The ESX-5 secretion system of mycobacterium marinum modulates the macrophage response

Abdallah Abdallah, Nigel D.L. Savage, Maaike Van Zon, Louis Wilson, Christina M.J.E. Vandenbroucke-Grauls, Nicole N. Van Der Wel, Tom H.M. Ottenhoff, Wilbert Bitter*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    109 Scopus citations


    The ESX-5 secretion system of pathogenic mycobacteria is responsible for the secretion of various PPE and PE-PGRS proteins. To better understand the role of ESX-5 effector proteins in virulence, we analyzed the interactions of Mycobacterium marinum ESX-5 mutant with human macrophages (Mφ). Both wild-type bacteria and the ESX-5 mutant were internalized and the ESX-5 mutation did not affect the escape of mycobacteria from phagolysosomes into the cytosol, as was shown by electron microscopy. However, the ESX-5 mutation strongly effected expression of surface Ags and cytokine secretion. Whereas wild-type M. marinum actively suppressed the induction of appreciable levels of IL-12p40, TNF-α, and IL-6, infection with the ESX-5 mutant resulted in strongly induced production of these proinflammatory cytokines. By contrast, infection with M. marinum wild-type strain resulted in a significant induction of IL-1γ production as compared with the ESX-5 mutant. These results show that ESX-5 plays an essential role in the modulation of immune cytokine secretion by human Mφ. Subsequently, we show that an intact ESX-5 secretion system actively suppresses TLR signaling-dependent innate immune cytokine secretion. Together, our results show that ESX-5 substrates, directly or indirectly, strongly modulate the human Mφ response at various critical steps.

    Original languageEnglish (US)
    Pages (from-to)7166-7175
    Number of pages10
    JournalJournal of Immunology
    Issue number10
    StatePublished - Nov 15 2008

    ASJC Scopus subject areas

    • Immunology

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