IL-22 is mainly produced by IFNγ-secreting cells but is dispensable for host protection against Mycobacterium tuberculosis infection

PLoS One. 2013;8(2):e57379. doi: 10.1371/journal.pone.0057379. Epub 2013 Feb 27.

Abstract

Anti-inflammatory treatment of autoimmune diseases is associated with an increased risk of reactivation tuberculosis (TB). Besides interleukin (IL-17)A, IL-22 represents a classical T helper (TH)17 cytokine and shares similar pathological effects in inflammatory diseases such as psoriasis or arthritis. Whereas IL-17A supports protective immune responses during mycobacterial infections, the role of IL-22 after infection with Mycobacterium tuberculosis (Mtb) is yet poorly characterized. Therefore, we here characterize the cell types producing IL-22 and the protective function of this cytokine during experimental TB in mice. Like IL-17A, IL-22 is expressed early after infection with Mtb in an IL-23-dependent manner. Surprisingly, the majority of IL-22-producing cells are not positive for IL-17A but have rather functional characteristics of interferon-gamma-producing TH1 cells. Although we found minor differences in the number of naive and central memory T cells as well as in the frequency of TH1 and polyfunctional T cells in mice deficient for IL-22, the absence of IL-22 does not affect the outcome of Mtb infection. Our study revealed that although produced by TH1 cells, IL-22 is dispensable for protective immune responses during TB. Therefore, targeting of IL-22 in inflammatory disease may represent a therapeutic approach that does not incur the danger of reactivation TB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Bacterial / immunology
  • CD4-Positive T-Lymphocytes / immunology
  • Granulocytes / metabolism
  • Host-Pathogen Interactions / immunology*
  • Immunity / immunology
  • Inflammation Mediators / metabolism
  • Interferon-gamma / biosynthesis
  • Interferon-gamma / metabolism*
  • Interleukin-22
  • Interleukin-23 / metabolism
  • Interleukins / biosynthesis*
  • Interleukins / deficiency
  • Lymphocyte Activation / immunology
  • Macrophage Activation / immunology
  • Macrophages / metabolism
  • Macrophages / microbiology
  • Mice
  • Mice, Inbred C57BL
  • Mycobacterium tuberculosis / physiology*
  • Th1 Cells / immunology
  • Th17 Cells / immunology
  • Tuberculosis / immunology*
  • Tuberculosis / microbiology
  • Tuberculosis / prevention & control*

Substances

  • Antigens, Bacterial
  • Inflammation Mediators
  • Interleukin-23
  • Interleukins
  • Interferon-gamma

Grants and funding

This study was supported by a BMBF grant 01KI0784 to C.H. and S.E. and the German Research Foundation Cluster of Excellence “Inflammation at Interfaces” EXC306 to C.H. and S.E. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.