IL6 and synovitis: As illustrated in Fig. 2B,C, relative IL-6 mRNA expression in knee OA synovium with severe synovitis was significantly greater than that in those with mild synovitis (P = 0.009) and no synovitis (P = 0.008), and a marked up-regulation of IκB mRNA expression was observed in knee OA synovium with severe synovitis compared with those without synovitis (P = 0.030).