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  • Title: Specific T cells restore the autophagic flux inhibited by Mycobacterium tuberculosis in human primary macrophages.
    Author: Petruccioli E, Romagnoli A, Corazzari M, Coccia EM, Butera O, Delogu G, Piacentini M, Girardi E, Fimia GM, Goletti D.
    Journal: J Infect Dis; 2012 May 01; 205(9):1425-35. PubMed ID: 22457295.
    Abstract:
    BACKGROUND: Autophagy inhibits survival of intracellular Mycobacterium tuberculosis when induced by rapamycin or interferon γ (IFN-γ), but it remains unclear whether M. tuberculosis itself can induce autophagy and whether T cells play a role in M. tuberculosis-mediated autophagy. The aim of this study was to evaluate the impact of M. tuberculosis on autophagy in human primary macrophages and the role of specific T cells in this process. METHODS: M. tuberculosis (H37Rv)-infected macrophages were incubated with naive or M. tuberculosis-specific T cells. Autophagy was evaluated at 4 hours and 8 hours after infection by analyzing the levels of LC3-II (a hallmark of autophagy) and p62 (a protein degraded by autophagy). M. tuberculosis survival was evaluated by counting the colony-forming units. RESULTS: M. tuberculosis infection of macrophages inhibited the autophagic process at 8 hours after infection. Naive T cells could not rescue this block, whereas M. tuberculosis-specific T cells restored autophagy degradation, accompanied by enhanced bacterial killing. Notably, the effect of M. tuberculosis-specific T cells was not affected by neutralization of endogenous IFN-γ and tumor necrosis factor α and was blocked by preventing contact between macrophages and T cells, suggesting that cell-cell interaction is crucial. CONCLUSIONS: M. tuberculosis inhibits autophagy in human primary macrophages, and specific T cells can restore functional autophagic flux through cell-cell contact.
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