Helicobacter pylori -induced IL-33 modulates mast cell responses, benefits bacterial growth, and contributes to gastritis

Interleukin (IL)-induced inflammatory responses are critical for the pathogenesis of Helicobacter pylori ( H. pylori )-induced gastritis. IL-33 represents a recently discovered proinflammatory cytokine involved in inflammatory diseases, but its relevance to H. pylori -induced gastritis is unknown. Here, we found that gastric IL-33 mRNA and protein expression were elevated in gastric mucosa of both patients and mice infected with H. pylori , which is positively correlated with bacterial load and the degree of gastritis. IL-33 production was promoted via extracellular regulated protein kinases (ERK) signaling pathway activation by gastric epithelial cells in a cagA -dependent manner during H . pylori infection, and resulted in increased inflammation and bacteria burden within the gastric mucosa. Gastric epithelial cell-derived IL-33 promoted TNF-α production from mast cells in vitro, and IL-33 increased TNF-α production in vivo. Increased TNF-α inhibited gastric epithelial cell proliferation, conducing to the progress of H . pylori -associated gastritis and bacteria colonization. This study defined a patent regulatory networks involving H. pylori , gastric epithelial cell, IL-33, mast cell, and TNF-α, which jointly play a pathological effect within the gastric circumstances. It may be a valuable strategy to restrain this IL-33-dependent pathway in the treatment of H. pylori -associated gastritis.