Role of mycobacterial dynamin-like proteins in the biogenesis of membrane vesicles, and host-pathogen interactions

尽管减毒疫苗和几种抗生素的广泛使用，结核病（TB）仍然是一个严重的疾病。 一个全球性的公共卫生问题。2019年有超过120万人死于结核病。这一可怕的情况是复杂的， 由于结核分枝杆菌（Mtb）抗生素耐药菌株的流行增加， 人类结核病的病原体。结核分枝杆菌成功的核心是它逃避、调节甚至操纵的能力 宿主免疫防御反应。因此，参与破坏免疫系统的细菌因素 是结核病干预的潜在良好目标。 像许多其他细菌一样，Mtb在体外和体内积极产生细胞外囊泡（EV）。这些是 膜封闭的球形结构，使细菌集中和分泌各种 分子，并与环境中的其他细胞进行交流。结核分枝杆菌感染释放EV 巨噬细胞能够将致病因子和免疫调节分子递送到宿主细胞中， 和细胞外环境。来自体外研究的强有力证据表明，EV可能允许Mtb远程感染 影响旁观者免疫细胞。然而，对所涉及的分子机制的有限理解 在囊泡生物发生中，以及缺乏囊泡产生缺陷突变体阻碍了 阐明了囊泡分泌与Mtb毒力的相关性。我们的初步工作确定了 Mtb的DLP蛋白作为有效EV释放的必需因子，并表征了一种DLP突变体， 囊泡生物发生我们现在可以很好地解剖DLP在囊泡形成中的功能，并评估 在感染过程中EV生产的作用，使用结核病小鼠模型;这些是本提案的主要目标。 我们预计，这些发现将通过突出靶向囊泡释放或破坏肺结核的方法来推动结核病领域的发展。 囊泡在宿主抗结核病中的作用。

Despite the widespread use of an attenuated vaccine and several antibiotics, tuberculosis (TB) continues to be a global public health problem. Over 1.2 million people died from TB in 2019. This dire situation is compounded by increasing prevalence of antibiotic resistant strains of Mycobacterium tuberculosis (Mtb), the main etiological agent of human TB. Central to Mtb success is its ability to evade, modulate, and even manipulate host immune defense response. Consequently, bacterial factors involved in undermining the immune system are potentially good targets for TB intervention. Like many other bacteria, Mtb actively produces extracellular vesicles (EVs) in vitro and in vivo. These are membrane enclosed spherical structures that allow the bacteria to concentrate and secrete a variety of molecules, and communicate with other cells in their environment. The release of EVs by Mtb infecting macrophages enables the delivery of pathogenicity factors and immunomodulatory molecules into the host cell, and the extracellular milieu. Strong evidence from in vitro studies indicates that EVs may allow Mtb to remotely influence bystander immune cells. However, the limited understanding of the molecular mechanisms involved in vesicle biogenesis, and the lack of mutants deficient in vesicle production have impeded progress in elucidating the relevance of vesicle secretion to Mtb virulence. Our preliminary work identified the dynamin-like proteins (DLP) of Mtb as essential factors for efficient EVs release and characterized a DLP mutant deficient in vesicle biogenesis. We are now well positioned to dissect DLP's function in vesicle formation and assess the role of EV production during infection, using a mouse model of TB; those are the main goals of this proposal. We anticipate the findings will advance the TB field by highlighting ways to target vesicle release, or disrupt the effects of vesicles in host-resistance to TB.