The role of T cells in adipose tissue inflammation and insulin resistance during weight cycling

项目摘要 平均而言，成功减肥的人会在5年内恢复80%的体重。 体重减轻（WL）和体重恢复（称为“体重循环”（WC））的发作与以下因素有关： 增加人类心血管疾病和发展2型糖尿病的风险。到 确定在以下人群中观察到的进行性代谢失调的原因和相关性： WC，我们已经开发了WC小鼠模型，其中交替60%高和10%低脂饮食 强烈地诱导体重增加和WL的周期。WC动物的葡萄糖耐量受损， 与年龄、体重和肥胖相匹配的高脂肪喂养对照动物。全身葡萄糖变化 调节部分依赖于渗透代谢组织的适应性免疫细胞，包括 脂肪组织（AT），在肥胖的进展。然而，这些重要细胞的表型 在WL和WC期间尚未表征。基于新的初步发现，CD 8 + T细胞 细胞在WL期间显示免疫耐受标记物，在WC期间显示侵袭性炎症潜能， 我假设AT CD 8 + T细胞在WL过程中暂时变得耐受，但在WL过程中， 在WC后重新激活，并且是WC期间观察到的胰岛素敏感性受损所必需的。我们 已经观察到肥胖时内脏AT中T细胞受体多样性的丧失，表明T细胞 对营养触发的抗原作出反应而克隆扩增。为了进一步阐明克隆 T细胞扩增可能在WL和WC小鼠的全身葡萄糖处理中起作用，我将描述T细胞的特征。 使用基于测序和流式细胞术的方法进行单细胞分辨率。此外，我们将 使用消耗和遗传模型来阻断长寿命的CD 8 + T细胞对葡萄糖的贡献 上厕所时观察到的不耐受。将使用单克隆抗体耗尽肥胖经历的CD 8 + T细胞。 在WL之前的抗体。恢复后，将再次用饮食诱导的肥胖症挑战动物， 鉴定缺乏经验的CD 8 + T细胞是否不能促进AT的胰岛素抵抗特征， 厕所。伴随地，不能长期维持活化T细胞存活的CD 70-/-小鼠将被移植到小鼠体内。 WC和代谢表型，以确定是否是长寿命的AT驻留的CD 8 + T细胞， 是驱动全身性葡萄糖失调所必需的。这两种模型都将进行表型分析， 金标准高胰岛素正常血糖钳夹，以暴露胰岛素敏感性的差异， 对照小鼠。最终，该提案旨在填补代谢和炎症方面未满足的需求， 关于AT重塑期间T细胞表型和功能的领域。因此，这一结果 该项目将通过提供对T细胞驱动的机制的清晰洞察来影响后续工作。 炎症和体重维持的治疗目标。

Project Summary On average, people who successfully lose weight will regain 80% of the lost weight within 5 years. Bouts of weight loss (WL) and weight regain, referred to as “weight cycling” (WC), are associated with increased risk of cardiovascular disease and of development of type 2 diabetes mellitus in humans. To identify causes and correlation of the progressive metabolic dysregulation observed in humans who WC, we have developed a mouse model of WC in which alternating 60% high and 10% low-fat diets robustly induce cycles of weight gain and WL. Glucose tolerance in WC animals is impaired compared to age, weight, and adiposity-matched high-fat fed control animals. Alterations in systemic glucose regulation is partially dependent on adaptive immune cells that infiltrate metabolic tissues, including adipose tissue (AT), during progression of obesity. However, the phenotype of these important cells during WL and WC has not been characterized. Premised on novel preliminary findings that CD8+ T cells display markers of immunotolerance during WL and aggressive inflammatory potential during WC, I hypothesize that AT CD8+ T cells transiently become tolerant during WL, but are potently reactivated after WC and are necessary for impaired insulin sensitivity observed during WC. We have observed a loss of T cell receptor diversity in visceral AT during obesity, indicating that T cells clonally expand in response to a nutritionally-triggered antigen. To further elucidate the role that clonal T cell expansion may play in systemic glucose handling in WL and WC mice, I will characterize T cells with single-cell resolution using sequencing and flow cytometry-based approaches. Additionally, we will use depletion and genetic models to block long-lived CD8+ T cells from contributing to glucose intolerance observed during WC. Obesity-experienced CD8+ T cells will be depleted using monoclonal antibodies prior to WL. After recovery, animals will again be challenged with diet-induced obesity to identify if inexperienced CD8+ T cells are unable to promote insulin resistance characteristic of AT after WC. Concomitantly, CD70-/- mice, which fail to maintain survival of activated T cells long-term, will be WC and metabolically phenotyped to determine whether it is long-lived AT-resident CD8+ T cells that are necessary for driving systemic glucose dysregulation. Both of these models will be phenotyped with gold-standard hyperinsulinemic euglycemic clamps to expose differences in insulin sensitivity from control mice. Ultimately, this proposal seeks to fill an unmet need in the metabolism and inflammation fields regarding T cell phenotype and function during AT remodeling. As a result, the outcomes of this project will influence subsequent work by providing clear insight into mechanisms of T-cell driven inflammation and therapeutic targets for weight maintenance.