Type 1 IFN Function and Signaling in Immunity to Viruses

描述（由申请人提供）：1型干扰素（ifn），包括ifn α和β，具有强大的抗病毒作用，但也介导广泛的免疫调节功能。这些包括对淋巴细胞亚群的影响。有些是矛盾的，控制1型IFN效应的机制，在需要时允许访问子集功能，却没有得到很好的描述。细胞因子确实刺激信号通路，这取决于信号转导和转录激活因子（STAT） 1和2，但它们可以有条件地激活所有的STAT，包括STAT4。实验表明，在感染后的早期，总STAT1蛋白被显著诱导，并且1型IFN激活STAT4与STAT1水平呈负相关，因此，本项目提出验证1型IFN效应受不同细胞内信号通路的调节控制，并且这种调节在对病毒感染的先天和适应性免疫反应中是必需的和传递的假设。这项工作已经证明了这些假设是正确的，并且正在定义与不同途径相关的子集反应。本更新申请中提出了实验来验证以下假设：STATs作为分子开关，通过增强和抑制1型IFN效应来促进细胞反应，STAT1和STAT4在相互信号通路上的作用受到其他STAT分子的影响，并对其他STAT分子产生影响。这将通过关注T细胞反应的四个特定目标来实现。目的1将扩大对STAT表达的理解，以及感染期间不同T细胞亚群中1型IFN获取个体STAT的变化的后果。Aim 2将从机制上定义调控STAT水平的途径。目的3将通过评估实验调节STAT水平的后果，以及对体外细胞反应产生积极和消极影响的机制，来检验STAT作为主开关的假设。目标4将定义在感染期间调节STAT开关对调节生物反应的重要性。将使用免疫学、病毒学、生化和分子技术，并通过对野生型和转基因小鼠暴露于细胞因子后的体外反应和淋巴细胞性脉络丛脑膜炎病毒感染后的体内反应的研究来推进这项工作。该项目承诺继续推进对1型IFN在形成感染免疫反应中的控制作用的理解，并为细胞因子在治疗应用中的使用提供见解。然而，更广泛地说，它将确定如何调节细胞因子的作用以增加有限数量基因的价值的范例。

DESCRIPTION (provided by applicant): The type 1 interferons (IFNs), including the IFNs alpha and beta, have potent antiviral effects, but also mediate a wide range of immunoregulatory functions. These include effects on lymphocyte subsets. Some are paradoxical, and the mechanisms controlling type 1 IFN effects, to allow access to subset functions when needed, are poorly characterized. The cytokines do stimulate a signaling pathway, depending on the signal transducers and activators of transcription (STAT) 1 and 2, but they can conditionally activate all of the STATs, including STAT4. As a result of experiments demonstrating that total STAT1 protein is dramatically induced at early times after infection, and that type 1 IFN activation of STAT4 negatively correlates with STAT1 levels, this project proposed to test the hypotheses that type 1 IFN effects are controlled by regulation of access to different intracellular signaling pathways, and that this regulation is required and delivered during innate and adaptive immune responses to viral infections. The work has proven the hypotheses to be correct, and subset responses linked to different pathways are being defined. Experiments are proposed in this renewal application to test the hypotheses that STATs act as molecular switches in promoting cellular responses by both enhancing and inhibiting type 1 IFN effects, and that the STAT1 and STAT4 effects on the reciprocal signaling pathway are influenced by, and have consequences for, other STAT molecules. This will be accomplished through four specific aims focusing on T cell responses. Aim 1 will broaden the understanding of STAT expression and the consequences of changes for type 1 IFN access to individual STATs in different T cell subsets during infection. Aim 2 will mechanistically define the pathways regulating STAT levels. Aim 3 will test the hypothesis that STATs act as master switches by evaluating the consequences of experimentally modulating STAT levels and the mechanisms for resulting positive and negative effects on cellular responses ex vivo. Aim 4 will define the importance of modulating STAT switches for regulating biological responses during infections. Immunological, virological, biochemical, and molecular techniques will be used, and the work will be advanced by studies of responses ex vivo following exposure to cytokines, and in vivo following lymphocytic choriomeningitis virus infections in wild type and genetically altered mice. The project promises to continue to advance understanding of the control of type 1 IFN effects in shaping immune responses to infection, and to provide insights for use of cytokines in therapeutic applications. Even more broadly, however, it will identify paradigms for how cytokine effects are regulated to add value to a limited number of genes. PUBLIC HEALTH RELEVANCE: The type 1 interferons (IFNs) mediate a wide range of biological effects, and some of these are paradoxical. This work is directed at understanding how their functions are regulated to access and control subset responses as needed in promoting health during infections. Because type 1 IFNs are also being used, with uneven success, in the treatments of cancer, chronic hepatitis C virus infections, and multiple sclerosis, and ablation protocols are being developed to block their contribution to autoimmune diseases, the results have broad relevance for the design of therapeutic protocols in protection against disease.