The role of redox imbalance in relation to immunological process in adjuvant arthritis

The model of adjuvant arthritis (AA) is well characterized concerning the immunological processes involved. However knowledge on the participation of redox imbalance in the progression of AA is scarce. The link between oxidative stress (OS) and immunological status in arthritis should be more precisely investigated. In our experiments, we focused on AA development in the time domain. AA was induced in rats by a single intradermal injection of Mycobacterium butyricum in incomplete Freund’s adjuvant. All experiments included healthy animals (HC) and arthritic animals not treated. We confirmed that the clinical parameters hind paw volume and body weight became significantly modified starting around day 14 after AA induction and this change was maintained until the end of the experiment (day 28). We obtained a good agreement of clinical parameters with parameters of OS. Measurements of plasmatic protein carbonyls revealed damage of proteins caused by OS. Progression of lipid peroxidation in AA was described by analysis of TBARS, HNE- /MDA-protein adducts and F2 isoprostane levels in plasma. Total antioxidant status analyzed in plasma was decreased significantly in both the acute (day 21) and the subchronic phase (day 28) of AA. Further we focused on evaluating CoQ9 plasmatic levels. The arthritic process increased significantly the level of CoQ9 in comparison to HC. Evidently, the arthritic process stimulates the synthesis of CoQ9 and its transport to plasma. In the model of AA, we observed already on experimental day 7 that AA was accompanied by an increased number of neutrophils in blood and by a more pronounced spontaneous as well as phorbol myristate acetate stimulated chemiluminescence. As the changes in neutrophils occur before the clinical parameter HPV starts to be increased, for further evaluation of neutrophil functionality we chose experimental day 7. The functionality of peripheral blood neutrophils in AA was described by phagocytosis, oxidative burst and metabolic activity. Both phagocytosis and oxidative burst were increased due to arthritis, and that despite the decreased metabolic activity. Analysis of OS in tissue showed changed GGT activity in spleen and joint homogenate accompanied by increased chemiluminescence. The OS parameters were in close relationship with time profiles of selected cytokines, chemokine MCP-1 and of C-reactive protein levels in plasma. Measurements of the immunoregulatory index in peripheral blood and lipoxygenase tissue activity (lung, liver) were also included. Our observations have evidenced the importance of pharmacological regulation of redox imbalance in arthritis. (VEGA 2/0090/08, COST B35, APVV-51-017905, APVV-21-055205

Glycine reduces platelet aggregation

It has been demonstrated that a wide variety of white blood cells and macrophages (i.e. Kupffer cells, alveolar and peritoneal macrophages and neutrophils) contain glycine-gated chloride channels. Binding of glycine on the receptor stimulates Cl(−) influx causing membrane hyperpolarization that prevents agonist-induced influx of calcium. Since platelet-aggregation is calcium-dependent, this study was designed to test the hypothesis that glycine would inhibit platelet aggregation. Rats were fed diets rich of glycine for 5 days, while controls received isonitrogenous valine. The bleeding time and ADP- and collagen-induced platelet aggregation were measured. Dietary glycine significantly increased bleeding time about two fold compared to valine-treated controls. Furthermore, the amplitude of platelet aggregation stimulated with ADP or collagen was significantly decreased in whole blood drawn from rats fed 2.5 or 5 % dietary glycine by over 50 %. Addition of glycine in vitro (1–10 mM) also blunted rat platelet aggregation in a dose-dependent manner. Strychnine, a glycine receptor antagonist, abrogated the inhibitory effect of glycine on platelet-aggregation in vitro suggesting the glycine works via a glycine receptor. Glycine also blunted aggregation of human platelets. Further, the glycine receptor was detected in both rat and human platelets by western blotting. Based on these data, it is concluded that glycine prevents aggregation of platelets in a dose-dependent manner via mechanisms involving a glycine receptor