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PLoS Pathog. 2015 Feb 6;11(2):e1004650. doi: 10.1371/journal.ppat.1004650. eCollection 2015 Feb.

Cytosolic access of Mycobacterium tuberculosis: critical impact of phagosomal acidification control and demonstration of occurrence in vivo.

Author information

1
Institut Pasteur, Unit for Integrated Mycobacterial Pathogenomics, Institut Pasteur, Paris, France; Inserm U1019, CNRS UMR8204, Université de Lille-Nord de France, Institut Pasteur de Lille, Center for Infection and Immunity, Lille, France.
2
Institut Pasteur, Unit for Integrated Mycobacterial Pathogenomics, Institut Pasteur, Paris, France.
3
Inserm U1019, CNRS UMR8204, Université de Lille-Nord de France, Institut Pasteur de Lille, Center for Infection and Immunity, Lille, France.

Abstract

Mycobacterium tuberculosis (Mtb) uses efficient strategies to evade the eradication by professional phagocytes, involving--as recently confirmed--escape from phagosomal confinement. While Mtb determinants, such as the ESX-1 type VII secretion system, that contribute to this phenomenon are known, the host cell factors governing this important biological process are yet unexplored. Using a newly developed flow-cytometric approach for Mtb, we show that macrophages expressing the phagosomal bivalent cation transporter Nramp-1, are much less susceptible to phagosomal rupture. Together with results from the use of the phagosome acidification inhibitor bafilomycin, we demonstrate that restriction of phagosomal acidification is a prerequisite for mycobacterial phagosomal rupture and cytosolic contact. Using different in vivo approaches including an enrichment and screen for tracking rare infected phagocytes carrying the CD45.1 hematopoietic allelic marker, we here provide first and unique evidence of M. tuberculosis-mediated phagosomal rupture in mouse spleen and lungs and in numerous phagocyte types. Our results, linking the ability of restriction of phagosome acidification to cytosolic access, provide an important conceptual advance for our knowledge on host processes targeted by Mtb evasion strategies.

PMID:
25658322
PMCID:
PMC4450080
DOI:
10.1371/journal.ppat.1004650
[Indexed for MEDLINE]
Free PMC Article

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