Cholangiocyte Epithelial to Mesenchymal Transition (EMT) is a potential molecular mechanism driving ischemic cholangiopathy in liver transplantation

Donation after circulatory death (DCD) has expanded the donor pool for liver transplantation. However, ischemic cholangiopathy (IC) after DCD liver transplantation causes inferior outcomes. The molecular mechanisms of IC are currently unknown but may depend on ischemia-induced genetic reprograming of the biliary epithelium to mesenchymal-like cells. The main objective of this study was to determine if cholangiocytes undergo epithelial to mesenchymal transition (EMT) after exposure to DCD conditions and if this causally contributes to the phenotype of IC. Human cholangiocyte cultures were exposed to periods of warm and cold ischemia to mimic DCD liver donation. EMT was tested by assays of cell migration, cell morphology, and differential gene expression. Transplantation of syngeneic rat livers recovered under DCD conditions were evaluated for EMT changes by immunohistochemistry. Human cholangiocytes exposed to DCD conditions displayed migratory behavior and gene expression patterns consistent with EMT. E-cadherin and CK-7 expressions fell while N-cadherin, vimentin, TGFβ, and SNAIL rose, starting 24 hours and peaking 1–3 weeks after exposure. Cholangiocyte morphology changed from cuboidal (epithelial) before to spindle shaped (mesenchymal) a week after ischemia. These changes were blocked by pretreating cells with the Transforming Growth Factor beta (TGFβ) receptor antagonist Galunisertib (1 μM). Finally, rats with liver isografts cold stored for 20 hours in UW solution and exposed to warm ischemia (30 minutes) at recovery had elevated plasma bilirubin 1 week after transplantation and the liver tissue showed immunohistochemical evidence of early cholangiocyte EMT. Our findings show EMT occurs after exposure of human cholangiocytes to DCD conditions, which may be initiated by upstream signaling from autocrine derived TGFβ to cause mesenchymal specific morphological and migratory changes.

COVID-19 Infection Causing Liver Infarction, Severe Cholangiopathy, and Biliary Cast Syndrome

We present a patient with COVID-19 pneumonia with severe multi-organ failure who developed a liver infarction in the setting of acute illness and following recovery, had persistent cholestatic liver injury. On further evaluation, he was found to have a severe destruction of the intrahepatic bile ducts and biliary cast syndrome and ultimately, was felt to have severe ischemic cholangiopathy in the setting of recent COVID-19 infection. Because of the extent of destruction and persistent cholestasis, he is at risk of secondary biliary cirrhosis and is therefore undergoing a liver transplant evaluation. This case highlights a rare entity of liver infarction and severe cholangiopathy with biliary cast syndrome in the setting of COVID-19 infection. It is the first case of this reported to date, and its recognition in the presence of the COVID-19 pandemic is important. Keywords: Biliary cast, Cirrhosis, Cholangiopathy , COVID-19, Liver infarction.