Differential influence of IL-1-β, TNF-α, and PDGF-BB on the expression of matrix-metalloproteinases (MMPs) and 'total'-MMP activity in early-passage RA- and OA-synovial fibroblasts (SFB)

Objectives

To characterize the influence of stimulation with IL-1-β, TNF-α or PDGF-BB on the mRNA expression of MMP-1 to MMP-19 in rheumatoid arthritis (RA)-SFB and osteoarthritis (OA)-SFB, and to assess the 'total' MMP activity in the supernatants of the cells.

Methods

RNA was isolated from 2nd passage RA- and OA-SFB (enrichment 98%; with/without stimulation by IL-1-β, TNF-α or PDGF-BB for 24 hours). The expression of MMP-1 to MMP-19 was analyzed by semiquantitative RT-PCR with gene-specific primers. 'Total' MMP-activity was assessed in the supernatant of stimulated RA- and OA-SFB using the nonspecific fluorogenic MMP-substrate Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2.

Results

No significant differences were observed between unstimulated 2nd passage RA- and OA-SFB for the expression of any MMP. Following IL-1-β stimulation, MMP-1, MMP-2, MMP-3, MMP-9, MMP-10, MMP-13, and MMP-19 were upregulated in RA-SFB, but only MMP-3, MMP-9, MMP-10, and MMP-12 in OA-SFB. In addition, MMP-11 and MMP-14 were downregulated in OA-SFB. TNF-α upregulated MMP-1, MMP-9, and MMP-13, but downregulated MMP-8, MMP-12, MMP-14, and MMP-19 in RA-SFB. In OA-SFB, TNF-α upregulated MMP-3, MMP-7, and MMP-9, but downregulated MMP-8 and MMP-16. Following PDGF-BB stimulation, MMP-8 was upregulated, but MMP-3, MMP-10, and MMP-13 were downregulated in RA-SFB. Strikingly, stimulation of OA-SFB with PDGF-BB led to significant downregulation of 8 MMPs (MMP-1, MMP-2, MMP-3, MMP-8, MMP-11, MMP-12, MMP-13, and MMP-14). IL-1-β and TNF-α significantly downregulated 'total' MMP-activity in the supernatants of OA-SFB, but not in the supernatants of RA-SFB. In contrast, PDGF-BB downregulated 'total' MMP-activity in the supernatants of both RA-SFB and OA-SFB.

Conclusion

IL-1-β and TNF-α may contribute to prodestructive features of RA-SFB by upregulating MMP expression and by failing to downregulate 'total' MMP activity. More extensive downregulation of MMP expression in OA-SFB than in RA-SFB suggests a differential, tissue-protective role of PDGF-BB in different inflammatory joint diseases.