Suppression of the Immune Response in Spaceflight and Aging

描述（由申请人提供）：项目概述。随着年龄的增长，免疫系统会衰退，老年人更容易受到感染。年龄相关的变化包括t细胞活化/增殖减少，IL-2产生减少和IL-2R1表达减少。这些关键的免疫变化也出现在返航的宇航员身上，他们在太空飞行中经历了免疫功能的改变，更容易受到感染。在衰老和太空飞行中免疫反应的丧失已经在T细胞中发现。我们之前已经确定了在正常和改变重力条件下微重力诱导人类CD4+ t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。我们在本提案中描述的来自国际空间站（ISS）的初步数据表明，在正常重力(g)下激活的早期t细胞中，至少有一种miRNA被上调，而在微重力（<g）下，miRNA的诱导被减弱。此外，miRNA的三个蛋白靶点在1。g环境提示微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，同样类型的免疫反应变化发生在微重力下，无论是宇航员还是人类t细胞，并且很容易测量。中心假设是<g调节人类t细胞中的MiRNA，失重是研究衰老中所见的免疫抑制的新模型。这些实验将有助于我们对太空飞行和衰老中免疫抑制的分子机制的基本理解。具体目的如下：(1)在正常重力下鉴定t细胞活化过程中miRNAs的基因表达（使用阵列和qRTPCR）。(2)利用生物信息学技术鉴定MiRNA(s)靶基因，并验证这些靶信息的表达变化（qRTPCR）。我们将测试微重力诱导/减少miRNA及其靶标表达的能力，并使用miRNA过表达病毒构建体或dsRNA验证这些结果。(3)分析正常重力和微重力条件下受t细胞活化影响的上调/下调靶基因的蛋白合成（SDS PAGE凝胶和Western Blot蛋白组学）。(4)比较正常重力和微重力下活化后关键候选mirna和基因的表达与老年人群淋巴细胞的表达。

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.