Role of T_reg and T_H17 cells of the gastric mucosa in children with helicobacter pylori gastritis

OBJECTIVE: The aim of the present study was to examine the expression of FOXP3, interleukin (IL)-10, transforming growth factor (TGF)-β1, IL-17A, and T helper 17 (T_H17) cells/FOXP3+ regulatory T (T_reg) cells balance in the gastric mucosa of children with Helicobacter pylori infection, in relation to the gastric histopathology. METHODS: Antral mucosal biopsies were obtained from 20 children with H pylori(+) gastritis and 20 age-and sex-matched normal controls. Histopathology was assessed by the updated Sydney classification. Gene expression of FOXP3, IL-10, and TGF-β1 was analyzed by quantitative real-time polymerase chain reaction. Immunohistochemical staining for FOXP3+ T_reg and T_H17 cells was performed. RESULTS: The gene expression levels of FOXP3, TGF-β1, and IL-10 messenger RNA (mRNA) and the number of FOXP3+ T_reg were significantly higher in the H pylori(+) gastritis group than in the control group (P < 0.01). FOXP3 mRNA levels were correlated positively with TGF-β1 and IL-10 mRNA levels in the H pylori(+) gastritis group (P < 0.05). Furthermore, FOXP3 mRNA levels were correlated positively with the bacterial density, infiltration of polymorphonuclear cells, and mononuclear cells in the H pylori(+) gastritis group (P < 0.05). The number of T _H17 cells was significantly higher in the H pylori(+) gastritis group than in the control group (P < 0.05). In addition, the number of T _H17 cells was correlated negatively with the bacterial density and positively with the inflammatory scores of polymorphonuclear cells and mononuclear cells in the H pylori(+) gastritis group (P < 0.05). A negative correlation between the T_H17 cells/FOXP3+ T_reg ratio and the bacterial density was demonstrated in the H pylori(+) gastritis group (P < 0.05). CONCLUSIONS: This study suggested that a T_H17/T _reg balance toward a T_reg-biased response favors the persistence of bacteria, causing chronic active gastritis.