To study the mechanism of treatment of rheumatoid arthritis with Tripterygium wilfordii Hook. f. (TWHF).
Chondrocytes from the resected knee joint cartilage of patients with rheumatoid and TWHF, dexamethasone, or (arthritis were isolated and cultured. IL-1 indomethacin of different concentrations were added into the culture solution overnight. Griess reagent was added to the supernatant to detect the content of NO. Chondrocytes were collected to examine the iNOS activity by detecting the conversion of L-14C-arginine into L-14C-citruline. The total RNA of chondrocyte was extracted and the iNOS-mRNA was examined by Northern blotting.
The inhibitory rates of NO production by TWHF of concentrations of 2 mg/L, 4 mg/L, 8 mg/L, and 16 mg/L were 10.8%, 25.48%, 55.17%, and 80.45% respectively. The inhibitory rates of iNOS activity by TWHF of concentrations of 2 mg/L, 4 mg/L, 8 mg/L, and 16 mg/L were 12.29%, 27.67%, 59.04%, and 85.06% respectively. Such inhibitory effects were dosage-dependent. TWHF ffectively inhibited the expression of iNOS-mRNA induced by IL-1 in chondrocyte (r = 0.976 and 0.974). Dexamethasone inhibited NO production, iNOS activity, and expression of iNOS-mRNA significantly but not dosage-dependently. Indomethcin only had weak inhibitory effect.
TWHF inhibits NO production in chondrocytes by limiting the transcription of iNOS gene, which may be one of the mechanisms of treatment of RA with TWHF.