Interception of host angiogenic signalling limits mycobacterial growth.
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2015-01-29
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Abstract
Pathogenic mycobacteria induce the formation of complex cellular aggregates called granulomas that are the hallmark of tuberculosis. Here we examine the development and consequences of vascularization of the tuberculous granuloma in the zebrafish-Mycobacterium marinum infection model, which is characterized by organized granulomas with necrotic cores that bear striking resemblance to those of human tuberculosis. Using intravital microscopy in the transparent larval zebrafish, we show that granuloma formation is intimately associated with angiogenesis. The initiation of angiogenesis in turn coincides with the generation of local hypoxia and transcriptional induction of the canonical pro-angiogenic molecule Vegfaa. Pharmacological inhibition of the Vegf pathway suppresses granuloma-associated angiogenesis, reduces infection burden and limits dissemination. Moreover, anti-angiogenic therapies synergize with the first-line anti-tubercular antibiotic rifampicin, as well as with the antibiotic metronidazole, which targets hypoxic bacterial populations. Our data indicate that mycobacteria induce granuloma-associated angiogenesis, which promotes mycobacterial growth and increases spread of infection to new tissue sites. We propose the use of anti-angiogenic agents, now being used in cancer regimens, as a host-targeting tuberculosis therapy, particularly in extensively drug-resistant disease for which current antibiotic regimens are largely ineffective.
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Oehlers, Stefan H, Mark R Cronan, Ninecia R Scott, Monica I Thomas, Kazuhide S Okuda, Eric M Walton, Rebecca W Beerman, Philip S Crosier, et al. (2015). Interception of host angiogenic signalling limits mycobacterial growth. Nature, 517(7536). pp. 612–615. 10.1038/nature13967 Retrieved from https://hdl.handle.net/10161/11178.
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Scholars@Duke
Rebecca Beerman
David M. Tobin
Tuberculosis: Mycobacterial Pathogenesis and Host Susceptibility
Tuberculosis kills 1.5 million people annually. Our laboratory aims to understand the intricate interplay between mycobacteria and their hosts using a combination of model organism genetics, human genetics, pharmacology and high-resolution microscopy. By identifying key pathways utilized by the infecting bacteria and the host innate immune system, we hope to discover new therapeutic targets and interventions to combat this enduringly destructive disease.
Using a Mycobacterium/zebrafish model, we have identified new host susceptibility loci for tuberculosis. Zebrafish are natural hosts to Mycobacterium marinum, the closest relative of the Mycobacterium tuberculosis complex. Because zebrafish embryos and larvae are optically transparent, we are able to visualize the complex details of mycobacterial pathogenesis in whole, live animals. The facile genetics of the zebrafish allow us to map and positionally clone affected host susceptibility genes. In addition, zebrafish larvae are remarkably permeable to small molecules, providing a platform for whole-animal pharmacological manipulation of specific host immune responses.
We have identified novel pathways that modulate susceptibility to tuberculosis. We have shown that genes identified in the zebrafish model are also important in human tuberculosis. We find robust associations of human variants in a specific eicosanoid pathway with susceptibility to both tuberculosis and leprosy.
We have active collaborations in both Vietnam and Guatemala. In Guatemala, we are working with the Clínica Familiar Luis Angel García and the Asociación de Salud Integral to support projects involving HIV-infected patients and to understand the dynamics of TB transmission in Central America.
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