Toll-Like Receptor Pathway Mediates Melatonin To Regulate Gastritis Caused By Helicobacter Pylori Infection

Object: Helicobacter pylori(Hp)infection is the main cause of various diseases in the stomach.At present,in patients with symptoms of Hp infection,the therapy is triple therapy.In recent years,however,with the increasingly serious antibiotic resistance and the side effects caused by proton pump inhibitors,the traditional eradication therapy has failed to keep the efficacy of the treatment.Clarifying the pathogenetic mechanism of HP is a clinically important issue.Through the establishment of H.pylori infection in mice with gastritis model,and intervention of different concentrations of melatonin,this research try to explore the immunomodulatory mechanism of melatonin on H.pylori-induced gastritis,and understanding of the immune response mechanism and neuroendocrine-immune network regulation mechanism after H.pylori infection,in order to provide a theoretical basis for the potential clinical application of new ideas.Methods: In the current study,after mices were intragastrically inoculated with SSI to acquire GI diseases,different concentration(0mg/g?25mg/kg?50mg/kg)of melatonin were injected after 2 weeks.The samples were got after melatonin injected 2 weeks,4 weeks,and 6 weeks.Gastric mucosa damage level were observed by HE staining.The TLR2,TLR4 in stomach and Foxp3 in spleen protein were determined by immunohistochemistry;IL-2,IL-6,IL-10,IL17-A,IFN-? and TNF-? concentration in plasma were measured by CBA assay.Protein levels of TLR2,MyD88,p65,p50,pERK,p-p38 in stomach were detected by Western Blot,respectively.Results: HE staining showed that inflammatory cells dispersed in mucosa and submucosa layer,which indicating success of H.pylori colonization.IHC staining showed that TLR2 in gastric mucosa of mice was significantly up-regulated in the infected group,down-regulated after the intervention of melatonin,and significantly increased in the melatonin antagonist group.There was no significant change in the expression of TLR4 between the groups,Foxp3 in the spleen up-regulated in the infected group.The expression was significantly down-regulated after melatonin intervention,and there was no significant change in the antagonist intervention group compared with the non-antagonist group.CBA test results showed that at 2 and 6 weeks,the levels of IL-2,IL-6,IL-10,IL17-A,IFN-? and TNF-? in mouse plasma were significantly decreased compared with those in the infected group and the cytokines in the antagonist group were increased significantly,while the group of 4 weeks' changes is not obvious.Western Blot results shows that in the stomach of mice,the levels of TLR2,MyD88,p-ERK and p-p38 in melatonin intervention group were significantly lower than those in control group at 2 weeks,and no significant changes were found at 4 and 6 weeks;The expression of p65 and p50 at 2 weeks were slightly down-regulated after the melatonin treatment,but not obvious at 4 and 6 weeks.Conclusion : The mechanisms of melatonin to gastritis in Hp-infected mice may include down-regulating the expression of TLR2,inhibiting the expression of plasma inflammatory cytokines;it also may regulate gastritis in Hp-infected mice by downregulating Foxp3 expression in the spleen.