- Pulmonary Critical Care
- Lung Transplantation
- Heart-Lung Transplantation
- Transplantation Immunology
- Pulmonary Hypertension
- Pulmonary Disease
Member, Institute for Immunity, Transplantation and Infection (2007 - Present)
Joint Appointment, Immunology & Rheumatology (2007 - Present)
Director, Lung Immunology (2007 - Present)
Member, Stanford Cardiovascular Institute (2007 - Present)
Faculty, Vera Moulton Wall Center For Pulmonary Vascular Disease (2007 - Present)
Program Director, Pulmonary and Critical Care Fellowship (2009 - 2010)
Chief, Pulmonary and Critical Care Medicine (2010 - Present)
Chairman of the Board, Palo Alto Veterans Administration Institute for Research (2015 - Present)
Honors & Awards
Elected Member, The American Society for Clinical Investigation (2014-)
Residency:Stanford University School of Medicine (1996) CA
Board Certification: Internal Medicine, American Board of Internal Medicine (1996)
Board Certification, ABIM, Critical Care Medicine (1999)
Board Certification: Pulmonary Disease, American Board of Internal Medicine (1998)
Fellowship:University of Colorado School of Medicine (1999) CO
BS, University of Portland, Biology (1987)
Medical Education:Stanford University School of Medicine (1993) CA
Current Research and Scholarly Interests
Our lab focuses primarily on the contribution of the immune response to lung disease. We are specifically examining the contribution of inflammation to the development of pulmonary hypertension. We also study how airway remodeling occurs in transplantation with specific respect to the microvascular circulation and to the initiation of fibroproliferation.
Rituximab for Treatment of Systemic Sclerosis-Associated Pulmonary Arterial Hypertension (SSc-PAH)
Systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) is a serious, life-threatening manifestation of systemic sclerosis (SSc), an autoimmune disease of the connective tissue characterized by scarring (fibrosis) and atrophy of the skin, joints and tendons, skeletal muscles, and internal organs, and immunological disturbances. One-year survival for patients with SSc-PAH ranges from 50-81%. There is currently no cure for SSc-PAH and treatment is limited to vasodilator therapy used in all forms of PAH. In recent studies, immunotherapy was shown to be effective in treating SSc-interstitial lung disease, another serious, life-threatening manifestation of SSc. In addition, there are compelling pre-clinical data and anecdotal clinical reports that suggest modulation of the immune system may be an effective strategy for treating SSc-PAH. To test this approach, this trial will determine if rituximab, an immunotherapy, has a marked beneficial effect on clinical disease progression, with minimal toxicity, in patients with SSc-PAH when compared to placebo.
Independent Studies (10)
- Directed Reading in Immunology
IMMUNOL 299 (Aut, Win, Spr, Sum)
- Directed Reading in Medicine
MED 299 (Aut, Win, Spr, Sum)
- Early Clinical Experience in Immunology
IMMUNOL 280 (Aut, Win, Spr, Sum)
- Early Clinical Experience in Medicine
MED 280 (Aut, Win, Spr, Sum)
- Graduate Research
IMMUNOL 399 (Aut, Win, Spr, Sum)
- Graduate Research
MED 399 (Aut, Win, Spr, Sum)
- Medical Scholars Research
MED 370 (Aut, Win, Spr, Sum)
- Teaching in Immunology
IMMUNOL 290 (Aut, Win, Spr, Sum)
- Undergraduate Research
IMMUNOL 199 (Aut, Win, Spr, Sum)
- Undergraduate Research
MED 199 (Aut, Win, Spr, Sum)
- Directed Reading in Immunology
Graduate and Fellowship Programs
Lung Quality and Utilization in Controlled Donation After Circulatory Determination of Death Within the United States
AMERICAN JOURNAL OF TRANSPLANTATION
2016; 16 (4): 1207-1215
Although controlled donation after circulatory determination of death (cDCDD) could increase the supply of donor lungs within the United States, the yield of lungs from cDCDD donors remains low compared with donation after neurologic determination of death (DNDD). To explore the reason for low lung yield from cDCDD donors, Scientific Registry of Transplant Recipient data were used to assess the impact of donor lung quality on cDCDD lung utilization by fitting a logistic regression model. The relationship between center volume and cDCDD use was assessed, and the distance between center and donor hospital was calculated by cDCDD status. Recipient survival was compared using a multivariable Cox regression model. Lung utilization was 2.1% for cDCDD donors and 21.4% for DNDD donors. Being a cDCDD donor decreased lung donation (adjusted odds ratio 0.101, 95% confidence interval [CI] 0.085-0.120). A minority of centers have performed cDCDD transplant, with higher volume centers generally performing more cDCDD transplants. There was no difference in center-to-donor distance or recipient survival (adjusted hazard ratio 1.03, 95% CI 0.78-1.37) between cDCDD and DNDD transplants. cDCDD lungs are underutilized compared with DNDD lungs after adjusting for lung quality. Increasing transplant center expertise and commitment to cDCDD lung procurement is needed to improve utilization.
View details for DOI 10.1111/ajt.13599
View details for Web of Science ID 000373075400021
- A Critical Role for Airway Microvessels in Lung Transplantation. American journal of respiratory and critical care medicine 2016; 193 (5): 479-481
Effect of Transplant Center Volume on Cost and Readmissions in Medicare Lung Transplant Recipients.
Annals of the American Thoracic Society
While lung transplant recipient survival is better at higher volume centers, the effect of center volume on admission cost and early hospital readmission is unknown.To understand the association between transplant center volume and recipient risk-adjusted transplant admission cost, in-hospital mortality, and early hospital readmission in lung transplant recipients.Medicare lung transplant recipients from May 4, 2005 to December 31, 2011 were identified through linkage of transplant registry and Medicare administrative claims. Transplant admission cost was extracted, adjusted for regional price variation, and compared across low, intermediate, and high volume centers. A multivariable hierarchical generalized linear regression model was used to assess the effect of transplant center volume on recipient adjusted cost. Modified Poisson regression models were used to assess adjusted in-hospital mortality and early hospital readmission by transplant center volume.There were 3,128 Medicare lung transplant recipients identified. Unadjusted transplant cost was lower at high volume centers (mean $131,352, SD±$106,165; median $90,177, IQR $79,165-$137,915) than intermediate (mean $138,792, SD±$106,270; median $93,024, IQR $82,700-$154,857) or low volume (mean $143,609, SD±$123,316; median $95,234, IQR $83,052-$152,149) centers (p<0.0001). After adjusting for recipient health risk, low volume centers had an 11.66% greater transplant admission cost (p=0.040), a 41% greater risk for in-hospital mortality (p=0.015), and a 14% greater risk for early hospital readmission (p=0.033) compared to high volume centers. There was no significant difference in transplant cost, in-hospital mortality, or early hospital readmission between intermediate and high volume centers.Lung transplant admission cost, in-hospital mortality, and early hospital readmission rate are lower at high volume centers compared to low volume centers.
View details for DOI 10.1513/AnnalsATS.201601-017OC
View details for PubMedID 27064753
Microvascular injury after lung transplantation.
Current opinion in organ transplantation
Airway microvessel injury following transplantation has been implicated in the development of chronic rejection. This review focuses on the most recent developments in the field describing preclinical and clinical findings that further implicate the loss of microvascular integrity as an important pathological event in the evolution of irreversible fibrotic remodeling.When lungs are transplanted, the airways appear vulnerable from the perspective of perfusion. Two vascular systems are lost, the bronchial artery and the lymphatic circulations, and the remaining vasculature in the airways expresses donor antigens susceptible to alloimmune-mediated injury via innate and adaptive immune mechanisms. Preclinical studies indicate the importance of hypoxia-inducible factor-1α in mediating microvascular repair and that hypoxia-inducible factor-1α can be upregulated to bolster endogenous repair.Airway microvascular injury is a feature of lung transplantation that limits short-term and long-term organ health. Although some problems are attributable to a missing bronchial artery circulation, another significant issue involves alloimmune-mediated injury to transplant airway microvessels. For a variety of reasons, bronchial artery revascularization surgery at the time of transplantation has not been widely adopted, and the current best hope for this era may be new medical approaches that offer protection against immune-mediated vascular injury or that promote microvascular repair.
View details for DOI 10.1097/MOT.0000000000000307
View details for PubMedID 26967995
Challenges and opportunities in treating inflammation associated with pulmonary hypertension.
Expert review of cardiovascular therapy
Inflammatory cells are present in the lungs from patients with many, if not all, forms of severe pulmonary hypertension. Historically the first inflammatory cell identified in the pulmonary vascular lesions was the mast cell. T and B lymphocytes, as well as macrophages, are present in and around the pulmonary arterioles and many patients have elevated blood levels of interleukin 1 and 6; some patients show elevated levels of leukotriene B4. An overlap between collagen-vascular disease-associated pulmonary arterial hypertension (PAH) and idiopathic PAH exists, yet only a few studies have been designed that evaluate the effect of anti-inflammatory treatments. Here we review the pertinent data that connect PAH and inflammation/immune dysregulation and evaluate experimental models of severe PAH with an emphasis on the Sugen/athymic rat model of severe PAH. We postulate that there are more than one inflammatory phenotype and predict that there will be several anti-inflammatory treatment strategies for severe PAH.
View details for DOI 10.1080/14779072.2016.1180976
View details for PubMedID 27096622
Leukotriene B-4 Activates Pulmonary Artery Adventitial Fibroblasts in Pulmonary Hypertension
2015; 66 (6): 1227-1239
A recent study demonstrated a significant role for leukotriene B4 (LTB4) causing pulmonary vascular remodeling in pulmonary arterial hypertension. LTB4 was found to directly injure luminal endothelial cells and promote growth of the smooth muscle cell layer of pulmonary arterioles. The purpose of this study was to determine the effects of LTB4 on the pulmonary adventitial layer, largely composed of fibroblasts. Here, we demonstrate that LTB4 enhanced human pulmonary artery adventitial fibroblast proliferation, migration, and differentiation in a dose-dependent manner through its cognate G-protein-coupled receptor, BLT1. LTB4 activated human pulmonary artery adventitial fibroblast by upregulating p38 mitogen-activated protein kinase as well as Nox4-signaling pathways. In an autoimmune model of pulmonary hypertension, inhibition of these pathways blocked perivascular inflammation, decreased Nox4 expression, reduced reactive oxygen species production, reversed arteriolar adventitial fibroblast activation, and attenuated pulmonary hypertension development. This study uncovers a novel mechanism by which LTB4 further promotes pulmonary arterial hypertension pathogenesis, beyond its established effects on endothelial and smooth muscle cells, by activating adventitial fibroblasts.
View details for DOI 10.1161/HYPERTENSIONAHA.115.06370
View details for Web of Science ID 000364481400021
Noninvasive monitoring of infection and rejection after lung transplantation
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2015; 112 (43): 13336-13341
The survival rate following lung transplantation is among the lowest of all solid-organ transplants, and current diagnostic tests often fail to distinguish between infection and rejection, the two primary posttransplant clinical complications. We describe a diagnostic assay that simultaneously monitors for rejection and infection in lung transplant recipients by sequencing of cell-free DNA (cfDNA) in plasma. We determined that the levels of donor-derived cfDNA directly correlate with the results of invasive tests of rejection (area under the curve 0.9). We also analyzed the nonhuman cfDNA as a hypothesis-free approach to test for infections. Cytomegalovirus is most frequently assayed clinically, and the levels of CMV-derived sequences in cfDNA are consistent with clinical results. We furthermore show that hypothesis-free monitoring for pathogens using cfDNA reveals undiagnosed cases of infection, and that certain infectious pathogens such as human herpesvirus (HHV) 6, HHV-7, and adenovirus, which are not often tested clinically, occur with high frequency in this cohort.
View details for DOI 10.1073/pnas.1517494112
View details for Web of Science ID 000363458100063
Cyclosporine Does Not Prevent Microvascular Loss in Transplantation but Can Synergize With a Neutrophil Elastase Inhibitor, Elafin, to Maintain Graft Perfusion During Acute Rejection
AMERICAN JOURNAL OF TRANSPLANTATION
2015; 15 (7): 1768-1781
The loss of a functional microvascular bed in rejecting solid organ transplants is correlated with fibrotic remodeling and chronic rejection; in lung allografts, this pathology is predicted by bronchoalveolar fluid neutrophilia which suggests a role for polymorphonuclear cells in microcirculatory injury. In a mouse orthotopic tracheal transplant model, cyclosporine, which primarily inhibits T cells, failed as a monotherapy for preventing microvessel rejection and graft ischemia. To target neutrophil action that may be contributing to vascular injury, we examined the effect of a neutrophil elastase inhibitor, elafin, on the microvascular health of transplant tissue. We showed that elafin monotherapy prolonged microvascular perfusion and enhanced tissue oxygenation while diminishing the infiltration of neutrophils and macrophages and decreasing tissue deposition of complement C3 and the membrane attack complex, C5b-9. Elafin was also found to promote angiogenesis through activation of the extracellular signal-regulated kinase (ERK) signaling pathway but was insufficient as a single agent to completely prevent tissue ischemia during acute rejection episodes. However, when combined with cyclosporine, elafin effectively preserved airway microvascular perfusion and oxygenation. The therapeutic strategy of targeting neutrophil elastase activity alongside standard immunosuppression during acute rejection episodes may be an effective approach for preventing the development of irreversible fibrotic remodeling.
View details for DOI 10.1111/ajt.13189
View details for Web of Science ID 000356494300013
Elafin Reverses Pulmonary Hypertension via Caveolin-1-Dependent Bone Morphogenetic Protein Signaling
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
2015; 191 (11): 1273-1286
Pulmonary arterial hypertension is characterized by endothelial cell dysfunction, impaired BMPR2 signaling, and increased elastase activity. Synthetic elastase inhibitors reverse experimental pulmonary hypertension but cause hepatotoxicity in clinical studies. The endogenous elastase inhibitor elafin attenuates the development of hypoxic pulmonary hypertension in mice, but its potential to improve endothelial cell function and BMPR2 signaling, and to reverse severe experimental pulmonary hypertension or vascular pathology in the human disease was unknown.To assess elafin-mediated regression of pulmonary vascular pathology in rats with pulmonary hypertension induced by VEGF receptor blockade and hypoxia (Sugen/Hypoxia), and in lung explants from pulmonary hypertension patients. To determine if elafin amplifies BMPR2 signaling in pulmonary artery endothelial cells from controls and patients, and to elucidate the underlying mechanism. Methods, Measurements and Main Results: In Sugen/Hypoxia rats, elafin reduced elastase activity and reversed pulmonary hypertension, judged by regression of right ventricular systolic pressure and hypertrophy and pulmonary artery occlusive changes. Elafin improved endothelial function by increasing apelin, a product of BMPR2 signaling. Elafin induced apoptosis in human pulmonary arterial smooth muscle cells and in lung organ culture elafin decreased neointimal lesions. In normal and patient pulmonary artery endothelial cells, elafin enhanced survival and promoted angiogenesis by increasing pSMAD dependent and independent BMPR2 signaling. This was linked mechanistically to augmented interaction of BMPR2 with caveolin-1 via elafin-mediated stabilization of caveolin-1 on endothelial surfaces.Elafin reverses obliterative changes in rat and human pulmonary arteries via elastase inhibition and caveolin-1 dependent amplification of BMPR2 signaling.
View details for DOI 10.1164/rccm.201412-2291OC
View details for Web of Science ID 000356105000014
Increased Resource Use in Lung Transplant Admissions in the Lung Allocation Score Era
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
2015; 191 (3): 302-308
Rationale: In 2005, the lung allocation score (LAS) was implemented to prioritize organ allocation to minimize waiting-list mortality and maximize one-year survival. It resulted in transplantation of older and sicker patients without changing one-year survival. Its effect on resource utilization is unknown. Objective: To determine changes in resource utilization over time in lung transplant admissions Methods: Solid organ transplant recipients were identified within the Nationwide Inpatient Sample (NIS) data from 2000 to 2011. Joinpoint regression methodology was performed to identify a time point of change in mean total hospital charges amongst lung transplant and other solid organ transplant recipients. Two temporal lung transplant recipient cohorts identified by joinpoint regression were compared for baseline characteristics and resource utilization, including total charges for index hospitalization, charges per day, length of stay, discharge disposition, tracheostomy, and need for extracorporeal membrane oxygenation (ECMO). Measurements and Main Results: A significant point of increased total hospital charges occurred for lung transplant recipients in 2005, corresponding to LAS implementation, that was not seen in other solid organ transplant recipients. Total transplant hospital charges increased by 40% in the post-LAS cohort [$569,942 ($53,229) vs. $407,489 ($28,360)] along with an increased median length of stay, daily charges, and discharge disposition other than to home. Post-LAS recipients also had higher post-transplant utilization of ECMO (OR 2.35, 95% CI 1.56, 3.55) and higher incidence of tracheostomy (OR 1.52, 95% CI 1.22, 1.89). Conclusions: LAS implementation is associated with a significant increase in resource utilization during index hospitalization for lung transplant.
View details for DOI 10.1164/rccm.201408-1562OC
View details for Web of Science ID 000348827000014
Activation of the Wnt/Planar Cell Polarity Pathway Is Required for Pericyte Recruitment during Pulmonary Angiogenesis
AMERICAN JOURNAL OF PATHOLOGY
2015; 185 (1): 69-84
Pericytes are perivascular cells localized to capillaries that promote vessel maturation, and their absence can contribute to vessel loss. Whether impaired endothelial-pericyte interaction contributes to small vessel loss in pulmonary arterial hypertension (PAH) is unclear. Using 3G5-specific, immunoglobulin G-coated magnetic beads, we isolated pericytes from the lungs of healthy subjects and PAH patients, followed by lineage validation. PAH pericytes seeded with healthy pulmonary microvascular endothelial cells failed to associate with endothelial tubes, resulting in smaller vascular networks compared to those with healthy pericytes. After the demonstration of abnormal polarization toward endothelium via live-imaging and wound-healing studies, we screened PAH pericytes for abnormalities in the Wnt/planar cell polarity (PCP) pathway, which has been shown to regulate cell motility and polarity in the pulmonary vasculature. PAH pericytes had reduced expression of frizzled 7 (Fzd7) and cdc42, genes crucial for Wnt/PCP activation. With simultaneous knockdown of Fzd7 and cdc42 in healthy pericytes in vitro and in a murine model of angiogenesis, motility and polarization toward pulmonary microvascular endothelial cells were reduced, whereas with restoration of both genes in PAH pericytes, endothelial-pericyte association was improved, with larger vascular networks. These studies suggest that the motility and polarity of pericytes during pulmonary angiogenesis are regulated by Wnt/PCP activation, which can be targeted to prevent vessel loss in PAH.
View details for DOI 10.1016/j.ajpath.2014.09.013
View details for Web of Science ID 000346887200008
Unique Predictors of Mortality in Patients With Pulmonary Arterial Hypertension Associated With Systemic Sclerosis in the REVEAL Registry
2014; 146 (6): 1494-1504
Background:Patients with pulmonary arterial hypertension associated with systemic sclerosis (SSc-APAH) experience higher mortality rates than patients with idiopathic disease and those with other connective tissue diseases (CTD-APAH). We sought to identify unique predictors of mortality associated with SSc-APAH in the CTD-APAH population. Methods:The Registry to Evaluate Early and Long-Term PAH Management (REVEAL) is a multicenter, prospective US-based registry of patients with previously and newly diagnosed (enrollment within 90 days of diagnostic right heart catheterization) PAH. Cox regression models evaluated all previously identified candidate predictors of mortality in the overall REVEAL population to identify significant predictors of mortality in the SSc-APAH (n=500) versus non-SSc-CTD-APAH (n=304) populations. Results:Three-year survival in the previously diagnosed and newly diagnosed SSc-APAH group was 61.4±2.7% and 51.2±4.0%, respectively, compared with 80.9±2.7% and 76.4±4.6%, respectively, in the non-SSc-CTD-APAH group (P<.001). In multivariate analyses, males aged >60 years, systolic blood pressure (SBP) ≤110 mmHg, 6-minute walk distance (6MWD) <165 m, mean right atrial pressure (mRAP) >20 mmHg within 1 year, and pulmonary vascular resistance (PVR) >32 WU remained unique predictors of mortality in the SSc-APAH group; 6MWD ≥440 m was protective in the non-SSc-CTD-APAH group, but not the SSc-APAH group. Conclusions:Patients with SSc-APAH have higher mortality rates than non-SSc-CTD-APAH patients. Identifying SSc-APAH patients who are at particularly high risk of death, including elderly males and patients with low baseline SBP or 6MWD, or markedly elevated mRAP or PVR, will enable clinicians to identify patients who may benefit from closer monitoring and more aggressive treatment. Registered at:www.clinicaltrials.gov #NCT00370214.Patients with pulmonary arterial hypertension associated with systemic sclerosis (SSc-APAH) experience higher mortality rates than patients with idiopathic disease and those with other connective tissue diseases (CTD-APAH). We sought to identify unique predictors of mortality associated with SSc-APAH in the CTD-APAH population.The Registry to Evaluate Early and Long-Term PAH Management (REVEAL) is a multicenter, prospective US-based registry of patients with previously and newly diagnosed (enrollment within 90 days of diagnostic right heart catheterization) PAH. Cox regression models evaluated all previously identified candidate predictors of mortality in the overall REVEAL population to identify significant predictors of mortality in the SSc-APAH (n=500) versus non-SSc-CTD-APAH (n=304) populations.Three-year survival in the previously diagnosed and newly diagnosed SSc-APAH group was 61.4±2.7% and 51.2±4.0%, respectively, compared with 80.9±2.7% and 76.4±4.6%, respectively, in the non-SSc-CTD-APAH group (P<.001). In multivariate analyses, males aged >60 years, systolic blood pressure (SBP) ≤110 mmHg, 6-minute walk distance (6MWD) <165 m, mean right atrial pressure (mRAP) >20 mmHg within 1 year, and pulmonary vascular resistance (PVR) >32 WU remained unique predictors of mortality in the SSc-APAH group; 6MWD ≥440 m was protective in the non-SSc-CTD-APAH group, but not the SSc-APAH group.Patients with SSc-APAH have higher mortality rates than non-SSc-CTD-APAH patients. Identifying SSc-APAH patients who are at particularly high risk of death, including elderly males and patients with low baseline SBP or 6MWD, or markedly elevated mRAP or PVR, will enable clinicians to identify patients who may benefit from closer monitoring and more aggressive treatment.www.clinicaltrials.gov #NCT00370214.
View details for DOI 10.1378/chest.13-3014
View details for Web of Science ID 000347217600037
View details for PubMedID 24992469
Impact of the lung allocation score on survival beyond 1 year.
American journal of transplantation
2014; 14 (10): 2288-2294
Implementation of the lung allocation score (LAS) in 2005 led to transplantation of older and sicker patients without altering 1-year survival. However, long-term survival has not been assessed and emphasizing the 1-year survival metric may actually sustain 1-year survival while not reflecting worsening longer-term survival. Therefore, we assessed overall and conditional 1-year survival; and the effect of crossing the 1-year threshold on hazard of death in three temporal cohorts: historical (1995-2000), pre-LAS (2001-2005) and post-LAS (2005-2010). One-year survival post-LAS remained similar to pre-LAS (83.1% vs. 82.1%) and better than historical controls (75%). Overall survival in the pre- and post-LAS cohorts was also similar. However, long-term survival among patients surviving beyond 1 year was worse than pre-LAS and similar to historical controls. Also, the hazard of death increased significantly in months 13 (1.44, 95% CI 1.10-1.87) and 14 (1.43, 95% CI 1.09-1.87) post-LAS but not in the other cohorts. While implementation of the LAS has not reduced overall survival, decreased survival among patients surviving beyond 1 year in the post-LAS cohort and the increased mortality occurring immediately after 1 year suggest a potential negative long-term effect of the LAS and an unintended consequence of increased emphasis on the 1-year survival metric.
View details for DOI 10.1111/ajt.12903
View details for PubMedID 25208599
- Impact of the Lung Allocation Score on Survival Beyond 1 Year AMERICAN JOURNAL OF TRANSPLANTATION 2014; 14 (10): 2288-2294
Nuclear Factor kappa B Inhibition Reduces Lung Vascular Lumen Obliteration in Severe Pulmonary Hypertension in Rats
AMERICAN JOURNAL OF RESPIRATORY CELL AND MOLECULAR BIOLOGY
2014; 51 (3): 413-425
Nuclear factor-κB (NF-κB) and interleukin-6 (IL-6), a NF-κB downstream mediator, play a central role in the inflammatory response of tissues. We aimed to determine the role of the classical NF-κB pathway in severe pulmonary arterial hypertension (PAH) induced by SU5416 and chronic hypoxia (SuHx) in rats. Tissue samples from patients with idiopathic PAH (iPAH) and control subjects were investigated. SuHx rats were treated from days 1-3, 1-21 and 29-42 with the NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) and/or from days 1-21 with anti-IL-6 antibody. Nuclear staining for NF-κB, an indicator of the activation of the classical NF-κB pathway, was detected in pulmonary arterial lesions of iPAH patients and SuHx rats. NF-κB inhibition with PDTC prevented and reduced pulmonary arterial obliteration without reducing muscularization. However, the elevated lung levels of IL-6 were not reduced in PDTC-treated SuHx animals. PDTC treatment prevented or reduced apoptosis of pulmonary artery wall cells and pulmonary arterial obliteration. IL-6 inhibition had only a partial effect on apoptosis and obliteration. Pulmonary arterial media wall thickness was not affected by any of these treatments. Preventive and therapeutic PDTC treatment promoted immune regulation by increasing the number of perivascular CD4+ T cells, in particular regulatory T cells (early treatment) and by reducing the number of perivascular CD8+ T lymphocytes and CD45RA+ B lymphocytes. Therapeutic PDTC treatment further preserved right ventricular function in SuHx animals. Inhibition of NF-κB may represent a therapeutic option for pulmonary arterial obliteration via reduced vessel wall cell apoptosis and improved regulation of the immune system.
View details for DOI 10.1165/rcmb.2013-0355OC
View details for Web of Science ID 000347417800010
View details for PubMedID 24684441
Graft microvascular disease in solid organ transplantation
JOURNAL OF MOLECULAR MEDICINE-JMM
2014; 92 (8): 797-810
Alloimmune inflammation damages the microvasculature of solid organ transplants during acute rejection. Although immunosuppressive drugs diminish the inflammatory response, they do not directly promote vascular repair. Repetitive microvascular injury with insufficient regeneration results in prolonged tissue hypoxia and fibrotic remodeling. While clinical studies show that a loss of the microvascular circulation precedes and may act as an initiating factor for the development of chronic rejection, preclinical studies demonstrate that improved microvascular perfusion during acute rejection delays and attenuates tissue fibrosis. Therefore, preservation of a functional microvasculature may represent an effective therapeutic strategy for preventing chronic rejection. Here, we review recent advances in our understanding of the role of the microvasculature in the long-term survival of transplanted solid organs. We also highlight microvessel-centered therapeutic strategies for prolonging the survival of solid organ transplants.
View details for DOI 10.1007/s00109-014-1173-y
View details for Web of Science ID 000339975500002
Inflammation and Immunity in the Pathogenesis of Pulmonary Arterial Hypertension
2014; 115 (1): 165-175
This review summarizes an expanding body of knowledge indicating that failure to resolve inflammation and altered immune processes underlie the development of pulmonary arterial hypertension. The chemokines and cytokines implicated in pulmonary arterial hypertension that could form a biomarker platform are discussed. Pre-clinical studies that provide the basis for dysregulated immunity in animal models of the disease are reviewed. In addition, we present therapies that target inflammatory/immune mechanisms that are currently enrolling patients, and discuss others in development. We show how genetic and metabolic abnormalities are inextricably linked to dysregulated immunity and adverse remodeling in the pulmonary arteries.
View details for DOI 10.1161/CIRCRESAHA.113.301141
View details for Web of Science ID 000337738900018
Leukotrienes in pulmonary arterial hypertension
2014; 58 (2-3): 387-393
Leukotrienes (LTs) are lipid mediators derived from the 5-lipoxygenase (5-LO) pathway of arachidonic acid metabolism and are markers and mediators of pulmonary inflammation. Research over the past two decades has established that LTs modulate inflammation in pulmonary arterial hypertension (PAH). The purpose of this review was to summarize the current knowledge of LTs in the pathophysiology of PAH and to highlight a recent study that advances our understanding of how leukotriene B4 (LTB4) specifically contributes to pulmonary vascular remodeling. The results of these studies suggest that pharmacological inhibition of LT pathways, especially LTB4, has high potential for the treatment of PAH.
View details for DOI 10.1007/s12026-014-8492-5
View details for Web of Science ID 000336333700026
Complement components as potential therapeutic targets for asthma treatment
2014; 108 (4): 543-549
Asthma is the most common respiratory disorder, and is characterized by distal airway inflammation and hyperresponsiveness. This disease challenges human health because of its increasing prevalence, severity, morbidity, and the lack of a proper and complete cure. Asthma is characterized by TH2-skewed inflammation with elevated pulmonary levels of IL-4, IL-5, and IL-13 levels. Although there are early forays into targeting TH2 immunity, less-specific corticosteroid therapy remains the immunomodulator of choice. Innate immune injury mediated by complement components also act as potent mediators of the allergic inflammatory responses and offer a new and exciting possibility for asthma immunotherapy. The complement cascade consists of a number of plasma- and membrane-bound proteins, and the cleavage products of these proteins (C3 and C5) regulate the magnitude of adaptive immune responses. Complement protein are responsible for many pathophysiological features of asthma, including inflammatory cell infiltration, mucus secretion, increases in vascular permeability, and smooth muscle cell contraction. This review highlights the complement-mediated injury during asthma inflammation, and how blockade of active complement mediators may have therapeutic application.
View details for DOI 10.1016/j.rmed.2014.01.005
View details for Web of Science ID 000333856400001
View details for PubMedID 24468195
Efficacy of Transthoracic Echocardiography for Diagnosing Heart Failure in Septic Shock
AMERICAN JOURNAL OF THE MEDICAL SCIENCES
2014; 347 (4): 295-298
Cardiac dysfunction occurs in up to 80% of patients with septic shock. Transthoracic echocardiography (TTE) is an ideal tool for the detailed characterization of cardiac function. Its feasibility is perceived to be poor in critically ill patients, but this has never been studied. To address this question, the authors evaluated the efficacy of TTE to diagnose heart failure in septic shock.This was a retrospective study. Patients admitted to the intensive care unit with septic shock and who had a TTE within 72 hours of intensive care unit admission were identified by a computer algorithm and validated by chart review. Echocardiography images were reviewed by a single cardiologist blinded to clinical outcomes. Clinical information was collected from patients' medical record.Seventy-six patients met the studies' inclusion criteria. The feasibility of TTE to calculate left ventricular ejection fraction was 90% and to assess diastolic function was 74%. Significant mitral regurgitation or aortic stenosis was the most frequent impediments for the assessment of diastolic function. Seventy-four percent of all patients showed some type of cardiac dysfunction (left or right ventricular systolic dysfunction and/or left ventricular diastolic dysfunction). In regression analyses, TTE feasibility was not impacted by factors previously associated with poor image acquisition: high body mass index, mechanical ventilation, tachycardia, advanced age or high severity of illness.This study demonstrated that TTE is a useful tool to assess myocardial function in critically ill patients and suggested its potential to assist in the management of patients with septic shock.
View details for DOI 10.1097/MAJ.0b013e318297d616
View details for Web of Science ID 000335788700008
Application of a non-amplification-based technology to detect invasive fungal pathogens
DIAGNOSTIC MICROBIOLOGY AND INFECTIOUS DISEASE
2014; 78 (2): 137-140
Current diagnostic techniques for fungal diseases could be improved with respect to sensitivity, specificity, and timeliness. To address this clinical need, we adapted a non-amplification-based nucleic acid detection technology to identify fungal pathogens. We demonstrate a high-specificity, detection sensitivity, reproducibility, and multiplex capacity for detecting fungal strains.
View details for DOI 10.1016/j.diagmicrobio.2013.11.013
View details for Web of Science ID 000330149700007
View details for PubMedID 24359934
Working toward immune tolerance in lung transplantation.
The Journal of clinical investigation
Long-term allograft survival is a major challenge facing solid organ transplantation. Recent studies have shown a negative correlation between infiltration of memory T cells and allograft survival. Furthermore, blockade of leukocyte activation increases acceptance of transplanted organs, including heart, liver, and kidney. Lung allografts are associated with high rates of rejection, and therapies that increase acceptance of other transplanted organs have not translated into the lung. In this issue of the JCI, Krupnick and colleagues demonstrate in a murine model that lung allograft acceptance requires infiltration of a specific T cell population into the graft. This study highlights the unique immunobiology of the lung and the complexity of lung transplant tolerance.
View details for DOI 10.1172/JCI74701
View details for PubMedID 24569371
- Traumatic Brain Injury: Lungs in a RAGE. Science translational medicine 2014; 6 (252): 252fs34
Macrophages in solid organ transplantation.
2014; 6 (1): 5-?
Macrophages are highly plastic hematopoietic cells with diversified functions related to their anatomic location and differentiation states. A number of recent studies have examined the role of macrophages in solid organ transplantation. These studies show that macrophages can induce allograft injury but, conversely, can also promote tissue repair in ischemia-reperfusion injury and acute rejection. Therapeutic strategies that target macrophages to improve outcomes in solid organ transplant recipients are being examined in preclinical and clinical models. In this review, we discuss the role of macrophages in different types of injury and rejection, with a focus on macrophage-mediated tissue injury, specifically vascular injury, repair and remodeling. We also discuss emerging macrophage-centered therapeutic opportunities in solid organ transplantation.
View details for DOI 10.1186/2045-824X-6-5
View details for PubMedID 24612731
Promotion of airway anastomotic microvascular regeneration and alleviation of airway ischemia by deferoxamine nanoparticles
2014; 35 (2): 803-813
Airway tissue ischemia and hypoxia in human lung transplantation is a consequence of the sacrifice of the bronchial circulation during the surgical procedure and is a major risk factor for the development of airway anastomotic complications. Augmented expression of hypoxia-inducible factor (HIF)-1α promotes microvascular repair and alleviates allograft ischemia and hypoxia. Deferoxamine mesylate (DFO) is an FDA-approved iron chelator which has been shown to upregulate cellular HIF-1α. Here, we developed a nanoparticle formulation of DFO that can be topically applied to airway transplants at the time of surgery. In a mouse orthotopic tracheal transplant (OTT) model, the DFO nanoparticle was highly effective in enhancing airway microvascular perfusion following transplantation through the production of the angiogenic factors, placental growth factor (PLGF) and stromal cell-derived factor (SDF)-1. The endothelial cells in DFO treated airways displayed higher levels of p-eNOS and Ki67, less apoptosis, and decreased production of perivascular reactive oxygen species (ROS) compared to vehicle-treated airways. In summary, a DFO formulation topically-applied at the time of surgery successfully augmented airway anastomotic microvascular regeneration and the repair of alloimmune-injured microvasculature. This approach may be an effective topical transplant-conditioning therapy for preventing airway complications following clinical lung transplantation.
View details for DOI 10.1016/j.biomaterials.2013.09.092
View details for Web of Science ID 000328594800019
View details for PubMedID 24161166
The Critical Role of mRNA Destabilizing Protein Heterogeneous Nuclear Ribonucleoprotein D in 3 ' Untranslated Region-Mediated Decay of Low-Density Lipoprotein Receptor mRNA in Liver Tissue
ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY
2014; 34 (1): 8-?
Previous studies showed that low-density lipoprotein receptor (LDLR) mRNA 3' untranslated region (UTR) contains regulatory elements responsible for rapid mRNA turnover in hepatic cells and mediates the mRNA stabilization induced by berberine (BBR). Here, we elucidate the underlying mechanism of BBR's action by characterizing mRNA-binding proteins that modulate LDLR mRNA decay via 3'UTR in liver tissue in vivo.We generated a transgenic mouse model (Alb-Luc-UTR) that expresses Luc-LDLR3'UTR reporter gene driven by the albumin promoter to study 3'UTR function in mediating LDLR mRNA decay in liver tissue. We show that treating Alb-Luc-UTR mice with BBR led to significant increases in hepatic bioluminescence signals, Luc-UTR mRNA, and LDLR mRNA levels as compared with control mice. These effects were accompanied by specific reductions of mRNA decay-promoting factor heterogeneous nuclear ribonucleoprotein D (hnRNP D) in liver of BBR-treated mice. Knockdown and overexpression studies further demonstrated that hnRNP D p37 isoform plays a major role in promoting hepatic LDLR mRNA degradation. In addition, we examined LDLR mRNA half-life, Luc-UTR reporter activity, and hnRNP D expression levels in cell lines derived from extrahepatic tissues. We demonstrated that strengths of 3'UTR in promoting mRNA degradation correlate with hnRNP D cellular abundances in nonhepatic cell lines, thereby suggesting its involvement in LDLR mRNA degradation beyond liver tissue.hnRNP D is critically involved in LDLR mRNA degradation in liver tissue in vivo. The inverse relationship of hnRNP D abundance with LDLR mRNA levels after BBR treatment suggests the potential of hnRNP D of being a novel therapeutic target for LDL cholesterol lowering.
View details for DOI 10.1161/ATVBAHA.112.301131
View details for Web of Science ID 000337731100005
View details for PubMedID 24158514
Temporal Response of the Human Virome to Immunosuppression and Antiviral Therapy
2013; 155 (5): 1178-1187
There are few substantive methods to measure the health of the immune system, and the connection between immune strength and the viral component of the microbiome is poorly understood. Organ transplant recipients are treated with posttransplant therapies that combine immunosuppressive and antiviral drugs, offering a window into the effects of immune modulation on the virome. We used sequencing of cell-free DNA in plasma to investigate drug-virome interactions in a cohort of organ transplant recipients (656 samples, 96 patients) and find that antivirals and immunosuppressants strongly affect the structure of the virome in plasma. We observe marked virome compositional dynamics at the onset of the therapy and find that the total viral load increases with immunosuppression, whereas the bacterial component of the microbiome remains largely unaffected. The data provide insight into the relationship between the human virome, the state of the immune system, and the effects of pharmacological treatment and offer a potential application of the virome state to predict immunocompetence.
View details for DOI 10.1016/j.cell.2013.10.034
View details for Web of Science ID 000327500600020
View details for PubMedID 24267896
Aspergillus fumigatus Invasion Increases with Progressive Airway Ischemia
2013; 8 (10)
Despite the prevalence of Aspergillus-related disease in immune suppressed lung transplant patients, little is known of the host-pathogen interaction. Because of the mould's angiotropic nature and because of its capacity to thrive in hypoxic conditions, we hypothesized that the degree of Aspergillus invasion would increase with progressive rejection-mediated ischemia of the allograft. To study this relationship, we utilized a novel orthotopic tracheal transplant model of Aspergillus infection, in which it was possible to assess the effects of tissue hypoxia and ischemia on airway infectivity. Laser Doppler flowmetry and FITC-lectin were used to determine blood perfusion, and a fiber optic microsensor was used to measure airway tissue oxygen tension. Fungal burden and depth of invasion were graded using histopathology. We demonstrated a high efficacy (80%) for producing a localized fungal tracheal infection with the majority of infection occurring at the donor-recipient anastomosis; Aspergillus was more invasive in allogeneic compared to syngeneic groups. During the study period, the overall kinetics of both non-infected and infected allografts was similar, demonstrating a progressive loss of perfusion and oxygenation, which reached a nadir by days 10-12 post-transplantation. The extent of Aspergillus invasion directly correlated with the degree of graft hypoxia and ischemia. Compared to the midtrachea, the donor-recipient anastomotic site exhibited lower perfusion and more invasive disease; a finding consistent with clinical experience. For the first time, we identify ischemia as a putative risk factor for Aspergillus invasion. Therapeutic approaches focused on preserving vascular health may play an important role in limiting Aspergillus infections.
View details for DOI 10.1371/journal.pone.0077136
View details for Web of Science ID 000325887300058
View details for PubMedID 24155924
- Tie2-dependent VHL knockdown promotes airway microvascular regeneration and attenuates invasive growth of Aspergillus fumigatus JOURNAL OF MOLECULAR MEDICINE-JMM 2013; 91 (9): 1081-1093
Blocking Macrophage Leukotriene B-4 Prevents Endothelial Injury and Reverses Pulmonary Hypertension
SCIENCE TRANSLATIONAL MEDICINE
2013; 5 (200)
View details for Web of Science ID 000323705100010
Epithelial to mesenchymal transition in murine tracheal allotransplantation: an immunohistochemical observation.
2013; 45 (5): 1797-1801
Aberrant epithelial repair is a crucial event in the airway remodeling that characterizes obliterative bronchiolitis (OB) in transplanted lungs. Recent data from experiments using epithelial cell lines and human airway tissues from lung transplant recipients suggest that epithelial to mesenchymal transition (EMT) plays an important role in OB. The aim of this study was to clarify whether EMT is involved in airway remodeling in an animal model.We performed orthotopic tracheal transplantation from BALB/c to C57BL/6 mice with from BALC/c to BALB/c mouse grafts as controls. Five allogeneic and 3 syngeneic recipients were humanely killed at predetermined postoperative days 2-12 as well as 14 and 21. Histology was evaluated using hematoxylin-eosin (H&E) staining. We studied the expression of specific markers, including E-cadherin, an epithelial marker; ?-smooth muscle actin (SMA), and S100A4, mesenchymal markers, and zinc finger E-box-binding homeobox 1 (ZEB1), an EMT-related transcription factor.Histologic assessment of serial H&E stains of allogeneic grafts showed remarkable pseudostratified respiratory epithelium with subepithelial inflammatory cell infiltration, as well as denuded and flattened epithelium and subepithelial fibrosis. The dynamic epithelial changes occurred earlier than the subepithelial fibrosis. Immunohistochemical evaluation indicated the emergence of ?-SMA- positive epithelial cells that were most prominent on day 7. The expression of E-cadherin was attenuated in ?-SMA-positive epithelial cells. S100A4 was also expressed in epithelial cells. A few days before the intraepithelial expression of ?-SMA, ZEB1 emerged in the nuclei of epithelial cells.We observed expression of an EMT-related transcription factor and mesenchymal markers along with the attenuation of epithelial marker expression in epithelial cells, several days before prominent subepithelial fibrosis formation, results that suggest epithelial cells to play an important fibrosis role in airway remodeling during epithelial to mesenchymal transition.
View details for DOI 10.1016/j.transproceed.2012.11.024
View details for PubMedID 23769046
Targeting complement component 5a promotes vascular integrity and limits airway remodeling
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2013; 110 (15): 6061-6066
Increased microvascular dilatation and permeability is observed during allograft rejection. Because vascular integrity is an important indicator of transplant health, we have sought to limit injury to blood vessels by blocking complement activation. Although complement component 3 (C3) inhibition is known to be vasculoprotective in transplantation studies, we recently demonstrated the paradoxical finding that, early in rejection, C3(-/-) transplant recipients actually exhibit worse microvascular injury than controls. In the genetic absence of C3, thrombin-mediated complement component 5 (C5) convertase activity leads to the generation of C5a (anaphylatoxin), a promoter of vasodilatation and permeability. In the current study, we demonstrated that microvessel thrombin deposition is significantly increased in C3(-/-) recipients during acute rejection. Thrombin colocalization with microvessels is closely associated with remarkably elevated plasma levels of C5a, vasodilatation, and increased vascular permeability. Administration of NOX-D19, a specific C5a inhibitor, to C3(-/-) recipients of airway transplants significantly improved tissue oxygenation, limited microvascular leakiness, and prevented airway ischemia, even in the absence of conventional T-cell-directed immunosuppression. As C3 inhibitors enter the clinics, the simultaneous targeting of this thrombin-mediated complement activation pathway and/or C5a itself may confer significant clinical benefit.
View details for DOI 10.1073/pnas.1217991110
View details for Web of Science ID 000317537900065
View details for PubMedID 23530212
- Editorial: Developing Better Biomarkers for Connective Tissue DiseaseAssociated Interstitial Lung Disease: Citrullinated Hsp90 Autoantibodies in Rheumatoid Arthritis ARTHRITIS AND RHEUMATISM 2013; 65 (4): 864-868
Complement-mediated microvascular injury leads to chronic rejection.
Advances in experimental medicine and biology
2013; 735: 233-246
Microvascular loss may be an unappreciated root cause of chronic rejection for all solid organ transplants. As the only solid organ transplant that does not undergo primary systemic arterial revascularization at the time of surgery, lung transplants rely on the establishment of a microcirculation and are especially vulnerable to the effects of microvascular loss. Microangiopathy, with its attendant ischemia, can lead to tissue infarction and airway fibrosis. Maintaining healthy vasculature in lung allografts may be critical for preventing terminal airway fibrosis, also known as the bronchiolitis obliterans syndrome (BOS). BOS is the major obstacle to lung transplant success and affects up to 60% of patients surviving 5 years. The role of complement in causing acute microvascular loss and ischemia during rejection has recently been examined using the mouse orthotopic tracheal transplantation; this is an ideal model for parsing the role of airway vasculature in rejection. Prior to the development of airway fibrosis in rejecting tracheal allografts, C3 deposits on the vascular endothelium just as tissue hypoxia is first detected. With the eventual destruction of vessels, microvascular blood flow to the graft stops altogether for several days. Complement deficiency and complement inhibition lead to markedly improved tissue oxygenation in transplants, diminished airway remodeling, and accelerated vascular repair. CD4+ T cells and antibody-dependent complement activity independently mediate vascular destruction and sustained tissue ischemia during acute rejection. Consequently, interceding against complement-mediated microvascular injury with adjunctive therapy during acute rejection episodes, in addition to standard immunosuppression which targets CD4+ T cells, may help prevent the subsequent development of chronic rejection.
View details for PubMedID 23402031
Tie2-dependent VHL knockdown promotes airway microvascular regeneration and attenuates invasive growth of Aspergillus fumigatus.
Journal of molecular medicine (Berlin, Germany)
Microvascular ischemia and infections are associated with the development of chronic rejection following lung transplantation. The von Hippel-Lindau protein (VHL) controls protein levels of hypoxia-inducible factors (HIFs), regulates vascular repair, and improves tissue perfusion. Here, we studied the role of VHL in microvascular repair by orthotopically transplanting tracheas into mice with VHL haplodeficiency in Tie2 lineage cells. We showed that VHL haplodeficiency prolonged airway microvascular perfusion and promoted tissue blood flow through the production of the angiogenic factors, SDF-1 and angiopoietin 1. VHL-haplodeficient pulmonary endothelial cells exhibited increased angiogenic activity, resistance to serum deprivation-induced cell death, and enhanced microvascular repair. By contrast, in recipient mice with HIF-1? deficiency in Tie2 lineage cells, microvascular repair was significantly diminished and suggested that recipient-derived HIF-1? normally participates in the repair of alloimmune-mediated microvascular damage. To evaluate the translational impact of our findings, we compared VHL-haplodeficient mice with wild-type controls using a model of Aspergillus airway infection. In 83 % of the VHL-haplodeficient recipients, Aspergillus fumigatus was noninvasive in contrast to 75 % of wild-type mice in which the mold was deeply invasive. Our study demonstrated that stabilization of HIF-1? in angiogenic cells, through Tie2 cell VHL haplodeficiency, promoted airway microvascular regeneration and vascular normalization and thereby minimized tissue ischemia and hypoxia. By also mitigating the virulence of A. fumigatus, a common pathogen and itself a risk factor for the development of lung transplant rejection, the selective enhancement of HIF-1? expression has the prospect of offering several novel therapeutic effects to transplant recipients.Microvascular loss and prolonged ischemia occurs with acute rejection. Von Hippel-Lindau (VHL) protein controls hypoxia inducible factors (HIFs). In tracheal allografts, VHL haplodeficient Tie2 cells promote neovascularization. Reduced transplant ischemia limits Aspergillus invasion.
View details for PubMedID 23797537
Pathobiology of pulmonary arterial hypertension and right ventricular failure
EUROPEAN RESPIRATORY JOURNAL
2012; 40 (6): 1555-1565
Pulmonary arterial hypertension (PAH) is no longer an orphan disease. There are three different classes of drugs for the treatment of PAH that are currently being used and an increasing number of patients are being treated with a single drug or combination therapy. During the last 25 yrs, new insights into the pathobiology of PAH have been gained. The classical mechanical concepts of pressure, flow, shear stress, right ventricle wall stress and impedance have been complemented with the new concepts of cell injury and repair and interactions of complex multicellular systems. Integrating these concepts will become critical as we design new medical therapies in order to change the prognosis of patients with these fatal diseases. This review intends to summarise recent pathobiological concepts of PAH and right ventricle failure mainly derived from human studies, which reflect the progress made in the understanding of this complex group of pulmonary vascular diseases.
View details for DOI 10.1183/09031936.00046612
View details for Web of Science ID 000312055200033
View details for PubMedID 22743666
New methods for monitoring dynamic airway tissue oxygenation and perfusion in experimental and clinical transplantation
AMERICAN JOURNAL OF PHYSIOLOGY-LUNG CELLULAR AND MOLECULAR PHYSIOLOGY
2012; 303 (10): L861-L869
A dual circulation, supplied by bronchial and pulmonary artery-derived vessels, normally perfuses the airways from the trachea to the terminal bronchioles. This vascular system has been highly conserved through mammalian evolution and is disrupted at the time of lung transplantation. In most transplant centers, this circulation is not restored. The Papworth Hospital Autopsy study has revealed that an additional attrition of periairway vessels is associated with the development of chronic rejection, otherwise known as the bronchiolitis obliterans syndrome (BOS). Experimental studies subsequently demonstrated that airway vessels are subject to alloimmune injury and that the loss of a functional microvascular system identifies allografts that cannot be rescued with immunosuppressive therapy. Therefore, surgical and medical strategies, which preserve the functionality of the existent vasculature in lung transplant patients, may conceivably limit the incidence of BOS. Given these unique anatomic and physiological considerations, there is an emerging rationale to better understand the perfusion and oxygenation status of airways in transplanted lungs. This article describes novel methodologies, some newly developed by our group, for assessing airway tissue oxygenation and perfusion in experimental and clinical transplantation.
View details for DOI 10.1152/ajplung.00162.2012
View details for Web of Science ID 000311208400003
View details for PubMedID 23002078
Severe Pulmonary Arterial Hypertension Induced by SU5416 and Ovalbumin Immunization
AMERICAN JOURNAL OF RESPIRATORY CELL AND MOLECULAR BIOLOGY
2012; 47 (5): 679-687
The combination of chronic hypoxia and treatment of rats with the vascular endothelial growth factor (VEGF) receptor blocker, SU5416, induces pulmonary angio-obliteration, resulting in severe pulmonary arterial hypertension (PAH). Inflammation is thought to contribute to the pathology of PAH. Allergic inflammation caused by ovalbumin (OVA) immunization causes muscularization of pulmonary arteries, but not severe PAH. Whether disturbance of the immune system and allergic inflammation in the setting of lung endothelial cell apoptosis causes PAH is unknown. We investigated the effects of OVA-allergic inflammation on the development of PAH initiated by VEGF blockade-induced lung endothelial cell apoptosis. OVA-immunized rats were treated with SU5416 to induce pulmonary vascular endothelial cell apoptosis. The combination of OVA and SU5416 treatment resulted in severe angio-obilterative PAH, accompanied by increased IL-6 expression in the lungs. c-Kit(+) and Sca-1(+) cells were found in and around the lung vascular lesions. Pan-caspase inhibiton, dexamethasone treatment, and depletion of B-lymphocytes using an anti-CD20 antibody suppressed this remodeling. OVA immunization also increased lung tissue hypoxia-induced factor-1? and VEGF expression. Our results also suggest that the increased expression of hypoxia-induced factor-1? and IL-6 induced by the allergic lung inflammation may be a component of the pathogenesis of PAH.
View details for DOI 10.1165/rcmb.2012-0077OC
View details for Web of Science ID 000314406400015
View details for PubMedID 22842496
New models of pulmonary hypertension based on VEGF receptor blockade-induced endothelial cell apoptosis.
2012; 2 (4): 434-442
In spite of treatment, severe angioproliferative pulmonary arterial hypertension (PAH) remains a disease characterized by great morbidity and shortened survival. New treatment strategies for patients with PAH are needed, and after drug development, preclinical studies are best conducted in animal models which present with pulmonary angio-obliterative disease and right heart failure. A rat model of severe pulmonary hypertension and right heart failure, described a decade ago, continues to be investigated and provide insight into the nature of the lung vascular lesions and mechanisms of cardiac adaptation to an altered lung circulation. This rat model is based on the combination of VEGF receptor blockade with Su5416 and chronic hypoxia; use of this pulmonary hypertension induction strategy led to developing the concept of apoptosis-dependent compensatory vascular cell growth. Although, often employed in experimental designs, chronic hypoxia is not necessary for the development of angio-obliterative pulmonary hypertension. Left pneumonectomy combined with Su5416 also results in severe pulmonary hypertension in normoxic conditions. Similarly, the immune insufficiency component of severe PAH can be modeled in athymic rats (lacking T-lymphocytes). In these rats housed under normoxic conditions, treatment with the VEGFR receptor blocker results in angioproliferative pulmonary hypertension; cardiopulmonary disease in these animals can be prevented by immune reconstitution of regulatory T-cells (Tregs). Finally, chronic hypoxia can be replaced with another stimulator of HIF-1?: Ovalbumin (Ova). Immunization of rats with Ova increases lung tissue HIF-1? protein expression, and in Su5416-treated rats causes lethal pulmonary hypertension. Finally, we postulate that these models may also be useful for "reverse translation"; that is, the mechanisms of lung vascular cell death and growth and the modifying influences of immune and bone marrow cells that have been identified in the Su5416 VEGFR inhibitor models can be informative about heretofore undescribed processes in human PAH.
View details for DOI 10.4103/2045-8932.105031
View details for PubMedID 23372927
Neonatal mice genetically modified to express the elastase inhibitor elafin are protected against the adverse effects of mechanical ventilation on lung growth.
American journal of physiology. Lung cellular and molecular physiology
2012; 303 (3): L215-27
Mechanical ventilation (MV) with O(2)-rich gas (MV-O(2)) offers life-saving treatment for newborn infants with respiratory failure, but it also can promote lung injury, which in neonates translates to defective alveolar formation and disordered lung elastin, a key determinant of lung growth and repair. Prior studies in preterm sheep and neonatal mice showed that MV-O(2) stimulated lung elastase activity, causing degradation and remodeling of matrix elastin. These changes yielded an inflammatory response, with TGF-? activation, scattered elastic fibers, and increased apoptosis, culminating in defective alveolar septation and arrested lung growth. To see whether sustained inhibition of elastase activity would prevent these adverse pulmonary effects of MV-O(2), we did studies comparing wild-type (WT) and mutant neonatal mice genetically modified to express in their vascular endothelium the human serine elastase inhibitor elafin (Eexp). Five-day-old WT and Eexp mice received MV with 40% O(2) (MV-O(2)) for 24-36 h. WT and Eexp controls breathed 40% O(2) without MV. MV-O(2) increased lung elastase and MMP-9 activity, resulting in elastin degradation (urine desmosine doubled), TGF-? activation (pSmad-2 increased 6-fold), apoptosis (cleaved-caspase-3 increased 10-fold), and inflammation (NF-?B activation, influx of neutrophils and monocytes) in lungs of WT vs. unventilated controls. These changes were blocked or blunted during MV-O(2) of Eexp mice. Scattered lung elastin and emphysematous alveoli observed in WT mice after 36 h of MV-O(2) were attenuated in Eexp mice. Both WT and Eexp mice showed defective VEGF signaling (decreased lung VEGF-R2 protein) and loss of pulmonary microvessels after lengthy MV-O(2), suggesting that elafin's beneficial effects during MV-O(2) derived primarily from preserving matrix elastin and suppressing lung inflammation, thereby enabling alveolar formation during MV-O(2). These results suggest that degradation and remodeling of lung elastin can contribute to defective lung growth in response to MV-O(2) and might be targeted therapeutically to prevent ventilator-induced neonatal lung injury.
View details for DOI 10.1152/ajplung.00405.2011
View details for PubMedID 22683569
- Neonatal mice genetically modified to express the elastase inhibitor elafin are protected against the adverse effects of mechanical ventilation on lung growth AMERICAN JOURNAL OF PHYSIOLOGY-LUNG CELLULAR AND MOLECULAR PHYSIOLOGY 2012; 303 (3): L215-L227
A brief overview of mouse models of pulmonary arterial hypertension: problems and prospects
AMERICAN JOURNAL OF PHYSIOLOGY-LUNG CELLULAR AND MOLECULAR PHYSIOLOGY
2012; 302 (10): L977-L991
Many chronic pulmonary diseases are associated with pulmonary hypertension (PH) and pulmonary vascular remodeling, which is a term that continues to be used to describe a wide spectrum of vascular abnormalities. Pulmonary vascular structural changes frequently increase pulmonary vascular resistance, causing PH and right heart failure. Although rat models had been standard models of PH research, in more recent years the availability of genetically engineered mice has made this species attractive for many investigators. Here we review a large amount of data derived from experimental PH reports published since 1996. These studies using wild-type and genetically designed mice illustrate the challenges and opportunities provided by these models. Hemodynamic measurements are difficult to obtain in mice, and right heart failure has not been investigated in mice. Anatomical, cellular, and genetic differences distinguish mice and rats, and pharmacogenomics may explain the degree of PH and the particular mode of pulmonary vascular adaptation and also the response of the right ventricle.
View details for DOI 10.1152/ajplung.00362.2011
View details for Web of Science ID 000304357600001
View details for PubMedID 22307907
Potential for overuse of corticosteroids and vasopressin in septic shock.
Critical care (London, England)
2012; 16 (5): 447
View details for PubMedID 23102413
- Potential for overuse of corticosteroids and vasopressin in septic shock CRITICAL CARE 2012; 16 (5)
CD4(+) T Cells and Complement Independently Mediate Graft Ischemia in the Rejection of Mouse Orthotopic Tracheal Transplants
2011; 109 (11): 1290-U256
While microvascular injury is associated with chronic rejection, the cause of tissue ischemia during alloimmune injury is not yet elucidated.We investigated the contribution of T lymphocytes and complement to microvascular injury-associated ischemia during acute rejection of mouse tracheal transplants.Using novel techniques to assess microvascular integrity and function, we evaluated how lymphocyte subsets and complement specifically affect microvascular perfusion and tissue oxygenation in MHC-mismatched transplants. To characterize T cell effects on microvessel loss and recovery, we transplanted functional airway grafts in the presence and absence of CD4(+) and CD8(+) T cells. To establish the contribution of complement-mediated injury to the allograft microcirculation, we transplanted C3-deficient and C3-inhibited recipients. We demonstrated that CD4(+) T cells and complement are independently sufficient to cause graft ischemia. CD8(+) T cells were required for airway neovascularization to occur following CD4-mediated rejection. Activation of antibody-dependent complement pathways mediated tissue ischemia even in the absence of cellular rejection. Complement inhibition by CR2-Crry attenuated graft hypoxia, complement/antibody deposition on vascular endothelium and promoted vascular perfusion by enhanced angiogenesis. Finally, there was a clear relationship between the burden of tissue hypoxia (ischemia×time duration) and the development of subsequent airway remodeling.These studies demonstrated that CD4(+) T cells and complement operate independently to cause transplant ischemia during acute rejection and that sustained ischemia is a precursor to chronic rejection.
View details for DOI 10.1161/CIRCRESAHA.111.250167
View details for Web of Science ID 000296872200016
View details for PubMedID 21998328
Regulatory T Cells Limit Vascular Endothelial Injury and Prevent Pulmonary Hypertension
2011; 109 (8): 867-U120
Pulmonary arterial hypertension (PAH) is an incurable disease associated with viral infections and connective tissue diseases. The relationship between inflammation and disease pathogenesis in these disorders remains poorly understood.To determine whether immune dysregulation due to absent T-cell populations directly contributes to the development of PAH.Vascular endothelial growth factor receptor 2 (VEGFR2) blockade induced significant pulmonary endothelial apoptosis in T-cell-deficient rats but not in immune-reconstituted (IR) rats. T cell-lymphopenia in association with VEGFR2 blockade resulted in periarteriolar inflammation with macrophages, and B cells even prior to vascular remodeling and elevated pulmonary pressures. IR prevented early inflammation and attenuated PAH development. IR with either CD8 T cells alone or with CD4-depleted spleen cells was ineffective in preventing PAH, whereas CD4-depleting immunocompetent euthymic animals increased PAH susceptibility. IR with either CD4(+)CD25(hi) or CD4(+)CD25(-) T cell subsets prior to vascular injury attenuated the development of PAH. IR limited perivascular inflammation and endothelial apoptosis in rat lungs in association with increased FoxP3(+), IL-10- and TGF-?-expressing CD4 cells, and upregulation of pulmonary bone morphogenetic protein receptor type 2 (BMPR2)-expressing cells, a receptor that activates endothelial cell survival pathways.PAH may arise when regulatory T-cell (Treg) activity fails to control endothelial injury. These studies suggest that regulatory T cells normally function to limit vascular injury and may protect against the development of PAH.
View details for DOI 10.1161/CIRCRESAHA.110.236927
View details for Web of Science ID 000295368300008
View details for PubMedID 21868697
Inhibiting Lung Elastase Activity Enables Lung Growth in Mechanically Ventilated Newborn Mice
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
2011; 184 (5): 537-546
Mechanical ventilation with O?-rich gas (MV-O?) offers life-saving treatment for respiratory failure, but also promotes lung injury. We previously reported that MV-O2 of newborn mice increased lung elastase activity, causing elastin degradation and redistribution of elastic fibers from septal tips to alveolar walls. These changes were associated with transforming growth factor (TGF)-? activation and increased apoptosis leading to defective alveolarization and lung growth arrest, as seen in neonatal chronic lung disease.To determine if intratracheal treatment of newborn mice with the serine elastase inhibitor elafin would prevent MV-O?-induced lung elastin degradation and the ensuing cascade of events causing lung growth arrest.Five-day-old mice were treated via tracheotomy with recombinant human elafin or vehicle (lactated-Ringer solution), followed by MV with 40% O? for 8-24 hours; control animals breathed 40% O? without MV. At study's end, lungs were harvested to assess key variables noted below.MV-O? of vehicle-treated pups increased lung elastase and matrix metalloproteinase-9 activity when compared with unventilated control animals, causing elastin degradation (urine desmosine doubled), TGF-? activation (pSmad-2 tripled), and apoptosis (cleaved-caspase-3 increased 10-fold). Quantitative lung histology showed larger and fewer alveoli, greater inflammation, and scattered elastic fibers. Elafin blocked these MV-O?-induced changes.Intratracheal elafin, by blocking lung protease activity, prevented MV-O?-induced elastin degradation, TGF-? activation, apoptosis, and dispersion of matrix elastin, and attenuated lung structural abnormalities noted in vehicle-treated mice after 24 hours of MV-O?. These findings suggest that elastin breakdown contributes to defective lung growth in response to MV-O? and might be targeted therapeutically to prevent MV-O?-induced lung injury.
View details for DOI 10.1164/rccm.201012-2010OC
View details for Web of Science ID 000294478200014
View details for PubMedID 21562133
Regulatory T Cells and Pulmonary Hypertension
TRENDS IN CARDIOVASCULAR MEDICINE
2011; 21 (6): 166-171
Pulmonary hypertension (PH) is a disease of high lethality arising from numerous causes. For a significant subset of PH patients, autoimmune biomarkers or frank autoimmune disease are simultaneously present, but the extent to which lung inflammation contributes to PH is unknown. However, emerging experimental and clinical evidence suggests that immune dysregulation may lead to the propagation of vascular injury and PH. A recent preclinical study demonstrated that regulatory T cells are important mediators normally enlisted to control inflammation and that, if absent or dysfunctional, may predispose to the development of PH.
View details for Web of Science ID 000306942700003
View details for PubMedID 22814424
- Survival in Pulmonary Hypertension Registries The Importance of Incident Cases Response CHEST 2011; 139 (6): 1548-1549
Adenovirus-mediated HIF-1 alpha gene transfer promotes repair of mouse airway allograft microvasculature and attenuates chronic rejection
JOURNAL OF CLINICAL INVESTIGATION
2011; 121 (6): 2336-2349
Chronic rejection, manifested as small airway fibrosis (obliterative bronchiolitis [OB]), is the main obstacle to long-term survival in lung transplantation. Recent studies demonstrate that the airways involved in a lung transplant are relatively hypoxic at baseline and that OB pathogenesis may be linked to ischemia induced by a transient loss of airway microvasculature. Here, we show that HIF-1? mediates airway microvascular repair in a model of orthotopic tracheal transplantation. Grafts with a conditional knockout of Hif1a demonstrated diminished recruitment of recipient-derived Tie2? angiogenic cells to the allograft, impaired repair of damaged microvasculature, accelerated loss of microvascular perfusion, and hastened denudation of epithelial cells. In contrast, graft HIF-1? overexpression induced via an adenoviral vector prolonged airway microvascular perfusion, preserved epithelial integrity, extended the time window for the graft to be rescued from chronic rejection, and attenuated airway fibrotic remodeling. HIF-1? overexpression induced the expression of proangiogenic factors such as Sdf1, Plgf, and Vegf, and promoted the recruitment of vasoreparative Tie2? cells. This study demonstrates that a therapy that enhances vascular integrity during acute rejection may promote graft health and prevent chronic rejection.
View details for DOI 10.1172/JCI46192
View details for Web of Science ID 000291234300032
View details for PubMedID 21606594
The Role of C3 Activation in Airway Hypoxia and Ischemia in Murine Model of Orthotopic Tracheal Transplantation
ELSEVIER SCIENCE INC. 2011: S130-S131
View details for Web of Science ID 000288924300378
Immunomodulatory strategies prevent the development of autoimmune emphysema
The presence of anti-endothelial cell antibodies and pathogenic T cells may reflect an autoimmune component in the pathogenesis of emphysema. Whether immune modulatory strategies can protect against the development of emphysema is not known.Sprague Dawley rats were immunized with human umbilical vein endothelial cells (HUVEC) to induce autoimmune emphysema and treated with intrathymic HUVEC-injection and pristane. Measurements of alveolar airspace enlargement, cytokine levels, immuno histochemical, western blot analysis, and T cell repertoire of the lung tissue were performed.The immunomodulatory strategies protected lungs against cell death as demonstrated by reduced numbers of TUNEL and active caspase-3 positive cells and reduced levels of active caspase-3, when compared with lungs from HUVEC-immunized rats. Immunomodulatory strategies also suppressed anti-endothelial antibody production and preserved CNTF, IL-1alpha and VEGF levels. The immune deviation effects of the intrathymic HUVEC-injection were associated with an expansion of CD4+CD25+Foxp3+ regulatory T cells. Pristane treatment decreased the proportion of T cells expressing receptor beta-chain, V?16.1 in the lung tissue.Our data demonstrate that interventions classically employed to induce central T cell tolerance (thymic inoculation of antigen) or to activate innate immune responses (pristane treatment) can prevent the development of autoimmune emphysema.
View details for DOI 10.1186/1465-9921-11-179
View details for Web of Science ID 000285638200001
View details for PubMedID 21162738
Strategic Plan for Lung Vascular Research An NHLBI-ORDR Workshop Report
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
2010; 182 (12): 1554-1562
The Division of Lung Diseases of the National Heart, Lung, and Blood Institute, with the Office of Rare Diseases Research, held a workshop to identify priority areas and strategic goals to enhance and accelerate research that will result in improved understanding of the lung vasculature, translational research needs, and ultimately the care of patients with pulmonary vascular diseases. Multidisciplinary experts with diverse experience in laboratory, translational, and clinical studies identified seven priority areas and discussed limitations in our current knowledge, technologies, and approaches. The focus for future research efforts include the following: (1) better characterizing vascular genotype-phenotype relationships and incorporating systems biology approaches when appropriate; (2) advancing our understanding of pulmonary vascular metabolic regulatory signaling in health and disease; (3) expanding our knowledge of the biologic relationships between the lung circulation and circulating elements, systemic vascular function, and right heart function and disease; (4) improving translational research for identifying disease-modifying therapies for the pulmonary hypertensive diseases; (5) establishing an appropriate and effective platform for advancing translational findings into clinical studies testing; and (6) developing the specific technologies and tools that will be enabling for these goals, such as question-guided imaging techniques and lung vascular investigator training programs. Recommendations from this workshop will be used within the Lung Vascular Biology and Disease Extramural Research Program for planning and strategic implementation purposes.
View details for DOI 10.1164/rccm.201006-0869WS
View details for Web of Science ID 000285534600016
View details for PubMedID 20833821
Characterization of Connective Tissue Disease-Associated Pulmonary Arterial Hypertension From REVEAL Identifying Systemic Sclerosis as a Unique Phenotype
2010; 138 (6): 1383-1394
REVEAL (the Registry to Evaluate Early and Long-term Pulmonary Arterial Hypertension Disease Management) is the largest US cohort of patients with pulmonary arterial hypertension (PAH) confirmed by right-sided heart catheterization (RHC), providing a more comprehensive subgroup characterization than previously possible. We used REVEAL to analyze the clinical features of patients with connective tissue disease-associated PAH (CTD-APAH).All newly and previously diagnosed patients with World Health Organization (WHO) group 1 PAH meeting RHC criteria at 54 US centers were consecutively enrolled. Cross-sectional and 1-year mortality and hospitalization analyses from time of enrollment compared CTD-APAH to idiopathic disease and systemic sclerosis (SSc) to systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), and rheumatoid arthritis (RA).Compared with patients with idiopathic disease (n = 1,251), patients with CTD-APAH (n = 641) had better hemodynamics and favorable right ventricular echocardiographic findings but a higher prevalence of pericardial effusions, lower 6-min walk distance (300.5 ± 118.0 vs 329.4 ± 134.7 m, P = .01), higher B-type natriuretic peptide (BNP) levels (432.8 ± 789.1 vs 245.6 ± 427.2 pg/mL, P < .0001), and lower diffusing capacity of carbon monoxide (Dlco) (44.9% ± 18.0% vs 63.6% ± 22.1% predicted, P < .0001). One-year survival and freedom from hospitalization were lower in the CTD-APAH group (86% vs 93%, P < .0001; 67% vs 73%, P = .03). Compared with patients with SSc-APAH (n = 399), those with other CTDs (SLE, n = 110; MCTD, n = 52; RA, n = 28) had similar hemodynamics; however, patients with SSc-APAH had the highest BNP levels (552.2 ± 977.8 pg/mL), lowest Dlco (41.2% ± 16.3% predicted), and poorest 1-year survival (82% vs 94% in SLE-APAH, 88% in MCTD-APAH, and 96% in RA-APAH).Patients with SSc-APAH demonstrate a unique phenotype with the highest BNP levels, lowest Dlco, and poorest survival of all CTD-APAH subgroups. Trial registry: ClinicalTrials.gov; No.: NCT00370214; URL: clinicaltrials.gov.
View details for DOI 10.1378/chest.10-0260
View details for Web of Science ID 000285494000017
View details for PubMedID 20507945
Bronchial blood supply after lung transplantation without bronchial artery revascularization
CURRENT OPINION IN ORGAN TRANSPLANTATION
2010; 15 (5): 563-567
This review discusses how the bronchial artery circulation is interrupted following lung transplantation and what may be the long-term complications of compromising systemic blood flow to allograft airways.Preclinical and clinical studies have shown that the loss of airway microcirculations is highly associated with the development of airway hypoxia and an increased susceptibility to chronic rejection.The bronchial artery circulation has been highly conserved through evolution. Current evidence suggests that the failure to routinely perform bronchial artery revascularization at the time of lung transplantation may predispose patients to develop the bronchiolitis obliterans syndrome.
View details for DOI 10.1097/MOT.0b013e32833deca9
View details for Web of Science ID 000281837400004
View details for PubMedID 20689435
Lung Transplant Airway Hypoxia A Diathesis to Fibrosis?
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
2010; 182 (2): 230-236
Chronic rejection, manifested pathologically as airway fibrosis, is the major problem limiting long-term survival in lung transplant recipients. Airway hypoxia and ischemia, resulting from a failure to restore the bronchial artery (BA) circulation at the time of transplantation, may predispose patients to chronic rejection. To address this possibility, clinical information is needed describing the status of lung perfusion and airway oxygenation after transplantation.To determine the relative pulmonary arterial blood flow, airway tissue oxygenation and BA anatomy in the transplanted lung was compared with the contralateral native lung in lung allograft recipients.Routine perfusion scans were evaluated at 3 and 12 months after transplantation in 15 single transplant recipients. Next, airway tissue oximetry was performed in 12 patients during surveillance bronchoscopies in the first year after transplant and in 4 control subjects. Finally, computed tomography (CT)-angiography studies on 11 recipients were reconstructed to evaluate the post-transplant anatomy of the BAs.By 3 months after transplantation, deoxygenated pulmonary arterial blood is shunted away from the native lung to the transplanted lung. In the first year, healthy lung transplant recipients exhibit significant airway hypoxia distal to the graft anastomosis. CT-angiography studies demonstrate that BAs are abbreviated, generally stopping at or before the anastomosis, in transplant airways.Despite pulmonary artery blood being shunted to transplanted lungs after transplantation, grafts are hypoxic compared with both native (diseased) and control airways. Airway hypoxia may be due to the lack of radiologically demonstrable BAs after lung transplantation.
View details for DOI 10.1164/rccm.200910-1573OC
View details for Web of Science ID 000280206700014
View details for PubMedID 20339145
Immune Reconstitution Prevents Autoimmune Inflammation and Right Ventricular Remodeling in Immunodeficiency-Associated Pulmonary Hypertension
LIPPINCOTT WILLIAMS & WILKINS. 2009: S1135-S1135
View details for Web of Science ID 000271831504181
- Prevention of Adverse Right Ventricular Remodeling and Autoimmune Inflammation after Splenocyte Therapy in Pulmonary Hypertension: Contribution of HOX11+, C-kit+, FOXP3+Cells ACADEMIC PRESS INC ELSEVIER SCIENCE. 2009: S69-S70
Increased regulatory and decreased CD8+ cytotoxic T cells in the blood of patients with idiopathic pulmonary arterial hypertension
2008; 75 (3): 272-280
An association between pulmonary arterial hypertension (PAH) and various immune disorders is well established. Recently, the role of an intact immune system in protecting against pulmonary angioproliferation was shown in an animal model.To elucidate the role of T cells in human PAH, we comparatively studied T cell subclasses with emphasis on regulatory T cells (T(reg)) in the peripheral blood of patients with idiopathic pulmonary arterial hypertension (IPAH) and healthy controls.Isolated peripheral blood mononuclear cells from 36 patients diagnosed with IPAH and 33 healthy controls were stained with fluorescently labeled monoclonal antibodies against superficial T cell markers (CD3, CD4, CD8, CD25) and FoxP3, the intracellular marker of T(reg) cells. The relative cell distribution was analyzed by flow cytometry. The functionality of patient and control T(reg) cells was assessed by coculture of T(reg) with nonregulatory T cells from the same individual.Significantly less CD8+ T cells (p = 0.02) and more CD25hi+ and FoxP3+CD4+ T cells were found in the peripheral blood of patients compared with controls (p = 0.009 and p < 0.001, respectively). The percentage of FoxP3+ cells within the CD25hi+CD4+ T(reg) cells was similar. T(reg) cell functionality was equal in patients and controls.Our findings of decreased CD8+ T cells and increased T(reg) cells in the peripheral blood of patients with IPAH are novel and may have implications for directing future research in the field to elucidate the differential role of T cells and the immune system in IPAH.
View details for DOI 10.1159/000111548
View details for Web of Science ID 000255895400006
View details for PubMedID 18025812
Microvascular destruction identifies murine allografts that cannot be rescued from airway fibrosis
JOURNAL OF CLINICAL INVESTIGATION
2007; 117 (12): 3774-3785
Small airway fibrosis (bronchiolitis obliterans syndrome) is the primary obstacle to long-term survival following lung transplantation. Here, we show the importance of functional microvasculature in the prevention of epithelial loss and fibrosis due to rejection and for the first time, relate allograft microvascular injury and loss of tissue perfusion to immunotherapy-resistant rejection. To explore the role of alloimmune rejection and airway ischemia in the development of fibroproliferation, we used a murine orthotopic tracheal transplant model. We determined that transplants were reperfused by connection of recipient vessels to donor vessels at the surgical anastomosis site. Microcirculation through the newly formed vascular anastomoses appeared partially dependent on VEGFR2 and CXCR2 pathways. In the absence of immunosuppression, the microvasculature in rejecting allografts exhibited vascular complement deposition, diminished endothelial CD31 expression, and absent perfusion prior to the onset of fibroproliferation. Rejecting grafts with extensive endothelial cell injury were refractory to immunotherapy. After early microvascular loss, neovascularization was eventually observed in the membranous trachea, indicating a reestablishment of graft perfusion in established fibrosis. One implication of this study is that bronchial artery revascularization at the time of lung transplantation may decrease the risk of subsequent airway fibrosis.
View details for DOI 10.1172/JCI32311
View details for Web of Science ID 000251396600026
View details for PubMedID 18060031
Endogenous signals released from necrotic cells augment inflammatory responses to bacterial endotoxin
2007; 111 (1): 36-44
Stressed cells undergoing necrosis release molecules that acts as endogenous danger signals to alert and activate innate immune cells. Both HMGB1 and HSP70 are induced in activated monocytes/macrophages and also are released from stressed or injured cells. We investigated whether HMGB1 and HSP70 released from necrotic monocytes/macrophages, can act as danger signals to mediate proinflammatory cytokine responses to bacterial endotoxin or lipopolysaccharide (LPS). We show that cell lysate, obtained from necrotic cells directly stimulates the proinflammatory cytokine and chemokine responses in human monocyte/macrophage cell line, THP-1, as revealed by the induction of TNF-alpha, IL-6 and IL-8 mRNA expression and protein production. In the presence of LPS, necrotic cell lysate induced a more robust increase in all three proteins. We found that HMGB1 and HSP70 were indeed present in the necrotic cell lysate and were responsible for the significant induction of the proinflammatory cytokine expression, as neutralization with antibodies against both proteins blocked the increase in the cytokine production seen after incubating LPS-stimulated cells with the necrotic cell lysate. We also found that the newly identified triggering receptor expressed on myeloid cells-1 (TREM-1) was involved in mediating the HMGB1- and HSP70-induced cytokine production. Blocking TREM-1 on THP-1 cells with a recombinant chimera prevented the increase in cytokine production, while simultaneous blocking of TLR4 and TREM-1 completely abolished the proinflammatory response, suggesting that TREM-1 synergizes with TLR4 to mediate the effects of such signals from necrotic cells. In addition, blocking HMGB1 or HSP70 simultaneously with TREM-1 did not decrease the cytokine level further, confirming the involvement of TREM-1 in mediating the effect of HMGB1 and HSP70. Although the interaction of HMGB1 and HSP70 with TREM-1 induced I kappa B alpha and p38 expression, both of which are required for the inflammatory cytokine expression, blockade of TREM-1 did not affect I kappa B alpha expression but markedly reduced p38 activation, as revealed by Western blot analysis. Together, these results demonstrate that HMGB1 and HSP70 released from necrotic cells function as endogenous danger signals to augment the proinflammatory responses in monocytes/macrophage and that TREM-1 relays such signals to the cytokine expression cascade. This mechanism may contribute to the amplification and persistence of the inflammatory response to bacterial infection.
View details for DOI 10.1016/j.imlet.2007.04.011
View details for Web of Science ID 000248672100006
View details for PubMedID 17568691
Oxidant stress, immune dysregulation, and vascular function in type I diabetes
ANTIOXIDANTS & REDOX SIGNALING
2007; 9 (7): 879-889
Although high glucose is an important contributor to diabetic vasculopathies, complications still occur in spite of tight glycemic control, suggesting that some critical event prior to or concurrent with hyperglycemia may contribute to early vascular changes. Utilizing previously published and new experimental evidence, this review will discuss how prior to the hyperglycemic state, an imbalance between oxidants and antioxidants may contribute to early vascular dysfunction and set in motion proinflammatory insults that are further amplified as the diabetes develops. This imbalance results from the resetting of the equilibrium between vessel superoxide/H(2)O(2) production and/or decreased antioxidant defenses. Such an imbalance may cause endothelial dysfunction, characterized by abnormal endothelium-dependent vasoreactivity, as the first sign of blood vessel damage, followed by morphological changes of the vessel wall and inflammation. As such, increased oxidant stress in preglycemic states may be a critically central initiating event that underlies the pathogenesis of life-threatening vascular diseases in autoimmune diabetes. This review focuses on the relationship between oxidative stress, immune dysregulation, and vascular injury in type 1 diabetes, and how the discovery of novel pathways of vascular disease in nonobese diabetic mice may direct future studies in patients with type 1 diabetes.
View details for DOI 10.1089/ars.2007.1631
View details for Web of Science ID 000246646200009
View details for PubMedID 17508913
Hypoxia and the lung: Beyond hypoxic vasoconstriction
ANTIOXIDANTS & REDOX SIGNALING
2007; 9 (6): 741-743
This article extends the influence and effects of hypoxia on the lung beyond vasoconstriction and regional blood flow control. Clearly, hypoxia, via the transcription factor hypoxia-inducible factor (HIF)-1alpha, induces a large number of genes encoding proteins, which control cellular metabolism and growth and also participate in inflammation. Hypoxia, likely via vascular endothelial growth factor (VEGF), recruits bone marrow precursor cells to the lung and affects the behavior of immune cells. How hypoxia shapes immune responses through VEGF and its receptors on mast cells, eosinophils, and dendritic cells and through lung endothelial cell/lymphocyte interactions will be a productive area for future research.
View details for DOI 10.1089/ars.2007.1574
View details for Web of Science ID 000246646000011
View details for PubMedID 17511589
Transfer of allograft specific tolerance requires CD4(+)CD25(+)T cells but not interleukin-4 or transforming growth factor-beta and cannot induce tolerance to linked antigens
2007; 83 (8): 1075-1084
The mechanisms by which CD4+T cells, especially CD4+ CD25+T cells, transfer allograft specific tolerance are poorly defined. The role of cytokines and the effect on antigen-presenting cells is not resolved.Anti-CD3 monoclonal antibody (mAb) therapy induced tolerance to PVG heterotopic cardiac transplantation in DA rats. Peripheral CD4+T cells or CD4+ CD25+ and CD4+ CD25-T cell subsets were adoptively transferred to irradiated DA hosts grafted with PVG heart grafts. For specificity studies, tolerant CD4+T cells were transferred to hosts with Lewis or (PVGxLewis)F1 heart grafts. Cytokine mRNA induction and the requirement for interleukin (IL)-4 and transforming growth factor (TGF)-beta in the transfer of tolerance was assessed.CD4+T cells transferred specific tolerance and suppressed naïve CD4+T cells capacity to effect rejection of PVG but not Lewis grafts. (PVGxLewis)F1 grafts had a major rejection episode but recovered. Later these hosts accepted PVG but not Lewis skin grafts. Adoptive hosts restored with tolerant or naïve cells had similar levels of mRNA expression for all Th1 and Th2 cytokines and effector molecules assayed. Transfer of tolerance by CD4+T cells was not blocked by mAb to IL-4 or TGF-beta. CD4+ CD25-T cells from either naïve or tolerant hosts effected rejection. In contrast neither tolerant nor naïve CD4+ CD25+T cells restored rejection.Specific tolerance transfer required CD4+ containing CD4+ CD25+T cells. An inflammatory response with induction of mRNA for Th1 and Th2 cytokines plus cytotoxic effector molecules occurred, but IL-4 and TGF-beta were not essential. Inhibition of antigen presenting cells was not the sole mechanism as there was no linked tolerance.
View details for DOI 10.1097/01.tp.0000259553.66185.2f
View details for Web of Science ID 000246234800012
View details for PubMedID 17452898
Thymoquinone attenuates proinflammatory responses in lipopolysaccharide-activated mast cells by modulating NF-kappaB nuclear transactivation
BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS
2007; 1770 (4): 556-564
Activated mast cells play an important role in the development and maintenance of chronic inflammation by releasing proinflammatory cytokines such as Tumor necrosis factor alpha (TNFalpha). TNFalpha is a key mediator of immune and inflammatory responses as it controls the expression of inflammatory genes network and its overproduction contributes significantly to the pathological complications observed in many inflammatory diseases. We have previously shown that thymoquinone (TQ), which has broad anti-inflammatory activities, attenuates allergic inflammation in mice. In the present study, we investigated the effect of TQ on LPS-induced TNFalpha production in the rat basophil cell line, RBL-2H3. Stimulation of RBL-2H3 cells with LPS markedly increased TNFalpha production. TQ treatment significantly inhibited LPS-induced TNFalpha mRNA expression and protein production. To understand the mechanism by which TQ inhibited TNFalpha production, we examined its effects on activation of NF-kappaB transcription factor, which has been shown to be involved in regulating TNFalpha responses. LPS activated the NF-kappaB pathway, resulting in accumulation of NF-kappaB p65 and p50 subunits in the nucleus and activation of TNFalpha promoter. TQ administration to LPS-stimulated cells did not noticeably alter NF-kappaB cytosolic activation or nuclear expression as demonstrated by western blot analysis. Instead, TQ significantly increased the amount of the repressive NF-kappaB p50 homodimer, and simultaneously decreased the amount of transactivating NF-kappaB p65:p50 heterodimer, bound to the TNFalpha promoter as revealed by electrophoretic mobility shift and chromatin immunoprecipitation assays. Transient transfection of RBL-2H3 cells with TNFalpha promoter-driven luciferase gene constructs demonstrated that one of the three NF-kappaB binding sites in the TNFalpha promoter, the kappaB3 site, played a major role in the induction of TNFalpha promoter-driven luciferase gene expression by LPS, as well as in mediating the inhibitory effects of TQ on TNFalpha production, as TQ had minimal effect on the TNFalpha promoter-luciferase construct that lacks the kappaB3 site. Together, these results suggest that TQ attenuates the proinflammatory response in LPS-stimulated mast cells by modulating nuclear transactivation of NF-kappaB and TNFalpha production.
View details for DOI 10.1016/j.bbagen.2007.01.002
View details for Web of Science ID 000245165900007
View details for PubMedID 17292554
The matrix comes to lung transplantation
2007; 83 (6): 683-684
Lung transplantation is complicated by fibroproliferation, which is likely mediated in part by matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs. This commentary briefly discusses what is known about these mediators in fibrotic pulmonary diseases and how an important new study by Yoshida and colleagues sheds light on the diverse functions of these proteins in alloimmune inflammation.
View details for DOI 10.1097/01.tp.0000258596.27071.69
View details for Web of Science ID 000245411400006
View details for PubMedID 17414698
Angiogenesis in chronic lung disease
2007; 131 (3): 874-879
Chronic lung diseases like COPD, severe progressive pulmonary hypertension (PH), and interstitial lung diseases all have a lung vascular disease component. Cellular and molecular mechanisms of pulmonary vascular remodeling have been experimentally explored in many animal models, and it is now clear that microvessels are involved. In emphysema patients, there is a loss of lung microvessels, and in many forms of severe PH there is obliteration of precapillary arterioles by angioproliferation. Thus, COPD/emphysema and severe angioproliferative PH are on the opposite ends of a spectrum of vascular biology responses. Animal experiments have provided insight regarding some of the initiating events that shape the various forms of pulmonary vascular remodeling. In pulmonary fibrosis and in the postinjury phase of acute lung injury, the angiogenic/angiostatic balance is also affected. This review will therefore discuss angiogenesis in several chronic lung diseases and will speculate on how altered vascular homeostasis may contribute to lung disease development.
View details for DOI 10.1378/chest.06-2453
View details for Web of Science ID 000245072900038
View details for PubMedID 17356107
- Absence of T cells confers increased pulmonary arterial hypertension and vascular remodeling. Am J Respir Crit Care Med 2007; 175 (12): 1280-9
Is alveolar destruction and emphysema in chronic obstructive pulmonary disease an immune disease?
Proceedings of the American Thoracic Society
2006; 3 (8): 687-690
The alveolar destruction leading to airspace enlargement in patients with end-stage chronic obstructive pulmonary disease (COPD) is frequently progressive, despite smoking cessation. Several laboratories have accumulated data demonstrating the presence of immune cells in bronchial biopsy specimens and lung tissue sections from patients with COPD. Recently, the accumulation of T and B lymphocytes, often forming follicles, in the lung parenchyma from patients with severe COPD has been reported. In addition, it has been postulated that there might be an autoimmune component to COPD. T-cell receptor analysis has provided data consistent with the concept of T-cell clones in the lung tissue from patients with COPD. Against this background, we developed a model of autoimmune emphysema in adult rats. Based on published data showing that immunization of mice with human umbilical vein endothelial cells (HUVECs) causes production of anti-vascular endothelial growth factor (VEGF) receptor II (KDR) antibodies, and our own data indicating that administration of a VEGF receptor blocker in adult rats causes emphysema, we reasoned that intraperitoneal injection of HUVECs in rats would generate both anti-VEGF receptor antibodies and emphysema. Indeed, intraperitoneal injection of HUVECs caused emphysema. We further explored the autoimmune nature of this model, identified KDR antibodies in the serum of HUVEC-immunized rats, and injected serum from the emphysematous rats into naive rats and mice, which resulted in emphysema. Presently, we are in the process of investigating whether cigarette smoke extract causes emphysema. We recently identified anti-endothelial cell antibodies in the serum of patients with end-stage emphysema.
View details for PubMedID 17065374
Critical pathways leading to obliterative bronchiolitis in lung allografts
CURRENT OPINION IN ORGAN TRANSPLANTATION
2006; 11 (5): 483-489
View details for Web of Science ID 000241448000002
Mechanisms of autoimmune emphysema.
Proceedings of the American Thoracic Society
2006; 3 (6): 486-487
View details for PubMedID 16921121
Effect of thymoquinone on cyclooxygenase expression and prostaglandin production in a mouse model of allergic airway inflammation
2006; 106 (1): 72-81
Prostaglandins (PGs) are potent proinflammatory mediators generated through arachidonic acid metabolism by cyclooxygenase-1 and -2 (COX-1 and COX-2) in response to different stimuli and play an important role in modulating the inflammatory responses in a number of conditions, including allergic airway inflammation. Thymoquinone (TQ) is the main active constituent of the volatile oil extract of Nigella sativa seeds and has been reported to have anti-inflammatory properties. We examined the effect of TQ on the in vivo production of PGs and lung inflammation in a mouse model of allergic airway inflammation. Mice sensitized and challenged through the airways with ovalbumin (OVA) exhibited a significant increase in PGD2 and PGE2 production in the airways. The inflammatory response was characterized by an increase in the inflammatory cell numbers and Th2 cytokine levels in the bronchoalveolar lavage (BAL) fluid, lung airway eosinophilia and goblet cell hyperplasia, as well as the induction of COX-2 protein expression in the lung. Intraperitoneal injection of TQ for 5 days before the first OVA challenge attenuated airway inflammation as demonstrated by the significant decrease in Th2 cytokines, lung eosinophilia, and goblet cell hyperplasia. This attenuation of airway inflammation was concomitant to the inhibition of COX-2 protein expression and PGD2 production. However, TQ had a slight inhibitory effect on COX-1 expression and PGE2 production. These findings suggest that TQ has an anti-inflammatory effect during the allergic response in the lung through the inhibition of PGD2 synthesis and Th2-driven immune response.
View details for DOI 10.1016/j.imlet.2006.04.012
View details for Web of Science ID 000239978400011
View details for PubMedID 16762422
Downregulation of leukotriene biosynthesis by thymoquinone attenuates airway inflammation in a mouse model of allergic asthma
BIOCHIMICA ET BIOPHYSICA ACTA-GENERAL SUBJECTS
2006; 1760 (7): 1088-1095
Chronic airway inflammation is a key feature of bronchial asthma. Leukotrienes are potent inflammatory mediators that play a role in the pathophysiology of asthma, and their levels are elevated in the airways in response to allergen challenge. We examined the anti-inflammatory effect of thymoquinone (TQ), the active principle in the volatile oil of Nigella sativa seeds, on leukotriene (LT) biosynthesis in a mouse model of allergic asthma. Mice sensitized and challenged with ovalbumin (OVA) antigen had an increased amounts of leukotriene B4 and C4, Th2 cytokines, and eosinophils in bronchoalveolar lavage (BAL) fluid. In addition, there was also a marked increase in lung tissue eosinophilia and goblet cell numbers. Administration of TQ before OVA challenge inhibited 5-lipoxygenase, the main enzyme in leukotriene biosynthesis, expression by lung cells and significantly reduced the levels of LTB4 and LTC4. This was accompanied by a marked decrease in Th2 cytokines and BAL fluid and lung tissue eosinophilia, all of which are characteristics of airway inflammation. These results demonstrate the anti-inflammatory effect of TQ in experimental asthma.
View details for DOI 10.1016/j.bbagen.2006.03.006
View details for Web of Science ID 000239040700013
View details for PubMedID 16624488
Anti-inflammatory effect of thymoquinone in a mouse model of allergic lung inflammation
2006; 6 (7): 1135-1142
Thymoquinone (TQ), the main active constituent of the volatile oil extracted from Nigella sativa's seeds, has been reported to have an anti-inflammatory and immune stimulatory effect on bronchial asthma and inflammation. However, little is known about the factors and mechanisms underlying these effects. In the present study, we examined the effect of TQ on airway inflammation in a mouse model of allergic asthma. Intraperitoneal injection of TQ before airway challenge of ovalbumin (OVA)-sensitized mice resulted in a marked decrease in lung eosinophilia and the elevated Th2 cytokines observed after airway challenge with OVA antigen; both in vivo, in the bronchoalveolar lavage (BAL) fluid and in vitro, following stimulation of lung cells with OVA. TQ also decreased the elevated serum levels of OVA-specific IgE and IgG1. Histological examination of lung tissue demonstrated that TQ significantly inhibited allergen-induced lung eosinophilic inflammation and mucus-producing goblet cells. While TQ showed a significant effect in inhibiting IL-4, IL-5 and IL-13 and some effect in inducing IFN-gamma production in the BAL fluid, it did show a slight effect on in vitro production of IL-4 by cultured lung cells stimulated with OVA antigen. These data suggest that TQ attenuates allergic airway inflammation by inhibiting Th2 cytokines and eosinophil infiltration into the airways; thus demonstrating its potential anti-inflammatory role during the allergic response in the lung.
View details for DOI 10.1016/j.intimp.2006.02.004
View details for Web of Science ID 000238155900012
View details for PubMedID 16714217
LFA-1 (CD11a) as a therapeutic target
AMERICAN JOURNAL OF TRANSPLANTATION
2006; 6 (1): 27-36
Leukocyte function associated antigen-1 (LFA-1) was one of the earliest of cell-surface molecules identified by monoclonal antibodies generated against leukocyte immunogens. This integrin heterodimer is perhaps best known as a classic adhesion molecule facilitating the interaction between T cells and antigen-presenting cells. However, varied studies indicate that LFA-1 has multi-faceted roles in the immune response including adhesion, activation and trafficking of leukocyte populations. While there has been long-standing interest in LFA-1 as a therapeutic target for regulating immunity, anti-LFA-1 therapy is still not a first-line indication for any clinical condition. Antagonism of LFA-1 with monoclonal antibodies, either alone or in combination with other agents, can result in regulatory tolerance in vivo. Furthermore, new generation humanized anti-LFA-1 monoclonal antibodies (Efalizumab) show at least modest promise for continued application in clinical trials. Thus, anti-LFA-1 forms a potential, but still largely unexploited, immunotherapy which may find its greatest application as an agent which augments other therapies.
View details for DOI 10.1111/j.1600-6143.2005.01158.x
View details for Web of Science ID 000234344900008
View details for PubMedID 16433753
Autoimmunity and pulmonary hypertension: a perspective
EUROPEAN RESPIRATORY JOURNAL
2005; 26 (6): 1110-1118
The association between autoimmunity and pulmonary arterial hypertension (PAH) has been appreciated for >40 yrs, but how autoimmune injury might contribute to the pathogenesis of this disease has only been examined in a case-specific manner. It is becoming increasingly clear that a variety of diverse clinical diseases, ranging from viral infections to connective tissue disorders, can culminate in pulmonary vascular pathology that is indistinguishable. Is there a hitherto unappreciated biology that unites these seemingly unrelated conditions? The answer to this question may come from the increasing body of evidence concerned with the central importance of regulatory T-cells in preventing inappropriate B-cell activity. Two striking similarities between conditions associated with severe angioproliferative pulmonary hypertension are a defect in the CD4 T-cell compartment and auto-antibody production. Pathogenic auto-antibodies targeting endothelial cells are capable of inducing vascular endothelial apoptosis and may initiate the development of PAH. The present review will focus on what is known about autoimmune phenomena in pulmonary arterial hypertension patients, in order to better consider whether an early loss of self-tolerance followed by autoimmune injury could influence the early development of severe angioproliferative pulmonary hypertension.
View details for DOI 10.1183/09031936.05.00045705
View details for Web of Science ID 000234203100023
View details for PubMedID 16319344
- The protective role of T-lymphocytes in pulmonary vascular remodeling CHEST 2005; 128 (6): 571S-572S
Type 2 diabetes mellitus as a conformational disease.
JOP : Journal of the pancreas
2005; 6 (4): 287-302
Conformational diseases are conditions that arise from the dysfunctional aggregation of proteins in non-native conformations. Type 2 diabetes mellitus can be defined as a conformational disease because a constituent beta cell protein, islet amyloid polypeptide, undergoes a change in tertiary structure followed by self-association and tissue deposition. Type 2 diabetes mellitus is associated with multiple metabolic derangements that result in the excessive production of reactive oxygen species and oxidative stress. These reactive oxygen species set in motion a host of redox reactions which can result in unstable nitrogen and thiol species that contribute to additional redox stress. The ability of a cell to deal with reactive oxygen species and oxidative stress requires functional chaperones, antioxidant production, protein degradation and a cascade of intracellular events collectively known as the unfolded protein response. It is known that beta cells are particularly susceptible to perturbations in this quality control system and that reactive oxygen species play an important role in the development and/or progression of diabetes mellitus. Oxidative stress and increased insulin production contribute to endoplasmic reticulum stress, protein misfolding, and induction of the unfolded protein response. As the cell's quality control system becomes overwhelmed, conformational changes occur to islet amyloid polypeptide intermediates, generating stable oligomers with an anti-parallel crossed beta-pleated sheet structure that eventually accumulate as space-occupying lesions within the islets. By approaching type 2 diabetes mellitus as a conformational disease in which there is a structural transition from physiological protein to pathological protein, it is possible that the relentless nature of disease progression can be understood in relation to other conformational diseases.
View details for PubMedID 16006679
Chemokine-mediated angiogenesis: an essential link in the evolution of airway fibroses?
JOURNAL OF CLINICAL INVESTIGATION
2005; 115 (5): 1133-1136
Angiogenesis may be an important factor in the development of fibrotic lung disease. Prior studies have strongly suggested a role for angiogenic vascular remodeling in pulmonary fibrosis, and emerging evidence indicates that new vessel formation is critical in airway fibrosis. Bronchiolitis obliterans syndrome is a fibrotic occlusion of distal airways that is largely responsible for the morbidity and mortality of patients after lung transplantation. In this issue, Belperio et al. demonstrate a role for CXC chemokine receptor 2 in the regulation of angiogenesis-mediated airway fibroproliferation. By integrating an understanding of neovascularization into the study of events that occur between inflammation and fibrosis, it becomes increasingly possible to rationally design therapies that can halt conditions of maladaptive fibrosis.
View details for DOI 10.1172/JCI200525193
View details for Web of Science ID 000228908300010
View details for PubMedID 15864341
Simultaneous LFA-1 and CD40 ligand antagonism prevents airway remodeling in orthotopic airway transplantation: Implications for the role of respiratory epithelium as a modulator of fibrosis
JOURNAL OF IMMUNOLOGY
2005; 174 (7): 3869-3879
Airway remodeling is a prominent feature of certain immune-mediated lung diseases such as asthma and chronic lung transplant rejection. Under conditions of airway inflammation, the respiratory epithelium may serve an important role in this remodeling process. Given the proposed role of respiratory epithelium in nonspecific injury models, we investigated the respiratory epithelium in an immune-specific orthotopic airway transplant model. MHC-mismatched tracheal transplants in mice were used to generate alloimmune-mediated airway lesions. Attenuation of this immune injury and alteration of antidonor reactivity were achieved by the administration of combined anti-LFA-1/anti-CD40L mAbs. By contrast, without immunotherapy, transplanted airways remodeled with a flattening of respiratory epithelium and significant subepithelial fibrosis. Unopposed alloimmune injury for 10 days was associated with subsequent epithelial transformation and subepithelial fibrosis that could not be reversed with immunotherapy. The relining of donor airways with recipient-derived epithelium was delayed with immunotherapy resulting in partially chimeric airways by 28 days. Partial chimerism was sufficient to prevent luminal fibrosis. However, epithelial chimerism was also associated with airway remodeling. Therefore, there appears to be an intimate relationship between the morphology and level of chimerism of the respiratory epithelium and the degree of airway remodeling following alloimmune injury.
View details for Web of Science ID 000228000100010
View details for PubMedID 15778341
An animal model of autoimmune emphysema
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
2005; 171 (7): 734-742
Although cigarette smoking is implicated in the pathogenesis of emphysema, the precise mechanisms of chronic progressive alveolar septal destruction are not well understood. We show, in a novel animal model, that immunocompetent, but not athymic, nude rats injected intraperitoneally with xenogeneic endothelial cells (ECs) produce antibodies against ECs and develop emphysema. Immunization with ECs also leads to alveolar septal cell apoptosis and activation of matrix metalloproteases MMP-9 and MMP-2. Anti-EC antibodies cause EC apoptosis in vitro and emphysema in passively immunized mice. Moreover, immunization also causes accumulation of CD4+ T cells in the lung. Adoptive transfer of pathogenic, spleen-derived CD4+ cells into naive immunocompetent animal also results in emphysema. This study shows for the first time that humoral- and CD4+ cell-dependent mechanisms are sufficient to trigger the development of emphysema, suggesting that alveolar septal cell destruction might result from immune mechanisms.
View details for DOI 10.1164/rccm.200409-127SOC
View details for Web of Science ID 000228053000011
View details for PubMedID 15563631
Following universal prophylaxis with intravenous ganciclovir and cytomegalovirus immune globulin, valganciclovir is safe and effective for prevention of CMV infection following lung transplantation
AMERICAN JOURNAL OF TRANSPLANTATION
2004; 4 (10): 1635-1642
We prospectively determined the safety and efficacy of valganciclovir for prevention of cytomegalovirus (CMV) in at-risk (donor positive/recipient negative [D+/R-] or R+) lung transplant recipients. We also determined the length of prophylaxis required to significantly decrease both CMV infection and disease. Consecutive lung transplant recipients surviving >30 days (n = 90) received combination prophylaxis with intravenous (i.v.) ganciclovir (GCV) 5 mg/kg/day and cytomegalovirus immune globulin (CMV-IVIG) followed by valganciclovir (450 mg twice-daily) to complete 180, 270 or 365 days of prophylaxis. This group was compared to a historical group (n = 140) who received high-dose oral acyclovir following i.v. GCV and CMV-IVIG. CMV disease was significantly lower in patients receiving valganciclovir compared to acyclovir (2.2% vs. 20%; p < 0.0001). Freedom from CMV infection and disease was significantly greater (p < 0.02) in patients receiving 180, 270 or 365 days of prophylaxis (90%, 95% and 90%, respectively) compared to those receiving 100-179 days (64%) or < 100 days (59%). No patient receiving valganciclovir died during the study. Following prophylaxis with i.v. GCV and CMV-IVIG, valganciclovir is safe and effective for prevention of CMV infection and disease in at-risk lung transplant recipients. The required length of prophylaxis was at least 180 days.
View details for DOI 10.1111/j.1600-6143.2004.00571.x
View details for Web of Science ID 000223862300010
View details for PubMedID 15367218
The Clinical and Biological Relationship between Type II Diabetes Mellitus and Alzheimer's Disease
CURRENT ALZHEIMER RESEARCH
2004; 1 (1): 47-54
The clinical relationship between Type II diabetes mellitus and Alzheimer's disease has been debated for over a decade. While several studies have not shown a clear clinical correlation, others have demonstrated that Type II diabetes is an independent risk factor for Alzheimer's disease. Why diabetes would increase the likelihood of Alzheimer's disease is not immediately clear, although recent studies have demonstrated an impact of insulin abnormalities, insulin resistance and advanced glycation end products on both the development of neural amyloid plaques and neurofibrillary tangles. Although endodermal in embryologic development, the pancreas is a highly innervated organ that shares a number of molecular similarities with brain at the level of the transcriptome and proteome. Type II diabetes and Alzheimer's disease are characterized by localized amyloid deposits that progress during the course of the disease. Comparing amyloid deposition in the brain and pancreas reveals some striking pathophysiologic similarities. Neurodegeneration in pancreatic islets, as manifested by neurofibrillary tangles, is less well studied than in Alzheimer's disease but may also occur. This review summarizes what is currently known about the clinical and biological relationships and similarities between Type II diabetes and Alzheimer's disease.
View details for Web of Science ID 000207883200007
View details for PubMedID 15975085
Gene microarray study corroborates proteomic findings in rodent islet cells
JOURNAL OF PROTEOME RESEARCH
2003; 2 (5): 553-555
As reported in an issue of Journal of Proteome Research, mass spectrometry has been used to identify numerous proteins in pancreatic islets. Our group studies beta cell gene expression, and we were interested in whether proteins described in this study could be found at the level of the transcriptome. Microarray analysis is a powerful technique for quantitative measurements of the expression of thousand genes in parallel. However, in crude tumor biopsies, only a subset of transcripts correlate with protein levels, and it is still unknown how frequently mRNA expression correlates with amount of protein in well-differentiated cells. To address this issue, we presently compared data from mouse primary islet proteins obtained by proteomic analysis with RNA data from FACS purified primary rat beta cells obtained by microarray analysis (Rasschaert J, Liu D, Cardozo AK, Kutlu B, Eizirik DL, manuscript in preparation).
View details for DOI 10.1021/pr034029o
View details for Web of Science ID 000186002600011
View details for PubMedID 14582652
Proteomics as a tool for discovery: Proteins implicated in Alzheimer's disease are highly expressed in normal pancreatic islets
JOURNAL OF PROTEOME RESEARCH
2003; 2 (2): 199-205
A proteomic analysis of islets was undertaken to determine the protein constituents of normal adult mouse islets. Unexpectedly, we identified several islet proteins that are associated with the pathogenesis of Alzheimer's disease. Some of these proteins had chaperone activity that is integral to proper protein folding. This group includes GRP78, valosin-containing protein, calreticulin, protein disulfide isomerase, DnaK, HSP70, HSP60, and TCP-1. Additionally, neuronal proteins key to coordinated neuronal guidance and survival were also identified in islets. This group includes proprotein convertase subtilisin, collapsin response mediator protein 2, ubiquinol-cytochrome c reductase core protein, L-3-hydroxyacyl-Coenzyme A dehydrogenase, glutamine synthetase, peroxiredoxin, and secretogogin. An important subset of the proteins identified here has not been reported previously in pancreatic islets. Abnormal activity of these proteins in brain may contribute to the pathogenesis of Alzheimer's disease, a neurodegenerative condition characterized by focal amyloid deposits with neurofibrillary tangles. The putative role of these proteins in Alzheimer's pathogenesis is intriguing given the possible clinical relationship and pathological similarity of Alzheimer's disease to type 2 diabetes. These findings have therefore led to the hypothesis that these proteins may also play a role in type 2 diabetes.
View details for DOI 10.1021/pr025576x
View details for Web of Science ID 000182143500010
View details for PubMedID 12716134
CD4-dependent generation of dominant transplantation tolerance induced by simultaneous perturbation of CD154 and LFA-1 pathways
JOURNAL OF IMMUNOLOGY
2002; 169 (9): 4831-4839
CD154 and LFA-1 (CD11a) represent conceptually distinct pathways of receptor/ligand interactions (costimulation and adhesion/homing, respectively) that have been effectively targeted to induce long-term allograft acceptance and tolerance. In the current study, we determined the relative efficacy and nature of tolerance induced by mAbs specific for these pathways. In vitro analysis indicated that simultaneous targeting of CD154 and LFA-1 resulted in profound inhibition of alloreactivity, suggesting that combined anti-CD154/anti-LFA-1 therapy could be highly effective in vivo. Thus, we evaluated combining mAb therapies targeting CD154 and LFA-1 for inducing transplantation tolerance to pancreatic islet allografts. Monotherapy with either anti-CD154 or anti-LFA-1 was partially effective for inducing long-term allograft survival, whereas the combination resulted in uniform allograft acceptance in high-responder C57BL/6 recipients. This combined therapy was not lymphocyte depleting and did not require the long-term deletion of donor-reactive T lymphocytes to maintain allograft survival. Importantly, combined anti-CD154/anti-LFA therapy uniquely resulted in "dominant" transplantation tolerance. Therefore, simultaneous perturbation of CD154 and LFA-1 molecules can result in profound tolerance induction not accomplished through individual monotherapy approaches. Furthermore, results show that such regulatory tolerance can coexist with the presence of robust anti-donor reactivity, suggesting that active tolerance does not require a corresponding deletion of donor-reactive T cells. Interestingly, although the induction of this regulatory state was highly CD4 dependent, the adoptive transfer of tolerance was less CD4 dependent in vivo.
View details for Web of Science ID 000178777400019
View details for PubMedID 12391193
Interferon-gamma is not a universal requirement for islet allograft survival
2002; 74 (4): 472-477
Although many transplantation studies have implicated a graft-destructive role for T helper (Th)1 cytokines and a graft-protective role for Th2 cytokines, more recent studies have challenged this paradigm by showing that long-term allograft survival can actually require the presence of Th1 cytokines, such as interleukin 2 and interferon (IFN)-gamma. The purpose of this study was to examine the requirement for IFN-gamma in the induction of islet allograft acceptance after monoclonal antibody therapy targeting conceptually distinct molecular pathways: the costimulatory molecule CD154, the CD4 coreceptor, or the beta2 integrin lymphocyte function-associated antigen (LFA)-1 (CD11a).Diabetic C57Bl/6 (B6; H2b) mice were grafted with fully MHC mismatched BALB/c (H2d) islets, or reciprocally, diabetic BALB/c mice underwent transplantation with B6 islets and were treated with anti-CD154, anti-CD4, or anti-LFA-1.When IFN-gamma gene knockout mice were used as graft recipients, the requirement for IFN-gamma in allograft survival was found to be highly conditional, depending on both the host strain and the induction therapy used. In both strain combinations studied, anti-CD154 was effective in the presence or absence of IFN-gamma, whereas anti-CD4 lost therapeutic potential in the absence of this cytokine. Alternatively, the requirement for IFN-gamma for allograft prolongation by anti-LFA-1 therapy was noted only in B6 transplant recipients.IFN-gamma is not always requisite in islet allograft survival but rather varies according to the molecular target of induction therapy and the genetic background of the transplant recipient.
View details for DOI 10.1097/01.TP.0000026310.54443.3E
View details for Web of Science ID 000177808600007
View details for PubMedID 12352904
Reversal of experimental allergic encephalomyelitis with non-mitogenic, non-depleting anti-CD3 mAb therapy with a preferential effect on T(h)1 cells that is augmented by IL-4
2001; 13 (9): 1109-1120
This study examined whether therapy with a non-mitogenic, non-activating anti-CD3 mAb (G4.18) alone, or in combination with the T(h)2 cytokines, could inhibit induction or facilitate recovery from experimental allergic encephalomyelitis (EAE) in Lewis rats. G4.18, but not rIL-4, rIL-5 or anti-IL-4 mAb, reduced the severity and accelerated recovery from active EAE. A combination of rIL-4 with G4.18 was more effective than G4.18 alone. The infiltrate of CD4(+) and CD8(+) T cells, B cells, dendritic cells, and macrophages in the brain stem was less with combined G4.18 and IL-4 than G4.18 therapy or no treatment. Residual cells had preferential sparing of T(r)1 cytokines IL-5 and transforming growth factor-beta with loss of T(h)1 markers IL-2, IFN-gamma and IL-12Rbeta2, and the T(h)2 cytokine IL-4 as well as macrophage cytokines IL-10 and tumor necrosis factor-alpha. Lymph nodes draining the site of immunization had less mRNA for T(h)1 cytokines, but T(h)2 and T(r)1 cytokine expression was spared. Treatment with G4.18, rIL-4 or rIL-5 from the time of immunization had no effect on the course of active EAE. MRC OX-81, a mAb that blocks IL-4, delayed onset by 2 days, but had no effect on severity of active EAE. G4.18 also inhibited the ability of activated T cells from rats with active EAE to transfer passive EAE. This study demonstrated that T cell-mediated inflammation was rapidly reversed by a non-activating anti-CD3 mAb that blocked effector T(h)1 cells, and spared cells expressing T(h)2 and T(r)1 cytokines.
View details for Web of Science ID 000171127200003
View details for PubMedID 11526091
The basis of immunogenicity of endocrine allografts
BEGELL HOUSE INC. 2001: 87-101
Two signals are required for optimal T-cell activation: the engagement of the antigen-specific receptor and the provision of a second non-antigen-specific inductive signal, or costimulator (CoS). Regarding allograft immunity, two primary pathways of donor antigen presentation can fulfill this two-signal requirement, resulting in cellular immunity to a transplant: (1) "direct" (donor MHC-restricted) presentation in which the antigen-presenting cells (APCs) resident within the transplant directly activate host T lymphocytes and (2) "indirect" (host MHC-restricted) presentation in which host-derived APCs acquire donor antigens that are then presented to host T lymphocytes. It appears that endocrine allografts, such as pancreatic islets and thyroid, are highly dependent on donor-derived APCs, or "passenger leukocytes," to trigger acute graft rejection. Tissue pretreatment aimed at selectively eliminating APCs within endocrine tissues can result in indefinite allograft survival in immune-competent recipients. Although such results implicate the "direct" pathway as the predominant route of host sensitization, the role of donor APCs in rejection appears to be more complex. Recently, we have found that indirect, CD4 T-cell-dependent reactivity can contribute to islet allograft rejection. However, such indirect recognition nevertheless requires donor-derived APCs as a source of antigen. Thus, whereas the donor-type APC is a critical limiting step for initiating islet allograft rejection, such cells can trigger both direct and indirect forms of immune responses that can result in graft rejection. That is, donor hematopoietic cells, rather than tissue parenchymal cells, probably play a major role in providing antigens that stimulate cellular immunity.
View details for Web of Science ID 000171493400007
View details for PubMedID 11642616
Anti-LFA-1 therapy induces long-term islet allograft acceptance in the absence of IFN-gamma or IL-4
JOURNAL OF IMMUNOLOGY
2000; 164 (7): 3627-3634
mAb therapy directed against a variety of cell surface accessory molecules has been effectively utilized to prolong allograft acceptance in various models of tissue and organ transplantation. The purpose of this study was to determine whether transient therapy directed against the adhesion molecule LFA-1 (CD11a) was sufficient to induce donor-specific tolerance to pancreatic islet allografts. Anti-LFA-1 monotherapy was found to be efficacious in inducing long-term islet allograft acceptance in multiple donor-recipient strain combinations. Graft acceptance following anti-LFA-1 therapy was not simply due to clonal ignorance of donor Ags in that the majority of recipients bearing established islet allografts resisted rejection induced by immunization with donor-type APCs. Furthermore, donor-specific tolerance from anti-LFA-1-treated animals could be transferred to secondary immune-deficient animals. Taken together, these results indicated that transient anti-LFA-1 monotherapy resulted in donor-specific tolerance. In vitro, functionally tolerant animals retained normal anti-donor reactivity as assessed by proliferative, cytotoxic, and cytokine release assays that demonstrated that tolerance was not secondary to general clonal deletion or anergy of donor-reactive T cells. Finally, anti-LFA-1 treatment was effective in both IL-4-deficient and IFN-gamma-deficient recipients, indicating that neither of these cytokines are universally required for allograft acceptance. These results suggest that anti-adhesion-based therapy can induce a nondeletional form of tolerance that is not overtly dependent on the prototypic Th1 and Th2 cytokines, IFN-gamma and IL-4, respectively, in contrast to results in other transplantation models.
View details for Web of Science ID 000086020700025
View details for PubMedID 10725719
Diffuse alveolar hemorrhage with underlying pulmonary capillaritis in the retinoic acid syndrome
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
1998; 158 (4): 1302-1305
All-trans-retinoic acid (ATRA) can induce a clinical remission in patients with acute promyelocytic leukemia. An adverse condition called "retinoic acid syndrome" limits this therapy. It is characterized by fever and respiratory distress, along with weight gain, pleural or pericardial effusions, peripheral edema, thromboembolic events, and intermittent hypotension. The lung disease has been previously ascribed to an infiltration of leukemic or maturing myeloid cells into lung parenchyma, which is sometimes associated with pleural effusions and diffuse alveolar hemorrhage. We report a case of retinoic acid syndrome in an 18-yr-old woman who developed diffuse alveolar hemorrhage while being treated with ATRA for acute promyelocytic leukemia. An open lung biopsy revealed pulmonary capillaritis.
View details for Web of Science ID 000076453300044
View details for PubMedID 9769296
Recognition and treatment of diffuse panbronchiolitis
INFECTIONS IN MEDICINE
1998; 15 (9): 657-662
View details for Web of Science ID 000076097100019
INDUCTION OF TOLERANCE TO HEART ALLOGRAFTS IN RATS USING POSTTRANSPLANT TOTAL LYMPHOID IRRADIATION AND ANTI-T CELL ANTIBODIES
1993; 56 (6): 1443-1447
This study examined whether posttransplant anti-T cell monoclonal or polyclonal antibody therapy could provide a window of treatment to allow posttransplant total lymphoid irradiation (TLI) to induce tolerance. These experiments were conducted in a high responder strain combination of an ACI cardiac allograft into a Lewis rat. In this situation, treatment with antibody or posttransplant TLI alone is insufficient to induce tolerance, while similar treatments alone have been shown to induce tolerance in low responder strains. The affects of three anti-T cell therapies were compared: anti-CD4 mAb therapy, anti-CD3 mAb, and rabbit antithymocyte globulin (RATG). None of these antibody therapies alone prolonged graft survival indefinitely. Combining anti-CD4 therapy with posttransplant TLI markedly delayed rejection but failed to induce long-term graft survival. Tolerance could be induced by a combination of anti-pan T cell antibody (anti-CD3) and TLI, and, all grafts survived beyond 100 days. RATG failed to prevent graft rejection when used alone or in combination with TLI. However, posttransplant therapy with a combination of RATG, TLI, and single-donor blood transfusion resulted in graft survival beyond 100 days. Recipients bearing long-term donor grafts rejected third-party (PVG) grafts within 2 weeks. Low density donor bone marrow cells used instead of a blood transfusion did not facilitate tolerance. The results indicate that monoclonal or polyclonal anti-pan T cell antibodies, TLI, and a donor blood cell infusion function synergistically in facilitating tolerance to allografts in the posttransplant period.
View details for Web of Science ID A1993MQ05600031
View details for PubMedID 8279017
INDUCTION OF LONG-TERM SPECIFIC TOLERANCE TO ALLOGRAFTS IN RATS BY THERAPY WITH AN ANTI-CD3-LIKE MONOCLONAL-ANTIBODY
1993; 55 (3): 459-468
Monoclonal antibodies to CD3 have been shown to activate T cells in vivo and in vitro but have also been shown to render T cells anergic in vitro. In this study G4.18, a mouse IgG3 mAb, was produced that appeared to recognize CD3 by its binding to all peripheral T cells, including a population not recognized by mAb to TCR-alpha/beta that was presumed to be TCR-gamma/delta cells. It precipitated molecules in the 24-26 kd region consistent with the CD3 complex as well as molecules approximately 45 and approximately 49 kd that corresponded to TCR alpha and beta chains and a 92-kd complex. Incubating T cells for 24 hr with saturating concentrations of G4.18 caused modulation of the TCR complex. In vitro, it activated T cells but only if prebound to plastic. In solution it inhibited MLC and CML, but not PHA or Con A activation. In vivo, G4.18 was not toxic even in high doses, and this was thought to be due to the inability of this mAb to activate T cells in vitro because the rat lacks Fc receptors for mouse IgG3. Therapy with G4.18 resulted in transient modulation of TCR/CD3 on T cells and depletion of these cells from blood. G4.18 had no depleting effects by lymph node or spleen cells but caused marked, transient thymic involution. Therapy with G4.18 also induced indefinite survival (> 100 days) of PVG (RTIc) heart grafts but not skin grafts in DA (RTIa) hosts. These hosts with long-surviving cardiac transplants, when grafted from PVG skin, accepted these grafts but rejected third-party skin in first-set. Thus G4.18 was shown to induce long-term specific tolerance to an organ allograft.
View details for Web of Science ID A1993KT96100001
View details for PubMedID 8456460