Defining the impact of membrane vesicle deficiency on M. tuberculosis-macrophage interactions

总结 结核分枝杆菌（Mtb）是人类结核病（TB）的病原体， 细胞外囊泡在体外和体内。就像革兰氏阳性菌释放的细胞外囊泡 分枝杆菌细胞外囊泡起源于质膜，因此被称为 膜囊泡（MV）。分枝杆菌MV含有广泛的免疫活性蛋白 和糖脂。当添加到培养物中的细胞中时，分离的MV可以调节细胞的免疫应答。 未感染的巨噬细胞、T细胞和树突细胞。然而，MV对相互作用的影响 Mtb和感染的巨噬细胞之间的关系以及感染期间MVs产生的总体相关性 目前还不清楚，主要是因为MV缺陷型Mtb突变体尚未被描述。已经 认识到MV在M.结核病是一个积极和调节的过程，但分子 所涉及的机制和因素在很大程度上仍不清楚。 我们以前的工作表明，铁限制，在主机遇到的条件，诱导 在Mtb生产MV。基于这一发现的初步研究确定了一对铁敏感的， 分枝杆菌动力蛋白样蛋白（DLP）编码基因，异烟肼诱导基因A和C（iniAC）， 这是MV制作所必需的。我们的初步数据表明，DLP无效突变体正常生长， 低铁条件和巨噬细胞中。然而，它在MV生物发生中表现出实质性的缺陷。我们 假设这种突变将有助于确定MV在免疫调节和致病性中的作用， 与主机的互动。拟议的研究将测试我们的中心假设，即MV生产 在巨噬细胞感染期间，需要DLPs介导的免疫应答和比较， 与感染WT Mtb或MV缺陷型iniAC突变体的巨噬细胞相关的基因将揭示 实质性差异。 该项目的结果将增加对结核分枝杆菌MV生物发生及其在结核病治疗中的相关性的理解。 巨噬细胞感染，并为评价MV相关性的体内研究提供基础 在Mtb-host接口处。

Summary Mycobacterium tuberculosis (Mtb), the etiological agent of tuberculosis (TB) in humans, releases extracellular vesicles in vitro and in vivo. Like extracellular vesicles released by Gram-positive bacteria mycobacterial extracellular vesicles originate at the plasma membrane and are therefore, refer to as membrane vesicles (MV). Mycobacterial MVs contain a broad range of immunologically active proteins and glycolipids. When added to cells in culture, isolated MVs can regulate the immune response of uninfected macrophages, T-cells and dendritic cells. However, the influence of MVs on the interaction(s) between Mtb and the infected macrophage and the overall relevance of MVs production during infection is unclear, mainly because MV-deficient Mtb mutants have not yet been described. It has been recognized that MV biogenesis in M. tuberculosis is an active and regulated process, but the molecular mechanisms and factors involved remain largely unknown. Our previous work demonstrated that iron limitation, a condition encountered in the host, induces the production of MVs in Mtb. Preliminary studies based on this finding identified a pair of iron-responsive, mycobacterial dynamin-like protein (DLP)-encoding genes, isoniazid‐inducible gene A and C (iniAC) that are necessary for MV production. Our preliminary data indicate that a DLP null mutant grows normally in low-iron conditions and in macrophages. However, it exhibits a substantial defect in MV biogenesis. We postulate that this mutant will help define the role of MVs in immunomodulation and pathogenic interactions with the host. The proposed research will test our central hypothesis that MV production during macrophage infection requires the DLPs IniAC and that comparison of the immune response associated with macrophages infected with WT Mtb or the MV-deficient iniAC mutant will reveal substantial differences. The outcome of this project will increase understanding of MV biogenesis in Mtb and its relevance during macrophage infection, and provide the foundation for in vivo studies that evaluate the relevance of MVs at the Mtb-host interface.