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

描述（由申请人提供）：T细胞对外来抗原有效反应，但对自身组织和正常肠道菌群耐受。T细胞的不适当激活或分化可导致严重的免疫紊乱，包括自身免疫和炎症。因此，更好地了解调节t细胞活化和耐受性的分子机制对于合理设计免疫疾病的治疗方法具有重要意义。本应用程序的总体目标是了解新发现的去泛素酶（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。在目前的资助期内，我们已经取得了开创性的发现，证实CYLD是t细胞活化和自身免疫性炎症的关键调节因子。CYLD缺陷T细胞对TCR刺激反应过度，CYLD敲除（CYLD-/-）小鼠自发发生肠道炎症，具有人类炎症性肠病（IBD）的主要特征。CYLD-/-小鼠也会经历严重的骨质流失，这是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的缺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症疾病的主要调节因子。本续申请中提出的研究是基于我们实验室强有力的初步和已发表的数据。特别是，我们已经证明T细胞中CYLD的缺失会导致NF-kB的组成性激活，NF-kB是一种介导T细胞激活和存活的转录因子，并参与许多炎症性疾病。CYLD-/- T细胞也表现出明显的共刺激分子ICOS的衰减，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细胞对肠道微生物的耐受性似乎存在缺陷，因为它们过继转移到淋巴细胞缺陷的Rag1-/-小鼠体内会诱发严重的结肠炎。此外，CYLD-/-小鼠产生异常高水平的炎性Th17和Th1细胞，并伴有EAE反应增强。我们已经获得了初步证据，CYLD调节巨噬细胞对tlr刺激的特定细胞因子亚群表达的反应，已知这些细胞因子亚群调节Th1和Th17的分化。基于这些发现，我们假设CYLD调节t细胞活化和分化以及耐受性诱导的关键信号事件。我们将实现三个具体目标，以实现总体目标。(1)研究cyld介导的T细胞NF-kB调控的分子机制及功能意义。(2)明确CYLD调控t细胞耐受性和炎性t细胞分化的分子和细胞机制。(3)研究CYLD调节骨侵蚀的免疫学和破骨细胞内在机制。

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.