Activated AXL Protects Against Hepatic Ischemia-reperfusion Injury by Upregulating SOCS-1 Expression

Background: Hepatic ischemia-reperfusion (I/R) injury is the main factor affecting the morbidity and mortality associated with perioperative complications of liver transplantation and major hepatectomy. Axl is a member of the TYRO3, Axl, MERTK family and is involved in immune and Apoptosis processes in multiple organs. However, the role of Axl in hepatic I/R injury remains to be elucidated.

Methods: Mice pretreated with rmGas6 or R428 and mice tail vein injected with adeno-associated virus knockdown suppressor of cytokine signaling protein-1 (SOCS-1) underwent liver I/R surgery to detect the function of activated Axl in vivo. Primary hepatocytes undergo hypoxic reoxygenation injury in vitro.

Results: Axl expression was significantly upregulated, and phosphorylated-AXL was substantially downregulated in liver transplantation patients and hepatic I/R surgery mice. A mouse model of hepatic I/R injury showed that Axl activation reduced liver inflammation and liver cells Apoptosis. The inhibition of Axl activation (AXL-specific inhibitor R428) aggravated hepatic I/R injury, resulted in larger areas of liver injury, aggravated inflammatory response, and increased Apoptosis of liver cells. In addition, activated Axl promotes the expression level of SOCS-1 and inhibits Toll-like Receptor 4 and its downstream signaling pathways. Finally, SOCS-1 was knocked down with an adeno-associated virus, and activated Axl failed to protect against hepatic I/R injury.

Conclusions: Axl activation protects the liver from I/R injury by upregulating SOCS-1 and inhibiting the Toll-like Receptor 4/myeloid differentiation factor-88/nuclear factor kappa-B signaling axis. Targeting Axl may be a new therapeutic option for ameliorating hepatic I/R injury.