The role of TIM-1 and Regulatory B cells in Allograft Tolerance

描述（由申请人提供）：现在很清楚，B细胞可以以il -10依赖性的方式下调免疫反应。除了在体外刺激后表达IL-10的能力外，这些罕见的调节性B细胞（Breg）缺乏特异性标记物，并且在各种B细胞亚群中发现，其频率可低至1%。这使得对Breg的研究具有挑战性。令人惊讶的是，一些被认为通过对T细胞的作用诱导同种异体移植物耐受的药物，最近被证明是依赖于B细胞的。这表明Breg可能参与并在同种异体移植物耐受中发挥广泛作用。这与在耐受的人类肾移植受者中观察到的“B细胞谱”相呼应。T细胞Ig Mucin蛋白1参与调节Th的分化。Anti- TIM-1 （RMT1-10）诱导异体移植物耐受被认为是Th2依赖性的。令人惊讶的是，我们发现TIM-1在B细胞上的表达水平比T细胞高得多。此外，抗tim -1诱导的Th2偏差和同种异体移植物耐受完全依赖于B细胞。事实上，在缺乏B细胞的情况下，与未经治疗的对照组相比，抗tim -1实际上加速了排斥反应。TIM-1在所有主要亚群中的绝大多数IL-10+和IL-4+ B细胞中表达。来自同种异体移植受体的B细胞TIM-1+，而不是TIM-1，可以向未经治疗的同种异体移植受体转移耐受性。最后，anti-TIM-1显著诱导IL-10+ (TIM-1+) Breg，但Breg的发育和诱导都需要IL-4信号。有了这些新的见解，我们现在可以确定TIM-1+ Breg同种异体移植物耐受的作用，并确定TIM-1在Breg生成中的作用。具体来说，在Aim 1中，我们将使用TIM-1功能丧失（LOF） KI小鼠来确定TIM-1+ Breg在同种异体移植物耐受中的作用，并确定TIM-1+ B细胞是否是其他药物介导耐受所需的特异性B细胞群。在Aim 2中，我们将定义B效应细胞、Th2细胞和Treg在Breg诱导和抗tim -1介导的耐受中的作用。在Aim 3中，我们将通过TIM-1研究Breg诱导的机制，确定同源Ag识别和特定细胞因子信号的作用。我们相信这些研究将极大地增强我们对Breg免疫生物学的理解，并提供与同种异体移植物耐受性高度相关的治疗见解。

DESCRIPTION (provided by applicant): It is now clear that B cells can play an important role downregulating immune responses in an IL-10-dependent fashion. Other than a capacity to express IL-10 after ex vivo stimulation, these rare regulatory B cells (Breg) lack specific markers and are found within various B cell subpopulations where their frequency can be as low as 1%. This has made study of Breg challenging. Surprisingly, a number of agents believed to induce allograft tolerance through their effects on T cells, were recently shown to be B cell dependent. This suggests that Breg may be involved, and play a broad role in allograft tolerance. This is echoed by the "B cell profile" observed in tolerant human renal allograft recipients. T cell Ig Mucin protein-1 helps regulate Th differentiation. Anti- TIM-1 (RMT1-10) induces allograft tolerance thought to be Th2 dependent. Surprisingly, we found TIM-1 is expressed at much higher levels on B than T cells. Moreover, Th2 deviation and allograft tolerance induced by anti-TIM-1, were completely B cell dependent. In fact, in the absence of B cells, anti-TIM-1 actually accelerates rejection compared to untreated controls. TIM-1 is expressed by the large majority of IL-10+ and IL-4+ B cells in all major subpopulations. TIM-1+, but not TIM-1-, B cells from allograft recipients can transfer tolerance to otherwise untreated allograft recipients. Finally, anti-TIM-1 significantly induces IL-10+ (TIM-1+) Breg, but both Breg development and induction require IL-4 signaling. Armed with these novel insights, we can now establish the role of TIM-1+ Breg allograft tolerance and determine the role of TIM-1 in Breg generation. Specifically, In Aim 1, we will define the role of TIM-1+ Breg in allograft tolerance using TIM-1 loss of function (LOF) KI mice, and determine whether TIM-1+ B cells are the specific B cell population required for tolerance mediated by various other agents. In Aim 2, we will define the roles of B effector cells, Th2 cells, and Treg in Breg induction and anti-TIM-1 mediated tolerance. In Aim 3 we will examine the mechanisms of Breg induction through TIM-1, identifying the role of cognate Ag recognition and specific cytokine signals. We believe these studies will greatly enhance our understanding of Breg immunobiology and provide therapeutic insight highly relevant to allograft tolerance.