Genetic dissection of angiogenesis in the tuberculous granuloma

摘要 结核分枝杆菌每年导致大约150万人死亡。长期 已经观察到，分枝杆菌肉芽肿可以广泛血管化，但 这种血管形成的功能性后果尚未得到充分的研究。使用 斑马鱼分枝杆菌感染模型，其再现了人类分枝杆菌感染的重要方面， 我们发现肉芽肿诱导的血管生成与 随着局部缺氧的产生和典型前体的转录诱导， 血管生成分子Vegfa。用临床使用的抑制剂阻断该途径 减轻了负担，改善了结局。根据我们的初步数据， 建议VEGF途径和细菌脂质海藻糖二霉菌酸酯的作用，我们将 确定致病分枝杆菌的细胞和分子机制 促进分枝杆菌肉芽肿的促血管生成环境， 自己的成长、传播和生存。我们还将探讨一个平行的作用 经典的血管生成信号通路-血管生成素/Tie 2通路-我们 已经确定了一种新的宿主导向药物，我们已经证明它可以有效地减少 斑马鱼中的分枝杆菌负担。最后，我们将根据最近的数据显示， 在人类肉芽肿标本中诱导这些途径，并探索功能性 人类基因变异在分枝杆菌感染中的作用。总的来说，这一提议测试了 这一假说与肿瘤生物学惊人地相似，即血管生成的相互作用， 缺氧和受损的脉管系统有助于分枝杆菌的发病机制。 最终，这些途径的调节可能为宿主提供新的策略， 结核病的定向治疗。

Abstract Mycobacterium tuberculosis kills approximately 1.5 million people annually. It has long been observed that mycobacterial granulomas can be extensively vascularized, but the functional consequences of this vascularization have not been fully examined. Using a zebrafish mycobacterial infection model that recapitulates important aspects of human mycobacterial granulomas, we found that granuloma-induced angiogenesis coincides with the generation of local hypoxia and transcriptional induction of the canonical pro- angiogenic molecule Vegfa. Interception of this pathway with clinically used inhibitors resulted in reduced burden and improved outcome. Building on our preliminary data that suggest a role for the VEGF pathway and the bacterial lipid trehalose dimycolate, we will define the cellular and molecular mechanisms by which pathogenic mycobacteria promote the pro-angiogenic environment of mycobacterial granulomas to facilitate their own growth, dissemination and survival. We also will probe the role of a parallel canonical angiogenic signaling pathway – the angiopoietin/Tie2 pathway – for which we have identified a novel host-directed drug that we have shown to be effective in reducing mycobacterial burden in zebrafish. Finally, we will build on our recent data showing induction of these pathways in human granuloma specimens and probe the functional effects of human genetic variants in mycobacterial infection. Overall, this proposal tests the hypothesis that, in a striking parallel to tumor biology, the interplay of angiogenesis, hypoxia and compromised vasculature contributes to mycobacterial pathogenesis. Ultimately, the modulation of these pathways may provide new strategies for host- directed therapies for tuberculosis.