SkQ1 improves immune status and normalises the activity of antioxidant and nadph-generating enzymes in adjuvant-induced rheumatoid arthritis in rats

Abstract

Rheumatoid arthritis (RA) is a severe systemic autoimmune inflammatory disease. Oxidative stress and excessive formation of mitochondrial reactive oxygen species (ROS) are now considered to be the central pathogenetic mechanisms of connective tissue component destruction and the factors responsible for a highly active inflammatory process and autoimmune response. The aim of the present work was to evaluate the effect of mitochondrial-directed antioxidant 10-(6′-plastoquinonyl)decyltriphenylphosphonium (SkQ1) on immune status, intensity of free radical-induced oxidation and functioning of antioxidant system (AOS) and NADPH-generating enzymes in rats with adjuvant-induced RA. Laboratory animals were divided into 4 groups: a control group; a group of animals with RA; animals injected intraperitoneally with SkQ1 at a dose of 1250 nmol/kg every 24 hours during the next 8 days from day 7 of RA development, and animals given SkQ1 at a dose of 625 nmol/kg according to the above scheme. Material for the study was taken on day 15 after the start of the experiment. The rate of erythrocyte sedimentation, the level of circulating immune complexes, and the concentration of immunoglobulins A, M and G were determined in rats by enzyme immunoassay. The intensity of free radical-induced oxidation was assessed by iron-induced biochemiluminescence, diene conjugate content and aconitate hydratase activity. Enzyme activity and metabolite content in animal tissues were analysed spectrophotometrically. The results of the work showed that the development of RA was associated with an increase in the indicators of immune response and intensity of free radical-induced oxidation. The development of an imbalance in AOS functioning and an increase in the activity of NADPH-generating enzymes was also observed. The administration of SkQ1 resulted in a dose-dependent change in the oxidative status indicators towards the control, which was accompanied by the normalization of the immune status parameters. It seems that the tested compound decreased the level of mitochondrial ROS, resulting in an inhibition of the inflammatory response. The consequence of these changes could be inhibition of free radical generation by immunocompetent cells and subsequent mitigation of the severity of oxidative stress in the tissues.