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

描述（由申请人提供）：现在清楚的是，B细胞可以以IL-10依赖性方式在下调免疫应答中发挥重要作用。除了在离体刺激后表达IL-10的能力之外，这些罕见的调节性B细胞（布雷格）缺乏特异性标志物，并且在各种B细胞亚群中发现，其中它们的频率可以低至1%。这使得对布雷格的研究具有挑战性。令人惊讶的是，许多被认为通过其对T细胞的作用诱导同种异体移植物耐受的试剂最近被证明是B细胞依赖性的。这表明布雷格可能参与了同种异体移植耐受，并在其中发挥广泛作用。这与在耐受的人肾移植受者中观察到的“B细胞谱”相呼应。T细胞IG粘蛋白-1有助于调节Th分化。抗TIM-1（RMT 1 -10）诱导的同种异体移植物耐受被认为是Th 2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Th 2偏移和同种异体移植耐受完全依赖于B细胞。事实上，在没有B细胞的情况下，与未处理的对照相比，抗TIM-1实际上加速了排斥反应。TIM-1由所有主要亚群中的大多数IL-10+和IL-4+ B细胞表达。来自同种异体移植物受体的TIM-1+而不是TIM-1-B细胞可以将耐受性转移到其他未经治疗的同种异体移植物受体。最后，抗TIM-1显著诱导IL-10+（TIM-1+）布雷格，但布雷格的发育和诱导都需要IL-4信号传导。有了这些新的见解，我们现在可以建立TIM-1+布雷格同种异体移植耐受的作用，并确定TIM-1在布雷格生成中的作用。具体而言，在目标1中，我们将使用TIM-1功能丧失（LOF）KI小鼠来确定TIM-1+布雷格在同种异体移植物耐受中的作用，并确定TIM-1+ B细胞是否是由各种其它试剂介导的耐受所需的特异性B细胞群体。在目标2中，我们将定义B效应细胞、Th 2细胞和Treg在布雷格诱导和抗TIM-1介导的耐受中的作用。在目标3中，我们将研究通过TIM-1诱导布雷格的机制，鉴定同源Ag识别和特异性细胞因子信号的作用。我们相信这些研究将大大提高我们对布雷格免疫生物学的理解，并提供与同种异体移植耐受高度相关的治疗见解。 公共卫生相关性：最近的数据表明调节性B细胞（布雷格）在预防移植排斥和抑制自身免疫性疾病中起重要作用。不幸的是，布雷格的身份很难辨认.我们发现TIM-1分子是布雷格的标志物，而布雷格是由抗TIM-1抗体诱导的。这使得布雷格在移植中的作用得以研究，并提供了利用这些强效细胞的治疗策略

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. PUBLIC HEALTH RELEVANCE: Recent data indicate regulatory B cells (Breg) play an important role in preventing transplant rejection and inhibiting autoimmune diseases. Unfortunately, Breg have been hard to identify. We discovered that the TIM-1 molecule is a marker for Breg, and Breg are induced by anti-TIM-1 antibody. This allows the role of Breg in transplantation to be studied and provides a therapeutic strategy to capitalize on these potent cells