MECHANISMS OF IMMUNOSUPPRESSION IN MODELED MICROGRAVITY

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 本项目的主要目的是阐明暴露在模拟微重力环境中的免疫抑制机制。极端环境，无论是高温、高压还是极端寒冷，在过去的几年里受到了极大的关注，因为在这些条件下发现了无数的生命有机体。研究这些生物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的信息。当太空飞行使人和动物长时间处于失重状态时，一个新的极端环境被揭开了面纱。在失重状态下，发生了重要的生理变化，其中一些对生存非常重要。免疫抑制就是其中之一。这表现为T细胞增殖减少，对有丝分裂原的反应减弱。造成这种效应的机制尚不清楚。在航天飞行期间，任何免疫抑制的情况都会对暴露的时间长度、机组人员的能力、可能遏制区域或人员所需的资源造成严格的限制，简而言之，就是任何涉及几天以上的太空任务的成功。在航天飞机上进行的体外研究表明，淋巴细胞的细胞骨架特性发生了重要变化，这表明T细胞的激活可能在T细胞受体相互作用的水平上受到影响。因此，我们假设失重时产生的免疫抑制是由于细胞骨架破坏导致T细胞受体激活受损所致。我们建议在模拟微重力中使用T细胞培养来评估这一假设，这是正常重力下可接受的失重替代方法。具体目标为1：利用Fura-2细胞内Ca+2测量，确定模拟微重力对人淋巴母细胞T细胞系Jurkat和CEM中T细胞活化和Ca+2信号的影响。2：通过免疫沉淀和Western blotting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、免疫沉淀和Western blotting评价微重力过程中观察到的T细胞骨架的破坏和重组。这项研究将提供有关微重力下T细胞激活特性的有用信息，从而加深我们对正常和低重力下免疫功能基本分子机制的理解。它还将提高我们治疗免疫抑制疾病的能力。

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.