Interleukin-22-deficiency and microbiota contribute to the exacerbation of Toxoplasma gondii-induced intestinal inflammation

Mucosal Immunol. 2018 Jul;11(4):1181-1190. doi: 10.1038/s41385-018-0005-8. Epub 2018 May 4.

Abstract

Upon oral infection with Toxoplasma gondii cysts (76 K strain) tachyzoites are released into the intestinal lumen and cross the epithelial barrier causing damage and acute intestinal inflammation in C57BL/6 (B6) mice. Here we investigated the role of microbiota and IL-22 in T.gondii-induced small intestinal inflammation. Oral T.gondii infection in B6 mice causes inflammation with IFNγ and IL-22 production. In IL-22-deficient mice, T.gondii infection augments the Th1 driven inflammation. Deficiency in either IL-22bp, the soluble IL-22 receptor or Reg3γ, an IL-22-dependent antimicrobial lectin/peptide, did not reduce inflammation. Under germ-free conditions, T.gondii-induced inflammation was reduced in correlation with parasite load. But intestinal inflammation is still present in germ-free mice, at low level, in the lamina propria, independently of IL-22 expression. Exacerbated intestinal inflammation driven by absence of IL-22 appears to be independent of IL-22 deficiency associated-dysbiosis as similar inflammation was observed after fecal transplantation of IL-22-/- or WT microbiota to germ-free-WT mice. Our results suggest cooperation between parasite and intestinal microbiota in small intestine inflammation development and endogenous IL-22 seems to exert a protective role independently of its effect on the microbiota. In conclusion, IL-22 participates in T.gondii induced acute small intestinal inflammation independently of microbiota and Reg3γ.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Disease Progression
  • Gastrointestinal Microbiome / immunology*
  • Inflammation / immunology*
  • Interleukin-22
  • Interleukins / genetics
  • Interleukins / metabolism*
  • Intestines / immunology*
  • Intestines / parasitology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Pancreatitis-Associated Proteins / genetics
  • Pancreatitis-Associated Proteins / metabolism
  • Parasite Load
  • Receptors, Interleukin / genetics
  • Receptors, Interleukin / metabolism
  • Toxoplasma / physiology*
  • Toxoplasmosis / immunology*

Substances

  • Interleukins
  • Pancreatitis-Associated Proteins
  • Receptors, Interleukin
  • Reg3g protein, mouse
  • interleukin-22 receptor