Objective: There is increasing evidence to suggest that toxic oxygen radicals play an essential role in the pathogenesis of ischemia/ reperfusion (I/R) injury in the kidney. This study was designed to investigate the effects of leflunomide, an isoxazole derivative and a unique immunomodulatory agent, in I/R-induced renal injury in rats. Methods: Forty female Sprague-Dawley rats were divided equally into four groups: (I) control (only leflunomide 10 mg/kg, intragastrically treated); (II) sham operated (only unilateral nephrectomy); (III) I/R; and (IV) leflunomide (10 mg/kg for two doses prior to experiment) plus I/R groups. In groups III and IV, after unilateral nephrectomy, the rats were subjected to 60 min of left renal pedicle occlusion, followed by 6 h of reperfusion. At the end of the reperfusion period, rats were killed and kidneys and blood were removed. Catalase, myeloperoxidase and xanthine oxidase activities, and malondialdehyde, nitric oxide and protein carbonyl levels were determined in renal tissue. Serum creatinine, blood urea nitrogen and aspartate aminotransferase were measured for the evaluation of renal function. In histopathological examination, renal damage was scored 0-3. Results: Group III animals demonstrated severe deterioration of renal function, renal morphology and a significant renal oxidative stress. Pretreatment of animals with leflunomide markedly attenuated renal dysfunction, morphological alterations, reduced elevated oxidative stress products levels and restored the depleted renal antioxidant enzyme. Conclusion:The findings imply that oxygen radicals play a causal role in I/R-induced renal injury, and leflunomide exerts renoprotective effects probably by the radical scavenging and antioxidant activities with immunomodulatory effect.

Cholestasis, or impaired bile flow, occurs in a wide variety of liver diseases and causes hepatic damage by retention and accumulation of toxic hydrophobic bile salts inducing persistent inflammation and oxidative stress. In the present research, we studied the effect of leflunomide, a novel immunosuppressive and anti-inflammatory agent against autoimmune disease, on hepatic damage produced by double ligature of the extrahepatic biliary duct in Wistar Albino rats. Cholestasis was done by double ligature and section of the extrahepatic biliary duct (BDL). Leflunomide was given i.g. 10 mg/kg/day. The severity of cholestasis and hepatic injury was determined by changes in the plasma enzyme activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and levels of direct bilirubin. Malondialdehyde (MDA), protein carbonyl (PC), nitric oxide (NO), catalase (CAT) and superoxide dismutase (SOD) were determined to the oxidative status in the liver tissue. Myeloperoxidase (MPO) activity and levels of tissue hydroxyproline (HPR) were determined to neutrophil activation and collagen accumulation, respectively. Further, histological changes were studied. Treatment with leflunomide markedly reduced serum transaminase activities as compared to BDL rats. At the same time leflunomide significantly inhibited increases in liver MDA, PC and NO levels and also attenuated the depletion of CAT and SOD in the liver after bile duct ligation. Similarly, increase in tissue MPO activity and HPR due to BDL was also attenuated by leflunomide treatment. These findings were supported by histopathological findings. These findings suggested that leflunomide can attenuate hepatic damage in extrahepatic cholestasis by prevention of oxidative stress and inflammatory process.

Hepatic ischemia-reperfusion (I/R) injury may be developed in some conditions, such as trauma, major hepatic resection, hemorrhagic shock or liver transplantation. I/R injury of the liver causes hepatocellular damage that may lead to hepatic failure. A considerable body of evidence indicates that reactive oxygen species (ROS) and inflammation may contribute to hepatocellular injury in liver I/R. Leflunomide is an isoxazole derivative, and a unique immunomodulatory agent. In the present study, we examined the effects of leflunomide on the neutrophil activation with oxidative stress and some antioxidant enzymes in the reperfusion following I/R in the rat liver. Thirty-two rats divided into four groups: group 1 (control); was given leflunomide 10 mg/kg, i.g.; group 2 (SHAM), animals were only laparotomized; group 3 (liver I/R), and group 4 (liver I/R + Leflunomide). In group 4, rats were pretreated with leflunomide (10 mg/kg, i.g.) two doses prior to experiment. In groups 3 and 4, occluding the hepatic pedicel for 60 min induced ischemia and reperfusion was allowed thereafter for 60 min. At the end of the reperfusion period, rats were sacrificed. superoxide dismutase, catalase, nitric oxide, xanthine oxidase, malondialdehyde, protein carbonyl and myeloperoxidase levels were determined in hepatic tissue as well as histological examination with H and E staining. Group 3 animals demonstrated severe deterioration of liver morphology and a significant liver oxidative stress. Pretreatment of animals with leflunomide markedly attenuated morphological alterations and neutrophil activation, reduced elevated oxidative stress products levels and restored the depleted hepatic antioxidant enzyme. The findings imply that ROS play a causal role in I/R-induced hepatic injury, and leflunomide exerts hepatoprotective effects probably by the anti-inflammatory effect with radical scavenging and antioxidant activities.

Inhibitors of 3-hydroxy-3methylglutarly coenzyme A, reductase, namely statins, exert pleiotropic actions beyond lipid-lowering effects. In ex vivo and in vitro studies, statins have antioxidative and antiinflammatory effects. Herein, we sought to determine whether treatment with fluvastatin (FV) would be beneficial in a rat model of common bile duct ligation (BDL)-induced liver injury. Female rats were subjected to a sham (n=10) or BDL (n=20). Obstructive jaundice was induced in rats by the ligation and division of the common bile duct. Three days after operation, rats subjected to CBDL were randomized to receive treatment with either FV (10 mg/kg) or saline every day over a 10 days experimental period. High levels of alanine aminotransferase, aspartate aminotransferase, and gamma glutamyltransferase decreased significantly (P<0.05) in animals treated with FV with compared to saline-administrated BDL animals. Compared with sham-operated rats, CBDL rats showed significantly higher levels of total nitrite and nitrate, malondihaldehyde, tumor necrosis factor alpha, myeloperoxidase, and lower concentrations of glutathione, superoxide dismutase, and catalase in the liver tissue (P<0.001). All of these changes were significantly attenuated (P<0.05) by treatment with FV after CBDL. CBDL was associated with increased apoptosis and nuclear factor kappa beta expression in saline-treated rats. Treatment with FV also decreased these parameters. These data support the view that FV ameliorates hepatic inflammation, lipid peroxidation, and tissue injury in rats subjected to CDBL. FV warrants further evaluation as an adjunctive treatment to ameliorate liver injury from extrahepatic biliary obstruction.