In the present study, the lipid peroxidation product, i.e., MDA levels, has increased significantly in erythrocytes of patients with osteoarthritis. Rise in MDA could be due to increased generation of reactive oxygen species (ROS) due to the excessive oxidative damage generated in these patients. These oxygen species in turn can oxidize many other important biomolecules, including membrane lipids. Similar results of elevated MDA levels have been reported in patients with rheumatic disease.
We observed a significant decrease in the levels of erythrocyte GSH, ascorbic acid and plasma vitamin E (non-enzymatic antioxidant defense system) in patients with osteoarthritis when compared to controls. The decrease in the levels of these non-enzymatic antioxidant parameters may be due to the increased turnover for preventing oxidative damage in these patients, suggesting an increased defense against oxidant damage in osteoarthritis. Similar results of decreased vitamin E levels were reported by Scherak et al
In our study, the erythrocyte antioxidant enzymes', i.e., of SOD and GPx, activities have been increased significantly in patients with osteoarthritis. Similar results of raised SOD and GPX activities have been reported in patients with rheumatic diseases.
SOD is an important antioxidant enzyme having an antitoxic effect against superoxide anion. The over-expression of SOD might be an adaptive response, and it results in increased dismutation of superoxide to hydrogen peroxide. GPX, an oxidative stress inducible enzyme, plays a significant role in the peroxyl-scavenging mechanism and in maintaining functional integration of the cell membranes.
The rise in the levels of GPX could be due to its induction to counter the effect of increased oxidative stress. Ostalowska et al.
have reported increased activities of SOD, glutathione peroxidase and glutathione reductase in synovial fluid of patients with primary and secondary osteoarthritis of the knee joint.
The glutathione - S - transferases are a group of multifunctional proteins which play a central role in detoxification of electrophilic chemicals and the hepatic removal of potentially harmful hydrophobic compounds from blood.
We have observed a significant increase in the levels of GST patients with osteoarthritis compared to controls. Similar reports of raised GST levels were observed.
The rise in the levels of GST could be due to its induction to counter the effect of increased oxidative stress.