In spite of treatment, severe angioproliferative pulmonary arterial hypertension (PAH) remains a ... more 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-1α: Ovalbumin (Ova). Immunization of rats with Ova increases lung tissue HIF-1α 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.
This study examined whether posttransplant anti-T cell monoclonal or polyclonal antibody therapy ... more 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.
Although many transplantation studies have implicated a graft-destructive role for T helper (Th)1... more 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 requiremen...
... doi: 10.1097/01.mot.0000244650.00717.9c. Lung transplantation. Critical pathways leading to o... more ... doi: 10.1097/01.mot.0000244650.00717.9c. Lung transplantation. Critical pathways leading to obliterative bronchiolitis in lung allografts. Babu, Ashok Na; Nicolls, Mark Rb. Article Outline. Collapse Box Author Information. a Departments of Surgery, USA. ...
Patients with pulmonary arterial hypertension (PAH) associated with systemic sclerosis (SSc-APAH)... more Patients with pulmonary arterial hypertension (PAH) 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 Registry) is a multicenter, prospective US-based registry of patients with previously and newly diagnosed (enrollment within 90 days of diagnostic right-sided heart catheterization) PAH. Cox regression models evaluated all previously identified candidate predictors of mortality in the overall REVEAL Registry population to identify significant predictors of mortality in the SSc-APAH (n = 500) vs non-SSc-CTD-APAH (n = 304) populations. Three-year survival rates in the previously diagnosed and newly diagnosed SSc-APAH group were 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, men aged > 60 years, systolic BP (SBP) ≤ 110 mm Hg, 6-min walk distance (6MWD) < 165 m, mean right atrial pressure (mRAP) > 20 mm Hg within 1 year, and pulmonary vascular resistance (PVR) > 32 Wood units 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 patients with non-SSc-CTD-APAH. Identifying patients with SSc-APAH who are at a particularly high risk of death, including elderly men and patients with low baseline SBP or 6MWD, or markedly elevated mRAP or PVR, will enable physicians to identify patients who may benefit from closer monitoring and more aggressive treatment. ClinicalTrials.gov; No.: NCT00370214; URL: www.clinicaltrials.gov.
Conformational diseases are conditions that arise from the dysfunctional aggregation of proteins ... more 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 ...
The alveolar destruction leading to airspace enlargement in patients with end-stage chronic obstr... more 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.
This review summarizes an expanding body of knowledge indicating that failure to resolve inflamma... more 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.
The mechanisms by which CD4+T cells, especially CD4+ CD25+T cells, transfer allograft specific to... more 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. Ad...
Aberrant epithelial repair is a crucial event in the airway remodeling that characterizes obliter... more 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; α-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 α-SMA- positive epithelial cells that were most prominent on day 7. The expression of E-cadherin was attenuated in α-SMA-positive epithelial cells. S100A4 was also expressed in epithelial cells. A few days before the intraepithelial expression of α-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.
Monoclonal antibodies to CD3 have been shown to activate T cells in vivo and in vitro but have al... more 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.
Lung transplantation is complicated by fibroproliferation, which is likely mediated in part by ma... more 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.
The presence of anti-endothelial cell antibodies and pathogenic T cells may reflect an autoimmune... more 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.
An association between pulmonary arterial hypertension (PAH) and various immune disorders is well... more 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.
In spite of treatment, severe angioproliferative pulmonary arterial hypertension (PAH) remains a ... more 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-1α: Ovalbumin (Ova). Immunization of rats with Ova increases lung tissue HIF-1α 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.
This study examined whether posttransplant anti-T cell monoclonal or polyclonal antibody therapy ... more 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.
Although many transplantation studies have implicated a graft-destructive role for T helper (Th)1... more 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 requiremen...
... doi: 10.1097/01.mot.0000244650.00717.9c. Lung transplantation. Critical pathways leading to o... more ... doi: 10.1097/01.mot.0000244650.00717.9c. Lung transplantation. Critical pathways leading to obliterative bronchiolitis in lung allografts. Babu, Ashok Na; Nicolls, Mark Rb. Article Outline. Collapse Box Author Information. a Departments of Surgery, USA. ...
Patients with pulmonary arterial hypertension (PAH) associated with systemic sclerosis (SSc-APAH)... more Patients with pulmonary arterial hypertension (PAH) 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 Registry) is a multicenter, prospective US-based registry of patients with previously and newly diagnosed (enrollment within 90 days of diagnostic right-sided heart catheterization) PAH. Cox regression models evaluated all previously identified candidate predictors of mortality in the overall REVEAL Registry population to identify significant predictors of mortality in the SSc-APAH (n = 500) vs non-SSc-CTD-APAH (n = 304) populations. Three-year survival rates in the previously diagnosed and newly diagnosed SSc-APAH group were 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, men aged > 60 years, systolic BP (SBP) ≤ 110 mm Hg, 6-min walk distance (6MWD) < 165 m, mean right atrial pressure (mRAP) > 20 mm Hg within 1 year, and pulmonary vascular resistance (PVR) > 32 Wood units 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 patients with non-SSc-CTD-APAH. Identifying patients with SSc-APAH who are at a particularly high risk of death, including elderly men and patients with low baseline SBP or 6MWD, or markedly elevated mRAP or PVR, will enable physicians to identify patients who may benefit from closer monitoring and more aggressive treatment. ClinicalTrials.gov; No.: NCT00370214; URL: www.clinicaltrials.gov.
Conformational diseases are conditions that arise from the dysfunctional aggregation of proteins ... more 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 ...
The alveolar destruction leading to airspace enlargement in patients with end-stage chronic obstr... more 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.
This review summarizes an expanding body of knowledge indicating that failure to resolve inflamma... more 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.
The mechanisms by which CD4+T cells, especially CD4+ CD25+T cells, transfer allograft specific to... more 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. Ad...
Aberrant epithelial repair is a crucial event in the airway remodeling that characterizes obliter... more 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; α-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 α-SMA- positive epithelial cells that were most prominent on day 7. The expression of E-cadherin was attenuated in α-SMA-positive epithelial cells. S100A4 was also expressed in epithelial cells. A few days before the intraepithelial expression of α-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.
Monoclonal antibodies to CD3 have been shown to activate T cells in vivo and in vitro but have al... more 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.
Lung transplantation is complicated by fibroproliferation, which is likely mediated in part by ma... more 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.
The presence of anti-endothelial cell antibodies and pathogenic T cells may reflect an autoimmune... more 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.
An association between pulmonary arterial hypertension (PAH) and various immune disorders is well... more 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.
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Papers by Mark Nicolls