The effect of interleukin-22 antibody intraperitoneal injection on the formation of gastric mucosa associated lymphoid tissue in mice after Helicobacter suis infection

Abstract

Objective To investigate the effect of interleukin-22 antibody intraperitoneal injection in the formation of gastric mucosa associated lymphoid tissue(MALT) in mice after Helicobacter suis infection and its possible mechanism. Methods Forty female C57BL/6 mice were randomly divided into four groups(10 mice per group), which were named as normal control(NC) group, H.suis infection(HS) group, antibody treated(Ab) group and H.suis infection plus antibody treated(HS+ Ab) group.The mice of Ab group and HS+ Ab group were administrated with 50 μg mouse IL-22 Ab by intraperitoneal injection from the second day postinfection.The mice of NC group and HS group were administrated with the equal amount of isotype control Ab by intraperitoneal injection.The antibody treatment was given once a week and for 12 weeks.Mice were sacrificed to collect gastric tissues.The number and size of gastric lymphoid follicles were detected by HE staining and the expression levels of IL-22 and chemokine CXCL13 in the stomachs of mice were detected by real-time PCR and Western blotting respectively.Human spleen fibroblasts were cultured in vitro and stimulated by IL-22 under the concentration of 100 ng/mL for 24 h or 48 h. The expression levels of CXCL13 in the cells and culture medium were detected.The immune cells from gastric tissues in H.suis-infected mice were isolated and stimulated by IL-22 under the concentration of 50 ng/mL, 100 ng/mL and 200 ng/mL for 24 h. The expression levels of CXCL13 in the cells and culture medium were detected. Results H.suis infection induced the formation of lymphoid follicles in the gastric mucosa.The number and size of gastric lymphoid follicles and the expression levels of IL-22 and chemokine CXCL13 in the stomachs of HS+ Ab group were significantly decreased compared with HS group.After IL-22 stimulation in vitro, the expression levels of CXCL13 in the spleen fibroblasts and culture medium were significantly increased compared with corresponding unstimulated group, which were higher after 48 h stimulation compared with 24 h stimulation.After stimulation of IL-22 under different concentrations, the expression levels of CXCL13 in the immune cells and culture medium were significantly increased compared with corresponding unstimulated group, which were upregulated along with the increased IL-22 concentation. Conclusion IL-22 may play an important role in the formation of gastric MALT after H.suis infection by upregulating the expression of CXCL13. Key words: Interleukin 22; Helicobacter suis; CXCL13; Mucosa associated lymphoid tissue