Fig. 6

The impact of recombinant human proteoglycan-4 (rhPRG4) treatment on basal and IL-1β-induced gene expression of matrix metalloproteinases (MMPs), aggrecanases 1 and 2 (ADAMTS4 and ADAMTS5), and tissue inhibitor of metalloproteinases (TIMPs) in OA fibroblast-like synoviocytes (OA FLS). Data are presented as the average ± standard error of the mean (SEM) of four independent experiments. Data are represented 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 (200 μg/ml) reduced expression of MMP1, MMP3, and MMP13. rhPRG4 (200 μg/ml) increased expression of TIMP-2. b Impact of IL-1β treatment on catabolic enzyme gene expression in OA FLS. IL-1β induced MMP1, MMP3, MMP9, MMP13, TIMP-1, ADAMTS4, and ADAMTS5 gene expression. c Impact of rhPRG4 treatment in IL-1β-stimulated OA FLS. rhPRG4 (200 μg/ml) treatment reduced MMP1, MMP3, MMP9, MMP13 and ADAMTS5 gene expression in IL-1β-stimulated OA FLS. d Role of CD44 in modulating the effect of rhPRG4 on MMP1, MMP3, MMP9, MMP-13, and ADAMTS5 expression in IL-1β-stimulated OA FLS. CD44 neutralization using a CD44 monoclonal antibody (CD44 Ab) significantly inhibited the effect of rhPRG4 treatment on MMP9, MMP13, and ADAMTS5 expression