Role of metabolic Me-macrophages in the pathogenesis of tuberculosis during diabetes

摘要 2型糖尿病（T2 D）大流行是公认的结核病重新出现的风险和挑战 (TB)控制然而，识别和预防数百万有患结核病风险的T2 D患者的战略 需要了解潜在的机制，而这些机制目前还知之甚少。分枝杆菌 结核病（Mtb）是一种细胞内病原体，可以在巨噬细胞（MΦ）内复制或被杀死。的 Mtb在MΦ内存活的能力在很大程度上取决于其逃避含Mtb的融合的能力。 吞噬体与溶酶体或自吞噬体（自噬途径）。然而，体外研究表明， 在适当的MΦ活化（例如用IFN-γ）下，细胞内Mtb被靶向至吞噬溶酶体或自身免疫系统。 吞噬溶酶体用于更有效地杀伤、消化和向T细胞呈递抗原。人MΦ的研究 表型和功能通常通过M1和M2范式来概念化，其中M1表征 通过增加促炎细胞因子的产生，而M2具有更多的免疫抑制表型。 我们和其他人已经使用M1/M2范式来研究TB发病机制，其中M1 MΦ发挥更好的Mtb 当与更宽容的M2相比时（M1> M2）。虽然M1-M2 MΦ框架是有用的， 为了在体外研究结核病发病机制，它没有捕捉到影响MΦ的不同环境线索 T2 D宿主的可塑性。我们通过建议开发一种研究结核病的体外模型来解决这一差距 使用最近描述的极化为“代谢”的MΦ表型的T2 D患者的发病机制 当在高棕榈酸、葡萄糖和胰岛素的条件下培养时，表型。我们建议研究使用 这种代谢MΦs（Me），以确定T2 D患者中改变的代谢环境如何影响 MΦ对Mtb的表型和功能反应（相对于M1或M2）。我们的团队是进行这些研究的理想选择： BIR（MPI）居住在德克萨斯州-墨西哥边境，她在那里表现出高TB-T2 D率，并记录了 来自T2 D患者的单核细胞和MΦ的缺陷。CJ（MPI）在MΦ对TB的反应方面有30多年的经验。 我们的顾问开发了Me MΦ模型（LB），或具有结核病肺生物学（JT）方面的专业知识。我们的目标是： 目标1。评价在受控培养下分化的人Me MΦ对Mtb的应答 模拟肺中的T2 D的条件。 目标二。鉴定来源于健康与T2 D +/- TB患者单核细胞的Me MΦ的差异。 我们的体外TB-T2 D MΦ模型将与T2 D或TB-T2 D患者或动物模型中的体内发现反向进料， 便于假设生成和检验。我们从结核病或T2 D患者中获得单核细胞将有助于 在体外识别“代谢”或“炎症”记忆，这些记忆在长期暴露于改变的环境后保留下来。 体内代谢物。因此，我们的模型将有直接的影响，为有效的主机设计铺平道路， 针对治疗人糖尿病MΦ以获得最佳Mtb杀伤。

ABSTRACT The type 2 diabetes mellitus (T2D) pandemic is a recognized re-emerging risk and challenge to tuberculosis (TB) control. However, strategies to identify and prevent the millions of T2D patients at risk of developing TB requires an understanding of the underlying mechanisms, which are poorly understood. Mycobacterium tuberculosis (Mtb) is an intracellular pathogen that can replicate or get killed within macrophages (MΦs). The ability of Mtb to survive within MΦs depends largely on its ability to evade fusion of the Mtb-containing phagosomes with lysosomes or auto-phagosomes (autophagy pathway). However, in-vitro studies show that with appropriate MΦ activation (e.g. with IFN-γ), intracellular Mtb is targeted to the phagolysosome or auto- phagolysosome for more effective killing, digestion and antigen presentation to T cells. Studies of human MΦ phenotype and function are often conceptualized through an M1 and M2 paradigm, with the M1 characterized by increased production of pro-inflammatory cytokines, while M2 having more immunosuppressive phenotype. We and others have used the M1/M2 paradigm to study TB pathogenesis, with M1 MΦs exerting better Mtb killing when compared to the more permissive M2 (M1> M2). While the M1-M2 MΦ framework has been useful to study TB pathogenesis in-vitro, it does not capture the different environmental cues that influence MΦ plasticity in the T2D host. We address this gap by proposing the development of an in-vitro model to study TB pathogenesis in T2D patients using a recently described MΦ phenotype that is polarized to a “metabolic” phenotype when cultured under conditions of high palmitate, glucose and insulin. We propose studies using this Metabolic MΦs (Me) to determine how the altered metabolic environment in T2D patients affects the phenotype and functional responses of MΦs to Mtb (vs M1 or M2). Our team is ideal conduct these studies: BIR (MPI) lives in the Texas-Mexico border where she has demonstrated high TB-T2D rates, and documented defects in monocytes and MΦs from T2D patients. CJ (MPI) has 30+ yrs experience in MΦ responses to TB. Our consultants developed the Me MΦ model (LB), or have expertise in TB lung biology (JT). Our Aims are: Aim 1. Evaluate the response to Mtb by human Me MΦs differentiated under controlled culture conditions that simulate T2D in the lungs. Aim 2. Identify differences in the Me MΦs derived from monocytes of healthy vs T2D +/- TB patients. Our in-vitro TB-T2D MΦ model will retro-feed with in-vivo findings in T2D or TB-T2D patients or animal models, facilitating hypothesis generation and testing. Our access to monocytes from patients with TB or T2D will help identify the “metabolic” or “inflammatory” memories in vitro, that are retained after chronic exposure to altered metabolites in-vivo. Thus, our model will have an immediate impact for paving the design of effective host- directed therapies to polarize human diabetic MΦs for optimal Mtb killing.