TIM recognition of PtdSer on apoptotic cells and the regulation of immunity

描述（由申请人提供）：使用同种小鼠模型鉴定TIM基因家族，其中TIM-1和TIM-3中的多态性与BALB/c和同种HBA小鼠之间Th 1-Th 2分化和变应原诱导的气道高反应性（AHR）的差异相关。我们的目标是了解Tim基因如何调节外周耐受性，适应性免疫反应和过敏。我们已经表明，TIM-1是T细胞的重要共刺激分子，TIM-1和TIM-4调节T细胞反应和耐受性的发展，TIM-1和TIM-4是磷脂酰丝氨酸（PtdSer）的受体，磷脂酰丝氨酸是识别和摄取凋亡细胞的关键分子。我们最近发现，TIM-3，在Th 1细胞和APC上表达，也是PtdSer的受体，并且与哮喘相关的TIM-3的等位基因变体与PtdSer的结合不同。这些结果表明了TIM蛋白作为PtdSer受体的新范例，其通过调节对凋亡细胞的识别、清除和应答，可以调节T细胞应答和外周耐受的诱导。为了了解TIM蛋白识别PtdSer如何调节免疫应答，我们提出：具体目标1：确定TIM-4和TIM-3对APC与凋亡细胞上的磷脂酰丝氨酸结合的功能后果。我们将检查凋亡细胞吞噬对DC和巨噬细胞的影响，包括（a）抗炎介质产生：IL-10、TGF-2、IDO;（B）共抑制分子的表达;和（c）共刺激分子的表达。我们将确定TIM-4和TIM-3介导的凋亡细胞抗原吞噬作用对TReg和辅助性T细胞亚群发育的影响。 具体目标2。确定TIM等位基因变体对磷脂酰丝氨酸识别、吞噬作用和T细胞活化的结构/功能关系。我们将确定表达TIM-1和TIM-3的HBA和BALB/c等位基因的细胞是否具有不同的识别PtdSer和吞噬凋亡细胞的能力。我们将确定凋亡细胞上的PtdSer与T细胞上的TIM-1和TIM-3的结合如何调节T细胞活化和TReg发育，并比较BALB/c和HBA T细胞。 具体目的3：研究TIM-1和TIM-3等位基因变体在免疫应答和外周耐受调节中的体内作用。我们将比较TIM-3通路在体内清除凋亡细胞和在BALB/c和HBA小鼠中呈递凋亡细胞相关抗原中的作用。我们将确定TIM-1和TIM-3在调节BALB/c和HBA小鼠AHR发展中的相对作用。 这些研究将大大增加我们对TIM在调节T细胞反应和耐受性中的功能的理解，并表征一个新的和极其重要的哮喘易感基因家族。 公共卫生相关性：TIM基因已被证明是重要的疾病易感性基因（哮喘、过敏、特应性皮炎、类风湿性关节炎），并有效地调节免疫应答和外周耐受。TIM蛋白识别死亡细胞并帮助将它们从体内清除。增加对TIM蛋白如何调节免疫反应的理解将使我们能够设计哮喘，过敏，自身免疫性疾病和癌症的治疗方法。

DESCRIPTION (provided by applicant): The TIM gene family was identified using a congenic mouse model in which polymorphisms in TIM-1 and TIM-3 were associated with differences in Th1-Th2 differentiation and allergen-induced airway hyperreactivity (AHR) between BALB/c and congenic HBA mice. Our goal is to understand how the Tim genes regulate peripheral tolerance, adaptive immune responses, and allergy. We have shown that TIM-1 is an important costimulatory molecule for T cells, that TIM-1 and TIM-4 regulate T cell responses and the development of tolerance, and that TIM-1 and TIM-4 are receptors for phosphatidylserine (PtdSer), a key molecule for recognition and uptake of apoptotic cells. We have recently found that TIM-3, expressed on Th1 cells and APC, is also a receptor for PtdSer and that the allelic variants of TIM-3 associated with asthma differ in binding to PtdSer. These results suggest a new paradigm for TIM proteins as PtdSer receptors that by regulating the recognition, clearance, and response to apoptotic cells, can regulate T cell responses and the induction of peripheral tolerance. To understand how TIM protein recognition of PtdSer regulates immune responses, we propose to: Specific Aim 1: Determine the functional consequences of TIM-4 and TIM-3 on APC binding to phosphatidylserine on apoptotic cells. We will examine effects of apoptotic cell engulfment on DCs and macrophages including (a) anti-inflammatory mediator production: IL-10, TGF-2, IDO; (b) expression of co- inhibitory molecules; and (c) expression of co-stimulatory molecules. We will determine the effects of TIM-4- and TIM-3 mediated phagocytosis of apoptotic cell antigen on TReg and T helper subset development. Specific Aim 2. Determine the structure/function relationship of TIM allelic variants on recognition of phosphatidylserine, phagocytosis, and T cell activation. We will determine if cells expressing HBA and BALB/c alleles of TIM-1 and TIM-3 have different capacities to recognize PtdSer and phagocytose apoptotic cells. We will determine how binding of PtdSer on an apoptotic cell to TIM-1 and TIM-3 on a T cell regulates T cell activation and TReg development, and compare BALB/c and HBA T cells. Specific Aim 3: Investigate the in vivo role of TIM-1 and TIM-3 allelic variants in immune responses and regulation of peripheral tolerance. We will compare the roles of the TIM-3 pathway in clearance of apoptotic cells in vivo and in the presentation of apoptotic cell-associated antigen in BALB/c and HBA mice. We will determine the relative roles of TIM-1 and TIM-3 in regulating the development of AHR in BALB/c and HBA mice. These studies will greatly increase our understanding of the function of TIMs in the regulation of T cell responses and tolerance, and characterize a novel and extremely important asthma susceptibility gene family. PUBLIC HEALTH RELEVANCE: The TIM genes have been shown to be important disease susceptibility genes (asthma, allergy, atopic dermatitis, rheumatoid arthritis) and to potently regulate immune responses and peripheral tolerance. TIM proteins recognize dead cells and help remove them from the body. Increased understanding of how TIM proteins regulate immune responses will allow us to design therapies for asthma, allergies, autoimmune disease and cancer.