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 (Treg) 是全身代谢的主要决定因素。 在瘦小鼠中，预防与肥胖相关的炎症和并发症是关键。 瘦 AT 中的稳态维持，但肥胖 AT 中的丰度显着降低，导致炎症， 我们的初步数据表明胰岛素抵抗和其他炎症引起的并发症。 与肥胖人群的血液 Tregs 相比，肥胖导致 AT Tregs 的减少。 程序性细胞死亡蛋白 1 (PD-1) 和其他抑制性辅助受体（OX40、CTLA4）的表达受损； 抑制功能，这是可逆的；肝激酶 B1 (LKB1) 减少，可保护 Tregs 免受 耗尽；FOXP3 基因座 CNS2 甲基化增加表明不稳定。 特征构成了我们对耗竭的工作定义，此外，人类 AT PD-1 高的 RNAseq 分析。 与阴性细胞相比，75% 的显着变化基因下调，包括参与 此外，在培养物中，抑制功能，而上调的基因包括凋亡和细胞死亡基因。 人 Tregs、干扰素 γ (IFNG) 刺激抑制性共受体和凋亡标记物的表达 和 LKB1 表达，表明它可能介导 AT Treg 耗竭。这些发现强调了这一点。 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 AT Tregs 在表型上已耗尽，这导致 摄入高脂肪饮食 (HFD) 期间人类 AT Tregs 的下降 我们将： A) 确定是否存在。 与瘦 AT 相比，肥胖 AT 中的 Tregs 更加疲惫；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和肥胖 AT Tregs 亚群；以及 C) 确定是否； 吡格列酮将通过防止疲劳和减少 HFD 引起的瘦人 AT Treg 下降 影响 AT Treg 转录变化。 目标 2. 假设：干扰素 γ (IFNG)、有毒脂质和/或 Treg PPARγ 活性降低是 确定是否会导致肥胖中的疲劳和 Tregs 下降。 Tregs 中特定途径的减弱/敲除（有体内代谢变化证据支持）导致 针对 AT Treg 耗竭、AT Treg 丰度和 HFD 诱导的全身胰岛素抵抗的变化，我们将 使用几种预测会促进 Treg 耗竭的小鼠模型：A) Treg 特异性敲除 IFNG 受体 (IFNGR1)；B) Treg 特异性丢失丝氨酸棕榈酰转移酶 2（由 Sptlc2 编码），一种限速酶 神经酰胺生物合成所需的；C) AT Tregs 关键支持因子 PPARγ 的 Treg 特异性消融。 总而言之，这些研究将揭示一个新的、潜在的重要机制，解释 HFD 和肥胖症会导致 AT Tregs 显着丧失。