Direct interactions with HDL promote regulatory T cells survival

与 HDL 直接相互作用促进调节性 T 细胞存活

• 批准号: 9225304
• 负责人: CLAIRE A CHOUGNET
• 金额: $ 24.89万
• 依托单位: CINCINNATI CHILDRENS HOSP MED CTR
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-12-01 至 2018-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9225304
• 关键词: Address; Adult; Affect; Animal Model; Anti-Inflammatory Agents; Anti-inflammatory; Apolipoprotein A-I; Binding; Biological; Biology; Blood Vessels; CD4 Positive T Lymphocytes; Cell Survival; Complications of Diabetes Mellitus; Data; Death Rate; Dendritic Cells; Drug usage; Fatty Acids; Frequencies; Future; Generations; Glycolysis; Heterogeneity; High Density Lipoprotein Cholesterol; High Density Lipoproteins; Homeostasis; Human; Immunologics; Immunology; In Vitro; Individual; Inflammation; Inflammatory; Injury; Intraperitoneal Injections; Knowledge; Link; Lipid Biochemistry; Lipids; Lipoprotein Binding; Low-Density Lipoproteins; Mediating; Memory; Metabolic; Metabolic Diseases; Metabolic Pathway; Metabolism; Microscopy; Mitochondria; Molecular; Mus; Obesity; Pathway interactions; Process; Property; Proteins; Proteomics; Pulmonary Hypertension; Recombinants; Regulatory T-Lymphocyte; Role; SR-B proteins; SR-BI receptor; Signal Transduction; T-Lymphocyte; Testing; Triglycerides; Up-Regulation; adaptive immune response; cell type; cohort; fatty acid oxidation; improved; insight; macrophage; novel; particle; peroxisome; pleiotropism; prevent; reconstitution; time use; uptake

Abstract Regulatory T cells (Treg) control both innate and adaptive immune responses and are essential to curb exacerbated inflammatory processes. Notably, Treg limit vascular endothelial injury and prevent pulmonary hypertension in human cohorts and animal models. Treg also appear dysfunctional in several metabolic diseases, including obesity and its diabetic complications. Interestingly, Treg were recently shown to mediate their survival through distinct metabolic pathways than effector T cells, relying more on fatty acid oxidation than glycolysis for energy generation. Treg take up externally derived fatty acids to support these high rates of fatty acid oxidation, but the involved molecules and pathways involved are not known. Thus understanding the interaction between Treg and lipids would provide novel insight into Treg biology. High-density lipoproteins have anti-inflammatory properties, which could be at least partially mediated by an effect of HDL on Treg. For example, intra-peritoneal injection of HDL into LDLR-/- mice increased splenic Treg counts. In addition, we recently showed in normocholesterolemic adults treated with statins that Treg frequency positively correlated with HDL cholesterol (HDL-c) levels, but not with those of LDL-c or triglycerides. Although these data strongly suggest that HDL-c promote Treg accrual, underlying mechanisms remain unclear. In particular, it is not clear whether HDL exert their effects on Treg homeostasis directly or indirectly. Our preliminary studies suggest the hypothesis that HDL interact directly with Treg, which enhances their survival through increased metabolic activity. Indeed, we showed that in vitro incubation of purified human Treg with HDL, but not LDL, significantly improved Treg survival. In contrast, HDL did not affect the survival of memory and naïve CD4+ T cells. Supporting a direct effect of HDL on Treg, we found that Treg bind, and then internalize, HDL significantly more than their naïve and memory counterparts. Significantly increased expression of the Scavenger Receptor class B (SR-BI/II) on Treg compared to other CD4+ T cell subsets appeared critical for this preferential uptake, as a blocking anti-SR-BI/II Ab abolished the HDL pro-survival effect. Mechanistically, we found that HDL uptake increased Treg metabolism, notably Treg mitochondrial activity, and that blocking fatty acid oxidation also abolished the HDL pro-survival effect. However, key gaps in knowledge remain. Notably, the pathways involved in HDL internalization by Treg and the molecular mechanisms by which HDL promote increased metabolic activity remain poorly understood. It is also not established whether HDL interactions may modify Treg functionality. Finally, we do not know which HDL component(s) is/are operational for Treg survival, although our preliminary data identified apoA-I as a prime candidate. In this proposal, we will address these gaps in knowledge through 2 Aims. In Sp. Aim 1, we will (1) study the role of the SR-BI/II-mediated pathway in HDL internalization; (2) decipher the molecular mechanisms by which HDL promote Treg survival; and (3) determine whether HDL interactions modify Treg functionality. In Sp. Aim 2, we will identify the HDL component(s) that is/are operational for Treg survival. We will use 2 complementary approaches, first testing the role of apoA-I in enhanced Treg survival, using reconstituted apoA-I HDL particles or conversely, apoA-I devoid particles, and then using proteomics to identify the HDL components that mediate their effect on Treg.

摘要 调节性T细胞(Treg)控制先天和获得性免疫反应，对抑制 加剧了炎症过程。值得注意的是，Treg限制血管内皮损伤并防止肺 人类队列和动物模型中的高血压。Treg也出现了几种代谢功能障碍 疾病，包括肥胖及其糖尿病并发症。有趣的是，最近有证据表明，特雷格 它们的生存通过不同的代谢途径而不是效应T细胞，更多地依赖于脂肪酸氧化而不是 糖酵解产生能量。Treg摄取外部衍生的脂肪酸来支持这些高脂肪率 酸氧化，但涉及的分子和途径尚不清楚。从而理解了 Treg和脂质之间的相互作用将为Treg生物学提供新的见解。 高密度脂蛋白具有抗炎特性，这可能至少部分地由一种 高密度脂蛋白对Treg的影响例如，在LDLR-/-小鼠体内注射高密度脂蛋白可增加脾Treg。 算了。此外，我们最近在接受他汀类药物治疗的正常胆固醇血症成年人中显示，Treg频率 与高密度脂蛋白水平呈正相关，但与低密度脂蛋白或甘油三酯水平无相关性。虽然 这些数据有力地表明，高密度脂蛋白促进Treg的增加，其潜在的机制尚不清楚。在……里面 特别是，目前还不清楚高密度脂蛋白是否直接或间接地影响Treg的稳态。 我们的初步研究表明，高密度脂蛋白与Treg直接相互作用的假设，这增强了他们的 通过增加新陈代谢活动生存。事实上，我们证明了纯化的人Treg的体外孵育 使用高密度脂蛋白，而不是低密度脂蛋白，显著提高了Treg的存活率。相反，高密度脂蛋白并不影响小鼠的存活 记忆力和幼稚的CD4+T细胞。支持高密度脂蛋白对Treg的直接作用，我们发现Treg结合，然后 内化、高密度脂蛋白明显多于天真和记忆对应的人。显著增加 清道夫受体B类(SR-BI/II)在Treg上的表达与其他CD4+T细胞亚群的比较 似乎对这种优先摄取至关重要，因为阻断的抗SR-BI/II抗体消除了高密度脂蛋白的亲生存 效果。从机制上讲，我们发现高密度脂蛋白的摄取增加了Treg代谢，特别是Treg线粒体 而阻断脂肪酸氧化也消除了高密度脂蛋白促进生存的作用。 然而，知识方面的关键差距仍然存在。值得注意的是，Treg和Terg参与高密度脂蛋白内化的途径 高密度脂蛋白促进代谢活性增加的分子机制仍然知之甚少。它是 也没有确定高密度脂蛋白的相互作用是否会改变Treg的功能。最后，我们不知道是哪一个 高密度脂蛋白成分(S)对于Treg生存是可操作的，尽管我们的初步数据确定apoA-I是一种 头号候选人。 在这项提案中，我们将通过两个目标来解决这些知识差距。在Sp.目标1，我们将(1)研究 SR-BI/II介导的途径在高密度脂蛋白内化中的作用；(2)破译 高密度脂蛋白促进Treg存活；以及(3)确定高密度脂蛋白相互作用是否改变Treg功能。在Sp.目标 2，我们将确定对Treg生存起作用的高密度脂蛋白成分(S)。我们将使用2个互补 方法，首先使用重组的apoA-I高密度脂蛋白颗粒测试apoA-I在增强Treg存活中的作用 或者相反，apoA-I去除颗粒，然后使用蛋白质组学来鉴定介导 他们对特雷格的影响。