The aim of the research. To identify changes in tryptophan and cytokine metabolism in synovial joint tissue in rheumatoid arthritis. Research materials and methods. The experiments were performed on 40 WISTAR rats. At the beginning of the study, each animal of the experimental groups received an intraperitoneal injection of collagen type 2 solution (Chondrex, Inc., USA) in Freund's incomplete adjuvant. The content of tryptophan, kynurenine, 3-hydroxykinurinine, L-5-hydrotryptophan by HPLC with fluorimetric and spectrophotometric detection, and the concentration of cytokines: IL1b, IL6, IL10, IL17, IL18, TNFa were determined in the tissues of the synovial membrane of the knee joint. They were determined using Rat Inflammation Panel V02 multiplex assay kits (Biolegend, USA) on a Cytomics FC500 flow cytofluorimeter (Beckman Coulter, USA). Statistical analysis was performed using the Jamovi program version 2.3.Results. The concentration of cytokines: IL1b, IL6, IL10, IL17, IL18, TNFa was found to be high during the acute development of rheumatoid arthritis. With experimental rheumatoid arthritis, the content of tryptophan metabolites along the kynurenine pathway increases and the concentration of metabolites along the serotonin pathway decreases. Direct positive correlations of IL1b, IL6, IL10, IL17, IL18, TNFa with the content of tryptophan metabolites along the kynurenine pathway have been established.Conclusions. Tryptophan metabolism and IL1b, IL6, IL10, IL17, IL18, and TNFa content are altered in rheumotoid arthritis.
