NOD1 is required for Helicobacter pylori induction of IL ‐33 responses in gastric epithelial cells

SUMMARY Helicobacter pylori causes chronic inflammation which is a key precursor to gastric carcinogenesis. It has been suggested that H. pylori may limit this immunopathology by inducing the production of IL‐33 in gastric epithelial cells, thus promoting T helper 2 immune responses. The molecular mechanism underlying IL‐33 production in response to H. pylori infection, however, remains unknown. In the current study, we demonstrate that H. pylori activates signalling via the pathogen recognition molecule NOD1 and its adaptor protein RIPK2, to promote production of both full‐length and processed IL‐33 in gastric epithelial cells. Furthermore, IL‐33 responses were dependent on the actions of the H. pylori type IV secretion system (T4SS), required for activation of the NOD1 pathway, as well as on the T4SS effector protein, CagA. Importantly, Nod1+/+ mice with chronic H. pylori infection exhibited significantly increased gastric IL‐33 and splenic IL‐13 responses, but decreased IFN‐γ responses, when compared with Nod1‐/‐ animals. Collectively, our data identify NOD1 as an important regulator of mucosal IL‐33 responses in H. pylori infection. We suggest that NOD1 may play a role in protection against excessive inflammation.
Source: Cellular Microbiology - Category: Microbiology Authors: Tags: RESEARCH ARTICLE Source Type: research