MOLECULAR AND CELL BIOLOGY OF PATHOGENIC MYCOBACTERIA

溃疡分枝杆菌和海分枝杆菌是引起人类持续性皮肤病变的致病性分枝杆菌。M. marinum和M.结核病是一种兼性细胞内病原体，其在人类中引起肉芽肿性皮肤病，并在免疫功能低下的患者中引起危及生命的全身感染。就像M tuberculosis，M. marinum在细胞内隔室中的巨噬细胞内复制，其显示成熟停滞。我们实验室的工作是为了了解M. marinum为了自己的目的征用巨噬细胞，并避免通过溶酶体途径降解。由于M. marinum和M.结核病，我们假设，在巨噬细胞内相关的机制将是相似的，如果不是相同的。利用与绿色荧光蛋白的融合，我们从M. marinum在巨噬细胞中差异表达，并显示在M.结核一旦确定了这些基因在发病机制中的作用，我们将在M。结核病同源物。这项工作的总体目标是了解细胞内分枝杆菌如何能够在吞噬细胞内生存和复制。溃疡引起严重的坏死性皮肤损伤（布鲁里溃疡），显著的是在存在广泛组织损伤的情况下没有急性炎症反应。我们已经从M.溃疡，并且用生化和遗传证据表明该分子在布鲁里溃疡的发病机制中起主要作用。毒素分子，菌内酯，是一种12元环大环内酯，在皮克数量的地方真核细胞在细胞周期停滞（G1），然后通过细胞凋亡死亡。我们目前正在研究霉菌内酯诱导细胞损伤和免疫抑制的确切机制。此外，我们正在探索是否毒素减去突变体，可能是一种有效的疫苗。虽然大环内酯类是亲脂性的，因此本身没有抗原性，我们正在探索使这种分子具有抗原性的可能性，并确定抗毒素是否可能作为布鲁里溃疡的治疗剂。最后，一些肿瘤细胞系的灵敏度和差异表明这种分子可能具有作为抗肿瘤剂的价值。我们正在探索这种可能性。- 大环内酯类，分枝杆菌聚酮，细胞内存活，避免溶酶体融合，L929细胞，J774巨噬细胞

Mycobacterium ulcerans and Mycobacterium marinum are pathogenic mycobacteria which cause persistent cutaneous lesions in humans. M. marinum, like M. tuberculosis is a facultative intracellular pathogen which causes a granulomatous skin disease in humans, and life threatening systemic infections in immunocompromised patients. Like M. tuberculosis, M. marinum replicates within macrophages in an intracellular compartment which shows arrested maturation. Work in our laboratory is directed towards understanding how M. marinum commandeers the macrophage for its own purposes and avoids degradation via the lysosomal pathway. Because of the close genetic relationship between M. marinum and M. tuberculosis, we hypothesize that the mechanisms involved in intramacrophage relication will be similar if not identical. Using fusions to Green Fluorescent Protein, we have isolated several genes from M. marinum expressed differentially in macrophages and have shown that close homologues are present in M. tuberculosis. Once the role of these genes in pathogenesis is established, we will make mutations in the M. tuberculosis homologues. The overall goal of this work is to understand how intracellular mycobacteria are able to survive and replicate within phagocytic cells.M. ulcerans causes a severe necrotic skin lesion (Buruli ulcer) remarkable for the absence of an acute inflammatory response in the presence of extensive tissue damage. We have isolated a toxin from M. ulcerans, amd shown with both biochemical and genetic evidence that this molecule plays a major role in the pathogenesis of Buruli ulcer. The toxin molecule, mycolactone, is a 12-membered ring macrolide which at picogram quantities places eucaryotic cells in cell cycle arrest (G1) followed by death via apoptosis. We are currently investigating the precise mechansm by which mycolactone induces cell damage and immunosuppression. In addition we are expoloring whether a toxin minus mutant, might be an effective vaccine. Although macrolides are lipophilic, and thus not antigenic by themselves, we are exploring the possibility of making this molecule antigenic and determining whether an anti-toxin might be valuable as a therapeutic agent for Buruli ulcer. Finally, the exquisite and differential sensitivity of some tumor cell lines suggests this molecule may have value as an anti-neoplastic agent. We are exploring this possibility. - macrolides, mycobacterial polyketides, intracellular survival, avoidance of lysosomal fusion, L929 cells, J774 macrophages