Pyrophosphate Homeostasis and Hepatic Expression of ABCC6. Pilot Study in Liver Transplantation

In animals, normal hepatic expression of ABCC6 (ATP-binding transporter cassette, subfamily C, member 6) determines plasma pyrophosphate (PPi) concentration. PPi prevents the formation of hydroxyapatite crystals on tissues by precipitation of calcium and inorganic phosphate (Pi). It is an endogenous compound whose deficiency causes diffuse vascular calcifications in certain rare monogenic diseases, including the elastic pseudoxanthoma caused by the mutation of ABCC6. PPi is produced by enzymatic transformation of extracellular ATP and, in animals, the liver is the main supplier of ATP and PPi (more than 90%). In humans, liver transplantation offers the possibility of correlating the plasma concentration of PPi ([PPi]pl) with hepatic expression of ABCC6. Liver transplantation is performed in the treatment of chronic liver failure (Child B or C) or, in the absence of liver failure, in the treatment of hepatocellular carcinoma. By measuring[PPi]pl before transplantation and after liver function restoration and by measuring ABCC6 in the diseased liver and healthy liver, it is possible to determine whether liver failure is associated with decreased[PPi]pl and decreased liver expression of ABCC6, which is the objective of our pilot study. Its interest is to establish a physiopathological link between the frequent vascular calcifications in obese patients with hepatic steatosis and the production of PPi.

prupose: Look for a deficit in[PPi]pl in patients before the transplant compared to the phase of restoration of liver function