Correlations between both the expression levels of inflammatory mediators and growth factor in medial perimeniscal synovial tissue and the severity of medial knee osteoarthritis

Abstract

An enhanced expression of the inflammatory mediators in the perimeniscal synovium in knee osteoarthritis (OA) has been suggested to contribute to progressive cartilage degeneration. However, whether the expression levels of these molecules correlated with the severity of OA still remained unclear. Medial perimeniscal synovial samples were obtained from 23 patients with Kellgren-Lawrence (K/L) grades 2 to 4 of medial knee OA. Immunohistochemical analysis of the synovium revealed that the MMP-1, COX-2 and IL-1β expression of the patients with K/L 4 to be significantly reduced in comparison to those with either K/L 2 or 3, while the TGF-β expression showed the opposite. The synovial expression of MMP-1 and IL-1β showed a significant negative correlation with the severity of OA, while that of TGF-β again showed the opposite. In conclusion, although synovial inflammation remained active, the MMP-1, COX-2 and IL-1β expression in synovium decreased depending upon the severity of OA, while the TGF-β expression increased.

Fig. 1

Expression patterns of the inflammatory mediators and growth factor in the medial perimeniscal synovial tissue of the patients

Fig. 2

Vascular proliferation detected by CD31 expression in medial perimeniscal synovial tissues of the patients

Fig. 3

Correlation between the expression levels of inflammatory mediators and growth factor in the medial perimeniscal synovial tissue with both the radiographic parameters and patient-oriented outcome measures for knee OA of the patients. Circles and triangles indicate the data from patients with K/L 4 and those with K/L 2 or 3, respectively (n = 23). JSW joint space width, FTA femoro-tibial angle, JKOM Japanese Knee Osteoarthritis measure