Fig. 7

The impact of recombinant human proteoglycan-4 (rhPRG4) treatment on basal and IL-1β-induced gene expression of IL-1β, IL-6, IL-8, TNF-α, and cyclooxygenase-2 (COX2) in osteoarthritis fibroblast-like synoviocytes (OA FLS). Data are presented as the average ± standard error of the mean of four independent experiments. Data are presented as fold change compared to untreated control OA FLS; *p < 0.001. a Effect of rhPRG4 treatment on basal gene expression in OA FLS. rhPRG4 (100 μg/ml and 200 μg/ml) increased basal COX2 expression. rhPRG4 (200 μg/ml) reduced basal IL-1β, IL-6, and IL-8 expression. b Impact of IL-1β treatment on pro-inflammatory cytokines and mediators of gene expression in OA FLS. IL-1β induced IL-1β, IL-6, IL-8, TNF-α, and COX2 gene expression. c Impact of rhPRG4 treatment in IL-1β-stimulated OA FLS. rhPRG4 (200 μg/ml) treatment reduced IL-1β, IL-6, IL-8, TNF-α, and COX2 gene expression in IL-1β-stimulated OA FLS. d Role of CD44 in modulating the effect of rhPRG4 on IL-6, IL-8, and COX2 expression in IL-1β-stimulated OA FLS. CD44 neutralization using a CD44 monoclonal antibody (CD44 Ab) significantly inhibited the effect of rhPRG4 treatment on IL-6, IL-8, and COX2 expression