Mechanisms of Adipose Tissue Immunoregulatory T cell (Treg) Exhaustion in Obesity

肥胖症中脂肪组织免疫调节 T 细胞 (Treg) 耗竭的机制

• 批准号: 10454627
• 负责人: David Paul Bradley
• 金额: $ 43.83万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-19 至 2023-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10454627
• 关键词: Ablation; Adipose tissue; Adoptive Transfer; Agonist; Anabolism; Anti-Inflammatory Agents; Antigens; Apoptosis; Attenuated; Blood; CD4 Positive T Lymphocytes; CTLA4 gene; Cell Death; Cells; Ceramides; Characteristics; Clinical Trials; Complex; DNA Methylation; Data; Down-Regulation; Drops; Endocrine Glands; Enzymes; Exhibits; FOXP3 gene; Fatty acid glycerol esters; Genes; Genetic Transcription; Goals; High Fat Diet; Human; IFNGR1 gene; IL2RA gene; Immune; Impairment; Inflammation; Inflammatory; Ingestion; Insulin; Insulin Resistance; Insulin-Dependent Diabetes Mellitus; Interferon Type II; Investigation; Knock-out; Light; Lipids; Maintenance; Mediating; Mediator of activation protein; Metabolic; Metabolism; Methylation; Mus; Non-Insulin-Dependent Diabetes Mellitus; Normal tissue morphology; OX40; Obese Mice; Obesity; Operative Surgical Procedures; PPAR gamma; Pathway interactions; Patients; Phenotype; Physiological; Pioglitazone; Population; Process; Regulatory T-Lymphocyte; Research; Role; STK11 gene; Serine; T-Lymphocyte; Testing; Th1 Cells; Thinness; Time; Tissues; Transferase; Translating; Treg therapy; Visceral; attenuation; base; exhaust; exhaustion; falls; feeding; high body mass index; immunoregulation; improved; in vivo; insulin sensitivity; insulin sensitizing drugs; mouse model; nonalcoholic steatohepatitis; novel; novel therapeutics; obesity treatment; peripheral blood; predictive modeling; preservation; prevent; programmed cell death protein 1; receptor; receptor expression; single-cell RNA sequencing; subcutaneous; transcriptome sequencing; translational study

Project Abstract. Adipose tissue (AT) regulatory T cells (Tregs) are major determinants of systemic metabolism, and in lean mice, protect against obesity-associated inflammation and complications. Tregs are key in homeostatic maintenance in lean AT, but abundance profoundly decreases in obese AT leading to inflammation, insulin resistance, and other inflammatory-driven complications. Our preliminary data suggests exhaustion contributes to the loss of AT Tregs in obesity. AT vs. blood Tregs from obese humans reveal increased expression of programmed cell death protein 1 (PD-1) and other inhibitory co-receptors (OX40, CTLA4); impaired suppressive function, which is reversible; decreased liver kinase B1 (LKB1), which protects Tregs from exhaustion; and increased methylation of the CNS2 in the FOXP3 locus suggesting instability. These characteristics form our working definition of exhaustion. Moreover, RNAseq analyses of human AT PD-1 high vs. negative cells revealed downregulation of 75% of significantly changed genes, including genes involved in suppressor function, while upregulated genes included apoptosis and cell death genes. Furthermore, in cultured human Tregs, interferon gamma (IFNG) stimulated expression of inhibitory co-receptors and apoptosis markers and decreased LKB1 expression, suggesting it may mediate AT Treg exhaustion. These findings underscore the need to investigate mechanisms regulating AT Treg abundance/function. Our Specific Aims include: Aim 1. Hypothesis: Human obese AT Tregs are phenotypically exhausted, which contributes to the decline in human AT Tregs during high fat diet (HFD) ingestion. We will: A) Determine whether there are more exhausted Tregs in obese vs. lean AT; B) Utilize single cell (sc)RNAseq and Global DNA methylation to define subpopulations of human lean and obese AT Tregs that may be exhausted; and C) Determine whether pioglitazone will attenuate the HFD-induced AT Treg decline in lean humans by preventing exhaustion and impacting AT Treg transcriptional changes. Aim 2. Hypothesis: Interferon-gamma (IFNG), toxic lipids, and/or decreased Treg PPARγ activity are mediators that contribute to exhaustion and declining Tregs in obesity. To determine whether attenuation/knockout of specific pathways in Tregs (supported by evidence of in vivo metabolic changes) leads to changes in AT Treg exhaustion, AT Treg abundance, and HFD-induced systemic insulin resistance, we will use several mouse models predicted to promote Treg exhaustion: A) Treg-specific knockout of the IFNG receptor (IFNGR1); B) Treg-specific loss of serine palmitoyl transferase 2 (encoded by Sptlc2), a rate limiting enzyme required for ceramide biosynthesis; and C) Treg specific ablation of a key supportive factor for AT Tregs, PPARγ. Taken together, these investigations will shed light on a new, potentially important mechanism explaining the striking loss of AT Tregs that occurs with HFD and obesity.

项目摘要。脂肪组织（AT）调节性T细胞（TCFs）是全身代谢的主要决定因素， 在瘦老鼠中，可以防止肥胖相关的炎症和并发症。关键在于 在瘦AT中维持稳态，但在肥胖AT中大量显著降低，导致炎症， 胰岛素抵抗和其他炎症引起的并发症。我们的初步数据显示 导致肥胖症患者AT T细胞减少。AT与来自肥胖人类的血液TdR显示增加 程序性细胞死亡蛋白1（PD-1）和其他抑制性共受体（OX 40、CTLA 4）表达受损 抑制功能，这是可逆的;减少肝激酶B1（LKB 1），这保护Tclase从 F0 XP 3基因座中CNS 2的甲基化增加，表明不稳定性。这些 这些特征构成了我们对衰竭的定义。此外，人AT PD-1高表达的RNAseq分析表明， vs.阴性细胞显示75%的显著改变的基因下调，包括参与 抑制功能，而上调的基因包括凋亡和细胞死亡基因。此外，在培养 人凝血酶、干扰素γ（IFNG）刺激抑制性共受体和凋亡标志物表达 降低LKB 1的表达，提示其可能介导AT Treg耗竭。这些发现强调了 需要研究调节AT Treg丰度/功能的机制。我们的具体目标包括： 目标1。假设：人类肥胖的AT T细胞表型耗尽，这有助于 在高脂肪饮食（HFD）摄取期间人AT TdR的下降。我们将：A）确定是否有 与瘦型AT相比，肥胖型AT中的T细胞更耗竭; B）利用单细胞（sc）RNAseq和全局DNA甲基化， 定义可能耗尽的人类瘦型和肥胖型AT T细胞亚群;和C）确定是否 吡格列酮将通过防止疲劳来减弱HFD诱导的瘦型人AT Treg下降， 影响AT Treg转录变化。 目标二。假设：干扰素-γ（IFNG）、毒性脂质和/或Treg PPARγ活性降低是 导致肥胖者疲劳和TdR下降的介质。以确定是否 TdR中特定途径的衰减/敲除（由体内代谢变化的证据支持） 针对AT Treg耗竭、AT Treg丰度和HFD诱导的全身性胰岛素抵抗的变化，我们将 使用几种预测促进Treg耗尽的小鼠模型：A）IFNG受体的Treg特异性敲除 （IFNGR 1）; B）丝氨酸棕榈酰转移酶2（由Sptlc 2编码）的Treg特异性损失，其是一种限速酶 神经酰胺生物合成所必需的;和C）Treg特异性消融AT T β，PPARγ的关键支持因子。 总之，这些研究将揭示一个新的，潜在的重要机制，解释 HFD和肥胖症患者AT T显著降低。