Cell-intrinsic role of caspase-1 in regulating antigen-specific CD8+ T cell responses

摘要 Caspase-1是炎症体复合体的重要组成部分，负责裂解前... 炎性细胞因子IL-1、β和IL-18与裂解赤霉素D引起的下睑下垂 西尼罗河病毒(WNV)感染的小鼠模型，我们和其他人之前已经证明了重要性 炎症体信号转导促进IL-1β介导的保护性免疫。我们现在已经延长了这些 观察并发现了caspase-1在调节抗原特异性CD8+T细胞中的一种新的细胞内在作用 西尼罗河病毒感染期间的反应。CD8+T细胞的缺失导致WNV复制失控和 大脑内严重的神经元损伤。为了了解大脑中的环境线索如何影响T细胞 在西尼罗河病毒感染期间的反应，我们对分离的抗原特异性CD8+T细胞进行了转录图谱分析 在西尼罗河病毒感染后的早期和晚期从脾和脑中提取。通过这个分析，我们发现， Caspase-1以及其他炎症体信号成分富含在脑驻留抗原中- 从脾中分离的特异性CD8+T细胞与抗原特异性CD8+T细胞的比较。我们确认了 与脾CD8+细胞相比，活性caspase-1在脑内CD8+T细胞中的表达更为丰富 T细胞。使用联合过继转移模型，我们观察到抗原特异性CASP1-/-CD8+T细胞增加 与WT相比，CD8+T细胞在感染期间存在于脾和脑内。值得注意的是，CD8+T细胞没有被感染 提示caspase-1的激活不依赖于病毒感染。接下来，我们描述了 利用体外T细胞受体(TCR)刺激实验发现caspase-1在体外发挥作用 CD3/CD28刺激后自身蛋白降解。此外，我们还发现ASC，而不是NLRP3或IL- 1β，在幼稚和刺激的CD8+T细胞中表达。最后，最近的研究将caspase-1与 线粒体功能。与这些观察结果一致，我们发现αCD3/αCD28启动了CASP1-/-CD8+ 与WT CD8+T细胞相比，T细胞表现出更强的氧化磷酸化，这表明 Caspase-1可能通过重新编程线粒体动力学和代谢来调节CD8+T细胞的功能。基座 根据这些发现，我们假设CD8+T细胞的TCR刺激触发了caspase-1的激活，这是 以组织特有的方式限制T细胞激活、线粒体生物能量学和细胞扩张的功能。在……里面 反过来，我们认为激活的caspase-1对于控制CNS内的病毒复制和 通过防止病毒期间过度活跃的T细胞反应来最大限度地减少相应的神经元损伤 感染。为了解决这一假设，我们有两个具体的目标：1)caspase-1如何介导CD8+T细胞 西尼罗河病毒感染期间的反应？2)目的2.caspase-1作用的分子机制是什么 在激活的CD8+T细胞中？这些目标的实现将使我们对 Caspase-1在病毒感染过程中调节CD8+T细胞反应的潜在机制。

ABSTRACT Caspase-1 is an essential component of the inflammasome complex and is responsible for cleaving pro- inflammatory cytokines IL-1β and IL-18 and initiating pyroptosis through cleavage of Gasdermin D. Using a murine model of West Nile virus (WNV) infection, we and others have previously demonstrated the importance of inflammasome signaling for promoting IL-1β-mediated protective immunity. We have now extended these observations and discovered a novel, cell-intrinsic role for caspase-1 in regulating antigen-specific CD8+ T cells responses during WNV infection. The absence of CD8+ T cells leads to uncontrolled WNV replication and significant neuronal injury within the brain. To understand how environmental cues within the brain impact T cell responses during WNV infection, we performed transcriptional profiling on antigen-specific CD8+ T cells isolated from the spleen and brain at early and late times post-WNV infection. Through this analysis, we found that caspase-1, as well as other inflammasome signaling components, were enriched within brain-resident antigen- specific CD8+ T cells as compared to antigen-specific CD8+ T cells isolated from the spleen. We confirmed that active caspase-1 is more abundantly expressed within brain-resident CD8+ T cells as compared to splenic CD8+ T cells. Using a co-adoptive transfer model, we observed increased antigen-specific Casp1-/- CD8+ T cells as compared to WT CD8+ T cells within the spleen and brain during infection. Of note, CD8+ T cells are not infected by WNV, suggesting that the activation of caspase-1 is independent of virus infection. Next, we characterized caspase-1 function in vitro using an in vitro T cell receptor (TCR) stimulation assay and found that caspase-1 is autoproteolytically cleaved following CD3/CD28 stimulation. Moreover, we found that ASC, but not NLRP3 or IL- 1β, is expressed in naïve and stimulated CD8+ T cells. Lastly, recent studies have linked caspase-1 with mitochondrial function. Consistent with these observations, we found that αCD3/αCD28 primed Casp1-/- CD8+ T cells displayed enhanced oxidative phosphorylation as compared to WT CD8+ T cells, suggesting that caspase-1 may regulate CD8+ T cell function by reprogramming mitochondrial dynamics and metabolism. Based on these findings, we hypothesize that TCR stimulation of CD8+ T cells triggers caspase-1 activation, which functions to limit T cell activation, mitochondrial bioenergetics, and cell expansion in a tissue-specific manner. In turn, we believe that active caspase-1 is critically required for controlling virus replication within the CNS and minimizing consequential neuronal damage by preventing an over-exuberant T cell response during viral infection. To address this hypothesis, we have two specific aims: 1) How does caspase-1 mediate CD8+ T cell responses during WNV infection? and 2) Aim 2. What are the molecular mechanisms of caspase-1 function in activated CD8+ T cells? The completion of these aims will provide us with a broader understanding of the underlying mechanisms by which caspase-1 regulates CD8+ T cells responses during virus infection.