 individuals and revealed several polymorphic regions in miR-499. Total run time was three days at an approximate cost of $100 per sample.Accurate, high throughput detection of mutations across numerous cardiac genes is achievable with cLPP technology. Moreover, this format allows facile insertion of additional probes as more cardiomyopathy and CHD genes are discovered, giving researchers a powerful new tool for DNA mutation detection and discovery.
View details for DOI 10.1161/CIRCRESAHA.115.306723
View details for Web of Science ID 000360967000006
- Alterations in DNA methylation may be the key to early detection and treatment of schistosomal bladder cancer. PLoS neglected tropical diseases 2015; 9 (6)
Macrophages are required for host survival in experimental urogenital schistosomiasis.
2015; 29 (1): 193-207
Urogenital schistosomiasis, Schistosoma haematobium worm infection, afflicts millions of people with egg-triggered, fibrotic bladder granulomata. Despite the significant global impact of urogenital schistosomiasis, the mechanisms of bladder granulomogenesis and fibrosis are ill defined due to the prior lack of tractable animal models. We combined a mouse model of urogenital schistosomiasis with macrophage-depleting liposomal clodronate (LC) to define how macrophages mediate bladder granulomogenesis and fibrosis. Mice were injected with eggs purified from infected hamsters or vehicle prepared from uninfected hamster tissues (xenoantigen and injection trauma control). Empty liposomes were controls for LC: 1) LC treatment resulted in fewer bladder egg granuloma-infiltrating macrophages, eosinophils, and T and B cells, lower bladder and serum levels of eotaxin, and higher bladder concentrations of IL-1α and chemokines (in a time-dependent fashion), confirming that macrophages orchestrate leukocyte infiltration of the egg-exposed bladder; 2) macrophage-depleted mice exhibited greater weight loss and bladder hemorrhage postegg injection; 3) early LC treatment postegg injection resulted in profound decreases in bladder fibrosis, suggesting differing roles for macrophages in fibrosis over time; and 4) LC treatment also led to egg dose-dependent mortality, indicating that macrophages prevent death from urogenital schistosomiasis. Thus, macrophages are a potential therapeutic target for preventing or treating the bladder sequelae of urogenital schistosomiasis.-Fu, C.-L., Odegaard, J. I., Hsieh, M. H. Macrophages are required for host survival in experimental urogenital schistosomiasis.
View details for DOI 10.1096/fj.14-259572
View details for PubMedID 25351984
- Identification of Orai1 Channel Inhibitors by Using Minimal Functional Domains to Screen Small Molecule Microarrays CHEMISTRY & BIOLOGY 2014; 21 (10): 1278-1292
- Immune responses to Schistosoma haematobium infection PARASITE IMMUNOLOGY 2014; 36 (9): 428-438
Identification of recurrent SMO and BRAF mutations in ameloblastomas.
2014; 46 (7): 722-725
Here we report the discovery of oncogenic mutations in the Hedgehog and mitogen-activated protein kinase (MAPK) pathways in over 80% of ameloblastomas, locally destructive odontogenic tumors of the jaw, by genomic analysis of archival material. Mutations in SMO (encoding Smoothened, SMO) are common in ameloblastomas of the maxilla, whereas BRAF mutations are predominant in tumors of the mandible. We show that a frequently occurring SMO alteration encoding p.Leu412Phe is an activating mutation and that its effect on Hedgehog-pathway activity can be inhibited by arsenic trioxide (ATO), an anti-leukemia drug approved by the US Food and Drug Administration (FDA) that is currently in clinical trials for its Hedgehog-inhibitory activity. In a similar manner, ameloblastoma cells harboring an activating BRAF mutation encoding p.Val600Glu are sensitive to the BRAF inhibitor vemurafenib. Our findings establish a new paradigm for the diagnostic classification and treatment of ameloblastomas.
View details for DOI 10.1038/ng.2986
View details for PubMedID 24859340
- Identification of recurrent SMO and BRAF mutations in ameloblastomas NATURE GENETICS 2014; 46 (7): 722-725
A new mouse model for female genital schistosomiasis.
PLoS neglected tropical diseases
2014; 8 (5)
Over 112 million people worldwide are infected with Schistosoma haematobium, one of the most prevalent schistosome species affecting humans. Female genital schistosomiasis (FGS) occurs when S. haematobium eggs are deposited into the female reproductive tract by adult worms, which can lead to pelvic pain, vaginal bleeding, genital disfigurement and infertility. Recent evidence suggests co-infection with S. haematobium increases the risks of contracting sexually transmitted diseases such as HIV. The associated mechanisms remain unclear due to the lack of a tractable animal model. We sought to create a mouse model conducive to the study of immune modulation and genitourinary changes that occur with FGS.To model FGS in mice, we injected S. haematobium eggs into the posterior vaginal walls of 30 female BALB/c mice. A control group of 20 female BALB/c mice were injected with uninfected LVG hamster tissue extract. Histology, flow cytometry and serum cytokine levels were assessed at 2, 4, 6, and 8 weeks post egg injection. Voiding studies were performed at 1 week post egg injection.Vaginal wall injection with S. haematobium eggs resulted in synchronous vaginal granuloma development within 2 weeks post-egg injection that persisted for at least 6 additional weeks. Flow cytometric analysis of vaginal granulomata revealed infiltration by CD4+ T cells with variable expression of the HIV co-receptors CXCR4 and CCR5. Granulomata also contained CD11b+F4/80+ cells (macrophages and eosinophils) as well as CXCR4+MerTK+ macrophages. Strikingly, vaginal wall-injected mice featured significant urinary frequency despite the posterior vagina being anatomically distant from the bladder. This may represent a previously unrecognized overactive bladder response to deposition of schistosome eggs in the vagina.We have established a new mouse model that could potentially enable novel studies of genital schistosomiasis in females. Ongoing studies will further explore the mechanisms by which HIV target cells may be drawn into FGS-associated vaginal granulomata.
View details for DOI 10.1371/journal.pntd.0002825
View details for PubMedID 24786606
- Cellular origin of bladder neoplasia and tissue dynamics of its progression to invasive carcinoma NATURE CELL BIOLOGY 2014; 16 (5): 469-U194
Cellular origin of bladder neoplasia and tissue dynamics of its progression to invasive carcinoma.
Nature cell biology
2014; 16 (5): 469-478
Understanding how malignancies arise within normal tissues requires identification of the cancer cell of origin and knowledge of the cellular and tissue dynamics of tumour progression. Here we examine bladder cancer in a chemical carcinogenesis model that mimics muscle-invasive human bladder cancer. With no prior bias regarding genetic pathways or cell types, we prospectively mark or ablate cells to show that muscle-invasive bladder carcinomas arise exclusively from Sonic hedgehog (Shh)-expressing stem cells in basal urothelium. These carcinomas arise clonally from a single cell whose progeny aggressively colonize a major portion of the urothelium to generate a lesion with histological features identical to human carcinoma in situ. Shh-expressing basal cells within this precursor lesion become tumour-initiating cells, although Shh expression is lost in subsequent carcinomas. We thus find that invasive carcinoma is initiated from basal urothelial stem cells but that tumour cell phenotype can diverge significantly from that of the cancer cell of origin.
View details for DOI 10.1038/ncb2956
View details for PubMedID 24747439
- Transplanted terminally differentiated induced pluripotent stem cells are accepted by immune mechanisms similar to self-tolerance NATURE COMMUNICATIONS 2014; 5
- A New Mouse Model for Female Genital Schistosomiasis PLOS NEGLECTED TROPICAL DISEASES 2014; 8 (5)
Transplanted terminally differentiated induced pluripotent stem cells are accepted by immune mechanisms similar to self-tolerance.
2014; 5: 3903-?
The exact nature of the immune response elicited by autologous-induced pluripotent stem cell (iPSC) progeny is still not well understood. Here we show in murine models that autologous iPSC-derived endothelial cells (iECs) elicit an immune response that resembles the one against a comparable somatic cell, the aortic endothelial cell (AEC). These cells exhibit long-term survival in vivo and prompt a tolerogenic immune response characterized by elevated IL-10 expression. In contrast, undifferentiated iPSCs elicit a very different immune response with high lymphocytic infiltration and elevated IFN-γ, granzyme-B and perforin intragraft. Furthermore, the clonal structure of infiltrating T cells from iEC grafts is statistically indistinguishable from that of AECs, but is different from that of undifferentiated iPSC grafts. Taken together, our results indicate that the differentiation of iPSCs results in a loss of immunogenicity and leads to the induction of tolerance, despite expected antigen expression differences between iPSC-derived versus original somatic cells.
View details for DOI 10.1038/ncomms4903
View details for PubMedID 24875164
Aortic wall thickness: an independent risk factor for aortic dissection?
journal of heart valve disease
2014; 23 (1): 17-24
Aortic aneurysm size is known to portend a higher likelihood of aortic complications in patients with connective tissue disorders (CTD), but other objective tools are needed to determine which patients are at greatest risk of dissection, especially those which reflect the structural integrity and strength of the aortic wall.The aortic wall pathology was evaluated in CTD patients with and without acute aortic dissection to identify parameters that affect the risk of dissection. A retrospective review was performed of aneurysm pathology from patients with Marfan syndrome (MFS; n = 53) without dissection undergoing prophylactic aortic root surgery, and acute type A aortic dissection patients (AAAoD; n = 16). Patients without a cardiovascular cause of death (n = 19) served as controls. The minimal aortic medial wall thickness was measured, and medial myxoid degeneration (MMD) and the degree of elastin loss and fragmentation were graded.The mean minimal aortic wall thickness was 1,625 +/- 364 microm in controls, and 703 +/- 256 microm and 438 +/- 322 microm for MFS and AAAoD patients, respectively. Aortic root diameters did not correlate with aortic wall thickness. A comparison of aortic medial thickness showed that the media was significantly thinner among acute dissection patients than either elective surgical patients (p = 0.02) or controls (p < 0.001). Aortic size, degree of MMD, and elastin loss did not vary significantly between CTD patients.A diminished aortic wall medial thickness may be linked to aortic dissection. High-resolution imaging techniques in the future may lead to the morphological assessment of aortic medial wall thickness in vivo becoming a reality which, in theory, could provide a more refined risk prognostication for acute aortic dissection.
View details for PubMedID 24779324
Costimulation-Adhesion Blockade Is Superior to Cyclosporine A and Prednisone Immunosuppressive Therapy for Preventing Rejection of Differentiated Human Embryonic Stem Cells Following Transplantation
2013; 31 (11): 2354-2363
Rationale: Human embryonic stem cell (hESC) derivatives are attractive candidates for therapeutic use. The engraftment and survival of hESC derivatives as xenografts or allografts require effective immunosuppression to prevent immune cell infiltration and graft destruction. Objective: To test the hypothesis that a short-course, dual-agent regimen of two costimulation-adhesion blockade agents can induce better engraftment of hESC derivatives compared to current immunosuppressive agents. Methods and Results: We transduced hESCs with a double fusion reporter gene construct expressing firefly luciferase (Fluc) and enhanced green fluorescent protein, and differentiated these cells to endothelial cells (hESC-ECs). Reporter gene expression enabled longitudinal assessment of cell engraftment by bioluminescence imaging. Costimulation-adhesion therapy resulted in superior hESC-EC and mouse EC engraftment compared to cyclosporine therapy in a hind limb model. Costimulation-adhesion therapy also promoted robust hESC-EC and hESC-derived cardiomyocyte survival in an ischemic myocardial injury model. Improved hESC-EC engraftment had a cardioprotective effect after myocardial injury, as assessed by magnetic resonance imaging. Mechanistically, costimulation-adhesion therapy is associated with systemic and intragraft upregulation of T-cell immunoglobulin and mucin domain 3 (TIM3) and a reduced proinflammatory cytokine profile. Conclusions: Costimulation-adhesion therapy is a superior alternative to current clinical immunosuppressive strategies for preventing the post-transplant rejection of hESC derivatives. By extending the window for cellular engraftment, costimulation-adhesion therapy enhances functional preservation following ischemic injury. This regimen may function through a TIM3-dependent mechanism. Stem Cells 2013;31:2354-2363.
View details for DOI 10.1002/stem.1501
View details for Web of Science ID 000327025600007
Excimer Laser-Assisted Removal of Embedded Inferior Vena Cava Filters A Single-Center Prospective Study
2013; 6 (5): 560-566
Although chronically implanted inferior vena cava filters may result in filter-related morbidity, there is currently no routine option for removing such filters when they become firmly embedded along the vena cava endothelium.During a 3-year period, 100 consecutive patients were prospectively enrolled in a single-center study. There were 42 men and 58 women (mean age, 46 years; limits, 18-76 years). Retrieval indications included filter-related acute inferior vena cava thrombosis, chronic inferior vena cava occlusion, and pain from retroperitoneal or bowel penetration. Filter retrieval was also performed to prevent risks from prolonged implantation and to potentially eliminate the need for lifelong anticoagulation. After standard methods failed, photothermal tissue ablation was attempted with a laser sheath powered by a 308-nm xenon chloride excimer laser. Applied forces were recorded with a digital tension meter before and during laser activation. Laser-assisted retrieval was successful in 98.0% (95% confidence interval [CI], 93.0%-99.8%) with mean implantation of 855 days (limits, 37-6663 days; >18 years). The following filter types were encountered in this study: Günther-Tulip (n=34), Celect (n=12), Option (n=17), Optease (n=20, 1 failure), TrapEase (n=6, 1 failure), Simon-Nitinol (n=1), 12F Stainless Steel Greenfield (n=4), and Titanium Greenfield (n=6). The average force during failed standard retrievals was 7.2 versus 4.6 pounds during laser-assisted retrievals (P<0.0001). The major complication rate was 3.0% (95% CI, 0.6%-8.5%), the minor complication rate was 7.0% (95% CI, 0.3%-13.9%), and there were 4 adverse events (2 coagulopathic hemorrhages, 1 renal infarction, and 1 cholecystitis; 4.0%; 95% CI, 1.1%-9.9%) at mean follow-up of 500 days (limits, 84-1079 days). Scar tissue ablation was histologically confirmed in 96.0% (95% CI, 89.9%-98.9%). Successful retrieval allowed cessation of anticoagulation in 30 of 30 (100%) patients and alleviated morbidity in 23 of 24 patients (96%).Excimer laser-assisted removal is effective in removing embedded inferior vena cava filters refractory to standard retrieval and high force. This method can be safely used to prevent and alleviate filter-related morbidity.http://www.clinicaltrials.gov. Unique identifier: NCT01158482.
View details for DOI 10.1161/CIRCINTERVENTIONS.113.000665
View details for Web of Science ID 000329923100014
View details for PubMedID 24065445
Eosinophils secrete IL-4 to facilitate liver regeneration.
Proceedings of the National Academy of Sciences of the United States of America
2013; 110 (24): 9914-9919
The liver is a central organ for the synthesis and storage of nutrients, production of serum proteins and hormones, and breakdown of toxins and metabolites. Because the liver is susceptible to toxin- or pathogen-mediated injury, it maintains a remarkable capacity to regenerate by compensatory growth. Specifically, in response to injury, quiescent hepatocytes enter the cell cycle and undergo DNA replication to promote liver regrowth. Despite the elucidation of a number of regenerative factors, the mechanisms by which liver injury triggers hepatocyte proliferation are incompletely understood. We demonstrate here that eosinophils stimulate liver regeneration after partial hepatectomy and toxin-mediated injury. Liver injury results in rapid recruitment of eosinophils, which secrete IL-4 to promote the proliferation of quiescent hepatocytes. Surprisingly, signaling via the IL-4Rα in macrophages, which have been implicated in tissue repair, is dispensable for hepatocyte proliferation and liver regrowth after injury. Instead, IL-4 exerts its proliferative actions via IL-4Rα in hepatocytes. Our findings thus provide a unique mechanism by which eosinophil-derived IL-4 stimulates hepatocyte proliferation in regenerating liver.
View details for DOI 10.1073/pnas.1304046110
View details for PubMedID 23716700
Complex retrieval of fractured, embedded, and penetrating inferior vena cava filters: a prospective study with histologic and electron microscopic analysis.
Journal of vascular and interventional radiology
2013; 24 (5): 622-630 e1
To evaluate clinical outcomes, characterize adherent tissue, and analyze inferior vena cava (IVC) filter fractures in patients undergoing complex retrieval for management of filter-related complications. To elucidate mechanisms of filter fracture by radiographic and electron microscopic (EM) evaluation.Over 2.5 years, 50 consecutive patients with fractured and/or penetrating filter components were prospectively enrolled into a single-center study. There were 19 men and 31 women (mean age, 42 y; range, 15-73 y). All patients underwent complex filter retrieval after failure of standard methods, and retrieval indications along with resultant clinical outcomes were evaluated. Specimens with adherent tissue underwent histologic analysis, and all fractured components were studied with EM.Retrieval was successful in all 50 cases (mean implantation, 815 d; range, 20-2,599 d) among the following filters: G2X (n = 23),G2 (n = 9), Eclipse (n = 3), Recovery (n = 4), ALN (n = 1), Celect (n = 7), OptEase (n = 2), and Simon Nitinol (n = 1). Mean indwell time in fractured filters (n = 31) was 1,082 days, versus 408 days in nonfractured filters (n = 19; P = .00169). Neointimal hyperplasia/fibrosis was seen in 46 of 48 specimens with adherent tissue (96%). Among 61 fractured components from conical filters, 35 had extravascular penetration whereas 26 remained intravascular (11 free-floating in IVC, 15 embolized centrally), and EM revealed fracture modes of high-cycle fatigue (n = 53), overload (n = 6), and indeterminate (n = 2). Following retrieval, previously prescribed lifelong anticoagulation was discontinued in 30 of 31 patients (97%). Filter-related symptoms from IVC occlusion, component embolization, and penetration-induced abdominal pain, duodenal injury, and/or small-bowel volvulus were alleviated in all 26 cases (100%). There were no long-term complications at a mean follow-up of 371 days (range, 67-878 d).The risk of filter fracture increases after 408 days (ie,>1 y) of implantation and is associated with symptomatic extravascular penetration and/or intravascular embolization. Complex methods can be used to safely remove these devices, alleviate filter-related morbidity, and allow cessation of anticoagulation.
View details for DOI 10.1016/j.jvir.2013.01.008
View details for PubMedID 23523157
- Complex Retrieval of Fractured, Embedded, and Penetrating Inferior Vena Cava Filters: A Prospective Study with Histologic and Electron Microscopic Analysis JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY 2013; 24 (5): 622-630
The immune system as a sensor of the metabolic state.
2013; 38 (4): 644-654
Mammals possess a remarkable ability to maintain and defend a constant internal milieu against diverse environmental threats. Unsurprisingly, the two systems tasked with these duties, metabolism and immunity, have evolved to share a common modular architecture that allows extensive bidirectional communication and coordination. Indeed, recent observations have highlighted numerous functionally critical immune regulatory modules located within diverse metabolic circuits. In this review, we discuss the architectural commonality between immunity and metabolism and highlight how these two primordially disparate systems leverage shared regulatory axes to coordinate metabolic physiology under conditions of normality and chronic overnutrition. Such an integrated perspective both advances our understanding of basic physiology and highlights potential opportunities for therapeutic intervention in metabolic dysfunction.
View details for DOI 10.1016/j.immuni.2013.04.001
View details for PubMedID 23601683
Pleiotropic Actions of Insulin Resistance and Inflammation in Metabolic Homeostasis
2013; 339 (6116): 172-177
Metabolism and immunity are inextricably linked both to each other and to organism-wide function, allowing mammals to adapt to changes in their internal and external environments. In the modern context of obesogenic diets and lifestyles, however, these adaptive responses can have deleterious consequences. In this Review, we discuss the pleiotropic actions of inflammation and insulin resistance in metabolic homeostasis and disease. An appreciation of the adaptive context in which these responses arose is useful for understanding their pathogenic actions in disease.
View details for DOI 10.1126/science.1230721
View details for Web of Science ID 000313328200036
View details for PubMedID 23307735
Adipose Tissue Macrophages: Amicus adipem?
2013; 18 (6): 767-8
Chronic overnutrition drives complex adaptations within both professional metabolic and bystander tissues that, despite intense investigation, are still poorly understood. Xu et al. (2013) now describe the unexpected ability of adipose tissue macrophages to buffer lipids released from obese adipocytes in a manner independent of inflammatory macrophage activation.
View details for DOI 10.1016/j.cmet.2013.11.011
View details for PubMedID 24315364
- Fat's Immune Sentinels SCIENTIST 2012; 26 (12): 30-35
Transcriptional Profiling of the Bladder in Urogenital Schistosomiasis Reveals Pathways of Inflammatory Fibrosis and Urothelial Compromise
PLOS NEGLECTED TROPICAL DISEASES
2012; 6 (11)
Urogenital schistosomiasis, chronic infection by Schistosoma haematobium, affects 112 million people worldwide. S. haematobium worm oviposition in the bladder wall leads to granulomatous inflammation, fibrosis, and egg expulsion into the urine. Despite the global impact of urogenital schistosomiasis, basic understanding of the associated pathologic mechanisms has been incomplete due to the lack of suitable animal models. We leveraged our recently developed mouse model of urogenital schistosomiasis to perform the first-ever profiling of the early molecular events that occur in the bladder in response to the introduction of S. haematobium eggs. Microarray analysis of bladders revealed rapid, differential transcription of large numbers of genes, peaking three weeks post-egg administration. Many differentially transcribed genes were related to the canonical Type 2 anti-schistosomal immune response, as reflected by the development of egg-based bladder granulomata. Numerous collagen and metalloproteinase genes were differentially transcribed over time, revealing complex remodeling and fibrosis of the bladder that was confirmed by Masson's Trichrome staining. Multiple genes implicated in carcinogenesis pathways, including vascular endothelial growth factor-, oncogene-, and mammary tumor-related genes, were differentially transcribed in egg-injected bladders. Surprisingly, junctional adhesion molecule, claudin and uroplakin genes, key components for maintaining the urothelial barrier, were globally suppressed after bladder exposure to eggs. This occurred in the setting of urothelial hyperplasia and egg shedding in urine. Thus, S. haematobium egg expulsion is associated with intricate modulation of the urothelial barrier on the cellular and molecular level. Taken together, our findings have important implications for understanding host-parasite interactions and carcinogenesis in urogenital schistosomiasis, and may provide clues for novel therapeutic strategies.
View details for DOI 10.1371/journal.pntd.0001912
View details for Web of Science ID 000311888900039
View details for PubMedID 23209855
Comparison of the acute inflammatory response of two commercial platelet-rich plasma systems in healthy rabbit tendons.
American journal of sports medicine
2012; 40 (6): 1274-1281
Numerous studies have shown platelet-rich plasma (PRP) preparations differ with respect to the inclusion of certain blood components, which may affect the host's cellular response.This study evaluated the inflammatory effect of Biomet GPS III leukocyte-rich PRP (LR-PRP) versus MTF Cascade leukocyte-poor PRP (LP-PRP) after intratendinous injection in an animal model. The authors anticipated that LR-PRP would incite a greater acute inflammatory response than LP-PRP.Controlled laboratory study.A total of 17 skeletally mature New Zealand White rabbits were tested. In all cases, healthy patellar tendons were treated. In the control animals, one patellar tendon was injected with 2 mL autologous whole blood, and the other was injected with 2 mL sterile saline. Seven total tendons were injected with whole blood, and 7 tendons were injected with saline. In the experimental animals, one patellar tendon was injected with 2 mL LR-PRP, and the other was injected with 2 mL LP-PRP. Ten tendons were injected with LR-PRP, and 10 tendons were injected with LP-PRP. Animals were euthanized at 5 or 14 days after injection. Tendons were harvested and stained using hematoxylin and eosin and scored semi-quantitatively for total white blood cells (WBCs), mononuclear cells (macrophages and lymphocytes), polymorphonuclear cells (PMNs), vascularity, fiber structure, and fibrosis.At 5 days after injection, tendons treated with LR-PRP had significantly greater overall tendon scores (6.3 ± 1.79 vs 1.8 ± 1.64, P = .012), as well as mean scores for fiber structure (1.4 ± 0.22 vs 0.50 ± 0.50, P = .012), denoting disrupted composition, total WBCs (1.1 ± 0.89 vs 0.10 ± 0.22, P = .014), mononuclear cells (macrophages and lymphocytes) (0.80 ± 0.45 vs 0.10 ± 0.22, P = .014), vascularity (1.7 ± 0.27 vs 0.80 ± 0.16, P = .008), and fibrosis (1.0 ± 0.35 vs 0.3 ± 0.45, P = .037) compared with tendons treated with LP-PRP. Otherwise, there were no significant differences in mononuclear cells (P = .590), PMN cells (P = 1.00), total WBCs (P = .811), vascularity (P = .650), or total tendon score (P = .596) in any of the treatment groups at 14 days.Compared with leukocyte-poor Cascade PRP, leukocyte-rich GPS III PRP causes a significantly greater acute inflammatory response at 5 days after injection. There is no significant difference in the inflammatory response or cellularity regardless of the injection type at 14 days after intratendinous injection.Platelet-rich plasma injections are frequently prepared using commercial systems and are administered for clinical treatment of chronic tendinopathy. It is important to characterize the cellular responses elucidated by different injection preparations to further understand their effect on tissue healing and aid clinical decision making. Future investigations are necessary to apply these findings to the clinical setting.
View details for DOI 10.1177/0363546512442334
View details for PubMedID 22495144
Connecting Type 1 and Type 2 Diabetes through Innate Immunity
COLD SPRING HARBOR PERSPECTIVES IN BIOLOGY
2012; 4 (4)
The escalating epidemic of obesity has driven the prevalence of both type 1 and 2 diabetes mellitus to historically high levels. Chronic low-grade inflammation, which is present in both type 1 and type 2 diabetics, contributes to the pathogenesis of insulin resistance. The accumulation of activated innate immune cells in metabolic tissues results in release of inflammatory mediators, in particular, IL-1β and TNFα, which promote systemic insulin resistance and β-cell damage. In this article, we discuss the central role of innate immunity and, in particular, the macrophage in insulin sensitivity and resistance, β-cell damage, and autoimmune insulitis. We conclude with a discussion of the therapeutic implications of this integrated understanding of diabetic pathology.
View details for DOI 10.1101/cshperspect.a007724
View details for Web of Science ID 000302553400007
A Novel Mouse Model of Schistosoma haematobium Egg-Induced Immunopathology
2012; 8 (3)
Schistosoma haematobium is the etiologic agent for urogenital schistosomiasis, a major source of morbidity and mortality for more than 112 million people worldwide. Infection with S. haematobium results in a variety of immunopathologic sequelae caused by parasite oviposition within the urinary tract, which drives inflammation, hematuria, fibrosis, bladder dysfunction, and increased susceptibility to urothelial carcinoma. While humans readily develop urogenital schistosomiasis, the lack of an experimentally-tractable model has greatly impaired our understanding of the mechanisms that underlie this important disease. We have developed an improved mouse model of S. haematobium urinary tract infection that recapitulates several aspects of human urogenital schistosomiasis. Following microinjection of purified S. haematobium eggs into the bladder wall, mice consistently develop macrophage-rich granulomata that persist for at least 3 months and pass eggs in their urine. Importantly, egg-injected mice also develop urinary tract fibrosis, bladder dysfunction, and various urothelial changes morphologically reminiscent of human urogenital schistosomiasis. As expected, S. haematobium egg-induced immune responses in the immediate microenvironment, draining lymph nodes, and systemic circulation are associated with a Type 2-dominant inflammatory response, characterized by high levels of interleukin-4, eosinophils, and IgE. Taken together, our novel mouse model may help facilitate a better understanding of the unique pathophysiological mechanisms of epithelial dysfunction, tissue fibrosis, and oncogenesis associated with urogenital schistosomiasis.
View details for DOI 10.1371/journal.ppat.1002605
View details for Web of Science ID 000302225600051
View details for PubMedID 22479181
Bilateral Thoracic Endometriosis Affecting the Lung and Diaphragm
JSLS-JOURNAL OF THE SOCIETY OF LAPAROENDOSCOPIC SURGEONS
2012; 16 (1): 140-142
Endometriosis of the lung and the diaphragm is rare. Patients may present with symptoms such as shortness of breath, chest pain, and shoulder pain or they may be asymptomatic. Of note, there have been few reports of bilateral catamenial disease, and no reports, to our knowledge, of bilateral pathology proven pulmonary parenchymal endometriosis.A 43-year-old with stage IV endometriosis and large leiomyoma underwent a laparoscopic hysterectomy and treatment of endometrial lesions in 2005. In March and April of 2011, she presented with bilateral pneumothoraces. She subsequently underwent video-assisted thoracoscopy as well as resection and fulguration of bilateral lung and diaphragmatic endometriosis. Pathology confirmed endometrial implants in the lung parenchyma bilaterally.Catamenial pneumothorax is the most common presentation of thoracic endometriosis. However, bilateral catamenial pneumothoraces are rare. To the best of our knowledge, this case reflects the first report of pathology proven bilateral lung and diaphragm endometriosis.
View details for DOI 10.4293/108680812X13291597716384
View details for Web of Science ID 000307316100022
View details for PubMedID 22906342
Leukocyte set points in metabolic disease.
F1000 biology reports
2012; 4: 13-?
Vertebrate tissues comprise precise admixtures of parenchymal and hematopoietic cells, whose interactions are vital to proper tissue function. By regulating this interaction, vertebrates are able to mitigate environmental stress and coordinate dramatic physiologic adaptations. For instance, under conditions of chronic nutrient excess, leukocyte recruitment and activation increase in an effort to decrease excess nutrient storage and alleviate adipocyte stress. While basal equilibria may be reestablished upon normalization of nutrient intake, a new set point characterized by insulin resistance and chronic inflammation is established if the stress persists. Consequently, although this response is adaptive in settings of acute overfeeding and infection, it has catastrophic health consequences in the modern context of obesity. Understanding how leukocyte set points (numbers and activation status) are established, maintained, and regulated in tissues is, thus, critical to our understanding of, and intervention in, chronic metabolic diseases, such as obesity and diabetes.
View details for DOI 10.3410/B4-13
View details for PubMedID 22802874
Photothermal Ablation with the Excimer Laser Sheath Technique for Embedded Inferior Vena Cava Filter Removal: Initial Results from a Prospective Study
JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY
2011; 22 (6): 813-823
To evaluate the safety and effectiveness of the excimer laser sheath technique for removing embedded inferior vena cava (IVC) filters.Over 12 months, 25 consecutive patients undergoing attempted IVC filter retrieval with a laser-assisted sheath technique were prospectively enrolled into an institutional review board-approved study registry. There were 10 men and 15 women (mean age 50 years, range 20-76 years); 18 (72%) of 25 patients were referred from an outside hospital. Indications for retrieval included symptomatic filter-related acute caval thrombosis (with or without acute pulmonary embolism), chronic IVC occlusion, and bowel penetration. Retrieval was also performed to remove risks from prolonged implantation and potentially to eliminate need for lifelong anticoagulation. After failure of standard methods, controlled photothermal ablation of filter-adherent tissue with a Spectranetics laser sheath and CVX-300 laser system was performed. All patients were evaluated with cavography, and specimens were sent for histologic analysis.Laser-assisted retrieval was successful in 24 (96%) of 25 patients as follows: 11 Günther Tulip (mean 375 days, range 127-882 days), 4 Celect (mean 387 days, range 332-440 days), 2 Option (mean 215 days, range 100-330 days), 4 OPTEASE (mean 387 days, range 71-749 days; 1 failed 188 days), 2 TRAPEASE (mean 871 days, range 187-1,555 days), and 2 Greenfield (mean 12.8 years, range 7.2-18.3 years). There was one (4%) major complication (acute thrombus, treated with thrombolysis), three (12%) minor complications (small extravasation, self-limited), and one adverse event (coagulopathic retroperitoneal hemorrhage) at follow-up (mean 126 days, range 13-302 days). Photothermal ablation of filter-adherent tissue was histologically confirmed in 23 (92%) of 25 patients.The laser-assisted sheath technique appears to be a safe and effective tool for retrieving embedded IVC filters, including permanent types, with implantation ranging from months to > 18 years.
View details for DOI 10.1016/j.jvir.2011.01.459
View details for Web of Science ID 000291414500011
View details for PubMedID 21530309
Alternative Macrophage Activation and Metabolism
ANNUAL REVIEW OF PATHOLOGY: MECHANISMS OF DISEASE, VOL 6
2011; 6: 275-297
Obesity and its attendant metabolic disorders represent the great public health challenge of our time. Recent evidence suggests that onset of inflammation in metabolic tissues pathogenically links obesity to insulin resistance and type 2 diabetes. In this review, we briefly summarize the extant literature, paying special attention to the central role of the tissue-associated macrophage in the initiation of metabolic inflammation. We argue that rather than representing simple inflammatory disease, obesity and metabolic syndrome represent derangements in macrophage activation with concomitant loss of metabolic coordination. As such, the sequelae of obesity are as much products of the loss of positive macrophage influences as they are of the presence of deleterious inflammation. The therapeutic implications of this conclusion are profound because they suggest that pharmacologic targeting of macrophage activation, rather than simply inflammation, might be efficacious in treating this global epidemic.
View details for DOI 10.1146/annurev-pathol-011110-130138
View details for Web of Science ID 000288922800012
View details for PubMedID 21034223
IL-4/STAT6 immune axis regulates peripheral nutrient metabolism and insulin sensitivity
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2010; 107 (52): 22617-22622
Immune cells take residence in metabolic tissues, providing a framework for direct regulation of nutrient metabolism. Despite conservation of this anatomic relationship through evolution, the signals and mechanisms by which the immune system regulates nutrient homeostasis and insulin action remain poorly understood. Here, we demonstrate that the IL-4/STAT6 immune axis, a key pathway in helminth immunity and allergies, controls peripheral nutrient metabolism and insulin sensitivity. Disruption of signal transducer and activator of transcription 6 (STAT6) decreases insulin action and enhances a peroxisome proliferator-activated receptor ? (PPAR?) driven program of oxidative metabolism. Conversely, activation of STAT6 by IL-4 improves insulin action by inhibiting the PPAR?-regulated program of nutrient catabolism and attenuating adipose tissue inflammation. These findings have thus identified an unexpected molecular link between the immune system and macronutrient metabolism, suggesting perhaps the coevolution of these pathways occurred to ensure access to glucose during times of helminth infection.
View details for DOI 10.1073/pnas.1009152108
View details for Web of Science ID 000285684200051
View details for PubMedID 21149710
Prospective, Double-Blind, Randomized, Placebo-Controlled Comparison of Acetazolamide Versus Ibuprofen for Prophylaxis Against High Altitude Headache: The Headache Evaluation at Altitude Trial (HEAT)
WILDERNESS & ENVIRONMENTAL MEDICINE
2010; 21 (3): 236-243
High altitude headache (HAH) is the most common neurological complaint at altitude and the defining component of acute mountain sickness (AMS). However, there is a paucity of literature concerning its prevention. Toward this end, we initiated a prospective, double-blind, randomized, placebo-controlled trial in the Nepal Himalaya designed to compare the effectiveness of ibuprofen and acetazolamide for the prevention of HAH.Three hundred forty-three healthy western trekkers were recruited at altitudes of 4280 m and 4358 m and assigned to receive ibuprofen 600 mg, acetazolamide 85 mg, or placebo 3 times daily before continued ascent to 4928 m. Outcome measures included headache incidence and severity, AMS incidence and severity on the Lake Louise AMS Questionnaire (LLQ), and visual analog scale (VAS).Two hundred sixty-five of 343 subjects completed the trial. HAH incidence was similar when treated with acetazolamide (27.1%) or ibuprofen (27.5%; P = .95), and both agents were significantly more effective than placebo (45.3%; P = .01). AMS incidence was similar when treated with acetazolamide (18.8%) or ibuprofen (13.7%; P = .34), and both agents were significantly more effective than placebo (28.6%; P = .03). In fully compliant participants, moderate or severe headache incidence was similar when treated with acetazolamide (3.8%) or ibuprofen (4.7%; P = .79), and both agents were significantly more effective than placebo (13.5%; P = .03).Ibuprofen and acetazolamide were similarly effective in preventing HAH. Ibuprofen was similar to acetazolamide in preventing symptoms of AMS, an interesting finding that implies a potentially new approach to prevention of cerebral forms of acute altitude illness.
View details for Web of Science ID 000282163300007
View details for PubMedID 20832701
PPAR-delta senses and orchestrates clearance of apoptotic cells to promote tolerance
2009; 15 (11): 1266-U59
Macrophages rapidly engulf apoptotic cells to limit the release of noxious cellular contents and to restrict autoimmune responses against self antigens. Although factors participating in recognition and engulfment of apoptotic cells have been identified, the transcriptional basis for the sensing and the silent disposal of apoptotic cells is unknown. Here we show that peroxisome proliferator-activated receptor-delta (PPAR-delta) is induced when macrophages engulf apoptotic cells and functions as a transcriptional sensor of dying cells. Genetic deletion of PPAR-delta decreases expression of opsonins such as complement component-1qb (C1qb), resulting in impairment of apoptotic cell clearance and reduction in anti-inflammatory cytokine production. This increases autoantibody production and predisposes global and macrophage-specific Ppard(-/-) mice to autoimmune kidney disease, a phenotype resembling the human disease systemic lupus erythematosus. Thus, PPAR-delta has a pivotal role in orchestrating the timely disposal of apoptotic cells by macrophages, ensuring that tolerance to self is maintained.
View details for DOI 10.1038/nm.2048
View details for Web of Science ID 000271543700014
View details for PubMedID 19838202
Mechanisms of macrophage activation in obesity-induced insulin resistance
NATURE CLINICAL PRACTICE ENDOCRINOLOGY & METABOLISM
2008; 4 (11): 619-626
Chronic inflammation is now recognized as a key step in the pathogenesis of obesity-induced insulin resistance and type 2 diabetes mellitus. This low-grade inflammation is mediated by the inflammatory (classical) activation of recruited and resident macrophages that populate metabolic tissues, including adipose tissue and liver. These findings have led to the concept that infiltration by and activation of macrophages in adipose tissue are causally linked to obesity-induced insulin resistance. Studies have shown, however, that alternatively activated macrophages taking residence in adipose tissue and liver perform beneficial functions in obesity-induced metabolic disease. Alternatively activated macrophages reduce insulin resistance in obese mice by attenuating tissue inflammation and increasing oxidative metabolism in liver and skeletal muscle. The discovery that distinct subsets of macrophages are involved in the promotion or attenuation of insulin resistance suggests that pathways controlling macrophage activation can potentially be targeted to treat these comorbidities of obesity. Thus, this Review focuses on the stimuli and mechanisms that control classical and alternative activation of tissue macrophages, and how these macrophage activation programs modulate insulin action in peripheral tissues. The functional importance of macrophage activation is further discussed in the context of host defense to highlight the crosstalk between innate immunity and metabolism.
View details for DOI 10.1038/ncpendmet0976
View details for Web of Science ID 000260165700012
View details for PubMedID 18838972
Alternative M2 activation of Kupffer cells by PPAR delta ameliorates obesity-induced insulin resistance
2008; 7 (6): 496-507
Macrophage infiltration and activation in metabolic tissues underlie obesity-induced insulin resistance and type 2 diabetes. While inflammatory activation of resident hepatic macrophages potentiates insulin resistance, the functions of alternatively activated Kupffer cells in metabolic disease remain unknown. Here we show that in response to the Th2 cytokine interleukin-4 (IL-4), peroxisome proliferator-activated receptor delta (PPARdelta) directs expression of the alternative phenotype in Kupffer cells and adipose tissue macrophages of lean mice. However, adoptive transfer of PPARdelta(-/-) (Ppard(-/-)) bone marrow into wild-type mice diminishes alternative activation of hepatic macrophages, causing hepatic dysfunction and systemic insulin resistance. Suppression of hepatic oxidative metabolism is recapitulated by treatment of primary hepatocytes with conditioned medium from PPARdelta(-/-) macrophages, indicating direct involvement of Kupffer cells in liver lipid metabolism. Taken together, these data suggest an unexpected beneficial role for alternatively activated Kupffer cells in metabolic syndrome and type 2 diabetes.
View details for DOI 10.1016/j.cmet.2008.04.003
View details for Web of Science ID 000256443400007
View details for PubMedID 18522831
Macrophage-specific PPAR gamma controls alternative activation and improves insulin resistance
2007; 447 (7148): 1116-U12
Obesity and insulin resistance, the cardinal features of metabolic syndrome, are closely associated with a state of low-grade inflammation. In adipose tissue chronic overnutrition leads to macrophage infiltration, resulting in local inflammation that potentiates insulin resistance. For instance, transgenic expression of Mcp1 (also known as chemokine ligand 2, Ccl2) in adipose tissue increases macrophage infiltration, inflammation and insulin resistance. Conversely, disruption of Mcp1 or its receptor Ccr2 impairs migration of macrophages into adipose tissue, thereby lowering adipose tissue inflammation and improving insulin sensitivity. These findings together suggest a correlation between macrophage content in adipose tissue and insulin resistance. However, resident macrophages in tissues display tremendous heterogeneity in their activities and functions, primarily reflecting their local metabolic and immune microenvironment. While Mcp1 directs recruitment of pro-inflammatory classically activated macrophages to sites of tissue damage, resident macrophages, such as those present in the adipose tissue of lean mice, display the alternatively activated phenotype. Despite their higher capacity to repair tissue, the precise role of alternatively activated macrophages in obesity-induced insulin resistance remains unknown. Using mice with macrophage-specific deletion of the peroxisome proliferator activated receptor-gamma (PPARgamma), we show here that PPARgamma is required for maturation of alternatively activated macrophages. Disruption of PPARgamma in myeloid cells impairs alternative macrophage activation, and predisposes these animals to development of diet-induced obesity, insulin resistance, and glucose intolerance. Furthermore, gene expression profiling revealed that downregulation of oxidative phosphorylation gene expression in skeletal muscle and liver leads to decreased insulin sensitivity in these tissues. Together, our findings suggest that resident alternatively activated macrophages have a beneficial role in regulating nutrient homeostasis and suggest that macrophage polarization towards the alternative state might be a useful strategy for treating type 2 diabetes.
View details for DOI 10.1038/nature05894
View details for Web of Science ID 000247564600038
View details for PubMedID 17515919
Quantitative expansion of ES cell-derived myeloid progenitors capable of differentiating into macrophages
JOURNAL OF LEUKOCYTE BIOLOGY
2007; 81 (3): 711-719
Macrophages participate in physiologic and pathologic processes through elaboration of distinct activation programs. Studies with macrophage cell systems have revealed much concerning the importance of this pleiotropic cell; however, these studies are inherently limited by three factors: heterogeneity of the target cell population, poor capacity to elaborate various activation programs, and lack of a genetically tractable model system for loss- and gain-of-function studies. Although definitive, hematopoietic lineages can be isolated from embryonic stem (ES) cells, these isolation procedures are inefficient and time-consuming and require elaborate cell-sorting protocols. We therefore examined whether myeloid precursors, capable of differentiating into macrophages, could be conditionally expanded in vitro. Here, we report methods for selective isolation and immortalization of ES cell-derived myeloid precursors by estrogen-regulated HoxA9 protein. Using this new macrophage differentiation system, an unlimited number of custom-designed macrophages with defined functional characteristics can be generated from any targeted ES cell. In combination with knockout or small interfering RNA knockdown technologies, this macrophage differentiation system provides a powerful tool for high throughput analysis of regulatory mechanisms controlling macrophage activation in health and disease.
View details for DOI 10.1189/jlb.0906590
View details for Web of Science ID 000244505800017
View details for PubMedID 17158607
Oxidative metabolism and PGC-1 beta attenuate macrophage-mediated inflammation
2006; 4 (1): 13-24
Complex interplay between T helper (Th) cells and macrophages contributes to the formation and progression of atherosclerotic plaques. While Th1 cytokines promote inflammatory activation of lesion macrophages, Th2 cytokines attenuate macrophage-mediated inflammation and enhance their repair functions. In spite of its biologic importance, the biochemical and molecular basis of how Th2 cytokines promote maturation of anti-inflammatory macrophages is not understood. We show here that in response to interleukin-4 (IL-4), signal transducer and activator of transcription 6 (STAT6) and PPARgamma-coactivator-1beta (PGC-1beta) induce macrophage programs for fatty acid oxidation and mitochondrial biogenesis. Transgenic expression of PGC-1beta primes macrophages for alternative activation and strongly inhibits proinflammatory cytokine production, whereas inhibition of oxidative metabolism or RNAi-mediated knockdown of PGC-1beta attenuates this immune response. These data elucidate a molecular pathway that directly links mitochondrial oxidative metabolism to the anti-inflammatory program of macrophage activation, suggesting a potential role for metabolic therapies in treating atherogenic inflammation.
View details for DOI 10.1016/j.cmet.2006.05.011
View details for Web of Science ID 000238821800006
View details for PubMedID 16814729