On the other hand, knee OA patients with severe synovitis had considerably increased plasma IL-34 levels compared with those with mild synovitis (P = 0.029) and without synovitis (P = 0.001), and its plasma levels in the patients with mild synovitis were significantly higher than that in those with no synovitis (P = 0.003) (Fig. 5B). This evidence concerns the gene IL34 and synovitis.