OBJECTIVETo investigate the effects of sinomenine (SIN) and methotrexate (MTX) on the proliferation and apoptosis of in vitro cultured fibroblast-like synoviocytes (FLS) in rheumatoid arthritis (RA) patients, as well as the expression of osteoclast differentiation factor in FLS.

METHODSFLS were isolated from the synovium of RA patients and cultured in vitro. FLS were incubated with different concentrations of SIN and MTX respectively or combined: 0.001, 0.010, 0.100, 1.000 mg/mL SIN; 0.001, 0.010, 0.100, 1.000 mg/mL MTX; 0.001 mg/mL SIN + 0.001 mg/mL MTX, 0.010 mg/mL SIN + 0.010 mg/mL MTX, 0.100 mg/mL SIN + 0.100 mg/mL MTX, 1.000 mg/mL SIN + 1.000 mg/mL MTX, namely SIN1, 2, 3, 4 groups; MTX1, 2, 3, 4 groups and the combination 1, 2, 3, 4 groups. The medium without drugs was used as a control group. There was a total of 13 groups, each group with 3 complex holes. MTT was applied to detect the growth of FLS. The flow cytometry was applied to detect the apoptosis of FLS. The expressions of FLS receptor activator of nuclear factor kappa B ligand (RANKL) mRNA and osteoprotegerin (OPG) mRNA were observed by semi-quantitative RT-PCR.

RESULTSCompared with the control group, RA FLS proliferation OD values of all the drug groups were lower (P < 0.05). The RA FLS apoptosis OD value of the combination 3 group increased, the OPG mRNA expression increased, the expression of RANKL mRNA decreased with statistical difference (P < 0.05). The RA proliferation OD values of the SIN3 group and the MTX3 group increased when compared with the combination 3 group (P < 0.05).

CONCLUSIONSSIN and MTX had synergistic effects in inhibiting FLS. This might be one of the mechanisms for inhibiting RA bone damage.