VASCULOPATHY, APOPTOSIS AND AUTOIMMUNITY

血管病、细胞凋亡和自身免疫

• 批准号: 6375300
• 负责人: Joseph M Ahearn
• 金额: $ 26.25万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-27 至 2004-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6375300
• 关键词: B lymphocyte; DNA topoisomerases; SDS polyacrylamide gel electrophoresis; Sf9 cell line; T lymphocyte; antigen presenting cell; apoptosis; autoantigens; autoimmunity; biopsy; cellular immunity; clinical research; complement pathway; complement receptor; cytokine; enzyme linked immunosorbent assay; flow cytometry; high performance liquid chromatography; human subject; immune tolerance /unresponsiveness; ion exchange chromatography; leukocyte activation /transformation; molecular cloning; molecular pathology; systemic scleroderma; western blottings

This proposal is focused upon the molecular mechanism by which vasculopathy leads to fibrotic and autoimmune manifestations of systemic sclerosis. Autoantibodies generated by patients with systemic sclerosis are uniquely targeted to nucleolar proteins such as DNA topoisomerase I (topo-I). It has been demonstrated that topo-I is a substrate for protease(s) specific to the apoptotic process, resulting in novel cleavage fragments that may reveal cryptic epitopes to which the host has not previously been tolerized. It has also been recently demonstrated that several of the autoantigens targeted in diffuse scleroderma are uniquely susceptible to cleavage by metal-catalyzed oxidation reactions similar to what may occur during ischemia-reperfusion in the presence of appropriate metals. This process may also reveal immunocryptic epitopes and provides a molecular explanation for why certain proteins are uniquely targeted by the immune response in systemic sclerosis. However, it is well known that a cryptic epitope alone is not sufficient to generate autoreactivity, which also requires the participation of a molecular adjuvant, and uptake of the potential autoantigen by an antigen presenting cell (APC) with costimulatory capacity. The central hypothesis of this proposal is that chronic ischemia-reperfusion injury in patients with systemic sclerosis not only generates immunocryptic epitopes within nucleolar autoantigens of cutaneous origin, but it also generates complement ligands that provide the molecular adjuvant required to break immune tolerance. The specific aims of this proposal are to: 1) Determine the capacity of apoptotic blebs bearing complement ligands to modulate the cytokine expression and costimulatory capacity of antigen presenting cells, 2) characterize the immune responses to self antigen- containing apoptotic blebs, and 3) examine the role of complement ligand C3d during induction of autoreactive T and B cell responses to topo I in vitro. Although systemic sclerosis is the focus of this proposal, the data generated by these studies should provide insight into our understanding of vasculopathic and autoimmune processes in general.

该提案的重点是血管病变导致系统性硬化症纤维化和自身免疫表现的分子机制。 系统性硬化症患者产生的自身抗体专门针对核仁蛋白，例如 DNA 拓扑异构酶 I (topo-I)。 已证明，topo-I 是细胞凋亡过程特异的蛋白酶的底物，产生新的切割片段，可能揭示宿主先前未耐受的隐藏表位。 最近还证明，弥漫性硬皮病中靶向的几种自身抗原特别容易被金属催化的氧化反应裂解，类似于在适当金属存在下缺血再灌注期间可能发生的情况。 这一过程还可能揭示免疫隐藏表位，并为为什么某些蛋白质成为系统性硬化症中免疫反应的独特目标提供分子解释。 然而，众所周知，单独的隐性表位不足以产生自身反应性，这还需要分子佐剂的参与，以及具有共刺激能力的抗原呈递细胞（APC）对潜在自身抗原的摄取。 该提议的中心假设是，系统性硬化症患者的慢性缺血再灌注损伤不仅在皮肤来源的核仁自身抗原内产生免疫隐性表位，而且还产生补体配体，提供打破免疫耐受所需的分子佐剂。 该提案的具体目标是：1) 确定携带补体配体的凋亡泡调节细胞因子表达和抗原呈递细胞共刺激能力的能力，2) 表征对含有自身抗原的凋亡泡的免疫反应，以及 3) 检查补体配体 C3d 在体外诱导自身反应性 T 和 B 细胞对拓扑 I 反应期间的作用。 尽管系统性硬化症是该提案的重点，但这些研究产生的数据应该可以帮助我们深入了解血管病变和自身免疫过程的总体情况。