Role of free radicals in liver diseases

Effect of preischemic treatment with fenofibrate, a peroxisome proliferator-activated receptor-α ligand, on hepatic ischemia-reperfusion injury in rats

Liver ischemia/reperfusion (I/R) injury is a serious clinical problem. The reactive oxygen species (ROS) and tumor necrosis factor alpha (TNF-α) are important mediators in liver I/R injury. This study was designed to investigate the effect of preischemic treatment with fenofibrate (Peroxisome proliferator-activated receptor- α agonist) on the oxidative stress and inflammatory response to hepatic I/R injury in rats. Hepatic I/R was induced by clamping the blood supply of the left lateral and median lobes of the liver for 60 min, followed by reperfusion for 4 h. Each animal group was pretreated with a single dose of fenofibrate (50 mg/kg body weight) intraperitoneally 1 h before ischemia. At the end of reperfusion, blood samples and liver tissues were obtained to assess serum alanine aminotransferase (ALT), TNF-α, hepatic malondialdehyde (MDA) and superoxide dismutase activity (SOD). Liver specimens were obtained and processed for light and electron microscopic study. Hepatic I/R induced a significant elevation of serum ALT and TNF-α with significant elevation of hepatic MDA and reduction of SOD activity. Histopathological examination revealed hepatic inflammation, necrosis and apoptosis. Preischemic treatment with fenofibrate at a dose of 50 mg/kg significantly attenuated the biochemical and structural alterations of I/R-induced liver injury.

Oxidized low-density lipoprotein is associated with viral load and disease activity in patients with chronic hepatitis C

BACKGROUND

The mechanisms of liver injury in chronic hepatitis C virus (HCV) infection are poorly understood. Recent evidence suggests that oxidative stress and lipid-peroxidation play a major role. The purpose of this study was to determine the serum level of oxidized low-density lipoprotein (ox-LDL), and evaluate its association with different clinically valuable parameters of liver disease in patients with chronic hepatitis C.

METHODS

Forty-five untreated chronic hepatitis C patients and 45 healthy adult volunteers, matched for age, sex and BMI, were enrolled. Blood samples were collected after 12 h of fasting, and serum bilirubin, albumin, liver aminotransferases, lipid profile, prothrombin time and ox-LDL were measured. Viral load of HCV was determined in patients. Liver biopsy was performed in patients and the stage of fibrosis and grade of necroinflammatory activity were determined. Healthy controls did not undergo liver biopsy.

RESULTS

Ox-LDL was significantly higher in HCV patients (42.54 ± 3.82 vs. 30.98 ± 1.66 μ/l, P < 0.01). Ox-LDL was significantly correlated to viral load (r = 0.457, P < 0.01), and grade of inflammation (r = 0.293, P < 0.05) in HCV patients. Ox-LDL was significantly higher in cirrhotic vs. noncirrhotic patients. No significant association was found between ox-LDL and Child-Pugh classification, serum albumin, liver enzymes, or prothrombin time.

CONCLUSION

This study provided new data from an in vivo setting which suggests the contribution of ox-LDL to HCV pathogenesis. Our results encourage further clinical studies to evaluate the potential diagnostic and therapeutic implications of ox-LDL in HCV patients.

Targeting the inflammation in HCV-associated hepatocellular carcinoma: a role in the prevention and treatment

Epidemiological, preclinical and clinical studies demonstrated that chronic inflammation induced by hepatitis C virus (HCV) is crucial in hepatocellular carcinogenesis. The interaction between hepatocytes and microenvironment regards virus, inflammatory and immunocompetent cells, chemo- and cyto-kines, reactive oxygen species (ROS) and nitric oxide (NO), generating cell transformation. We suggest hepatocarcinoma (HCC) as a model in which the targeting of microenvironment determine neoplastic transformation. The present review focuses on: the role of inflammation in carcinogenesis, the clinical impact of HCC and the inadequacy of the actual therapy, the chemoprevention targeting the microenvironment.

Combination therapy with andrographolide and d-penicillamine enhanced therapeutic advantage over monotherapy with d-penicillamine in attenuating fibrogenic response and cell death in the periportal zone of liver in rats during copper toxicosis

Long treatment regime with d-penicillamine is needed before it can exert clinically meaningful benefits in the treatment of copper toxicosis. The consequence of long-term d-penicillamine treatment is associated with numerous side effects. The limitations of d-penicillamine monotherapy prompted us to search for more effective treatment strategies that could decrease the duration of d-penicillamine therapy. The present study was designed to evaluate the therapeutic potential of d-penicillamine in combination with another hepatoprotective drug, andrographolide in treatment of copper toxicosis in rats. d-penicillamine treatment led to the excretion of copper through urine. Addition of andrographolide to d-penicillamine regime appeared to increase protection of liver by increasing the biliary excretion of copper and reduction in cholestatic injury. The early removal of the causative agent copper during combination treatment was the most effective therapeutic intervention that contributed to the early rectification of fibrosis in liver. Combination treatment reduced Kupffer cells accumulation and TNFα production in liver of copper exposed rats. In particular, andrographolide mediated the anti-inflammatory effect by inhibiting the cytokine production. However, another possible mechanism of cytoprotection of andrographolide was decreasing mitochondrial production of superoxide anions that resulted in better restoration of mitochondrial dysfunction during combination therapy than monotherapy. Furthermore, ROS inhibition by combination regimen resulted in significant decline in activation of caspase cascade. Inhibition of caspases attenuated apoptosis of hepatocytes, induced by chronic copper exposure. In summary, this study suggested that added benefit of combination treatment over use of either agent alone in alleviating the hepatotoxicity and fibrosis associated with copper toxicosis.

Liver disease and erythropoietic protoporphyria: A concise review

The porphyries are a group of metabolic disorders characterized by deficiencies in the activity of enzymes involved in the biosynthesis of heme. In erythropoietic protoporphyria (EPP), in the majority of cases an autosomal dominant disease, there is a mutation of the gene that encodes ferrochelatase (FECH). FECH deficiency is associated with increased concentrations of protoporphyrin in erythrocytes, plasma, skin and liver. The prevalence of this inherited disorder oscillates between 1:75 000 and 1:200 000. Clinical manifestations of EPP appear in early infancy upon first exposure to the sun. Nevertheless, approximately 5%-20% of patients with EPP develop liver manifestations. Retention of protoporphyrin in the liver is associated with cholestatic phenomena and oxidative stress that predisposes to hepatobiliary disease of varying degrees of severity, such as cholelithiasis, mild parenchymal liver disease, progressive hepatocellular disease with end-stage liver disease and acute liver failure. Liver damage is the major risk in EPP patients, so surveillance and frequent clinical and biochemical liver follow-up is mandatory. The diagnostic approach consists in detecting increased levels of protoporphyrin, decreased activity of FECH and genetic analysis of the FECH gene. A variety of non-surgical therapeutic approaches have been adopted for the management of EPP associated with liver disease, but none of these has been shown to be unequivocally efficacious. Nevertheless, some may have a place in preparing patients for liver transplantation. Liver transplantation does not correct the constitutional deficiency of FECH. Consequently, there is a risk of recurrence of liver disease after liver transplantation as a result of continuing overproduction of protoporphyrin. Some authors recommend that bone marrow transplantation should be considered in liver allograft recipients to prevent recurrence of hepatic disease.