OBJECTIVETo observe whether H. pylori administered orally in mice could arrive in their livers after a long-term infection, leading to active inflammation and even causing HCC as an independent etiological factor.

METHODSTwenty C57BL/6 mice were orally administered H. pylori SS1 and kept for 24 months (experimental group) along with 13 mice which served as blank controls (control group). H. pylori colonization and pathologic consequences were studied in the livers and gastric tissues of the mice. The bacterial DNA extracted from liver tissues was examined by nested PCR for H. pylori 16S rRNA genes. 16S rRNA PCR amplicons were sequenced and compared with sequencing results of 16S rRNA PCR amplicons of the bacteria cultured from gastric mucosa and compared with that of the inoculated H. pylori SS1.

RESULTSOf the 20 mice in the experimental group, H. pylori was found in the gastric mucosa of 12, and in 11 of them pathological gastric lesions were found, including one with gastric lymphoma. H. pylori were found in the livers of 7 mice. Liver lesions, one with mild inflammation, 3 with inflammation and fibrosis, 2 with inflammation, fibrosis and hepatocyte hyperplasia with atypia were found in 6 of them. No liver lesions were found in the mice of the control group. In the mice of the experimental group no liver lesions were found in those mice with no H. pylori in their gastric mucosae. Sequencing results of 16S rRNA PCR products of the liver showed 100% homogeneity with the cultured H. pylori from gastric mucosa and the administered H. pylori SS1.

CONCLUSIONTwo years after oral administration of H. pylori to C57BL/6 mice, gastric mucosal lesions and liver lesions, including inflammation, cirrhosis and hepatocyte hyperplasia with atypia were found in those animals.