These results suggest that HMGB1 plays a role in virus induced BA pathogenesis and could be a target for therapeutic interventions in a subset of patients with BA and high HMGB1. (Hepatology 2021;74:864-878). B iliary atresia (BA) is a disease of infancy in which a devastating fibroinflammatory cholangiopathy occurs, leading to obstructive jaundice. BA leads to end-stage liver disease (ESLD). (1)(2)(3)(4) In the United States, the incidence of BA is 1 in 15,000 births, (5) and it is the most common indication for pediatric liver transplantation. (6,7) In an effort to restore bile flow, a Kasai hepatoportoenterostomy (HPE) is typically performed soon after diagnosis. (8) However, even if an HPE is performed and cholestasis resolves, bile duct proliferation and fibrosis may progress, (7) resulting in the development of portal hypertension and the complications of ESLD. (9) It is estimated that 60% of the patients who overcome perinatal cholestasis will still need a liver transplantation before the age

No abstract

States. In the murine model of BA, Rhesus rotavirus (RRV) VP4 surface protein determines biliary duct tropism. In this study, we investigated how VP4 governs induction of murine BA. Newborn mice were injected with 16 strains of rotavirus and observed for clinical symptoms of BA and mortality. Cholangiograms were performed to confirm bile duct obstruction. Livers and bile ducts were harvested 7 days postinfection for virus titers and histology. Flow cytometry assessed mononuclear cell activation in harvested cell populations from the liver. Cytotoxic NK cell activity was determined by the ability of NK cells to kill noninfected cholangiocytes. Of the 16 strains investigated, the 6 with the highest homology to the RRV VP4 (Ͼ87%) were capable of infecting bile ducts in vivo. Although the strain Ro1845 replicated to a titer similar to RRV in vivo, it caused no symptoms or mortality. A Ro1845 reassortant containing the RRV VP4 induced all BA symptoms, with a mortality rate of 89%. Flow cytometry revealed that NK cell activation was significantly increased in the disease-inducing strains and these NK cells demonstrated a significantly higher percentage of cytotoxicity against noninfected cholangiocytes. Rotavirus strains with Ͼ87% homology to RRV's VP4 were capable of infecting murine bile ducts in vivo. Development of murine BA was mediated by RRV VP4-specific activation of mononuclear cells, independent of viral titers.cholangiocytes; natural killer cells; rotavirus; RRV; VP4 BILIARY ATRESIA (BA) is a neonatal disease characterized by obstructive cholangiopathy of extrahepatic bile ducts, leading to chronic cholestasis and biliary cirrhosis. The incidence is estimated at 1 in 8,000 -15,000 live births (27). Afflicted infants present with jaundice, acholic stool, and failure to thrive. Early diagnosis and surgical intervention with a Kasai portoenterostomy to establish biliary drainage are essential. Even after successful drainage, the progressive nature of this disease causes end-stage liver disease requiring liver transplantation for survival. BA remains the most common indication for liver transplantation in children (2). The importance of understanding the pathogenesis of BA is crucial such that alternative treatment options can be developed.The etiology of BA remains unknown but likely is multifactorial and may include viral infection of the biliary tree (6,7,16,20,28) with subsequent immune-mediated duct injury (4,15,26). Several viruses have been isolated from the livers of BA patients including group C rotaviruses (20). A well-established murine model of BA is employed to study disease pathogenesis (21). Intraperitoneal injection of neonatal BALB/c mice with Rhesus rotavirus (RRV) leads to symptoms (jaundice, acholic stools, bilirubinuria) and bile duct obstruction that mimic human disease (1,18). Previous studies demonstrated the unique tropism of RRV to the cholangiocyte (biliary epithelial cells) (12,23) and that development of the murine model is virus strain dependent (1). In a previous study, it was sho...

Cystic biliary atresia (CBA), a rare cystic expansion of atretic extrahepatic bile ducts in young infants, overlaps in age at presentation and imaging features with early choledochal cysts (CC). Treatment and prognosis differ; histologic differences are unsettled. We compared 10 patients with CBA, 1975 to 2015, to an age-similar cohort of 13 infants, and to older patients who had surgery for CC. Operative details, imaging, and clinical courses were correlated to pathologic specimens. Immunostains for smooth muscle actin and myosin heavy chain were used to evaluate cyst walls and atretic segments. CBA cysts typically lacked epithelium and inflammation; cyst walls had an inner, dense cicatricial layer associated with myofibroblastic (MF) hyperplasia that often delaminated producing a grossly visible inner cyst wall. Seven proximal biliary remnants in CBA featured circumferential peribiliary MF hyperplasia/fibrosis with little or no inflammation, similar to isolated BA. Extrahepatic atresia was usually both proximal and distal to the cyst. Features in 10/13 CC from infants and 8/8 CC in older patients had mostly preserved uninjured epithelium and no subepithelial cicatrix. Mural smooth muscle (absent in CBA) was present to some extent in CC at all ages. Unexpectedly, focal MF hyperplasia and laminar sclerosis was present in a few CC in infants, resembling CBA. CBA and infant CC are distinct histologic entities that occasionally overlap. CBA bile duct injury mimics non-CBA. Cystification is an aberrant manifestation of stromal proliferation in BA. The current management approach assuming CBA and CC in infants are 2 separate disease processes is supported but caution is advised.

Biliary atresia (BA) is a neonatal obstructive cholangiopathy which progresses to end stage liver disease, often requiring transplantation. The murine model of BA, employing rhesus rotavirus (RRV), parallels human disease and has been used to elucidate mechanistic aspects of a virus induced biliary cholangiopathy. We previously reported that RRV VP4 gene plays an integral role in activating the immune system and induction of BA. Utilizing rotavirus binding and blocking assays, this study elucidated how RRV VP4 protein governs cholangiocyte susceptibility to infection both in vitro and in vivo in the murine model of BA. We identified the amino acid sequence on VP4 and its cholangiocyte binding protein, finding that the sequence is specific to those rotavirus strains which cause an obstructive cholangiopathy. Pretreatment of murine and human cholangiocytes with this VP4 derived peptide (TRTRVSRLY), significantly reduced RRV’s ability to bind and infect the cells. However, the peptide did not block cholangiocyte binding of TUCH and Ro1845, strains which do not induce murine BA. The SRL sequence within TRTRVSRLY is required for cholangiocyte binding and viral replication. The cholangiocyte membrane protein bound by SRL was found to be Hsc70. Inhibition of Hsc70 by siRNAs reduced RRV’s ability to infect cholangiocytes. This virus-cholangiocyte interaction is also seen in vivo in the murine model of BA, where inoculation of mice with TRTRVSRLY peptide significantly reduced symptoms and mortality in RRV-injected mice. Conclusion The tri-peptide SRL on RRV VP4 binds to the cholangiocyte membrane protein Hsc70 defining a novel binding site governing VP4 attachment. Investigations are underway to determine the cellular response following this interaction to understand how it contributes to the pathogenesis of BA.