Regulation of Apoptotic Envelope Formation by MTB in the Host Macrophage

结核分枝杆菌（Mtb）生长在人类巨噬细胞中，巨噬细胞是主要的宿主细胞，它占据了一个小生境，使其能够复制而不被宿主识别。减毒的Mtb诱导宿主巨噬细胞的凋亡，导致细菌的遏制和它们被吞噬细胞消除。毒性Mtb和毒力因子的基本性质是诱导坏死，其特征在于质膜溶解和杆菌释放到细胞间隙中，导致感染扩散。相反，减毒的Mtb主要诱导宿主巨噬细胞的凋亡。细胞凋亡的标志是存在由交联蛋白组成的15 nm厚的细胞表面包膜支架，所述交联蛋白包括（膜联蛋白-1和蛋白酶抑制剂丝氨酸蛋白酶抑制剂纤溶酶原激活剂2型（派-2），如首次从美国专利申请公开号2009/00100111中描述的。 角质形成细胞被膜。膜联蛋白-1是一种具有磷脂酰丝氨酸（PS）结合结构域和交联所需的聚谷氨酰胺区的37 kDa蛋白质，其在细胞凋亡期间被转运至巨噬细胞表面并结合至凋亡Mcp表面上的PS晶格。我们发现，annexin-1不仅是减毒结核分枝杆菌感染的巨噬细胞的凋亡包膜的共同组成部分，但也是一个lorganizing原则所需的跨膜蛋白酶交联的包膜。在蛋白酶抑制剂如派-2的存在下，膜联蛋白-1的蛋白水解降解导致缺乏多聚谷氨酰胺区的无活性产物被阻断，并且能够形成凋亡包膜。在本申请中，我们提出研究毒性Mtb通过调节膜联蛋白-1的蛋白水解降解及其向细胞表面的转运来干扰宿主巨噬细胞上凋亡包膜的形成的能力。我们将进一步研究膜修复机制在Mtb感染巨噬细胞形成凋亡包膜中的作用。这些研究将提高我们对结核病中关键宿主-病原体相互作用的认识，从而促进新的治疗和预防方法的发展。

Mycobacterium tuberculosis (Mtb) grows in human macrophages, the principal host cell, where it occupies a niche allowing it to replicate without being recognized by the host. Attenuated Mtb induce apoptosis of the host macrophages resulting in containment of the bacilli and their elimination by phagocytes. An essential property of virulent Mtb and a virulence factor is the induction of necrosis characterized by plasma membrane lysis and release of the bacilli into the intercellular space that leads to spread of the infection. In contrast, attenuated Mtb induce predominantly apoptosis in the host macrophage. A hallmark of apoptosis is the presence of a 15 nm thick cell surface envelope scaffold consisting of cross-linked proteins including (annexin-1 and the protease inhibitor serpin plasminogen activator type 2 (PAI-2) as first described from the lkornified envelope of keratinocytes. Annexin-1, a 37 kDa protein with a phosphatidyl serine (PS) binding domain and a poly-gln region required for cross-linking is transported to the macrophage surface during apoptosis and binds to the PS lattice on the surface of the apoptotic Mcp. We found that annexin-1 is not only a common constituent of the apoptotic envelope of the macrophage infected with attenuated Mtb, but also an lorganizing principle required for cross-linking of the envelope by transglutaminases. In the presence of [protease inhibitors such as PAI-2 proteolytic degradation of annexin-1 resulting in an inactive product lacking lthe poly-gln region is blocked and formation of the apoptotic envelope is enabled. In this application we lpropose to investigate the capacity of virulent Mtb to interfere with the formation of the apoptotic envelope on host macrophages by modulating proteolytic degradation of annexin-1 and its transport to the cell surface. We will further study the role of membrane repair mechanisms in Mtb infection of the macrophage in the formation of the apoptotic envelope. These studies will enhance our knowledge about critical host-pathogen interactions in tuberculosis that could foster development of novel approaches to treatment and prevention.