Research ArticleProtective role of antithrombin in mouse models of liver injury

Background & AimsCoagulopathy caused by an imbalance of hemostatic factors is associated with the pathophysiology of liver disease. We have investigated the role of antithrombin (AT), a key anticoagulant serpin, in the onset of liver disease.MethodsLiver injury was induced by CCl4 injection and bile duct ligation (BDL) in wild type (WT) and AT-deficient (AT+/−) mice. Twenty-four hours after CCl4 treatment, aspartate-transaminase, alanine-transaminase, liver lesion size, leukocyte infiltration, and apoptosis were reduced in WT animals compared to AT+/− mice.ResultsAdministration of exogenous AT in AT+/− animals did not restore the values observed in WT mice, suggesting that intrahepatic AT might also offer protection against CCl4. In the BDL model, increased liver injury was also evident in AT+/− compared to WT mice. An 85 kDa covalent complex involving AT was identified in immunoblottings of liver lysates from CCl4-treated animals. This complex was also present in anoikis hepatocytes and H2O2-treated HepG2 cells, suggesting a role for AT in apoptosis. Expression of recombinant WT-AT by HEK-EBNA cells increased cell survival while expression of AT mutants, ΔR393 and R47C, did not modify viability. Finally, plasma anti-FXa activity was attenuated by liver injury, with AT+/− animals showing a greater reduction than WT mice.ConclusionsOur study reveals a protective role of AT against liver injury due to its recognized anticoagulant and anti-inflammatory action. AT may also act via a previously unrecognized antiapoptotic effect. The clinical implications of AT deficiency in patients with liver disease should be further addressed.