Attempts to Establish a Helicobacter bilis Biliary Tract Infection Model via Oral Administration of Helicobacter bilis

Background Although several studies have reported an association between <i>Helicobacter bilis</i> (<i>H. bilis</i>) and human biliary tract cancer, in vivo studies are necessary to further assess this phenomenon. In this study, we developed an animal model of <i>H. bilis</i> infection, determined whether oral exposure to <i>H. bilis</i> induces biliary carcinogenesis, and evaluated colonization and pathological changes. Methods Seven-week-old female Syrian golden hamsters were administered <i>H. bilis</i> via the intragastric route using a sonde and euthanized after two, four, 12, 24, and 48 weeks. We assessed the rate of bacterial colonization in the intrahepatic bile ducts and gallbladders, polymerase chain reaction (PCR) positivity rate using <i>H. bilis</i>-specific primers, carcinogenic or pathological alterations, and cholangitis scores. Results <i>H. bilis</i> was detected in the intestinal tract of hamsters but not in the biliary tract. PCR positivity was higher in the <i>H. bilis </i>group than in the control group at each time point, but not statistically significant. Histological alterations in the biliary system of the orally administered group were limited to gallbladder hyperplasia, with no evidence of carcinogenesis. The cholangitis scores were similar between the two groups. Conclusions In this study, the oral administration of <i>H. bilis</i> alone did not induce carcinogenesis. Because human epidemiological studies have revealed that <i>H. bilis</i> is involved in carcinogenesis, further research is needed to elucidate the relationship between <i>H. bilis</i> and human biliary tract cancer.