Serum levels of advanced oxidation protein products, malonyldialdehyde, and total radical trapping antioxidant parameter in patients with chronic hepatitis C

Evaluation of the effect of direct-acting antiviral agents on melatonin level and lipid peroxidation in chronic hepatitis C patients

Background: Oxidative stress and its end products, such as malondialdehyde (MDA) play a leading role in the pathogenesis of hepatitis C. Melatonin is a hormone that helps regulate circadian rhythms, which likely play a role in infectious diseases in terms of susceptibility, clinical expression, and outcome. Objective: The present study was conducted to assess serum malondialdehyde and melatonin levels in patients with chronic hepatitis C infection before and after the intake of direct-acting antivirals. Method: Forty hepatitis C patients were the subjects of this study. While ten healthy volunteers who matched in age and socioeconomic status served as the control subjects. Malondialdehyde and melatonin were assayed in the serum of the three groups, and the results were statistically analyzed. Results: Hepatitis C patients had significantly higher malondialdehyde (p < 0.001) but significantly lower melatonin (p < 0.001) as compared to the healthy controls. After 12 weeks of treatment with direct-acting antivirals, the malondialdehyde level decreased significantly (p < 0.001) and the melatonin level increased significantly (p < 0.001). A significant negative correlation between malondialdehyde and melatonin was observed. Conclusion: The present findings suggest that treatment of hepatitis C patients with Direct-acting antivirals improves liver function parameters and antioxidant profiles.

Advanced oxidation protein products play critical roles in liver diseases

There is a complex oxidant and antioxidant system that maintains the redox homoeostasis in the liver. While suffering from exogenous or endogenous risk factors, the balance between oxidants and antioxidants is disturbed and excessive reactive oxygen species are generated, resulting in oxidative stress. Oxidative stress is prevalent in various liver diseases and is thought to be involved in their pathophysiology. Advanced oxidation protein products are generated under conditions of oxidative damage and are newly described protein markers of oxidative stress. Previous studies have underscored the universal pathogenic roles of oxidation protein products in various diseases. However, investigations into how these products participate in the development of liver diseases have been superficial and insufficient. In this review, we highlight the current understanding of the roles of advanced oxidation protein products in liver disease pathogenesis and the underlying mechanisms. Moreover, we summarize the current studies on advanced oxidation protein products in infectious and noninfectious, acute and chronic liver diseases. Different strategies for targeting these advanced oxidation protein products and future perspectives, which may pave the way for developing new therapeutic strategies, will also be discussed here.

Hepatoprotective effects of rosmarinic acid: Insight into its mechanisms of action

Liver diseases such as hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma are one of the major health challenges in the world and many conditions such as inadequate nutrition, viral infection, ethanol and drug abuse, xenobiotic exposure, and metabolic diseases have been implicated in the development and progression of liver diseases. Several factors including lipid peroxidation, production of reactive oxygen species (ROS), peroxynitrite formation, complement factors and proinflammatory mediators, such as cytokines and chemokines, are involved in hepatic diseases. Rosmarinic acid (RA) is a natural phenolic compound found mainly in the family Lamiaceae consisting of several medicinal plants, herbs and spices. Several biological activities have been reported for RA and these include antioxidant properties as a ROS scavenger and lipid peroxidation inhibitor, anti-inflammatory, neuroprotective and antiangiogenic among others. This review is aimed at discussing the effects of RA on the liver, highlighting its hepatoprotective potential and the underlying mechanisms.

Oxidative stress as a crucial factor in liver diseases

Redox state constitutes an important background of numerous liver disorders. The redox state participates in the course of inflammatory, metabolic and proliferative liver diseases. Reactive oxygen species (ROS) are primarily produced in the mitochondria and in the endoplasmic reticulum of hepatocytes via the cytochrome P450 enzymes. Under the proper conditions, cells are equipped with special molecular strategies that control the level of oxidative stress and maintain a balance between oxidant and antioxidant particles. Oxidative stress represents an imbalance between oxidant and antioxidant agents. Hepatocytic proteins, lipids and DNA are among the cellular structures that are primarily affected by ROS and reactive nitrogen species. The process results in structural and functional abnormalities in the liver. Thus, the phenomenon of oxidative stress should be investigated for several reasons. First, it may explain the pathogenesis of various liver disorders. Moreover, monitoring oxidative markers among hepatocytes offers the potential to diagnose the degree of liver damage and ultimately to observe the response to pharmacological therapies. The present report focuses on the role of oxidative stress in selected liver diseases.

Advanced oxidation protein products induce intestine epithelial cell death through a redox-dependent, c-jun N-terminal kinase and poly (ADP-ribose) polymerase-1-mediated pathway

Advanced oxidation protein products (AOPPs), a novel protein marker of oxidative damage, have been confirmed to accumulate in patients with inflammatory bowel disease (IBD), as well as those with diabetes and chronic kidney disease. However, the role of AOPPs in the intestinal epithelium remains unclear. This study was designed to investigate whether AOPPs have an effect on intestinal epithelial cell (IEC) death and intestinal injury. Immortalized rat intestinal epithelial (IEC-6) cells and normal Sprague Dawley rats were treated with AOPP-albumin prepared by incubation of rat serum albumin (RSA) with hypochlorous acid. Epithelial cell death, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit activity, reactive oxygen species (ROS) generation, apoptosis-related protein expression, and c-jun N-terminal kinase (JNK) phosphorylation were detected both in vivo and in vitro. In addition, we measured AOPPs deposition and IEC death in 23 subjects with Crohn's disease (CD). Extracellular AOPP-RSA accumulation induced apoptosis in IEC-6 cultures. The triggering effect of AOPPs was mainly mediated by a redox-dependent pathway, including NADPH oxidase-derived ROS generation, JNK phosphorylation, and poly (ADP-ribose) polymerase-1 (PARP-1) activation. Chronic AOPP-RSA administration to normal rats resulted in AOPPs deposition in the villous epithelial cells and in inflammatory cells in the lamina propria. These changes were companied with IEC death, inflammatory cellular infiltration, and intestinal injury. Both cell death and intestinal injury were ameliorated by chronic treatment with apocynin. Furthermore, AOPPs deposition was also observed in IECs and inflammatory cells in the lamina propria of patients with CD. The high immunoreactive score of AOPPs showed increased apoptosis. Our results demonstrate that AOPPs trigger IEC death and intestinal tissue injury via a redox-mediated pathway. These data suggest that AOPPs may represent a novel pathogenic factor that contributes to IBD progression. Targeting AOPP-induced cellular mechanisms might emerge as a promising therapeutic option for patients with IBD.

Role of the Nrf2-ARE pathway in liver diseases

The liver is a central organ that performs a wide range of functions such as detoxification and metabolic homeostasis. Since it is a metabolically active organ, liver is particularly susceptible to oxidative stress. It is well documented that liver diseases including hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma are highly associated with antioxidant capacity. NF-E2-related factor-2 (Nrf2) is an essential transcription factor that regulates an array of detoxifying and antioxidant defense genes expression in the liver. It is activated in response to electrophiles and induces its target genes by binding to the antioxidant response element (ARE). Therefore, the roles of the Nrf2-ARE pathway in liver diseases have been extensively investigated. Studies from several animal models suggest that the Nrf2-ARE pathway collectively exhibits diverse biological functions against viral hepatitis, alcoholic and nonalcoholic liver disease, fibrosis, and cancer via target gene expression. In this review, we will discuss the role of the Nrf2-ARE pathway in liver pathophysiology and the potential application of Nrf2 as a therapeutic target to prevent and treat liver diseases.

Oxidative stress and liver disease

In humans, oxidative stress and antioxidant defenses are the sum of a complicated network of enzymatic and non-enzymatic processes. Depending on the stage and severity of diseases, a patient's antioxidant armamentarium may increase as an appropriate response to an oxidant challenge, whereas others may decrease as an indication of unbalanced consumption. In some cases, the formation of reactive oxygen species is a requisite and healthy event. In fact, free radicals can affect intracellular signal transduction and gene regulation, resulting in cytokine production essential to the inflammatory process. In many other cases, especially liver diseases, excessive oxidative stress undoubtedly contributes to the progression and pathological findings of disease and serves as a prognostic indicator. Reactive oxygen species are highly reactive molecules that are naturally generated in small amounts through metabolism and could damage cellular molecules such as lipids, proteins or DNA. Oxidative stress plays a major role in many liver diseases. In this review, we summarize the biological character of free radicals and some antioxidants, and the related methods of analysis. Then, we discusses the association of oxidative stress to many types of liver diseases.

Persistent oxidative stress in patients with chronic active hepatitis-C infection after antiviral therapy failure

BACKGROUND/AIMS

Oxidative stress and hepatocellular pathological changes are common associations with chronic hepatitis C virus (CHC) disease. The aim of this study was to assess serum antioxidant-oxidant (Redox) balance in patients with CHC infection before and after intake of the traditional antiviral therapy (pegylated interferon α-2b and oral ribavirin).

PATIENTS AND METHODS

Blood samples from 50 biopsy-proven CHC patients, with no prior anti-viral treatment and persistently elevated serum transaminase levels for 6 months, as well as 15 age- and sex-matched healthy subjects were used for determination of the antioxidants: reduced glutathione (GSH), superoxide dismutase (SOD), α tocopherol and ascorbic acid as well as lipid peroxidation (LPO) index (malondialdehyde [MDA]). The measurements were repeated in the diseased group 25 weeks after pegylated interferon α-2b and ribavirin combination therapy.

RESULTS

Serum levels of bilirubin, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were significantly higher in CHC patients than in the control group (P < 0.05). Pretreatment serum MDA values were significantly higher in patients with CHC infection than the control group (P < 0.001), while serum antioxidant levels were significantly lower (P < 0.001). Responders (10 patients) had lower pretreatment serum levels of MDA than non-responders (35 patients) (P < 0.001). Both groups were comparable for the antioxidant serum levels. There was significant negative correlation between serum MDA and serum SOD, GSH, α tocopherol, and ascorbic acid concentrations in CHC patients. On the other hand, there was no correlation between the studied parameters and serum bilirubin, albumin, ALT, and AST.

CONCLUSIONS

Redox imbalance was detected in patients with CHC. Responders had significantly lower levels of MDA than non-responders. Serum MDA may be used as a pretreatment predictor of response to antiviral treatment in patients with CHC.