Anti-Jo-1 Immune Responses in Autoimmune Myositis

描述(由申请人提供)： 这个指导临床科学家发展奖的主要目标是获得成为风湿病独立研究员所需的技能和专业知识。这将通过在约翰霍普金斯大学医学院风湿病学部进行一段时间的强化教学和研究培训来实现。这项建议的科学目标是确定自身免疫性肌炎和间质性肺疾病患者对组氨酰-tRNA合成酶(HRS，Jo-1)的特异性免疫反应的潜在机制。众所周知，大多数肌炎特异性自身抗原都是由其被细胞毒性淋巴细胞蛋白水解酶颗粒酶B(GRB)切割的敏感性统一的。然而，自身抗原这一独特性质的相关性仍不清楚。我们认为(1)T细胞对HRS的反应是针对GRB裂解位点的，(Ii)在启动和传播自身免疫反应的组织中，GRB对HRS的构象和裂解能力发生了改变。这项建议将通过以下特定目的在Jo-1阳性的自身免疫性肌炎和间质性肺疾病患者中解决这些假说：1.研究HRS GRB裂解位点在确定其免疫优势的CD4+T细胞表位中的作用。肌炎患者的T细胞将在体外使用跨越GRB裂解位点的纯化蛋白和多肽来探测抗HRS反应。2.鉴定肌炎患者外周血中CD8+细胞毒性T细胞是否具有HRS特异性。一种预测性的方法将被用来识别一组与肌炎患者中特定的细胞毒性淋巴细胞反应的人类白细胞抗原限制性HRS多肽，并将评估CD8+T细胞株裂解特定靶细胞的能力。3.确定肌炎/ILD患者肌肉和肺组织中HRS的免疫原性构象(GRB-裂解)是否有差异表达。来自肌炎/ILD患者的肺和肌肉组织样本将使用识别GRB裂解位点的新型抗体试剂进行探测。这些研究将提供有关GRB裂解位点和/或其裂解在HRS免疫反应中的作用以及自身抗原结构的组织特异性变化的重要信息，这些变化可能解释其在肌炎/间质性肺疾病中的靶向。

DESCRIPTION (provided by applicant): The primary objective of this mentored clinical scientist development award is to acquire the skills and expertise needed to become an independent investigator in the rheumatic diseases. This will occur through a period of intensive didactic and research training in the Division of Rheumatology at the Johns Hopkins University School of Medicine. The scientific objective of this proposal is to define the mechanisms underlying the specific immune response to histidyl-tRNA synthetase (HRS, Jo-1) in patients with autoimmune myositis and interstitial lung disease. It is known that the majority of myositis-specific autoantigens are unified by their susceptibility to cleavage by the cytotoxic lymphocyte protease granzyme B (GrB). However, the relevance of this unique property of autoantigens remains unknown. We propose that (i) the T cell response to HRS is directed at the GrB cleavage site, and (ii) that conformation and cleavability of HRS by GrB is altered in the tissue in which the autoimmune response is initiated and propagated. This proposal will address these hypotheses in Jo-1-positive patients with autoimmune myositis and interstitial lung disease, through the following specific aims: 1. To study the role of the HRS grB cleavage site in defining its immunodominant CD4+ T cell epitope. T cells from myositis patients will be probed for anti-HRS responses in-vitro using purified protein and peptides that span the GrB cleavage site. 2. To identify whether the CD8+ cytotoxic T cells in myositis patients are HRS-specific. A predictive approach will be used to identify a set of HLA-restricted HRS peptides that react with specific cytotoxic lymphocytes in myositis patients, and CD8+ T cell lines will be assessed for their ability to lyse specific target cells. 3. To determine whether an immunogenic (grB- cleavable) conformation of HRS is differentially expressed in muscle and lung tissue in patients with myositis/ILD. Lung and muscle tissue samples from patients with myositis/ILD will be probed using novel antibody reagents that recognize the GrB cleavage site. These studies will provide important information on the role of the GrB cleavage site and/or its cleavage in the immune response to HRS, as well as on tissue-specific changes in autoantigen structure that might account for its targeting in myositis/interstitial lung disease.