Novel signaling pathways in lupus pathogenesis

 描述（由申请人提供）：摘要由异常的T-B协作产生的高亲和力自身抗体是系统性红斑狼疮（SLE）发病机制的基础。除了T-B协作异常外，新出现的证据表明T细胞和髓系细胞之间的相互作用失调也有助于SLE的病理生理学。因此，精确调节不同细胞区室之间的串扰对于预防自身免疫是必不可少的，并且详细了解这些相互作用的分子机制可以为SLE发病机制提供关键见解。我们的实验室以前曾暗示ROCK 2（一种丝氨酸-苏氨酸激酶）的异常激活与自身免疫小鼠T细胞产生IL-17和IL-21的能力失调有关。我们还证明了ROCK 2通过其磷酸化IRF 4的能力控制IL-17和IL-21的产生，IRF 4是产生这两种细胞因子绝对需要的转录因子。与这些结果一致，我们还表明，施用法舒地尔（一种ROCK抑制剂）改善了狼疮易感小鼠如MRL/lpr和NZB/W F1小鼠的疾病。虽然我们最初的研究集中在ROCK-IRF 4轴在T细胞区室中的作用，但我们最近探索了ROCK可能在免疫应答的调节中发挥广泛作用的可能性。我们已经发现，用aCD 40和IL-21刺激B细胞导致ROCK 2的活化和IRF 4的磷酸化。B细胞中IRF 4的磷酸化然后通过控制关键靶基因的表达来调节其调节浆细胞分化的能力。我们还发现，在巨噬细胞中，ROCK激活导致另一种IRF IRF 8的磷酸化，IRF 8与IRF 4具有高度同源性，并且该步骤反过来调节BAFF的产生。重要的是，我们进行了一项初步的横断面研究，结果表明，与健康对照组相比，大约50-60%的SLE患者表现出高水平的ROCK活性。因此，我们现在提出，异常ROCK激活可以通过其控制多个细胞区室的功能的能力和广泛的遗传程序来促进SLE的发展，除了对T细胞功能的影响外，还包括对B细胞和骨髓细胞功能的影响。本研究的具体目的是：1）探讨ROCK-IRF 4轴在B细胞中的调节和作用，2）研究ROCK-IRF 8轴在巨噬细胞功能中的作用，3）进一步表征在SLE患者中观察到的ROCK激活异常。鉴于ROCK抑制剂已经在心血管疾病的临床试验中显示出益处，同时仅表现出最小的副作用，因此从本提案中描述的研究中获得的知识可以迅速转化为治疗SLE的新治疗方案。

 DESCRIPTION (provided by applicant): ABSTRACT Generation of high affinity autoantibodies resulting from aberrant T-B collaboration underlies the pathogenesis of Systemic Lupus Erythematosus (SLE). In addition to abnormalities in T-B collaboration, emerging evidence indicates that deregulated interactions between T cells and myeloid cells also contribute to the pathophysiology of SLE. Precise regulation of the cross-talk amongst different cellular compartments is thus essential for the prevention of autoimmunity and a detailed understanding of the molecular mechanisms underlying these interactions can provide key insights into SLE pathogenesis. Our laboratory has previously implicated aberrant activation of ROCK2, a serine-threonine kinase, in the deregulated ability of T cells from autoimmune mice to produce IL-17 and IL-21. We have furthermore demonstrated that ROCK2 controls IL-17 and IL-21 production via its ability to phosphorylate IRF4, a transcription factor that is absolutely required for the production of these two cytokines. In line with these results we have also shown that administration of Fasudil, a ROCK inhibitor, ameliorates disease in lupus-prone mice such as MRL/lpr and NZB/W F1 mice. While our initial studies focused on the role of the ROCK-IRF4 axis in the T cell compartment, we have recently explored the possibility that the ROCKs may play a broad role in the regulation of immune responses. We have found that stimulation of B cells with aCD40 and IL-21 leads to the activation of ROCK2 and to the phosphorylation of IRF4. Phosphorylation of IRF4 in B cells then modulates its ability to regulate plasma cell differentiation by controlling the expression of key target genes. We have furthermore discovered that, in macrophages, ROCK activation leads to the phosphorylation of another IRF, IRF8, which shares a high degree of homology with IRF4, and that this step, in turn, regulates the production of BAFF. Importantly, we have conducted a pilot cross-sectional study that has shown that, as compared to healthy controls, ˜50-60% of SLE patients exhibit a high level of ROCK activity. We thus now propose that aberrant ROCK activation can promote the development of SLE via its ability to control the function of multiple cell compartments and a broad genetic program that, in addition to effects on T cell function, also encompasses effects on the function of B cells and myeloid cells. The specific goals of this proposal are: 1) To dissec the regulation and role of the ROCK-IRF4 axis in B cells, 2) To investigate the role of the ROCK-IRF8 axis in macrophage function, 3) To further characterize the aberrancies in ROCK activation observed in SLE patients. Given that ROCK inhibitors have already shown benefits in clinical trials for cardiovascular disorders while exhibiting only minimal side effects, the knowledge derived from the studies described in this proposal could be rapidly translated into a novel therapeutic regimen for the treatment of SLE.