OBJECTIVETo observe whether H. pylori inoculated by oral route could arrive in livers and cause liver inflammation as an independent etiological factor.

METHODSC57BL/6 mice were orally inoculated with H. pylori SS1 strains and fed for 8 months. H. pylori colonization and pathologic consequences were studied in the liver and gallbladder tissues of the mice; the blood, liver tissue and gastric mucosa were obtained and cultured for H. pylori growth; The bacterial DNA extracted from the liver, bile and blood was examined by nested PCR for H. pylori genes. 16S rRNA PCR amplicons were sequenced and compared with the sequencing results of 16S rRNA PCR amplicons of the bacteria cultured from gastric mucosa and the inoculated H. pylori SS1.

RESULTSThe bacterial DNA extracted from the liver, bile and blood of the infected mice was detected for H. pylori genes by nested PCR. Six of the 15 samples were positive (40%) in the liver, 6 of 10 samples in the bile (60%), and 2 of 10 samples in the blood (20%). Sequencing results of 16S rRNA PCR products of the livers showed 100% homogeneity when compared with the cultured H. pylori from gastric mucosa and inoculated H. pylori SS1. H. pylori was found in 4 liver tissues of the 15 infected mice (26.7%) and 6 in the gallbladders (40%). Infiltrations of lymphocyte cells along hepatic sinusoids and a lower degree infiltration around interlobular arteries and veins were observed; ballooning degeneration was also observed in some hepatocytes.

CONCLUSIONH. pylori inoculated by oral route could arrive in the liver and cause inflammation as an independent etiological factor. The routes which the microorganisms took to reach the livers may involve hematogenous and/or biliary system dissemination.