Innate NLRC4 signaling controls adaptive immune responses

项目摘要 NLRC 4是NLR的核苷酸结合结构域和富含亮氨酸的重复序列受体（NLR）家族的成员。 胞质模式识别受体，主要在先天免疫细胞中表达。典型的NLRC 4 NAIP蛋白识别革兰氏阴性菌的组分后， 导致NLRC 4寡聚化和炎性体复合物的组装。激活NLRC 4 炎性小体在caspase-1介导的促炎细胞因子IL-1的加工和释放中达到高潮。 1美元。我们已经发现NLRC 4在用B16 F10或B16 F10皮下攻击的小鼠中起保护作用。 黑色素瘤细胞或甲型流感病毒感染的模型中。在这两种模型中，Nlrc 4缺陷型（Nlrc 4-/-）小鼠均具有明显的免疫反应。 效应CD 4 + T细胞的损失。产生和维持强大的T细胞反应依赖于T细胞相互作用 抗原呈递细胞。对Nlrc 4-/-巨噬细胞和树突状细胞（DC）的评估显示， AKT 1和FoxO 3a磷酸化的下调，反过来又导致细胞凋亡的上调。 诱导Nlrc 4-/-骨髓细胞上的配体FasL，其触发共培养的T细胞中的细胞死亡。重要的是，不像 经典NLRC 4途径，NLRC 4的抗肿瘤和抗病毒作用是炎性小体非依赖性的， 提示一种新的非经典NLRC 4信号通路。在本建议中，我们将扩展这些小说 发现并利用创新技术来探索未解答的问题。我们假设内源性 危险信号激活髓样细胞中的NLRC 4，从而通过阻止T细胞的增殖来维持效应T细胞应答。 FasL上调。我们将定义NLRC 4在抗原呈递细胞中被激活的机制， 新的非经典途径，NLRC 4通过该途径改变随后的T细胞应答。我们还将 确定哪些因素下调NLRC 4表达，以及如何利用这种下调， 病原体和肿瘤。这些研究将确定先天免疫细胞中的新途径， 增强特异性抗肿瘤或抗病毒应答或抑制致病性T细胞应答。

Project Summary NLRC4 is a member of the Nucleotide-Binding Domain and Leucine-Rich Repeat Receptor (NLR) family of cytosolic pattern recognition receptors and is primarily expressed in innate immune cells. The canonical NLRC4 pathway is activated following the recognition of components of Gram-negative bacteria by NAIP proteins resulting in NLRC4 oligomerization and assembly of the inflammasome complex. Activation of the NLRC4 inflammasome culminates in caspase-1-mediated processing and release of the pro-inflammatory cytokine IL- 1. We have found that NLRC4 plays a protective role in mice challenged subcutaneously with either B16F10 melanoma cells or in a model of influenza A virus infection. In both models, Nlrc4-deficient (Nlrc4-/-) mice had a loss of effector CD4+ T cells. Generation and maintenance of robust T cell responses relies on T cell interactions with antigen presenting cells. Evaluation of Nlrc4-/- macrophages and dendritic cells (DC) revealed a downregulation of AKT1 and FoxO3a phosphorylation, which in turn resulted in the upregulation of the apoptosis- inducing ligand FasL on Nlrc4-/- myeloid cells that triggered cell death in co-cultured T cells. Importantly, unlike the canonical NLRC4 pathway, the anti-tumor and anti-viral roles of NLRC4 were inflammasome-independent, suggesting a novel non-canonical NLRC4 signaling pathway. In this proposal we will expand on these novel findings and utilize innovate technologies to probe unanswered questions. We hypothesize that endogenous danger signals activate NLRC4 in myeloid cell, which in turn maintains effector T cell responses by preventing FasL upregulation. We will define the mechanism by which NLRC4 is activated in antigen presenting cells and the novel non-canonical pathway through which NLRC4 modifies subsequent T cell responses. We will also determine what factors downregulate NLRC4 expression and how this downregulation can be exploited by pathogens and tumors. These studies will identify novel pathways in innate immune cells that can be targeted to either augment specific anti-tumor or anti-viral responses or inhibit pathogenic T cell responses.