Marked liver tumorigenesis by Helicobacter hepaticus requires perinatal exposure.

BackgroundAlthough severe hepatitis and liver tumors occur in a high percentage of A/J male mice naturally infected with Helicobacter hepaticus, these effects have not been observed after injection of adult mice with the bacteria.ObjectivesWe tested the hypothesis that perinatal exposure to the bacteria is required for liver tumorigenesis.MethodsA/J female mice were infected by intragastric (ig) or intraperitoneal (ip) treatment with 1.5 × 108 H. hepaticus before pregnancy. We examined offspring at progressive time intervals, including some kept until natural death in old age. A/J, BALB/c, and C57BL/6 weanling male mice were similarly treated ig with the bacteria and observed for up to 2 years.ResultsAfter ip bacterial infection of A/J females, 41% of their male offspring developed hepatitis and 33% had hepatocellular tumors, including 18% with hepatocellular carcinoma. Treatment by the ig route resulted in a similar incidence of hepatitis in offspring (35%) but fewer total liver tumors (8%) and carcinoma...