Function of NLRP3 in regulatory T cell-mediated control of intestinal homeostasis

项目摘要 炎性小体是细胞质的多蛋白复合体，可以感知并被微生物或 组织损伤，然后导致激活caspase介导的炎症通路，涉及 释放细胞因子IL-1、β和IL-18。尽管炎症小体的促炎作用一直很好 建立在先天免疫细胞中，最近几项研究揭示了不同炎症小体的作用 调节多种不同T细胞反应的成分，这是获得性免疫的关键部分。具体地说，一个 T细胞的一个亚群，称为调节性T细胞(Treg)，以其抑制免疫的能力而闻名 反应和炎症，被证明受到其细胞固有的炎症体成分的影响。连 尽管Tregs在建立对广泛的无害外来抗原的耐受性方面发挥了关键作用 肠道中的共生微生物和食物早已被公认，NLRP3的功能 炎性小体在Treg介导的肠道稳态控制中的作用仍然是一个悬而未决的问题。基于 初步数据推测，NLRP3/炎症体可以作为一种完整的决定因素 控制Treg生物学和在肠道Treg中诱导NLRP3将是其特定需要的 肠道中Th17反应的控制。为了检验这一假说，第一个目的是阐明 NLRP3在控制健康和疾病肠道Treg生物学中的作用 通过使用实验室最近生成的两个新的鼠标模型来实现功能方法： Treg特异性缺失NLPR3的小鼠和Treg特异性表达的小鼠具有结构性活性 NLRP3。两种不同的Th17依赖性疾病模型：抗CD3诱导的肠炎和 将采用轮状柠檬酸杆菌感染模型。因此，NLRP3枯竭或 生理和非生理状态下Treg对肠道系统其他免疫细胞的结构性激活 病理情况将被阐明。在第二个目标中，NLRP3-的分子机制- 将对Treg生物学的介导性控制进行研究。首先，作为IL-1b，NLRP3/炎症小体的一个组成部分 也发现在炎症状态下选择性地诱导了肠道Tregs通路，我将确定 Treg来源的IL-1b在控制肠道内环境稳定中的潜在作用。接下来，潜在的参与 NLRP3介导的Treg生物学基础上的炎性小体非依赖性与依赖性机制也将是 检查过了。最后，由于Tregs的异构性现在得到了很好的认识， 将进行转录本和测序表位(CITE-SEQ)研究，以确定是否存在 表达NLRP3的Tregs的特定子集，或者NLRP3诱导是否是ALL的共同特征 炎症状态下的肠道蠕动。总而言之，这项研究将提供对 NLRP3在肠道Tregs中的抗炎作用被低估，无疑将促进 炎症性肠病和其他人类肠道疾病的未来治疗方法的发展。

Project Summary The inflammasomes are cytoplasmic multi-protein complexes that can sense and be activated by microbes or tissue damage, which then leads to the activation of caspase-mediated inflammatory pathways involving the release of cytokines IL-1β and IL-18. Although the pro-inflammatory role of inflammasomes have been well established in innate immune cells, recently, several studies have uncovered a role for different inflammasome components in regulating many different T cell responses, a key part of adaptive immunity. Specifically, a subset of T cells called regulatory T cells (Tregs), which are known for their ability to suppress immune responses and inflammation, were shown to be affected by their cell intrinsic inflammasome components. Even though the critical role of Tregs in establishing tolerance to a wide range of innocuous foreign antigens from commensal microbes and food in the gut has long been well-recognized, the function of the NLRP3 inflammasome in Treg-mediated control of intestinal homeostasis remains an open question. Based on preliminary data, it was hypothesized that NLRP3/inflammasome could serve as an integral determinant in controlling Treg biology and that induction of NLRP3 in intestinal Tregs would be specifically required for their control of Th17 responses in the intestine. To test this hypothesis, the first aim will elucidate the function of NLRP3 in controlling Treg biology in the gut in heath and disease using both loss-of-function and gain-of- function approaches through employing two novel mouse models that have been recently generated in the lab: mice with Treg-specific deletion of NLPR3 and mice with Treg-specific expression of constitutively active NLRP3. Two different Th17-dependent disease models: anti-CD3 induced intestinal inflammation and Citrobacter rodentium infection model will be employed. As such, the biological impact of NLRP3 depletion or constitutive activation in Tregs on the other immune cells in the intestinal system under both physiological and pathological conditions will be elucidated. In the second aim, the molecular mechanisms underlying NLRP3- mediated control of Treg biology will be investigated. First, as IL-1b, a component of the NLRP3/inflammasome pathway was also found to be selectively induced in intestinal Tregs under inflammation, I will determine the potential role of Treg-derived IL-1b in controlling intestinal homeostasis. Next, the potential involvement of inflammasome-independent vs. –dependent mechanism underlying NLRP3-mediated Treg biology will also be examined. Finally, as the heterogeneous nature of Tregs is now well appreciated, Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-seq) studies will be conducted to determine if there is a specific subset of Tregs that expresses NLRP3 or whether NLRP3 induction is a common feature for all intestinal Tregs under inflammation. Collectively, this study will provide mechanistic insights into the underappreciated anti-inflammatory role of NLRP3 in intestinal Tregs and will undoubtedly facilitate the development of future therapeutics for inflammatory bowel disease and other human intestinal disorders.