The Role of Toll-Like Receptor-3 in T1D and Efficacy of a Novel Therapeutic

描述（由申请人提供）：1型糖尿病（T1D）是一种自身免疫性疾病，其中产生胰岛素的胰腺β（¿）细胞被自身免疫系统误认为是外来细胞并逐渐被破坏。由于身体自身对这些细胞的破坏，胰岛素分泌减少，胰岛素水平不足以控制血糖水平，从而导致T1D。虽然目前对T1D的病因尚不完全清楚，但人们认为病毒在其发病机制中起着重要作用。病毒感染细胞可通过多种方式引发疾病，包括直接损伤细胞、释放细胞抗原刺激自身免疫破坏或通过各种抗病毒反应对细胞产生毒性。最近的研究表明toll样受体（TLR）参与了T1D的发病机制。具体来说，TLR是位于免疫细胞上的分子，它识别外来抗原并启动保护性免疫反应。TLR3最近被证明在新发T1D患者的胰腺细胞上直接异常表达。此外，与人类T1D发展相关的柯萨奇B病毒（CBV）可以激活TLR3信号并加速非肥胖糖尿病（NOD）小鼠T1D的发展。新型TLR信号抑制剂的开发可以阻断这种导致T1D的异常免疫反应，为在T1D发病前干预和防止细胞破坏或在初始发病时挽救细胞提供了一种潜在的新治疗范式。苯基甲巯咪唑（C10）是一种化合物，在其他TLR介导的自身免疫性疾病（如桥本甲状腺炎和系统性红斑狼疮）中，已被证明可预防病理性TLR过表达和信号传导。因此，C10可能通过抑制TLR3信号传导和细胞因子的产生，防止细胞凋亡（程序性细胞死亡）和/或细胞免疫破坏，在预防或治疗T1D方面具有潜在的功效。初步研究表明，C10对病毒诱导的T1D NOD小鼠模型具有预防作用。我们假设(1)t淋巴细胞介导的自身免疫破坏胰岛素产生细胞和诱导细胞死亡是细胞中TLR3信号的病毒激活的结果；(2)C10通过抑制TLR3信号介导的有效抗炎作用可能阻止T1D的发生和/或拯救细胞并保持新发T1D的胰岛素分泌功能。因此，本提案的具体目的是评估TLR3信号对CBV-4诱导的NOD小鼠T1D加速的贡献，以及C10通过研究其对(i)细胞TLR3信号，（ii）胰岛炎症（T1D之前的胰腺炎症），（iii）细胞数量和（iv）胰腺内特异性免疫细胞群的影响来减弱CBV-4在NOD小鼠T1D加速的机制。这些研究将(1)更好地了解TLR3信号在T1D发病机制中的作用，(2)评估治疗/预防T1D的潜在新药的疗效。

DESCRIPTION (provided by applicant): Type 1 Diabetes Mellitus (T1D) is an autoimmune disorder in which pancreatic beta (¿) cells, which produce insulin, are mistaken as foreign by one's own immune system and gradually destroyed. As a result of the body's own destruction of the ¿ cells, insulin production decreases and insulin levels become insufficient to control glucose levels, resulting in T1D. Although the etiology of T1D is only partially understood, it is felt that viruses play an important role in its pathogenesis. Viral infection of ¿ cells is suggested to initiate disease in a variety of ways including direct ¿ cell damage, release of ¿ cell antigens stimulating the autoimmune destruction, or toxicity to the ¿ cells by a variety of antiviral responses. Recent studies have implicated Toll-Like Receptors (TLR) in the pathogenesis of T1D. Specifically, TLR are molecules located on immune cells which recognize foreign antigens and initiate the protective immune response. TLR3 have recently been shown to be abnormally expressed directly on the pancreatic ¿ cells of patients with new onset T1D. In addition, the Coxsackie B virus (CBV), which has been associated with the development of T1D in humans, can activate TLR3 signaling and accelerate the development of T1D in non-obese diabetic (NOD) mice. The development of novel TLR signaling inhibitors which block this aberrant immune response causing T1D would offer a potentially new therapeutic paradigm to intervene and prevent ¿ cell destruction prior to onset of T1D or salvage ¿-cells at initial onset. Phenylmethimazole (C10) is a compound which has been shown to prevent pathologic TLR overexpression and signaling in other TLR-mediated autoimmune diseases such as Hashimoto's Thyroiditis and Systemic Lupus Erythematosis. Thus C10 may have potential efficacy in the prevention or treatment of T1D through inhibition of TLR3 signaling and cytokine production and prevent ¿ cell apoptosis (programmed cell death) and/or immune destruction of ¿ cells. Preliminary studies show that C10 can prevent T1D in a NOD mouse model of virus-induced T1D. We hypothesize (1) that T-lymphocyte-mediated autoimmune destruction of insulin producing ¿ cells, and induction of ¿ cell death is the result of viral-activation of TLR3 signaling in the ¿ cell and (2) that C10's effective anti- inflammatory actions, mediated through the inhibition of TLR3 signaling, may prevent the onset of T1D and/or rescue ¿ cells and preserve insulin secretory function in new-onset T1D. Thus, the specific aim of this proposal is to evaluate the contribution(s) of TLR3 signaling to CBV-4-induced acceleration of T1D in NOD mice and the mechanism by which C10 attenuates CBV-4 acceleration of T1D in the NOD mouse by investigating its effects on (i) ¿ cell TLR3 signaling, (ii) insulitis (inflammation of the pancreas which precedes T1D), (iii) ¿ cell number, and (iv) specific immune cell populations within the pancreas. These studies will (1) provide a better understanding of the involvement of TLR3 signaling in the pathogenesis of T1D, and (2) evaluate the efficacy of a potentially novel new drug for the treatment/prevention of T1D. PUBLIC HEALTH RELEVANCE: Toll-Like Receptors (TLRs) have recently been implicated in environmental (viral) induction of type 1 diabetes (T1D). We investigate the possibility that viral induction of T1D is mediated through TLR3, and evaluate the efficacy of a novel TLR signaling inhibitor to prevent/delay the onset of T1D. Pursuit of these data may provide a better understanding of the involvement of TLR3 signaling in the pathogenesis of T1D, and evaluate the efficacy of a potentially novel new drug for the treatment/prevention of T1D.