Type-I but not type-II interferon receptor knockout mice are susceptible to biliary atresia.

The etiology of biliary atresia (BA) is not yet understood, but recent studies have shown inflammation with an up-regulated interferon (IFN) activity in the intra- and extrahepatic bile ducts of patients with BA. These findings support an inflammatory/infectious cause of BA as mimicked in our infective murine model. To study the role of the IFN receptors in our model, we used mice with inactivated INF-alpha/beta receptor A129, with inactivated IFN-gamma receptor G129, or inactivation of both interferon receptors AG129 as well as the wild type controls W129. Mice were infected with rotavirus within 48h of birth and 7 d postpartum. The incidence of BA in each group was determined during a 3 wk period. In the second week the virus load was measured. BA incidence was 76% in A129 and 67% in AG129 animals, whereas in the G129 group only 33% of the pups developed BA. The wild type presented with a BA-incidence of 15%, while 7 d old mice failed to develop BA. There was no significant difference in the virus load of the livers between the groups independent of clinical symptoms. In conclusion, inactivation of type I INF-receptor significantly increases the incidence of BA following postpartal rotavirus infection. This effect is independent of the presence of type II-INF-receptors. Thus, in our model a type I IFN-linked deregulation of the innate immune system appears to be crucial for the induction of biliary atresia.

Computerized three-dimensional study of a rotavirus model of biliary atresia: comparison with human biliary atresia.

Biliary atresia is a panbiliary disease causing obstructive jaundice in neonates and infants. The clinical spectrum can be broadly categorized into the fetal and perinatal types. A consistent animal model that accurately mimics the whole clinical spectrum of biliary atresia is not yet available. However, rotavirus infection of neonatal mice has been shown to produce atresia in the biliary system. This study investigates the three-dimensional computerized morphology of the murine neonatal model comparing with age-matched control mice. Newborn Balb/c mice were injected intraperitoneally with rhesus rotavirus within 24-48 h after birth. Control mice received 0.9% NaCl. Pups with symptoms of cholestasis were sacrificed from the 5th to the 15th postinjection day, as were age-matched controls. Their hepatobiliary tissues were prepared for three-dimensional computerized image reconstruction. Rotavirus infection caused obliteration of the intrahepatic bile ducts and single to multiple atresias in the extrahepatic bile duct. At 15 days postinjection, intrahepatic ductal proliferation appeared, and the three-dimensional appearances of the intrahepatic biliary structures were similar to the human disease. Cystic duct and gallbladder dilatation was frequently seen in this model, and this feature distinguishes it from the human disease in which the gallbladder is almost always atretic. This rotavirus murine model demonstrates many of the features of human perinatal biliary atresia, and can be used as an investigative tool to further study the pathogenesis of biliary atresia.