Molecular mechanisms of taurine effect on the metabolism of blood cells and chondrocytes of knee articular cartilage in patients with late-stage rheumatoid arthritis

Previously, we demonstrated that the development of rheumatoid arthritis (RA) is accompanied not only by inflammation but also by disturbances in central metabolic processes, which are reflected in altered expression of genes involved in energy metabolism. Given the insufficient efficacy of current therapies and the occurrence of adverse events in some cases, the use of nutrients, such as taurine, may be reasonable. Objective: to evaluate the effect of taurine on the expression of genes responsible for the main pathways of energy metabolism, as well as inflammatory and regenerative activity, during in vitro culture of blood cells and articular cartilage explants obtained from patients with late-stage RA. Material and methods. Blood samples and articular cartilage explants were obtained from 20 patients with RA (3 men and 17 women; mean age 62.2±10.9 years; mean disease duration 18.2 years) prior to knee joint arthroplasty. Blood cells and cartilage explants were cultured in the presence of 50 μM taurine. Gene expression in cartilage explants was assessed using reverse transcription and real-time polymerase chain reaction. Results and discussion. Cultivation of blood cells from patients with RA in the presence of 50 μM taurine resulted in a significant increase in the expression of genes encoding pyruvate kinase (PKM2), succinate dehydrogenase (SDHB), uncoupling protein 2 (UCP2), ATP synthase (ATP5B), and unc-51-like kinase 1 (ULK1). In cartilage explants, taurine also activated the expression of SDHB and UCP2 genes and, to a lesser extent, ULK1 (p=0.07). Moreover, cultivation of the studied tissues in the presence of taurine was associated with a marked decrease in the expression of tumor necrosis factor alpha (TNF-á). Culturing articular cartilage explants with taurine significantly increased the expression of the collagen type II gene (COL2A1). Conclusion. Taurine exerts a beneficial effect on energy metabolism by increasing the expression of genes responsible for oxidative phosphorylation and autophagy in blood cells and articular cartilage explants, while reducing the expression of the inflammatory marker – TNF-á. However, unlike chondrocytes, taurine also enhanced glycolytic activity and increased ATP synthase expression in blood cells. Enhancement of the regenerative potential of chondrocytes in cartilage explants from patients with RA in the presence of taurine is evidenced by increased expression of the collagen type II gene.