Mechanistic and therapeutic role of the CD137-CD137L axis in Type 1 Diabetes

项目总结 我们的实验室一直在广泛研究T1D中的CD137-CD137L免疫信号。这些研究已经 揭示了我们建议在此应用程序中研究的其他关键机械问题。监管 CD137-CD137L系统很复杂，主要是因为CD137和CD137L都是信号进入细胞 在对CD137和CD137L信号的分析中必须考虑到这一点。在我们的 初步数据我们确定了CD137或CD137L信号的影响不同的许多具体实例 根据免疫细胞的类型。Foxp3调节性CD4T细胞(Tregs)，抗原提呈细胞 (APC)和效应器T细胞都以不同的动力学水平表达这些关键分子。 免疫反应。这些细节对于理解这个系统中的干预措施，尤其是 可溶性CD137(SCD137)通过CD137L下调免疫功能，影响肿瘤的进程和进展 T1D。我们最近发表了用主要由Tregs在体内表达的sCD137进行治疗的文章 结构性表达CD137，可改善急性T1D。我们直接证明了sCD137 通过与表达在这些细胞上的CD137L结合来抑制小鼠CD4和CD8T细胞的激活。 重要的是，我们最近证明了T细胞上CD137L的表达对Treg介导的抑制至关重要。 与我们在小鼠身上的发现类似，我们发现人类CD25hi CD127低Tregs是 SCD137。在小鼠中，Hu-sCD137抑制了人外周CD4T细胞的增殖。重要的是，我们发现 与年龄匹配的无关对照组相比，人类T1D患者的血清sCD137水平较低，类似 我们发现，与T1D基因相同的NOD鼠相比，NOD鼠的血清sCD137水平降低 保护性B10衍生的Idd9.3间期。此外，我们最近发表了确凿的证据，使用等位基因- 在特定的基因敲除小鼠中，Tnfrsf9(编码CD137)是nod Idd9.3区间中的糖尿病致病基因。 总之，这些结果表明CD137的生物学特性及其与CD137L相互作用的结果 在小鼠和人类的T1D中非常相似。然而，重要的是，在我们对CD137L生物学的研究中 (sCD137的靶点)，我们最近发表了T1D不能转移到缺乏T1D的小鼠的研究报告。 CD137L在髓系APC上的表达此外，CD137L表达的髓系APC是必需的 β细胞特异性自身反应性CD8T细胞积聚。这些发现突显了人们日益认识到的 先天免疫在自身免疫性T1D的启动和持续中的作用，以及是否需要额外的 CD137L在髓系APC上的机制研究，它是T细胞进入胰岛的关键守门人。vt.给出 针对这些发现，我们提出了以下目标。目的1：CD137阳性Treg亚群的机制 抑制免疫激活。目的2：CD137L表达的髓系APC在T1D中的机制作用 并以sCD137的发病机制和治疗效果为靶点。目标3：使用新型人和鼠可溶物 CD137-Fc蛋白在人源化小鼠模型以及人单核细胞和T细胞上测试疗效。

PROJECT SUMMARY Our labs have been extensively studying CD137-CD137L immune signaling in T1D. These studies have uncovered additional critical mechanistic issues which we propose to study in this application. The regulation of the CD137-CD137L system is complex, mainly because both CD137 and CD137L signal into the cells expressing them, which must be taken into account in any analysis of CD137 and CD137L signaling. In our preliminary data we identify many specific instances in which the effect of CD137 or CD137L signaling differs according to the type of immune cells. FOXP3+ regulatory CD4 T cells (Tregs), antigen-presenting cells (APCs), and effector T cells all express different levels of these key molecules with distinct kinetics during the immune response. The details are critical for understanding how interventions in this system, most specifically with soluble CD137 (sCD137) which down-regulates immunity via CD137L, affect the course and progression of T1D. We have recently published that treatment with sCD137, which is expressed in vivo mainly by Tregs that constitutively express CD137, can ameliorate acute T1D. We demonstrate that sCD137 directly suppresses mouse CD4 and CD8 T cell activation through binding to CD137L expressed on these cells. Critically, we have recently proven that CD137L expression on T cells is critical for Treg mediated suppression. Similar to our findings in mice, we found that human CD25hi CD127low Tregs are the primary source of sCD137. As in mice, hu-sCD137 inhibited proliferation of human peripheral CD4 T cells. Importantly, we found that serum sCD137 was lower in human T1D patients compared to age-matched unrelated controls, analogous to our finding that serum sCD137 is decreased in NOD mice compared to NOD mice congenic for the T1D protective B10-derived Idd9.3 interval. In addition, we have recently published conclusive proof, using allele- specific knockout mice, that Tnfrsf9 (encoding CD137) is the diabetogenic gene in the NOD Idd9.3 interval. Overall, these results indicate that the biology of CD137 and the consequence of its interaction with CD137L are very similar in mouse and human T1D. Importantly, however, in our investigation of the biology of CD137L (the target of sCD137), we have recently published that T1D could not be transferred into mice lacking expression of CD137L on myeloid APCs. Moreover, CD137L expressing myeloid APCs are essential for accumulation of β-cell specific autoreactive CD8 T cells. These findings highlight the increasingly recognized role of innate immunity in the initiation and perpetuation of autoimmune T1D, and the need for additional mechanistic studies of CD137L on myeloid APCs, the critical gatekeeper for T cell entry into the islet. Given these findings we propose the following aims. Aim 1: Mechanism by which the CD137-positive Treg subset suppresses immune activation. Aim 2: Mechanistic role of CD137L-expressing myeloid APCs in T1D pathogenesis and as a target for therapeutic effect of sCD137. Aim 3: Use novel human and mouse soluble CD137-Fc proteins to test efficacy in humanized mouse models and on human monocytes and T cells.