IL-17A or IL-17F is sufficient to maintain innate response and control of H. pylori immunopathogenesis

Abstract

Interleukin-17 receptor (IL-17R) signaling is required for control of many extracellular pathogens due to its impact on neutrophil recruitment and antimicrobial responses. Infection with the extracellular pathogen Helicobacter pylori results in Th1 and Th17 cell activation and a chronic inflammatory process which can lead to adverse outcomes such as gastric cancer. Previously, we identified IL-17RA as a requirement for the recruitment of neutrophils. Surprisingly, H. pylori infected IL-17RA−/− mice had significantly more chronic inflammation than H. pylori infected WT mice. In the current study, in vitro human epithelial cell cultures and in vivo mouse models were used to investigate differential roles for IL-17A, IL-17F and IL-17A/F during H. pylori infection. The data indicate generally that epithelial cells responded to IL-17A or IL-17A/F better than IL-17F. Increased gene expression of some factors, such as Cxcl8, required a co-stimulus such as H. pylori, TNF or IL-22 in epithelial cells, but expression of Pigr and Nox1 were induced by IL-17A alone. In vivo deficiencies of IL-17A or IL-17F alone did not significantly change the immunopathological response to H. pylori, but if both cytokines were absent, a hyperinflammatory lymphocytic response developed similar to what was observed in IL-17RA−/− mice. These data imply that IL-17A and IL-17F may have some overlapping role or compensatory roles in maintenance of the gastric mucosal response to infection which is required for preventing immunopathology.