Importance of phagosomal functionality for growth restriction of Mycobacterium tuberculosis in primary human macrophages
2011 (English)In: Journal of Innate Immunity, ISSN 1662-811X, E-ISSN 1662-8128, Vol. 3, no 5, 508-518 p.Article in journal (Refereed) Published
The best characterized survival mechanism of Mycobacterium tuberculosis inside the macrophage is the inhibition of phagosomal maturation. Phagosomal maturation involves several steps including fusion with lysosomes and acidification. However, it has not been elucidated which components of phagosomal maturation correlate with growth restriction of virulent mycobacteria in human macrophages, and we aimed to study this. We infected human monocyte-derived macrophages with M. tuberculosis and assessed bacterial replication, translocation of CD63 to the phagosome, and phagosomal acidification. We found that unstimulated macrophages were able to control infection with M. tuberculosis upon inoculation at a low, but not high, multiplicity of infection (MOI). H37Rv and H37Ra infection, at both high and low MOI, led to equally ineffective translocation of CD63 to the phagosome. This was true despite the impaired growth ability of H37Rv at the low MOI and of H37Ra even at the high MOI, indicating that inhibition of CD63 translocation was not sufficient for growth to occur. On the other hand, acidification of mycobacterial phagosomes was more efficient at a low MOI with both mycobacterial strains, consistent with a role for phagosomal acidification in restricting M. tuberculosis growth. Inhibition of the vacuolar H+-ATPase as well as of cathepsin D led to enhanced mycobacterial replication inside the macrophage. We conclude that acidification and related functional aspects of the mature phagosome are important factors for restriction of M. tuberculosis replication in human macrophages.
Place, publisher, year, edition, pages
S. Karger, 2011. Vol. 3, no 5, 508-518 p.
National CategoryBasic Medicine
IdentifiersURN: urn:nbn:se:liu:diva-65447DOI: 10.1159/000325297ISI: 000294572500008PubMedID: 21576918OAI: oai:DiVA.org:liu-65447DiVA: diva2:395797
Funding Agencies|Swedish Research Council|529-2003-5994,2005-7046,2006-5968,2007-2673,2009-3821|Bill and Melinda Gates Foundation||SIDA/SAREC||Ekhaga Foundation||Carl Trygger Foundation||King Gustaf V 80-Year Memorial Foundation||County Council of Ostergotland||Swedish Heart Lung Foundation||Oskar II Jubilee Foundation||Clas Groschinsky Foundation||Soderbergs Foundation||Colorado State University, Fort Collins (NIH, NIAID)|HHSN26620040 0091C|2011-02-082011-02-082014-09-24Bibliographically approved