Mycobacterial Secretion Systems ESX-1 and ESX-5 Play Distinct Roles in Host Cell Death and Inflammasome Activation

A.M. Abdallah, J. Bestebroer, N.D.L. Savage, K. de Punder, M. van Zon, L. Wilson, C.J. Korbee, A.M. van der Sar, T.H.M. Ottenhoff, N.N. van der Wel, W. Bitter, P.J. Peters

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

During infection of humans and animals, pathogenic mycobacteria manipulate the host cell causing severe diseases such as tuberculosis and leprosy. To understand the basis of mycobacterial pathogenicity, it is crucial to identify the molecular virulence mechanisms. In this study, we address the contribution of ESX-1 and ESX-5 - two homologous type VII secretion systems of mycobacteria that secrete distinct sets of immune modulators - during the macrophage infection cycle. Using wild-type, ESX-1- and ESX-5-deficient mycobacterial strains, we demonstrate that these secretion systems differentially affect subcellular localization and macrophage cell responses. We show that in contrast to ESX-1, the effector proteins secreted by ESX-5 are not required for the translocation of Mycobacterium tuberculosis or Mycobacterium marinum to the cytosol of host cells. However, the M. marinum ESX-5 mutant does not induce inflammasome activation and IL-1b activation. The ESX-5 system also induces a caspase-independent cell death after translocation has taken place. Importantly, by means of inhibitory agents and small interfering RNA experiments, we reveal that cathepsin B is involved in both the induction of cell death and inflammasome activation upon infection with wild-type mycobacteria. These results reveal distinct roles for two different type VII secretion systems during infection and shed light on how virulent mycobacteria manipulate the host cell in various ways to replicate and spread. Copyright © 2011 by The American Association of Immunologists, Inc.
Original languageEnglish
Pages (from-to)4744-4753
Number of pages10
JournalJournal of Immunology
Volume187
Issue number9
DOIs
Publication statusPublished - 1 Nov 2011

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