Metabolic cross-talk between Bartonella henselae and host cells

缓慢生长的人致病性亨塞巴尔通体引起猫抓病和血管增生性疾病（细菌性血管瘤病）。兼性细胞内病原体在内皮宿主细胞内迅速复制，表明这些细胞代表了为细菌提供氧气和营养的生态位。另一方面，蜜蜂B. henselae感染导致缺氧诱导因子(HIF)-1的激活，HIF -1是参与宿主细胞代谢（糖酵解、血管生成供氧和红细胞生成）的关键转录因子。初步实验显示，亨selae不复制内皮细胞与HIF-1敲除。此外，我们还鉴定了几个对细胞内存活至关重要的B. henselae基因。利用细胞培养模型，我们现在想分析兼性细胞内病原体B. henselae的细胞内生长和持久性如何依赖于HIF-1活性。为此，我们生成了几种HIF-1敲低的内皮细胞系（使用发夹siRNA），并建立了分析细胞内氧水平和HIF-1激活途径的方法。此外，一种新型巴尔通体液体生长培养基使我们能够研究哪些生物化合物（如蔗糖、氨基酸）是亨selae在宿主细胞中生长和持续所必需的。我们的研究结果应该(i)有助于在分子和细胞水平上理解细胞内细菌（如B. henselae）与其宿主细胞之间的代谢串扰，（ii）可能会为治疗细胞内细菌感染提供新的治疗策略。

Slow growing humapathogenic Bartonella henselae cause cat scratch disease and vasculoproliferative disorders (bacillary angiomatosis). The facultative intracellular pathogen replicates rapidly within endothelial host cells suggesting that these cells represent an ecological niche supplying the bacterium with oxygen and nutrients. On the other hand, infections with B. henselae result in the activation of hypoxia-inducible factor (HIF)-1, the key transcription factor involved in host cell metabolism (glycolysis, oxygen supply via angiogenesis, and erythropoiesis). Preliminary experiments revealed that B. henselae do not replicate in endothelial cells with a HIF-1 knock-down. Additionally, we identified several B. henselae genes crucial for intracellular survival. Using cell culture models, we now want to analyze how the intracellular growth and persistence of the facultative intracellular pathogen B. henselae depends on HIF-1 activity. For this purpose, we have generated several HIF-1 knock down endothelial cell lines (using hairpin siRNA) and established methods for analyzing intracellular oxygen levels and HIF-1 activation pathways. Moreover, a novel Bartonella-liquid growth medium allows us to investigate which biological compounds (e.g. sucrose, amino acids) are required for the growth and persistence of B. henselae in host cells. The results of our investigations should (i) help to understand the metabolic cross-talk between intracellular bacteria (e.g. B. henselae) and their host cells on a molecular and cellular level and (ii) should possibly result in new therapeutic strategies for the treatment of infections with intracellular bacteria.