ENDOTHELIAL MODIFICATIONS THAT REDUCE T CELL ACTIVATION

描述（改编自申请人摘要）：培养的人和猪 内皮细胞（EC）可以直接将MHC分子呈递给人T细胞 并且可以提供足够的共刺激信号， 静息T细胞结果。 在当前供资期间，调查人员 已经表明人外周血粘附细胞可以激活静息的 幼稚和记忆T细胞，人EC可以激活静息记忆，但不能激活静息记忆。 幼稚T细胞，而非免疫细胞类型（例如成纤维细胞）不能 激活静息T细胞，只能再刺激激活的T母细胞。 这些差异源于共刺激分子表达的差异， 由这些不同的细胞类型。 研究人员假设， 将在体内起作用，通过将抗原呈递给 循环记忆T细胞，但不能启动初级免疫反应 包括幼稚T细胞 他们进一步假设， 由EC表达的共刺激分子将改变T细胞活化， 并改变体内免疫反应的结果。 在续费 在此期间，研究人员提出在五个具体的测试这些假设， 目标。 (1)培养的人内皮细胞上的共刺激分子将被改变 通过减少LFA-3（CD 58），表达转染的B7.1（CD 80）或B7.2（CD 86）， 阻断CD 40，或用细胞因子预处理以及对T细胞的影响 使用体外测定（细胞因子 转录和分泌、增殖、分化和发育 （2）将表达B7.2的猪EC与人EC进行比较 在相同的试验中，当在人中表达时，将分析猪B7.2 （3）共刺激分子（LFA-3、B7.1、B7.2、CD 40）对内皮细胞的作用将被进一步研究。 在人外周血淋巴细胞-重度联合 血管化人皮肤免疫缺陷（huPBL-SCID）小鼠模型 同种异体移植排斥反应，由研究者开发;（4）huPBL-SCID 小鼠模型将被扩展到检查人T细胞-猪EC相互作用， （5）新的huPBL-SCID小鼠模型 将被开发来检查人类T细胞与人类EC的相互作用， 已经被遗传修饰以改变共刺激分子的表达 分子。 这些实验将（1）提供对假设的检验;（2） 测试EC的遗传改变可以改变T 同种异体移植物、异种移植物和其他环境中的细胞介导的损伤;和（3） 开发新的和有用的体内模型，用于评估 免疫抑制药物、抗人抗体和其它治疗药物 对人体免疫反应的干预。

DESCRIPTION (Adapted from the Applicant's abstract): Cultured human and pig endothelial cells (ECs) can present MHC molecules directly to human T cells and can provide sufficient costimulatory signals such that activation of resting T cells results. In the current funding period, the investigators have shown that human peripheral blood adherent cells can activate resting naive and memory T cells, that human ECs can activate resting memory but not naive T cells, and that non-immune cell types (e.g. fibroblasts) are unable to activate resting T cells and can only restimulate activated T blasts. These differences arise from differences in costimulator molecules expressed by these various cell types. The investigators hypothesize that human ECs will function in vivo to initiate recall responses by presenting antigen to circulating memory T cells but fail to initiate primary immune reactions involving naive T cells. They further hypothesize that alterations in the costimulator molecules expressed by ECs will alter T cell activation in vitro and alter the outcome of immune reactions in vivo. In the renewal period the investigators propose to test these hypotheses in five specific aims. (1) The costimulator molecules on cultured human ECs will be altered by reducing LFA-3 (CD58), expressing transfected B7.1 (CD80) or B7.2 (CD86), blocking CD40, or pretreating with cytokines and the consequences for T cell subset activation will be assessed using in vitro assays (cytokine transcription and secretion, proliferation, differentiation and development of anergy); (2) Pig ECs, which express B7.2, will be compared to human ECs in the same assays and pig B7.2 will be analyzed when expressed in human ECs; (3) The role of costimulators (LFA-3, B7.1, B7.2, CD40) on ECs will be studied in a human peripheral blood lymphocyte-severe combined immunodeficient (huPBL-SCID) mouse model of vascularized human skin allograft rejection, developed by the investigators; (4) The huPBL-SCID mouse model will be extended to examine human T cell-pig EC interactions by engraftment of vascularized pig skin grafts; (5) New huPBL-SCID mouse models will be developed to examine human T cell interactions with human ECs that have been genetically modified to alter the expression of costimulator molecules. These experiments will (1) provide a test of the hypotheses; (2) test the concept that genetic alterations of ECs can alter the course of T cell-mediated injury in allografts, xenografts and other settings; and (3) develop new and useful in vivo models for evaluating the efficacy of immunosuppressive drugs, anti-human antibodies, and other therapeutic interventions on human immune responses.