Regulation of T-cell function and autoimmune inflammation by deubiquitinase CYLD

描述（由申请人提供）：T细胞有效应答外源抗原，但对自身组织和正常肠道植物群耐受。T细胞的不适当活化或分化可导致严重的免疫紊乱，包括自身免疫和炎症。因此，更好地理解调节T细胞活化和耐受的分子机制对于合理设计免疫性疾病的治疗是重要的。本申请的总体目标是了解新鉴定的去泛素化酶（DUB）CYLD调节T细胞功能和自身免疫性炎症的分子和细胞机制。在目前的资助期间，我们已经取得了开创性的发现，确立了CYLD作为T细胞活化和自身免疫性炎症的关键调节因子。CYLD缺陷型T细胞对TCR刺激高度反应，CYLD敲除（CYLD-/-）小鼠自发发生具有人类炎症性肠病（IBD）主要特征的肠道炎症。CYLD-/-小鼠也经历严重的骨丢失，这被称为IBD和结肠炎动物模型的主要肠外并发症。此外，我们的初步研究表明，CYLD的损失使小鼠对实验性自身免疫性脑脊髓炎（EAE）的诱导过敏。因此，CYLD是T细胞功能和自身免疫性炎性疾病的主要调节剂。 本延续申请中提出的研究基于我们实验室的强有力的初步和已发表数据。特别是，我们已经表明，在T细胞中的CYLD的损失导致NF-κ B的组成性激活，转录因子介导的T细胞活化和存活，并参与许多炎症性疾病。CYLD-/- T细胞还显示出共刺激分子ICOS的显著衰减，这对于诱导T细胞耐受和调节T细胞分化至关重要。与这些分子研究一致，我们发现CYLD-/- T细胞似乎对肠道微生物的耐受性有缺陷，因为它们过继转移到淋巴细胞缺陷型Rag 1-/-小鼠中会诱导严重的结肠炎。此外，CYLD-/-小鼠产生异常高水平的炎性Th 17和Th 1细胞，伴随着增强的EAE反应。我们已经获得的初步证据表明，CYLD调节巨噬细胞对TLR刺激的细胞因子的特定子集的表达的反应，已知调节Th 1和Th 17分化。基于这些发现，我们假设CYLD调节参与T细胞活化和分化以及耐受诱导的关键信号事件。我们将执行三个具体目标，以实现我们的总体目标。(1)研究CYLD介导的NF-κ B调节T细胞的分子机制和功能意义。(2)描述CYLD调节T细胞耐受性和炎性T细胞分化的分子和细胞机制。(3)检查CYLD调节骨侵蚀的免疫和破骨细胞内在机制。 公共卫生相关性：T细胞对于对抗微生物感染的免疫反应至关重要。然而，由于遗传或环境因素，失调的T细胞活化可导致严重的免疫紊乱，包括自身免疫和慢性炎症。该研究项目的重点是了解去泛素化酶CYLD如何调节T细胞活化和耐受性，从而防止自身免疫和炎症的发展。这些知识对于合理设计有效的免疫疗法是重要的。

DESCRIPTION (provided by applicant): T cells effectively respond to foreign antigens but are tolerant to self-tissues and normal enteric flora. Inappropriate activation or differentiation of T cells can lead to severe immunological disorders, including autoimmunity and inflammation. Thus, a better understanding of the molecular mechanisms regulating T-cell activation and tolerance is important for rational design of therapies for immunological diseases. The overall objective of this application is to understand the molecular and cellular mechanisms by which a newly identified deubiquitinase (DUB), CYLD, regulates T-cell function and autoimmune inflammation. During the current funding period, we have made seminal findings that establish CYLD as a pivotal regulator of T-cell activation and autoimmune inflammation. CYLD-deficient T cells are hyper-responsive to TCR stimulation, and the CYLD knockout (CYLD-/-) mice spontaneously develop intestinal inflammation with major features of human inflammatory bowel disease (IBD). The CYLD-/- mice also experience severe bone loss, which is known as a major extra-intestinal complication of IBD and animal model of colitis. Moreover, our preliminary studies reveal that loss of CYLD renders mice hypersensitive to the induction of experimental autoimmune encephalomyelitis (EAE). Thus, CYLD is a master regulator of T-cell function and autoimmune inflammatory diseases. The studies proposed in this continuation application are based on strong preliminary and published data from our laboratory. In particular, we have shown that loss of CYLD in T cells causes constitutive activation of NF-kB, a transcription factor mediating T-cell activation and survival and being involved in many inflammatory disorders. The CYLD-/- T cells also display marked attenuation of the costimulatory molecule ICOS, which is crucial for the induction of T-cell tolerance and regulation of T-cell differentiation. Consistent with these molecular studies, we have found that the CYLD-/- T cells appear to be defective in tolerance to enteric microbes, since their adoptive transfer into lymphocyte-deficient Rag1-/- mice induces severe colitis. Furthermore, the CYLD-/- mice produce aberrantly high levels of inflammatory Th17 and Th1 cells, coupled with heightened EAE response. We have obtained preliminary evidence that CYLD regulates macrophage response to TLR-stimulated expression of a specific subset of cytokines known to regulate Th1 and Th17 differentiation. Based on these findings, we hypothesize that CYLD regulates key signaling events involved in T-cell activation and differentiation as well as tolerance induction. We will perform three specific aims to accomplish our overall objective. (1) Examine the molecular mechanism and functional significance of CYLD-mediated NF-kB regulation in T cells. (2) Characterize the molecular and cellular mechanisms by which CYLD regulate T-cell tolerance and inflammatory T-cell differentiation. (3) Examine the immunological and osteoclast-intrinsic mechanisms by which CYLD regulates bone erosion. PUBLIC HEALTH RELEVANCE: T cells are vital for immune responses against microbial infections. However, deregulated T cell activation, due to genetic or environmental factors, can lead to severe immunological disorders, including autoimmunity and chronic inflammation. The focus of this research project is to understand how a deubiquitinase, CYLD, regulates T-cell activation and tolerance, thereby preventing the development of autoimmunity and inflammation. This knowledge is important for rational design of effective immunological therapies.