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Immunity. 2017 Sep 19;47(3):552-565.e4. doi: 10.1016/j.immuni.2017.08.003. Epub 2017 Aug 24.

Phenolic Glycolipid Facilitates Mycobacterial Escape from Microbicidal Tissue-Resident Macrophages.

Author information

1
Department of Immunology, University of Washington, Seattle, WA 98195, USA; Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK; Department of Chemistry, Stanford University, Stanford, CT 94305, USA.
2
Department of Clinical Medicine, Trinity Translational Medicine Institute, Trinity College Dublin, Dublin 8, Ireland.
3
Department of Clinical Medicine, Trinity Translational Medicine Institute, Trinity College Dublin, Dublin 8, Ireland. Electronic address: josephmk@tcd.ie.
4
Department of Immunology, University of Washington, Seattle, WA 98195, USA; Molecular Immunity Unit, Department of Medicine, University of Cambridge, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK; Department of Microbiology, University of Washington, Seattle, WA 98195, USA; Department of Medicine, University of Washington, Seattle, WA 98195, USA. Electronic address: lr404@cam.ac.uk.

Abstract

Mycobacterium tuberculosis (Mtb) enters the host in aerosol droplets deposited in lung alveoli, where the bacteria first encounter lung-resident alveolar macrophages. We studied the earliest mycobacterium-macrophage interactions in the optically transparent zebrafish. First-responding resident macrophages phagocytosed and eradicated infecting mycobacteria, suggesting that to establish a successful infection, mycobacteria must escape out of the initially infected resident macrophage into growth-permissive monocytes. We defined a critical role for mycobacterial membrane phenolic glycolipid (PGL) in engineering this transition. PGL activated the STING cytosolic sensing pathway in resident macrophages, inducing the production of the chemokine CCL2, which in turn recruited circulating CCR2+ monocytes toward infection. Transient fusion of infected macrophages with CCR2+ monocytes enabled bacterial transfer and subsequent dissemination, and interrupting this transfer so as to prolong mycobacterial sojourn in resident macrophages promoted clearing of infection. Human alveolar macrophages produced CCL2 in a PGL-dependent fashion following infection, arguing for the potential of PGL-blocking interventions or PGL-targeting vaccine strategies in the prevention of tuberculosis. VIDEO ABSTRACT.

PMID:
28844797
PMCID:
PMC5610147
DOI:
10.1016/j.immuni.2017.08.003
[Indexed for MEDLINE]
Free PMC Article

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