Identification of Adipose Tissue Factors that Induce Regulatory iNKT Cells

项目摘要：不变自然杀伤T细胞是一种先天的αβT细胞，使用保守的T细胞 受体(TCR)重排以识别主要组织相容性背景下的脂类抗原 复合体(MHC)类分子CD1d。类似于经典的Th1、Th2和Th17辅助T细胞亚群， NKT1、NKT2和NKT17细胞已被描述为典型的细胞因子产生谱， 转录因子的表达和组织定位。C57BL/6小鼠体内绝大多数iNKT细胞是 NKT1细胞，驻留在肝脏和脾，当被激活时产生大量的干扰素γ和IL-4 TCR和先天细胞因子信号的组合。 许多报告描述了iNKT细胞在促炎免疫反应的背景下， 它们对危险信号和微生物脂类抗原做出反应，以调节宿主的防御。相比之下，我们最近 在小鼠和人类的脂肪组织中发现了iNKT细胞的独特作用，在那里它们表现出独特的 调节表型。维持脂肪组织中的非炎症状态对于保存 胰岛素敏感性，预防糖尿病，控制肥胖。我们发现脂肪iNKT细胞产生高水平的 IL-2推动脂肪树突状细胞的扩张，而IL-10驱动M2巨噬细胞的扩张。这些 INKT细胞的功能对抗炎脂肪微环境有显著贡献，在 缺乏iNKT细胞的小鼠容易肥胖和糖尿病。此外，脂肪iNKT的特异性激活 含有脂类抗原α-半乳糖基神经酰胺(αGalCer)的细胞可诱导体重减轻并改善许多 肥胖引起的代谢异常。有趣的是，脂肪iNKT细胞具有明显的转录 在iNKT细胞中表达的PLZF转录因子的分布和缺乏表达 器官。相反，它们表达转录因子E4BP4，该转录因子驱动它们产生IL-10。 我们有几条证据表明脂肪iNKT细胞的调节特性是 由于暴露在脂肪微环境中而引起的。该提案的目标是确定组件 脂肪组织驱动脂肪iNKT细胞的独特调控表型。为了实现这一目标， 我们建议首先表征脂肪组织诱导和维持调节性iNKT细胞的能力。 采用过继转移实验的体内表型研究(目标1)。然后，我们将分析 脂肪细胞CD1d表达对脂肪iNKT细胞表型的影响(目标2)。最后，我们将识别分子 脂肪组织释放诱导iNKT细胞表达E4BP4并赋予其调节能力 (目标3)。综合起来，这些研究将确定环境和分子诱导物对调节iNKT细胞的作用。 这将1)揭示在自身免疫性疾病中靶向这些细胞的新途径，2)提供对 可用于治疗代谢疾病的驻留脂肪的免疫细胞群的生物学 肥胖和糖尿病等疾病。

Project Summary: Invariant natural killer T (iNKT) cells are innate-like αβ T cells that use conserved T cell receptor (TCR) rearrangements to recognize lipid antigens in the context of the major histocompatibility complex (MHC) I-like molecule CD1d. Analogous to the classical Th1, Th2, and Th17 helper T cell subsets, NKT1, NKT2, and NKT17 cells have been described with stereotypical cytokine production profiles, transcription factor expression, and tissue localization. The vast majority of iNKT cells in C57BL/6 mice are NKT1 cells, which reside in the liver and spleen and produce high amounts of IFNγ and IL-4 when activated by a combination of TCR and innate cytokine signals. Many reports have described iNKT cells in the context of proinflammatory immune responses where they respond to danger signals and microbial lipid antigens to mediate host defense. In contrast, we recently identified a distinct role of iNKT cells in adipose tissues of mice and humans where they display a unique regulatory phenotype. Maintenance of the non-inflammatory state in adipose tissue is essential to preserve insulin sensitivity, prevent diabetes, and control obesity. We found that adipose iNKT cells produce high levels of IL-2 that drives the expansion of adipose Tregs and IL-10 that drives M2 macrophage expansion. These iNKT cell functions contribute significantly to the anti-inflammatory adipose microenvironment, and in the absence of iNKT cells mice are prone to obesity and diabetes. Furthermore, specific activation of adipose iNKT cells with the lipid antigen α-galactosylceramide (αGalCer) induces weight loss and ameliorates many metabolic abnormalities caused by obesity. Interestingly, adipose iNKT cells have a distinct transcriptional profile and lack expression of the PLZF transcription factor, which is expressed in iNKT cells in all other organs. Instead, they express the transcription factor E4BP4 that drives their production of IL-10. We have several lines of evidence to indicate that the regulatory properties of adipose iNKT cells are induced by exposure to the adipose microenvironment. The goal of this proposal is to identify components of adipose tissue that drive the unique regulatory phenotype of adipose iNKT cells. In line with this goal, we propose to first characterize the ability of adipose tissue to induce and maintain the regulatory iNKT cell phenotype in vivo using adoptive transfer experiments (Aim 1). Then, we will analyze the contribution of adipocyte CD1d expression to the phenotype of adipose iNKT cells (Aim 2). Finally, we will identify molecules released by adipose tissue induce E4BP4 expression in iNKT cells and endow them with regulatory capacity (Aim 3). Combined, these studies will identify environmental and molecular inducers of regulatory iNKT cells that will 1) reveal new pathways to target these cells in autoimmune diseases and 2) offer insight into the biology of an adipose-resident immune cell population that can be manipulated for the treatment of metabolic diseases such as obesity and diabetes.