Mycobacterium tuberculosis triggers host type I IFN signaling to regulate IL-1β production in human macrophages

J Immunol. 2011 Sep 1;187(5):2540-7. doi: 10.4049/jimmunol.1100926. Epub 2011 Jul 22.

Abstract

Mycobacterium tuberculosis is a virulent intracellular pathogen that survives in macrophages even in the presence of an intact adaptive immune response. Type I IFNs have been shown to exacerbate tuberculosis in mice and to be associated with disease progression in infected humans. Nevertheless, the mechanisms by which type I IFNs regulate the host response to M. tuberculosis infection are poorly understood. In this study, we show that M. tuberculosis induces an IFN-related gene expression signature in infected primary human macrophages, which is dependent on host type I IFN signaling as well as the mycobacterial virulence factor, region of difference-1. We further demonstrate that type I IFNs selectively limit the production of IL-1β, a critical mediator of immunity to M. tuberculosis. This regulation occurs at the level of IL1B mRNA expression, rather than caspase-1 activation or autocrine IL-1 amplification and appears to be preferentially used by virulent mycobacteria since avirulent M. bovis bacillus Calmette-Guérin (BCG) fails to trigger significant expression of type I IFNs or release of mature IL-1β protein. The latter property is associated with decreased caspase-1-dependent IL-1β maturation in the BCG-infected macrophages. Interestingly, human monocytes in contrast to macrophages produce comparable levels of IL-1β in response to either M. tuberculosis or BCG. Taken together, these findings demonstrate that virulent and avirulent mycobacteria employ distinct pathways for regulating IL-1β production in human macrophages and reveal that in the case of M. tuberculosis infection the induction of type I IFNs is a major mechanism used for this purpose.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Enzyme-Linked Immunosorbent Assay
  • Gene Expression
  • Gene Expression Regulation / immunology
  • Humans
  • Interferon Type I / immunology*
  • Interferon Type I / metabolism
  • Interleukin-1beta / biosynthesis*
  • Macrophages / immunology*
  • Macrophages / metabolism
  • Macrophages / microbiology
  • Mycobacterium tuberculosis / immunology*
  • Mycobacterium tuberculosis / pathogenicity*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / immunology*

Substances

  • Interferon Type I
  • Interleukin-1beta