Hepatic Ischemia-reperfusion Injury in Mice was Alleviated by Rac1 Inhibition - More Than Just ROS-inhibition

Background and Aims:Reducing reactive oxygen species(ROS)production has proven an effective way for allevi-ating oxidative stress during ischemia-reperfusion injury(IRI).Moreover,inhibition of Rac1 could reduce ROS pro-duction and prevent oxidative stress injury.Previous stud-ies have suggested a positive interactivation feedback loop between Rac1 and hypoxia-inducible factor(HIF)-1α,the latter being up-regulated early during ischemia.The posi-tive inter-activation between Rac1 and HIF-1αwould ag-gravate ROS production,thereby promoting IRI.This study was designed to verify the effects of Rac1 inhibition on he-patic IRI both at animal and cellular levels and to explore the interaction between Rac1 and HIF-1αduring hepatic IRI.Methods:C57B/6 mice and AML-12 cells were used for the construction of hepatic IRI animal and cell models.Rac1 inhibition was achieved by NSC23766(a specific Rac1 inhibitor).Lentiviral vectors were used for Rac1 knock-down.At designated time points,serum and liver tissues were collected from the mice and treated cells were col-lected for further analysis.Results:NSC23766 treatment significantly alleviated the hepatic IRI in mice,manifesting as lower vacuolation score and less apoptosis cells,lower ROS and serum/liver alanine aminotransferase/aspartate aminotransferase levels,and fewer activated inflammatory cells.IRI of AML-12 was also alleviated by 50μM NSC23766 or Rac1-knockdown,manifesting as reduced cell apoptosis,less extensive interruption of mitochondrial membrane po-tential,down-regulation of apoptosis,and effects on DNA damage-related proteins.Interestingly,Rac1 knockdown also down-regulated the expression level of HIF-1α.Con-clusions:Our study supports a protective effect of Rac1 inhibition on hepatic IRI.Aside from the classic topics of reducing ROS production and oxidative stress,our study showed an interaction between Rac1 and HIF-1αsignaling during hepatic IRI.