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性疾病独立研究者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流变学系进行一段时间的密集教学和研究培训来实现。本提案的科学目的是确定自身免疫性肌炎和间质性肺病患者对组氨酰-tRNA合成酶（HRS，Jo-1）的特异性免疫应答的机制。已知大多数肌炎特异性自身抗原通过它们对细胞毒性淋巴细胞蛋白酶颗粒酶B（GrB）切割的敏感性而统一。然而，自身抗原的这种独特性质的相关性仍然未知。我们提出，（i）对HRS的T细胞应答是针对GrB切割位点的，以及（ii）在自身免疫应答启动和传播的组织中，GrB对HRS的构象和可切割性发生改变。该提案将通过以下具体目标在患有自身免疫性肌炎和间质性肺病的Jo-1阳性患者中解决这些假设：1.研究HRS grB切割位点在确定其免疫显性CD 4 + T细胞表位中的作用。来自肌炎患者的T细胞将使用跨越GrB切割位点的纯化蛋白质和肽在体外探测抗HRS应答。2.鉴定肌炎患者的CD 8+细胞毒性T细胞是否具有HRS特异性。预测方法将用于鉴定一组HLA限制性HRS肽，其与肌炎患者中的特异性细胞毒性淋巴细胞反应，并且将评估CD 8 + T细胞系裂解特异性靶细胞的能力。3.确定HRS的免疫原性（grB-可切割）构象是否在肌炎/ILD患者的肌肉和肺组织中差异表达。将使用识别GrB切割位点的新型抗体试剂探测来自肌炎/ILD患者的肺和肌肉组织样本。这些研究将提供重要的信息GrB裂解位点和/或其裂解在HRS的免疫应答中的作用，以及自身抗原结构的组织特异性变化，这可能是其靶向肌炎/间质性肺病的原因。

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.