Biomedical subjects

Deborah A Knight

Publications and source records attributed to Deborah A Knight.

8 recordsLinked to original sources

PubMed2007

The role of anti-endothelial cell antibody-mediated microvascular injury in the evolution of pulmonary fibrosis in the setting of collagen vascular disease.

We encountered 16 patients with connective tissue disease in whom pulmonary fibrosis developed. Routine light microscopic, ultrastructural, and direct immunofluorescent analyses were conducted, and circulating antibodies, including those of endothelial cell derivation, were assessed using indirect immuno-fluorescence and Western blot assays. Underlying diseases were dermatomyositis, scleroderma, mixed connective tissue disease, sclerodermatomyositis, Sjögren syndrome, rheumatoid arthritis, and anti-Ro-associated systemic lupus erythematosus. Antibodies to one or more Ro, RNP, Jo 1, OJ, and/or nucleolar antigens were seen in all cases and antiphospholipid antibodies in half. All biopsies revealed microvascular injury in concert with intraparenchymal fibrosis; in some cases, there were corroborative ultrastructural findings of microvascular injury. Patterns of fibroplasia represented nonspecific interstitial pneumonitis and usual interstitial pneumonitis. We noted IgG, IgA, and/or complement in the septal microvasculature. In 6 cases with available serum samples, indirect immunofluorescent endothelial cell antibody studies were positive and Western Blot studies showed reactivity of serum samples to numerous endothelial cell lysate-derived proteins. Pulmonary fibrosis, a recognized complication of systemic connective tissue disease, develops in connective tissue disease syndromes with pathogenetically established immune-based microvascular injury at other sites. A similar mechanism of antibody-mediated endothelial cell injury may be the basis of the tissue injury and fibrosing reparative response.

Animals↗

PubMed2006

Idiopathic pulmonary fibrosis related to endothelial injury and antiendothelial cell antibodies.

Mechanisms underlying idiopathic pulmonary fibrosis are not well understood. This paper presents data supporting the hypothesis that microvascular endothelial cell injury and antiendothelial cell antibodies play roles in human idiopathic pulmonary fibrosis. Serologic and pathologic features of 40 patients diagnosed with idiopathic pulmonary fibrosis were evaluated. All patients had open lung biopsies indicating either usual or nonspecific interstitial pneumonitis. All biopsies had morphologic evidence of microvascular injury to the endothelium, and direct immunofluorescence testing revealed variable deposition of IgG, IgM, or IgA within septal microvasculature suggestive of humorally mediated microvascular injury. Ultrastructural studies revealed changes of endothelial cell injury and necrosis and evidence of repetitive episodes of microvascular injury characterized by basement membrane zone collagen deposition and lamellation. Serum samples demonstrated reactivity to multiple endothelial cell antigenic epitopes, and indirect immunofluorescent testing demonstrated a prominent pattern of fluorescence in pulmonary endothelial cell preparations. Serum samples were positive in 37/40 patients for antiphospholipid antibodies with one fourth having positive lupus anticoagulant tests accompanied by thrombotic episodes. In patients with idiopathic pulmonary fibrosis, Factor VIII levels and C-reactive protein levels were also elevated, supporting the presence of endothelial cell injury and inflammation. These data underscore a potential role for immune-based microvascular injury in the evolution of usual or nonspecific interstitial pneumonitis and indicate that those patients have evidence of microvascular injury and endothelial cell necrosis. The high prevalence of antiphospholipid antibodies in these patients may lead to an inherent thrombophilic tendency.

Adult↗

PubMed2005

Y-box factor YB1 controls p53 apoptotic function.

Nuclear localization and high levels of the Y-box-binding protein YB1 appear to be important indicators of drug resistance and tumor prognosis. YB1 also interacts with the p53 tumor suppressor protein. In this paper, we have continued to explore YB1/p53 interactions. We report that transcriptionally active p53 is required for nuclear localization of YB1. We go on to show that nuclear YB1 regulates p53 function. Our data demonstrate that YB1 inhibits the ability of p53 to cause cell death and to transactivate cell death genes, but does not interfere with the ability of p53 to transactivate the CDKN1A gene, encoding the kinase p21(WAF1/CIP1) required for cell cycle arrest, nor the MDM2 gene. We also show that nuclear YB1 is associated with a failure to increase the level of the Bax protein in normal mammary epithelial cells after stress activation of p53. Together these data suggest that (nuclear) YB1 selectively alters p53 activity, which may in part provide an explanation for the correlation of nuclear YB1 with drug resistance and poor tumor prognosis.

Active Transport, Cell Nucleus↗

PubMed2005

Mechanistic study of malononitrileamide FK778 in cardiac transplantation and CMV infection in rats.

BACKGROUND: FK778 is a malononitrilamide, a class of immune suppressive compounds with antiviral features and experimental activity in chronic rejection, a potentially interesting combination for organ transplantation. The goal of this project was to study the tolerability, immune suppressive efficacy, and anti-cytomegalovirus (CMV) activity of FK778 and to assess the in vivo relevance of its previously described inhibition of de novo pyrimidine synthesis. METHODS: Heart transplants were performed in rats (Brown Norway [BN] to Lewis) and treated with varying doses of FK778 or leflunomide for 28 days. At 28 days, at the time of rejection or at the death of the animal, the allograft and other vital organs were obtained for study by light microscopy and immunohistochemistry. In separate experiments, Lewis rats were given sublethal irradiation, inoculated with rat CMV (Maastricht strain), and treated with varying doses of FK778 and leflunomide. In both the transplant and CMV studies, IP uridine was given at 250 mg/kg to cohorts or animals receiving FK778 and leflunomide. RESULTS: FK778 controls acute rejection and inhibits CMV replication at 20 mg/kg but is toxic at 25 mg/kg. Toxicity is manifested as anemia, changes in hepatic and intestinal histology, and mortality. The toxicity but not the immune suppressive or antiviral efficacy, is reduced significantly by exogenous uridine administration. CONCLUSION: FK778 has both immune suppressive and antiviral activities, neither of which is entirely dependent on inhibition of pyrimidine synthesis. These, and other published observations, suggest that the antiviral activity and a considerable part of the efficacy of the malononitrilamide family of drugs is attributable to activities other than drug induced pyrimidine deficiency.

Alkynes↗

PubMed2005

Alpha-1 anti-trypsin deficiency and Henoch-Schönlein purpura associated with anti-neutrophil cytoplasmic and anti-endothelial cell antibodies of immunoglobulin-A isotype.

Alpha-1 anti-trypsin (A1AT) deficiency is an inherited enzyme deficiency that manifests with fatal lung and liver complications. In addition to pulmonary and hepatic involvement, the disease has also been linked to an increased incidence of vasculitic syndromes and autoimmune diseases, including Wegener's granulomatosis, microscopic polyarteritis nodosa and Henoch-Schonlein purpura (HSP). HSP, a systemic, small-vessel vasculitis syndrome, is characterized by a non-thrombocytopaenic purpuric rash, arthralgia, abdominal pain and nephritis. Both A1AT deficiency and HSP have been associated with anti-neutrophil cytoplasmic antibodies (ANCA) and anti-endothelial cell antibodies (AECA). We report a case of a 40-year-old man with severe A1AT deficiency, who developed HSP associated with AECA, ANCA and anti-phospholipid antibodies of the immunoglobulin-A isotype.

Adult↗

PubMed2004

Macrophage-mediated endothelial inflammatory responses to airborne particulates: impact of particulate physicochemical properties.

Epidemiological studies have implicated a role for airborne particulates of <2.5 microm diameter in the development/exacerbation of chronic cardiopulmonary disease; however, specific pathogenic mechanisms and the etiological significance of particle physicochemical properties remain unresolved. Using a microporous aluminosilicate zeolite Y as a manifold, we have synthesized 1 microm particulates of pure carbon (C), carbon-iron (C/Fe), and carbon-iron/fluoro-aluminum silicate (C-Fe/F-Al-Si). We have used these particulates, as well as coal fly ash (CFA) and diesel exhaust particulates (DEP), to test the hypotheses that human macrophages treated with particulates elaborate proinflammatory cytokines in quantities sufficient to induce endothelial adhesion molecule expression and that macrophage responses to particulate exposure vary as a function of particulate physicochemical properties. Human monocyte-derived macrophages (Mø) were exposed for 24 h to sublethal concentrations of particulates, at which time phagocytosis was evident from optical microscopy. Human arterial, microvascular, or venous endothelial cells (EC) were treated with clarified supernatants recovered from Mø cultures, stained with fluorescein-conjugated mononclonal antibodies specific for endothelial adhesion molecules intercellular adhesion molecule-1, vascular cell adhesion molecule-1, or E-selectin, and assayed by fluorescence flow cytometry. Data generated by these experiments demonstrate that while supernatants of Mø exposed to CFA and C particulates are relatively ineffective, supernatants from DEP, C/Fe, or C-Fe/F-Al-Si strongly induced adhesion molecule expression on EC, responses which were completely attenuated by antibody with blocking specificity for tumor necrosis factor alpha. Because the only difference between C and C/Fe particulates is the presence of surface iron on C/Fe, these findings suggest particulate-induced oxidative stress as a contributing factor in Mø activation and implicate redox active iron as a major determinant of particulate bioreactivity.

Air Pollutants↗

PubMed2003

The assessment of anti-endothelial cell antibodies in scleroderma-associated pulmonary fibrosis. A study of indirect immunofluorescent and western blot analysis in 49 patients with scleroderma.

We recently reported on the use of an indirect immunofluorescent method designated the rodent lung assay; this test assesses for the presence of circulating antibodies directed at components of the microvasculature. Serum samples from 49 patients with scleroderma were incubated with rodent lung tissue sections and visualized with fluoresceinated human anti-IgG. The assay also was performed on samples from a control group. Western blot analysis was performed with endothelial cell protein extracts using serum samples from patients with scleroderma and from healthy control subjects. The control subjects had a negative indirect immunofluorescent assay result. In the patients with scleroderma, there was a significant positive correlation between intensity of indirect immunofluorescent staining and pulmonary fibrosis (r = 0.316; P = .0347) and hypertension (r = 0.310; P = .0408). Western blot analysis revealed antibody binding to proteins in extracts of human endothelial cells in all patients in whom there was evidence of pulmonary disease. The indirect immunofluorescent rodent lung assay and Western blot data support a potential role of anti-endothelial cell antibodies in the propagation of scleroderma-associated pulmonary disease.

Adult↗

PubMed2002

T-cell activation response to allogeneic CMV-infected endothelial cells is not prevented by ganciclovir or foscarnet: implications for transplant vascular sclerosis.

BACKGROUND: Cytomegalovirus (CMV), a common infectious complication in transplant recipients, has been implicated as an exacerbating agent in the development of transplant vascular sclerosis (TVS); however, mechanisms defining this role remain to be fully resolved. Our previous studies suggest that CMV-infected graft endothelial cells (EC) can initiate a host T-cell activation cascade, and that cytokines produced as a consequence enhance graft endothelial alloimmunogenicity. Because antiviral therapy has not uniformly attenuated CMV-associated risk of TVS development, we have tested the hypothesis that antiviral agents do not affect T-cell activation by allogeneic CMV-infected EC. METHODS: Human umbilical vein EC, inoculated with CMV VHL/E and incubated in the presence or absence of ganciclovir (GCV) or foscarnet (PFA), were cocultured with CMV-seropositive or -seronegative donor-derived T cells in the presence of these agents, then labeled with [(3)H]thymidine. Cocultures were harvested, and radiolabel incorporation was assayed by scintillation counting. RESULTS: Limiting dilution analysis demonstrated that proliferation frequencies of CMV-seropositive donor-derived T cells in response to CMV-infected EC (approximately 80 cells/106, compared with approximately 4 cells/10(6) in response to uninfected EC) were not significantly modified by GCV (approximately 86 cells/10(6)) or PFA (approximately 82 cells/10(6)). Likewise, T-cell proliferation curves generated in response to stimulator cell titrations were essentially identical regardless of drug treatment. CONCLUSIONS: Results of these experiments suggest that although these drugs limit CMV replication and dissemination, they do not attenuate the inflammatory potential of infected EC, a force that may be a major factor in CMV-mediated exacerbation of the development of TVS.

Antiviral Agents↗