Phagosomal Rupture by Mycobacterium tuberculosis Results in Toxicity and Host Cell Death

PLoS Pathogens

Roland Brosch¹  Juliane Lippmann²  Alexandre Bobard²  Jost Enninga³  Roxane Simeone³  Laleh Majlessi⁴  Wilbert Bitter⁵ 

[1] INSERM U1041, Paris, France;Institut Pasteur, Research Group “Dynamics of Host-Pathogen Interactions”, Paris, France;Institut Pasteur, Unit for Integrated Mycobacterial Pathogenomics, Paris, France;Institut Pasteur, Unité de Régulation Immunitaire et Vaccinologie, Paris, France;VU University, Molecular and Medical Microbiology, Amsterdam, The Netherlands

关键词: Mycobacterium tuberculosis;    Fluorescence resonance energy transfer;    Cytosol;    Fluorescence microscopy;    Macrophages;    Necrosis;    Host cells;    Fluorescence imaging;   

DOI  :  10.1371/journal.ppat.1002507

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Survival within macrophages is a central feature of Mycobacterium tuberculosis pathogenesis. Despite significant advances in identifying new immunological parameters associated with mycobacterial disease, some basic questions on the intracellular fate of the causative agent of human tuberculosis in antigen-presenting cells are still under debate. To get novel insights into this matter, we used a single-cell fluorescence resonance energy transfer (FRET)-based method to investigate the potential cytosolic access of M. tuberculosis and the resulting cellular consequences in an unbiased, quantitative way. Analysis of thousands of THP-1 macrophages infected with selected wild-type or mutant strains of the M. tuberculosis complex unambiguously showed that M. tuberculosis induced a change in the FRET signal after 3 to 4 days of infection, indicating phagolysosomal rupture and cytosolic access. These effects were not seen for the strains M. tuberculosisΔRD1 or BCG, both lacking the ESX-1 secreted protein ESAT-6, which reportedly shows membrane-lysing properties. Complementation of these strains with the ESX-1 secretion system of M. tuberculosis restored the ability to cause phagolysosomal rupture. In addition, control experiments with the fish pathogen Mycobacterium marinum showed phagolysosomal translocation only for ESX-1 intact strains, further validating our experimental approach. Most importantly, for M. tuberculosis as well as for M. marinum we observed that phagolysosomal rupture was followed by necrotic cell death of the infected macrophages, whereas ESX-1 deletion- or truncation-mutants that remained enclosed within phagolysosomal compartments did not induce such cytotoxicity. Hence, we provide a novel mechanism how ESX-1 competent, virulent M. tuberculosis and M. marinum strains induce host cell death and thereby escape innate host defenses and favor their spread to new cells. In this respect, our results also open new research directions in relation with the extracellular localization of M. tuberculosis inside necrotic lesions that can now be tackled from a completely new perspective.

【 授权许可】

CC BY