CD73 maintains hepatocyte metabolic integrity and mouse liver homeostasis in a sex-dependentmanner
Background & AimsMetabolic imbalance and inflammation are common features of chronic liver diseases. Molecular factors controlling these mechanisms represent potential therapeutic targets. One promising target is CD73, the major enzyme that dephosphorylates extracellular adenosine monophosphate (AMP) to form the anti-inflammatory adenosine. In normal liver, CD73 is expressed on pericentral hepatocytes, which are important for long-term liver homeostasis. The aim of this study was to determine if CD73 has non-redundant hepatoprotective functions. Approach & ResultsWe generated mice with a targeted deletion of the CD73-encoding gene (Nt5e) in hepatocytes (CD73-LKO). Deletion of hepatocyte Nt5e resulted in approximately 70% reduction in total liver CD73 protein (p<0.0001). Male and female CD73-LKO mice developed normally during the first 21 weeks, without significant liver phenotypes. Between 21-42 weeks, the CD73-LKO mice developed spontaneous onset liver disease with significant severity in male mice. Notably, middle-aged male CD73-LKO mice displayed hepatocyte swelling and ballooning (p<0.05), inflammation (p<0.01) and variable steatosis. Female CD73-LKO mice had lower serum albumin (p<0.05) and elevated inflammatory markers (p<0.01), but did not exhibit the spectrum of histopathologic changes characteristic of the male mice, potentially due to compensatory induction of adenosine receptors. Serum analysis and proteomic profiling of hepatocytes from male CD73-LKO mice revealed significant metabolic imbalance, with elevated blood urea nitrogen (p<0.0001) and impairments in major metabolic pathways, including oxidative phosphorylation and AMP-activated protein kinase (AMPK) signaling. There was significant hypo-phosphorylation in AMPK substrate in CD73-LKO livers (p<0.0001), while in isolated hepatocytes treated with AMP, soluble CD73 induced AMPK activation (p<0.001). ConclusionsHepatocyte CD73 supports long-term metabolic liver homeostasis through AMPK in a sex-dependent manner. These findings have implications for human liver diseases marked by CD73 dysregulation.