Critical roles of endogenous TLR signaling in driving Th17 effector responses

描述(申请人提供)：这项建议将研究通过TLR2和TLR4信号通路直接调节CD4+T淋巴细胞的功能。我们之前已经证明，T细胞中TLR2的激活可以驱动Th17细胞的生成和效应功能。我们的初步数据表明，TLR4信号可能通过促进T淋巴细胞的增殖和存活而以类似的方式在T淋巴细胞中发挥作用。此外，CD4+T细胞中TLR2或TLR4通路的直接激活促进了实验性自身免疫性脑脊髓炎(EAE)的发展，EAE是多发性硬化症的小鼠模型。重要的是，发现CD4+T细胞通过激活TLR2促进EAE的发病，内源性产生的信号作为炎症的副产品释放。内源性TLR4信号是否也是如此还有待确定。因此，我们将首先在没有外源性TLR4刺激的情况下，使用WT和TLR4缺陷的CD4+T细胞转移的模型进行EAE，以确定这一途径在驱动自身免疫性炎症中的潜在重要性。此外，我们的目标是确定这些内源性TLR信号能够激活Th17细胞中的TLR2和TLR4通路的身份。已经确定了两个候选分子，HMGB1和Biglycan，这两个分子都能刺激TLR2和TLR4，并在发炎的中枢神经系统组织中发现。我们还将研究靶向这些内源性TLR配体，而不是TLRs本身，是治疗EAE/MS的可行策略。这些研究将包括通过抗体治疗直接中和内源性配体。我们的体外观察清楚地表明，TLR2信号促进了初始CD4+T细胞的增殖和直接极化为Th17血统。另一方面，TLR4信号对谱系承诺没有这样的影响，反而促进了Th17细胞的增殖和存活。这些结果共同表明，在不理想的条件下，通过任一种TLR的信号可以增强Th17细胞因子的产生和这种炎症亚群的持久性。因此，我们将分析TLRs用于调节CD4+T淋巴细胞的增殖、存活和IL-17产生的表观遗传学、信号和转录机制。我们的实验室发现，在IL-17基因位点丰富的特异组蛋白修饰允许在Th17分化期间进入转录机制。此外，TLR2在Th17细胞上的激活增强了Th17相关转录因子如ROR？T的表达。因此，我们将确定组蛋白H3乙酰化和甲基化事件是否通过TLR2信号在Th17分化过程中被放大。此外，我们的目标是通过微阵列分析在全球范围内研究CD4+T细胞中TLR2和TLR4信号的下游靶点。作为TLR信号转导的结果，识别控制T细胞存活和细胞因子产生的新的信号和转录途径将提供新的实验路线，使候选人能够建立独立的实验室，脱离当前导师的研究兴趣，并帮助申请R01资金。

DESCRIPTION (provided by applicant): This proposal will investigate the direct regulation CD4+ T lymphocyte function through the TLR2 and TLR4 signaling pathways. We have previously shown that TLR2 activation in T cells can drive the generation and effector function of Th17 cells. Our preliminary data indicates that TLR4 signaling additionally may function in a similar manner within T lymphocytes through the promotion of proliferation and survival. Furthermore, direct activation of the TLR2 or the TLR4 pathway in CD4+ T cells promotes the development of experimental autoimmune encephalomyelitis (EAE), the mouse model of multiple sclerosis. Importantly, CD4+ T cells were found to promote the pathogenesis of EAE through the activation of TLR2 by endogenously generated signals that are released as a byproduct of inflammation. Whether the same is true for endogenous TLR4 signaling has yet to be determined. Thus, we will first perform EAE using a model of WT and TLR4-deficient CD4+ T cell transfer in the absence of exogenous TLR4 stimuli to determine the potential importance of this pathway in driving autoimmune inflammation. Furthermore, we aim to ascertain the identity of such endogenous TLR signals capable of activating the TLR2 and TLR4 pathways in Th17 cells. Two candidate molecules have been identified, HMGB1 and biglycan, both of which stimulate TLR2 and TLR4 and are found in inflamed CNS tissue. We will also investigate is targeting these endogenous TLR ligands, rather than TLRs themselves, is a viable strategy for EAE/MS therapy. These studies will include directly neutralizing endogenous ligands through antibody treatment. Our in vitro observations have clearly demonstrated that TLR2 signaling promotes proliferation and the direct polarization of naive CD4+ T cells into the Th17 lineage. TLR4 signaling, on the other hand, had no such effect on lineage commitment but instead enhanced proliferation and survival of Th17 cells. These results collectively suggest that under sub optimal conditions, signaling through either TLR could enhance Th17 cytokine production and the persistence of this inflammatory subset. Thus, we will analyze the epigenetic, signaling, and transcriptional mechanisms TLRs utilize to regulate proliferation, survival, and the production of IL-17 in CD4+ T lymphocytes. Our laboratory has found that specific histone modifications enriched at the IL-17 locus allow permissive access of the transcriptional machinery during Th17 differentiation. Furthermore, TLR2 activation on Th17 cells enhanced the expression of Th17-related transcription factors such as ROR?t. Thus, we will determine if histone H3 acetylation and methylation events are amplified through TLR2 signaling during Th17 differentiation. Additionally, we aim to globally investigate the downstream targets of TLR2 and TLR4 signaling in CD4+ T cells through microarray analysis. Identification of novel signaling and transcriptional pathways governing T cell survival and cytokine production as a result of TLR signaling will provide new lines of experimentation that will allow the candidate to establish an independent laboratory, gain separation from the research interests of the current mentor, and aid in the application for R01 funding.