S1P Receptor subtypes: Regulating lymphocyte trafficking

描述（由申请人提供）：本提案的重点是了解淋巴细胞运输的调节作为自身免疫和移植排斥的基本治疗方法。免疫抑制方案通常影响淋巴细胞和髓细胞造血谱系，使患者极易受到细菌、真菌和病毒感染，以及当前药物类别的长期毒性，包括显著的肾毒性和骨质流失。该项目结合了化学和生物学方法来激活溶血磷脂鞘磷脂1-磷酸（S1P）受体，通过抑制淋巴细胞从淋巴结的流出来隔离淋巴细胞。血液中淋巴细胞的可逆消失导致对外周抗原的免疫抑制，并防止自身免疫组织损伤、移植排斥和移植物抗宿主病。对自身免疫性患者的潜在优势是通过保留骨髓单核细胞功能来增强宿主防御来扩大治疗窗口，并且相对没有肾毒性或代谢后遗症。本提案将着重于提高对S1P受体激动作用产生临床有用的免疫抑制的机制的理解，并将试图将抑制淋巴细胞分泌的机制与S1P对血压和心功能的多效性作用分离开来。该提案的具体目的是：(1)确定SIP受体在淋巴组织中的详细组织表达。这将通过原位杂交和免疫组织学来完成；(2)使用受体选择性激动剂和S1P受体亚型阴性小鼠，确定受体选择性对淋巴细胞运输改变的影响。受体选择性激动剂将被定义并用于野生型和S1P受体缺失小鼠，以确定特定受体在产生淋巴细胞减少和S1P的其他生理效应中的作用。(3)确定S1P激动剂在淋巴细胞隔离中的作用部位。通过对受体分布的研究和对淋巴器官中替代标志物原位变化的评价，可以确定S1P受体激动剂是对淋巴细胞起作用，还是对内皮细胞起作用，或者两者都起作用。(4)建立S1P受体激动作用诱导免疫应答的定量变化。我们将定量研究S1P激动作用对卵清蛋白肽转基因小鼠的免疫抑制或增强免疫反应的局部和全身功能影响，以了解S1P系统在控制淋巴细胞再循环中的作用。这些研究将增强对S1P受体激动作用诱导临床有用的免疫抑制潜在应用于自身免疫的基本机制的理解。

DESCRIPTION (provided by applicant): This proposal is focused on understanding the regulation of lymphocyte trafficking as a fundamental therapeutic approach to autoimmunity and transplantation rejection. Immunosuppressive regimens generally impact upon both lymphoid and myeloid hemopoietic lineages, rendering patients highly susceptible to bacterial, fungal and viral infection, as well as to the long term toxicities of current drug classes, which include significant nephrotoxicity and bone loss. The project brings together chemical and biological approaches to activation of the receptors for the lysophospholipid sphingosine 1-phosphate (S1P) that result in the sequestration of lymphocytes by inhibiting their egress from lymphnodes. The reversible disappearance of lymphocytes from blood results in immunosuppression to peripheral antigen and protects from autoimmune tissue damage, transplant rejection and graft versus host disease. Potential advantages to autoimmune patients are based on broadening therapeutic window by retaining myelomonocytic cell function to enhance host defense, and the relative absence of nephrotoxicity or metabolic sequelae. This proposal will focus on improving the understanding of the mechanism by which S1P receptor agonism produces clinically useful immunosuppression, and will attempt to separate the mechanism of inhibition of lymphocyte egress from the pleiotropic effects of S1P upon pressor and cardiac function. Specific aims of the proposal are to (1) Determine the detailed tissue expression of SIP receptors in lymphoid tissues. This will be done by in situ hybridization and immunohistology; (2) Determine receptor selectivity for alteration of lymphocyte trafficking using receptor selective agonists and S1P receptor subtype null mice. Receptor selective agonists will be defined and used in wild-type and S1P receptor deletant mice, to determine the role of specific receptors in producing lymphopenia and other physiological effects of S1P. (3) Identify the cellular site of action of S1P agonists in lymphocyte sequestration. The study on receptor distribution and evaluation of surrogate marker changes in situ in lymphoid organs will determine whether the effect of S1P receptor agonists is on lymphocytes, endothelium or both. (4) Establish the quantitative changes in immune responses induced by S1P receptor agonism. Local and systemic functional effects of S1P agonism will be studied quantitatively for immunosuppression or potentiation of immune responses in transgenic mice responding to ovalbumin peptide, to understand the roles of the S1P system in control of lymphocyte recirculation. These studies will yield an enhanced understanding of the basic mechanisms by which S1P receptor agonism induces clinically useful immunosuppression of potential use in autoimmunity.