Increased infiltration of CD4+IL-17A+FOXP3+ T cells in Helicobacter pylori-induced gastritis

Helicobacter pylori is one of the main predisposing factors for gastric cancer, causing chronic inflammation and proper glands atrophy in the gastric mucosa. Although H. pylori-induced inflammation is a key inducer of precancerous lesions in the gastric mucosa, it remains unclear which precise immune cell subsets are responsible for the progression of H. pylori-induced gastritis. Here, we observed an abundance of CD4(+)IL-17A(+)FOXP3(+) T cells exhibiting a Th17-like phenotype within the microenvironment of H. pylori-induced gastritis. Mechanistically, H. pylori upregulated the expression of IL-6 in Dendritic cells and macrophages, by activating NF-kappa B signaling through the virulence factor CagA and thus, induced IL-17A expression in FOXP3(+) T cells. Moreover, CD4(+)IL-17A(+)FOXP3(+) T cells were positively associated with advanced precancerous lesions. Therefore, these findings offer essential insights into how FOXP3(+) T cells sense inflammatory signals from the environment, such as IL-6, during H. pylori infections, thereby guiding the effector immune response and aggravating the gastritis.