MECHANISMS OF IMMUNOSUPPRESSION IN MODELED MICROGRAVITY

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。本计画的主要目的是探讨模拟微重力环境所诱发的免疫抑制机制。极端环境，无论是高温、高压还是极冷，在过去几年中都受到了极大的关注，因为在这些条件下发现了无数的生物体。研究这些生物体对环境的适应性为理解我们自己的基本生理过程提供了重要信息。当太空飞行使人类和动物长时间处于失重状态时，一种新的极端环境被揭开了面纱。在零重力状态下发生了重要的生理变化，其中一些对生存具有相当重要的意义。免疫抑制就是其中之一。这表现为T细胞增殖的减少和对有丝分裂原的应答降低。造成这种影响的机制尚不清楚。航天飞行期间发生的任何免疫抑制事件都会严重制约暴露时间的长短、机组人员的能力、可能控制区域或人员所需的资源，简而言之，也会严重制约任何涉及在太空停留数天以上的使命的成功。在航天飞机上进行的体外研究表明，淋巴细胞在其细胞骨架特性中表现出重要的变化，这表明T细胞活化可能在T细胞受体相互作用的水平上受到损害。因此，我们推测，在失重状态下产生的免疫抑制是由于受损的T细胞受体活化，由于细胞骨架破坏。我们建议在模拟微重力下使用T细胞培养物来评估这一假设，这是正常重力下失重的可接受替代品。具体目标是1：使用fura-2测定细胞内Ca+2，确定模拟微重力对人类淋巴母细胞样T细胞系Jurkat和CEM中T细胞活化和Ca+2信号传导的影响。第二章：使用免疫沉淀和蛋白质印迹确定模拟微重力对信号蛋白表达和磷酸化状态的影响3：使用免疫荧光显微镜和免疫沉淀和蛋白质印迹评价微重力期间观察到的T细胞细胞骨架的破坏和重组。这项研究将提供关于微重力下T细胞活化特性的有用信息，这将增加我们对正常和低重力下免疫功能的基本分子机制的理解。它还将提高我们治疗免疫抑制性疾病的能力。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The major goal of this project is to elucidate the mechanisms of immune suppression induced by exposure to the environment of modeled microgravity. Extreme environments, whether of elevated temperatures, high pressure, or extreme cold, have received much attention in the past years due to the myriad living organisms that have been found under those conditions. The study of the adaptations of these organisms to their environment has provided important information for the understanding of our own basic physiological processes. A new extreme environment was unveiled when spaceflight put humans and animals in weightlessness for extended periods of time. Important physiological changes, some of considerable importance to survival, occurred in zero gravity. Immune suppression was one of them. This is manifested by a decrease in T cell proliferation and a reduced response to mitogens. The mechanisms responsible for this effect are unknown. Any instance of immune suppresssion during spaceflight puts severe constraints on the length of exposure, on the capabilities of the crew, on the resources necessary for possible containment of areas or personnel, in short, on the success of any mission involving more than a few days in space. Studies performed in vitro on the space shuttle have revealed that lymphocytes exhibit important changes in their cytoskeletal properties, which suggests that T cell activation may be compromised at the level of the T cell receptor interaction. We thus hypothesize that immunosuppresion produced in weightlessness is due to impaired T cell receptor activation due to cytoskeletal disruption. We propose to evaluate this hypothesis using T cell cultures in modeled microgravity, which is an acceptable substitute of weightlessness at normal gravity. The Specific Aims are 1: Determine the effects of modeled microgravity on T cell activation and Ca+2 signaling in the human lymphoblastoid T cell lines Jurkat and CEM, using intracellular Ca+2 measurement with fura-2. 2: Determine the effects of modeled microgravity on the expression and phosphorylation state of signaling proteins, using immunoprecipitation and Western blotting 3: Evaluate the disruption and reorganization of the T cell cytoskeleton observed during microgravity using immunofluorescence microscopy and immunoprecipitation and Western blotting. This study will provide useful information on the properties of T cell activation in microgravity that will increase our understanding of the basic molecular mechanisms underlying immune function both at normal and low gravity. It will also improve our capabilities for the treatment of immunosuppressive disorders.