Suppression of the Immune Response in Spaceflight and Aging

描述(申请人提供)：项目摘要。随着年龄的增长，免疫系统会衰退，老年人更容易受到感染。与年龄相关的变化包括T细胞活化/增殖减少，IL-2的产生减少，IL-2R1的表达减少。这些关键的免疫变化与返回的宇航员相同，他们在太空飞行期间经历了免疫功能的变化和感染的易感性增加。在衰老和航天飞行中，免疫反应的丧失已经在T细胞中被发现。我们以前已经发现，在正常和改变重力条件下，微重力会导致人类CD4T细胞基因表达、启动子区域、转录因子和信号转导途径的变化。我们在本方案中描述的来自国际空间站(ISS)的初步数据表明，在T细胞的早期激活中，至少有一个miRNA在正常重力(G)下的激活过程中上调，而在微重力(&lt；g)下，miRNA的诱导被抑制。此外，miRNA的三个蛋白质靶标在1.g环境中表达增加，表明这是一种微小RNA机制。老年人免疫功能的变化是随着时间的推移而发生的，很难评估。然而，在宇航员和人类T细胞中，同样类型的免疫反应变化也发生在微重力中，而且很容易衡量，核心假设是-lt；g调节人类T细胞中的miRNA，失重是研究衰老过程中免疫抑制的新模型。这些实验将有助于我们从根本上理解航天和衰老过程中免疫抑制的分子机制。具体目标如下：(1)鉴定正常重力下T细胞激活过程中miRNAs的基因表达(使用阵列和qRTPCR)。(2)利用生物信息学方法鉴定S的靶基因，并验证这些靶信息的表达变化(qRT-PCR)。我们将测试微重力诱导/减少miRNAs及其靶标表达的能力，并使用miRNA过表达病毒构建物或dsRNA验证这些结果。(3)分析正常重力和微重力条件下T细胞活化对上调/下调的靶基因(SDS PAGE凝胶和Western Blot蛋白质组学)的影响。(4)比较在正常重力和微重力条件下激活后的关键miRNAs候选基因和基因的表达，并与老年人群的淋巴细胞进行比较。 与公共卫生相关：识别T细胞中已抑制航天免疫反应但在1G飞行控制中正常表达的改变的microRNAs及其靶标将有助于我们理解衰老，并可能揭示老年人免疫抑制的重要原因。在最近的ISS实验中，与机载1G对照组相比，飞行中的T细胞中一种miRNA的表达显著下调；随着更有效的miRNA收集，应该可以识别出更多的失调miRNAs。由于宇航员飞行期间的免疫抑制与老年人的免疫抑制有相当大的相似之处，我们预计我们的发现将与NIH的任务相关，并对研究免疫反应的分子机制的研究人员产生广泛的兴趣。

DESCRIPTION (provided by applicant): Project Summary. In aging, immune systems falter and the elderly are more susceptible to infection. Age related changes include decreased T-cell activation/proliferation, decreased production of IL-2 and decreased expression of IL-2R1. These are the same key immune changes that are seen in returning astronauts who have experienced altered immune function and increased vulnerability to infection during spaceflights. Loss of immune response in aging and spaceflight has been previously identified in T cells. We have previously identified microgravity induced changes in gene expression, promoter regions, transcription factors and signal transduction pathways in human CD4+ T-cells under normal and altered gravity conditions. Our preliminary data from International Space Station (ISS) described within this proposal show that in early T-cell activation at least one miRNA was upregulated during activation in normal gravity (g), while in microgravity (<g), the induction of the miRNA was muted. Moreover, three protein targets of the miRNA had increased expression in the 1.g environment suggesting a micro RNA mechanism. The changes in immune function in the elderly occur over time and are hard to evaluate. However, the same type of changes in immune response occurs microgravity, both in astronauts and in human T-cells and is easy to measure The central hypothesis is that <g regulates MiRNA in human T-cells and that weightlessness is a novel model to study the immunosuppression seen in aging. These experiments will contribute to our fundamental understanding of the molecular mechanism of immunosuppression in spaceflight and in aging. The Specific Aims are the following: (1) Identify gene expression of miRNAs during T-cell activation (using arrays and qRTPCR) under normal gravity. (2) Identify the MiRNA(s) target genes using bioinformatics and verify the changes in expression of those targets messages (qRTPCR). We will test the ability of microgravity to induce/reduce expression of MiRNAs and their targets and verify these results using miRNA overexpression viral constructs or dsRNA. (3) Analyze the protein synthesis of the upregulated/downregulated target genes (SDS PAGE gels and Western Blot proteomics) that are affected by T-cell activation under normal gravity and microgravity conditions. (4) Compare the expression of key MiRNAs candidates and genes after activation in normal gravity and microgravity, vs. that of the lymphocytes from an older population. PUBLIC HEALTH RELEVANCE: Identifying altered microRNAs and their targets in T-cells that have suppressed immune response in spaceflight but normal expression in 1g flight controls will contribute to our understanding of aging and will likely reveal important causes of immunosuppression in the elderly. In recent ISS experiments, one MiRNA is significantly downregulated in <g flown T cells when compared to onboard 1g controls; with more efficient miRNA collection, several more dysregulated MiRNAs should be identified. Because there are considerable similarities between immunosuppression in astronauts during flight and immunosuppression in the elderly, we expect that our findings will be relevant to the mission of the NIH and be broadly interesting to researchers studying molecular mechanisms of the immune response.