Mucosal Associated Invariant T cells in the Obese-asthma endotype

摘要 哮喘是一种炎症性肺部疾病，影响全球超过3亿人。虽然轻度哮喘是 由Th 2相关的嗜酸性粒细胞主导的免疫应答驱动，肥胖/代谢紊乱等因素 功能障碍与更严重的哮喘有关。因此，“肥胖性哮喘”的内型与 哮喘频繁加重，从Th 2为主的炎症向Th 17为主的炎症转变， 一个明显的女性偏见。我们对肥胖性哮喘发病机制的理解存在一个主要的差距， 由于普通小鼠肥胖模型的缺陷;标准高脂饮食（HFD）喂养的小鼠模型是 不能在女性中诱导广泛的体重增加和代谢功能障碍（与人类肥胖相关） 小鼠-考虑到在肥胖哮喘内型中观察到的雌性偏好，这是一个主要缺点。重要的是我们的 研究小组已经确定，在代谢温度下饲养的C57 BL/6小鼠的HFD喂养 稳态（热中性温度（TN）; 30-33°C）促进严重肥胖和代谢功能障碍， 雌性老鼠使用该模型的初步数据表明，过敏原激发的肥胖哮喘小鼠 证明：（1）与瘦型哮喘对照组相比，哮喘结局更差，（2）Th 2偏离 炎症与促炎性特征（Th 17或Th 2/Th 17）的关系，和（3）明显的女性偏好。类似 在雄性小鼠中未观察到变化。这些数据表明，TN圈养肥胖的雌性哮喘小鼠， 模拟人类肥胖哮喘内型。重要的是，肥胖哮喘雌性小鼠表现出深刻的 肺中IL-17 A产生细胞的频率增加，特别是粘膜相关的不变T细胞， （MAIT）细胞。MAIT细胞是在肺、肝和脂肪组织中大量存在的先天性T细胞。虽然被认为 在瘦型哮喘模型中具有保护作用，在肥胖症中，肝脏和脂肪组织MAIT转变为促炎状态 并导致代谢功能障碍。在本申请中，我们假设，在肥胖症中，肝脏和脂肪 组织MAIT细胞成为促炎细胞，并被许可迁移到肺部，在那里它们驱动 雌性肥胖哮喘小鼠的严重哮喘结果。这一假设将在两个具体的 目标。目的1：明确肥胖患者组织驻留MAIT细胞的功能和表型差异， 哮喘女性我们将检查MAIT细胞在肺中的积聚和细胞因子表达的模式， 代谢组织（肝脏，白色脂肪组织）随时间的变化，定量MAIT细胞对TCR的差异应答性。 依赖和独立的信号，并进行肺MAIT细胞的非偏倚转录谱分析， 瘦和肥胖哮喘雌性小鼠。目的2：确定MAIT细胞在哮喘预后中的作用， 肥胖的雌性小鼠我们将用MAIT细胞抑制配体或过继疗法治疗瘦型和肥胖型哮喘小鼠， 从瘦型或肥胖型哮喘小鼠转移肺MAIT细胞，并评估其对哮喘的必要性和充分性。 哮喘表型完成拟议的研究将有助于更好地了解这些机制 这是与“肥胖性哮喘”和MAIT细胞生物学相关的独特临床参数的基础。

ABSTRACT Asthma is an inflammatory lung disease that affects >300 million people worldwide. Although mild asthma is driven by a Th2-associated, eosinophil-dominated immune response, factors such as obesity/metabolic dysfunction are associated with more severe asthma. Thus, the “obese asthma” endotype is associated with frequent asthma exacerbations, a shift away from Th2-dominated inflammation towards a Th17-dominated profile, and a marked female bias. A major gap in our understanding of mechanisms driving obese asthma is due to deficiencies in common mouse models of obesity; standard high-fat diet (HFD)-fed mouse models are unable to induce extensive weight gain and metabolic dysfunction (associated with obesity in humans) in female mice - a major shortcoming given the female bias observed in the obese asthma endotype. Importantly, our group has determined that HFD feeding of C57BL/6 mice housed at a temperature in which they are at metabolic homeostasis (thermoneutral temperature (TN); 30-33°C) promotes severe obesity and metabolic dysfunction in female mice. Preliminary data using this model demonstrate that allergen-challenged obese asthmatic mice demonstrate: (1) worse asthmatic outcomes compared to lean asthma controls, (2) a shift away from Th2 inflammation to a pro-inflammatory profile (Th17 or Th2/Th17), and (3) a pronounced female bias. Similar changes are NOT observed in male mice. These data suggest that TN housed obese female asthmatic mice model the human obese asthma endotype. Importantly, obese asthmatic female mice demonstrated a profound increase in the frequency of IL-17A-producing cells in the lungs, particularly mucosal-associated invariant T (MAIT) cells. MAIT cells are innate-like T cells abundant in lungs, liver, and adipose tissue. Although considered protective in models of lean asthma, in obesity, liver and adipose tissue MAIT switch to a pro-inflammatory state and contribute to metabolic dysfunction. In this application we hypothesize that, in obesity, liver and adipose tissue MAIT cells become pro-inflammatory and are licensed to migrate to the lung, where they drive severe asthma outcomes in female obese-asthmatic mice. This hypothesis will be tested in two Specific Aims. Aim 1: To define the functional and phenotypic differences of tissue resident MAIT cells in obese asthmatic females. We will examine patterns of MAIT cell accumulation and cytokine expression in lung and metabolic tissue (liver, white adipose tissue) over time, quantify differential MAIT cell responsiveness to TCR- dependent and independent signals, and perform non-biased transcriptional profiling of lung MAIT cells from lean and obese asthmatic female mice. Aim 2: To determine the role of MAIT cells in asthma outcomes in obese female mice. We will treat lean and obese asthmatic mice with a MAIT cell inhibitory ligand or adoptively transfer lung MAIT cells from lean or obese asthmatic mice and assess their necessity and sufficiency on the asthma phenotype. Completion of the proposed studies will facilitate a better understanding of the mechanisms underlying the unique clinical parameters associated with “obese asthma” and MAIT cell biology.