To detect the concentrations of interleukin-18 (IL-18) and prostaglandin E2(PGE2) in synovial fluid (SF), and to determine the role of IL-18 and PGE2 in osteoarthritis (OA) pathogenesis.
IL-18 and PGE2 were measured concurrently in synovial fluid samples from 54 patients with knee OA (OA group) and from 9 controls (control group). Quantitative determination of IL-18 was performed by enzyme-linked immunosorbent assay (ELISA). PGE2 was examined by inhibitory enzyme-linked immunosorbent assay. A linear regression between IL-18 and PGE2 was analysed.
The concentrations of IL-18 and PGE2 in SF from the OA group were significantly higher than those from the control group (P<0.01). The average value of IL-18 in the control group was (28.768+/-13.575) x 10(-9)ng/L, and (72.303+/-40.130) x 10(-9)ng/L in the OA group (P<0.01); the average value of PGE2 in the control group was (24.697+/-7.814) x 10(-9)ng/L, and (42.302+/-23.818) x 10(-9)ng/L in the OA group (P<0.01). IL-18 was related with PGE2 in a linear curve fashion (the control group: r=0.76, P<0.001; the OA group: r=0.94, P<0.001).
IL-18 and PGE2 are significantly higher in the OA group than those in the control group, and they might take part in the cartilage degradation in OA pathogenesis. The increase of IL-18 might induce the increase of PGE2, and that might play an important role in OA pathogenesis.