Rhesus rotavirus receptor-binding site affects high mobility group box 1 release, altering the pathogenesis of experimental biliary atresia

Abstract

Biliary atresia (BA) is a neonatal inflammatory cholangiopathy that requires surgical intervention by Kasai portoenterostomy to restore biliary drainage. Even with successful portoenterostomy, most patients diagnosed with BA progress to end-stage liver disease, necessitating a liver transplantation for survival. In the murine model of BA, rhesus rotavirus (RRV) infection of neonatal mice induces an inflammatory obstructive cholangiopathy that parallels human BA. The model is triggered by RRV viral protein (VP)4 binding to cholangiocyte cell-surface proteins. High mobility group box 1 (HMGB1) protein is a danger-associated molecular pattern that when released extracellularly moderates innate and adaptive immune response. In this study, we investigated how mutations in three RRV VP4-binding sites, RRV^VP4-K187R (sialic acid-binding site), RRV^VP4-D308A (integrin α2β1-binding site), and RRV^VP4-R446G (heat shock cognate 70 [Hsc70]-binding site), affects infection, HMGB1 release, and the murine model of BA. Newborn pups injected with RRV^VP4-K187R and RRV^VP4-D308A developed an obstruction within the extrahepatic bile duct similar to wild-type RRV, while those infected with RRV^VP4-R446G remained patent. Infection with RRV^VP4-R446G induced a lower level of HMGB1 release from cholangiocytes and in the serum of infected pups. RRV infection of HeLa cells lacking Hsc70 resulted in no HMGB1 release, while transfection with wild-type Hsc70 into HeLa Hsc70-deficient cells reestablished HMGB1 release, indicating a mechanistic role for Hsc70 in its release. Conclusion: Binding to Hsc70 contributes to HMGB1 release; therefore, Hsc70 potentially serves as a therapeutic target for BA.