Effect of quercetin regulating the expression of B cell lymphoma/leukemia-2, B cell lymphoma/leukemia-2 associated X protein on apoptosis of fibroblast-like synoviocytes in human rheumatoid arthritis

Abstract

Objective To observe the effect of Quercetin regulating the expression levels of B cell lymphoma/leukemia-2 associated X protein (bax), B cell lymphoma/leukemia-2 (bcl-2) on the apoptosis of human rheumatoid arthritis fibroblasts-like synoviocytes (RAFLSs). Methods The synovial tissues were collected from patients with rheumatoid arthritis (RA). The standard of diagnosis of RA was the criteria revised by American College of Rheumatology (ACR). Fresh synovial tissues were chopped into fragments, washed in sterile phosphate-buffered saline (PBS), and digested with collagenase to obtain synoviocytes. Human RAFLSs morphology was observed under light microscope. Flow cytometry was used to measure the expression of cluster of differentiation 3 (CD3), CD14, CD19 and CD90 on the cell surface of RAFLSs. Human RAFLSs were treated with different concentrations of quercetin (0, 100, 200, and 300 μmol/L) for 24 h. Western blotting was used to detect the expression of anti-apoptotic protein bcl-2 and pro-apoptotic protein bax. The effect of quercetin through bcl-2/bax gray ratio on the apoptosis of fibroblast-like synoviocytes (FLSs) was analyzed. Results As compared with control group (the bcl-2/bax value was 8.26±0.08), the bcl-2/bax in the quercetin-treated groups (100, 200, and 300 μmol/L) (bcl-2/bax values were 3.23±0.11, 0.26±0.05 and 0.12±0.03 respectively) significantly decreased (P<0.01). The apoptosis rate of RAFLSs in the control group (6.5%±0.9%) was significantly lower than in 100 μmol/L quercetin-treated group (19.9%±3.8%) (P<0.05), and 200, 300 μmol/L quercetin-treated groups (34.3%±6.7% and 42.5%±4.8% respectively) (P<0.01). Conclusion Quercetin can regulate the expression of bax and bcl-2 to influence RAFLSs apoptosis, and the apoptosis rate of RAFLSs is inversely proportional to the bcl-2/bax value. Key words: Quercetin; Rheumatoid arthritis; Fibroblastlike synoviocytes; B cell lymphoma/leukemia 2 associated X protein; B cell lymphoma/leukemia-2