The Injury Effect Of Different Originated Helicobacter Pylori On Gastric Mucosa Of Mongolian Gerbils

IntroductionMany epidemiological researches showed that Helicobacter pylori(H.pylori) infection is strongly associated with gastric diseases,such as acute gastritis,chronic atrophic gastritis,intestinal metaplasia,peptic ulcers,gastric mucosa-associated lymphoid tissue(MALT) lymphoma,and gastric carcinoma.In 1994,H.pylori was defined as class-Ⅰcarcinogen by IARC based on three prospective case-control reports of 1991.Previously epidemiological researches showed that Zhuanghe of Liaoning Province is a high spot of gastric carcinoma in North China.The gastric carcinoma mortality in Zhuanghe ranges from 45.21/100,000 to 63.29/100,000,which accounts for 8.25%of local death rate,and 38.94%of cancer death rate,high above the national average level.Meanwhile,Zhuanghe has a high incidence of H.pylori infection.As we have previously reported,taking salty pork as food and H.pylori infection are the main dietary factor and environmental factor for the high local morbidity of gastric carcinoma.We have successfully cultured H.pylori strains from the salty pork, which is known as salty-pork-originated H.pylori.In vitro study showed that,in contrast with human-originated H.pylori,salty-pork-originated H.pylori may cause more severe injury to human gastric epithelial cell GES-1.Establishing an appropriate animal model of H.pylori infection is necessary to reveal the possible pathogenic mechanism.Researches indicated that the H.pylori infected Mongolian gerbil model resembles human in developing gastritis,gastric ulcers and gastric carcinoma,and the histopathological changes are similar too.These results are helpful to revealling pathogenic mechanism of H.pylori infection.Thus, whether H.pylori strains from each origin should differ,after infected the Mongolian gerbil model,in gastric mucosa lesion,extent of the lesion,and the mechanism of the lesion remains unsolved. In this study,Mongolian gerbil was infected with salty-pork-originated and human-originated H.pylori strains.The colonizing capability of H.pylori strains and gastric mucosa lesion of Mongolian gerbil were observed and compared.The mechanism of the lesion difference was investigated,in order to provide laboratory evidence for further study of transmission route of H.pylori.Materials and Methods1.Establishment of Mongolian gerbil models infected with H.pylori strains from different origins.Mongolian gerbil was innoculated by intragastric administration of H.pylori. Dissection was taken separately at 13weeks,26weeks,and 52weeks after infection.2.Mongolian gerbil gastric mucosa colonizing capability of H.pylori from different origins(1)Qualitative assessmentGastric mucosa specimens were HE-stained,specific WS-stained,Grams-stained, and cultured in urease medium and brain heart infusion agar medium.H.pylori infection of Mongolian gerbil gastric mucosa was identified by PCR amplification. PCR results,before and after lavage,were compared to determine that the Mongolian gerbil was infected with the lavage H.pylori strain.(2)Quantitative assessmentGastric mucosa homogenate was cultured and H.pylori colony was counted to compare the colonizing capability on gastric mucosa.3.Mongolian gerbil gastric mucosa lesion caused by H.pylori from different origins.Gastric diseases were histopathologically diagnosed with HE-stained paraffinembedded gastric mucosa slide to compare lesions caused by H.pylori strains from each origin.4.Mechanism of different Mongolian gerbil gastric mucosa lesion caused by H.pylori from different origins.(1)Immunohistochemical assay of Interleukin-8(IL-8),Nuclear factor kappa B (NF-kB) protein expression.(2)Western Blotting assay of IL-8 and NF-kB protein expression in gastric mucosa specimens. (3)RT-PCR assay of IL-8 and NF-kB mRNA expression in gastric mucosa specimens.Results1.Salty-pork-originated H.pylori colonized Mongolian gerbil gastric mucosa stably,colonization rate up to 100%.2.H.pylori strains from different origins colonized differently on Mongolian gerbil gastric mucosa,and the colony density of salty-pork-originated H.pylori was much higher than human-originated(p＜0.01).3.H.pylori strains from different origins caused different gastric mucosa lesion, and salty-pork-originated H.pylori caused more severe lesions(p＜0.05).4.H.pylori with high salt diet caused more severe lesions than the group without high salt diet(p＜0.05).5.NF-kB p65 protein and mRNA expression was higher in salty-pork-originated H.pylori than human-originated(p＜0.05).6.IL-8 protein and mRNA expression was higher in salty-pork-originated H.pylori than human-originated(p＜0.05).7.NF-kB p65 expression was significantly correlated to the H.pylori colony density(p＜0.05).8.IL-8 expression was significantly correlated to the H.pylori colony density (p＜0.05).9.IL-8 expression was significantly correlated to the expression of NF-kB p65 (p＜0.05).10.NF-kB p65 protein and mRNA expression was higher in the group of H.pylori with high salt diet than the group without high salt diet(p＜0.05).11.IL-8 protein and mRNA expression was higher in the group of H.pylori with high salt diet than the group without high salt diet(p＜0.05).Conclusion1.Salty-pork-originated H.pylori colonized Mongolian gerbil gastric mucosa stably,and caused Mongolian gerbil gastric mucosa lesion.2.In contrast with human-originated H.pylori,salty-pork-originated H.pylori colonizing capability was higher and caused more severe gastric mucosa lesions. 3.H.pylori infection with high salt diet caused more severe gastric mucosa lesions than pure H.pylori infection without high salt diet.4.After colonizing on gastric mucosa,salty-pork-originated H.pylori activated NF-kB p65,upregulated the expression of IL-8,caused more severe Mongolian gerbil gastric mucosa lesions.5.H.pylori with high salt diet activated NF-kB p65,upregulated the expression of IL-8.This is one of the mechanism that H.pylori with high salt diet caused more severe Mongolian gerbil gastric mucosa lesions.