ENDOTHELIAL MODIFICATIONS THAT REDUCE T CELL ACTIVATION

描述(改编自申请者摘要)：养殖的人和猪 内皮细胞(ECs)可将MHC分子直接呈递给人类T细胞 并且可以提供足够的共刺激信号，从而激活 静息T细胞的结果。在目前的资助期内，调查人员 已经表明人类外周血贴壁细胞可以激活静息 幼稚和记忆T细胞，人类内皮细胞可以激活静息记忆，但不能 幼稚的T细胞，非免疫细胞类型(如成纤维细胞)不能 激活静止的T细胞，只能重新刺激激活的T细胞。 这些差异是由共刺激分子表达的差异引起的 通过这些不同的细胞类型。研究人员假设人类内皮细胞 会在体内发挥作用，通过将抗原提呈给 循环记忆T细胞，但未能启动初级免疫反应 涉及幼稚T细胞。他们进一步假设，地球表面的变化 内皮细胞表达的共刺激分子将改变T细胞的激活 在体外并改变体内免疫反应的结果。在更新中 期间，研究人员建议从五个具体的方面来检验这些假设 目标。(1)培养的人内皮细胞表面共刺激分子将发生改变 通过降低LFA-3(CD58)，表达转染的B7.1(CD80)或B7.2(CD86)， 封闭CD40或细胞因子预处理对T细胞的影响 将使用体外试验(细胞因子)来评估亚群的激活 转录和分泌、增殖、分化和发育 (2)表达B7.2的猪内皮细胞将与人类内皮细胞进行比较 在相同的检测中，当猪B7.2在人中表达时，将进行分析 (3)共刺激因子(LFA-3、B7.1、B7.2、CD40)对ECs的作用如下 人外周血淋巴细胞-重症联合培养的研究 血管化人皮肤免疫缺陷(huPBL-SCID)小鼠模型 研究人员开发的同种异体移植排斥反应；(4)huPBL-SCID 小鼠模型将扩展到研究人T细胞与猪EC的相互作用 带血管猪皮移植；(5)新的huPBL-SCID小鼠模型 将被开发用于检测人类T细胞与人类内皮细胞的相互作用 已经通过基因改造改变了共刺激分子的表达 分子。这些实验将(1)检验假设；(2) 测试内皮细胞的基因改变可以改变T进程的概念 异体移植物、异种移植物和其他环境中的细胞介导性损伤； 开发新的、有用的体内模型来评估阿司匹林的疗效 免疫抑制药物、抗人抗体和其他治疗方法 对人类免疫反应的干预。

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.