Role of Autoreactivity in Pathogenesis of Chronic GVHD

描述（由申请人提供）：慢性移植物抗宿主病（GVHD）是一种自身免疫样胶原血管疾病，其临床特征与硬皮病和系统性红斑狼疮（SLE）相似，是同种异体造血细胞移植（HCT）长期幸存者发病和死亡的主要原因。在过去的二十年中，慢性GVHD的预防和治疗没有取得重大进展，部分原因是对该疾病的发病机制了解不足。我们研究的长期目标是揭示慢性GVHD中同种免疫和自身免疫发展的细胞和分子机制，并开发预防和治疗慢性GVHD的新方法。在第一个资助期内，我们建立了一种新的自身免疫样慢性GVHD模型，将mhc匹配的DBA/2供体与BALB/c宿主相匹配，在该模型中，受者出现了高水平的自身抗体，肾小球肾炎和硬皮病样皮肤损伤。该疾病是由供体CD25- cd4 + T效应（Teff）细胞和移植的B细胞介导的，但移植的CD25+Foxp3+ Treg细胞以剂量依赖的方式预防或改善疾病。我们还观察到，MHC II-/-和B7H1-/-受体以及野生型（WT）受体接受IFN-？中和抗体。相比之下，Teff扩增在MHC II-/-受体中没有减少，但在给予MHC II-/-供体APC细胞的受体中减少，在给予供体B细胞耗尽移植的受体中也减少。因此，我们假设1)供体Treg在异体宿主中的扩增需要与宿主apc和表达MHC II和B7H1的实质细胞相互作用。感应;2)在慢性GVHD的情况下，供体APCs，特别是供体B细胞，是致病性Teff细胞扩增所必需的；3) teff源性IFN-?诱导宿主实质细胞B7H1表达不仅增强供体Treg扩增，而且通过B7H1/PD-1相互作用直接抑制Teff扩增。为了验证这些假设，我们将1)使用新开发的MHCII-/-和B7H1-/-受体和骨髓嵌合体来测试这些分子在扩增Treg细胞中的作用；2)利用新开发的MHCII-/-供体、荧光素酶+供体和不能分泌抗体但具有完整B细胞受体的转基因供体，检测慢性GVHD供体apc，特别是B细胞的功能；3)使用IFN-？- r -/-和B7H1-/-宿主探讨IFN-？和B7H1在慢性gvhd诱导的组织损伤中的作用。这些研究将为慢性GVHD受体中调节供体Teff和Treg激活和扩增的机制提供新的见解，并导致预防和治疗慢性GVHD的新方法的发展。公共卫生相关性：同种异体造血细胞移植（HCT）是一种治疗血液系统恶性肿瘤的治疗方法。然而，慢性GVHD仍然是HCT长期幸存者发病和死亡的主要原因。在过去的二十年中，慢性GVHD的预防和治疗没有取得重大进展，部分原因是对慢性GVHD发病机制的了解不足。通过新建立的慢性GVHD动物模型，我们的研究将解剖慢性GVHD受体中调节致病性T细胞激活和扩增的因素。这些研究将为开发预防和治疗慢性GVHD的新方法提供新的科学依据。

DESCRIPTION (provided by applicant): Chronic graft versus host disease (GVHD), an autoimmune-like collagen-vascular disease with clinical features similar to scleroderma and systemic lupus erythematosus (SLE), remains the major cause of morbidity and mortality in long-term survivors of allogeneic hematopoietic cell transplantation (HCT). No major improvements in the prevention and treatment of chronic GVHD have been made over the past two decades, due in part to a poor understanding of the pathogenesis of the disease. Our study's long-term goal is to unravel the cellular and molecular mechanisms involved in the development of alloimmunity and autoimmunity in chronic GVHD, and develop novel approaches to prevent and treat chronic GVHD. During the first funding period, we established a new autoimmune-like chronic GVHD model of MHC-matched DBA/2 donors to BALB/c hosts, in which the recipients developed high serum levels of autoantibodies, glomerulonephritis, and scleroderma-like skin damage. The disease is mediated by both donor CD25-CD4+ T effector (Teff) cells and B cells in transplants, but CD25+Foxp3+ Treg cells in transplants prevents or ameliorates the disease in a dose-dependent manner. We also observed that donor Treg expansion was markedly reduced in MHC II-/- and B7H1-/- recipients as well as in wild-type (WT) recipients treated with an IFN-? neutralizing antibody. In contrast, Teff expansion was not reduced in MHC II-/- recipients but was reduced in recipients given MHC II-/- donor APC cells and also reduced in recipients given donor B cell-depleted transplants. Therefore, we hypothesize 1) donor Treg expansion in allogeneic hosts requires interactions with host APCs and parenchymal cells that express MHC II and B7H1 after IFN-? induction; 2) donor APCs, especially donor B cells, are required for the expansion of pathogenic Teff cells in the context of chronic GVHD; 3) host parenchymal cell expression of B7H1 induced by Teff-derived IFN-? not only augments donor Treg expansion, but also directly suppresses Teff expansion via B7H1/PD-1 interactions. To test these hypotheses, we will 1) use newly developed MHCII-/- and B7H1-/- recipients and bone marrow chimeras to test the role of these molecules in expanding Treg cells; 2) use newly developed MHCII-/- donors, luciferase+ donors, and transgenic donors that cannot secrete antibodies but have intact B cell receptors to test the functions of donor APCs, especially B cells, in chronic GVHD; 3) use a novel combination of IFN-?-R-/- and B7H1-/- hosts to explore the interplay between IFN-? and B7H1 in the context of chronic GVHD-induced tissue damage. These studies will provide new insights into mechanisms that regulate donor Teff and Treg activation and expansion in chronic GVHD recipients and lead to the development of novel approaches for preventing and treating chronic GVHD. PUBLIC HEALTH RELEVANCE: Allogeneic hematopoietic cell transplantation (HCT) is a curative therapy for hematological malignancies. However, chronic GVHD remains the major cause for morbidity and mortality for long-term survivors of HCT. There has been no significant progress in the prevention and treatment of chronic GVHD over the past two decades, due in part to the poor understanding of the pathogenesis of chronic GVHD. With a newly established chronic GVHD animal model, our studies will dissect the factors that regulate the activation and expansion of pathogenic T cells in chronic GVHD recipients. These studies will provide a new scientific basis for developing novel approaches for preventing and treating chronic GVHD.