Journal of Clinical & Experimental Pharmacology

Abstract

Cytokine-mediated Differential Regulation of Cyclooxygenase-2, High Mobility Group Box 1 Protein and Matrix Metalloproteinase-9 Expression in Fibroblast-like Synovial Cells

Alsousi AA, Siddiqui S and Igwe OJ

Persistent joint inflammation and pain with concomitant joint erosion, characterize Rheumatoid Arthritis (RA). We used a Fibroblast-like Synovial (FLS) cell line derived from a female rabbit, as a model system for studying the initiation and attenuation of conditions of RA in vitro. We used two pro-inflammatory cytokines, TNFα and IL-1β to examine potential inflammatory responses and cartilage erosion exerted by each cytokine alone and/or in combination. We determined the expression levels of cytokine-induced expression of Cyclooxygenase-2 (COX-2), production of Prostaglandin E2 (PGE2), release of high mobility group box-1 (HMGB1) protein and the activity of Metalloproteinase-9 (MMP-9) in FLS cells. Treatment with TNFα alone increased HMGB1 release levels, MMP-9 activity, COX-2 expression and PGE2 production in both concentration- and exposure time-dependent manner. But treatment with a low concentration of TNF-α in combination with an equivalent concentration of IL-1β produced similar levels of COX-2 expression and PGE2 production compared with the same concentration of TNF-α alone. This suggests that the effects observed could only be due to the TNFα. IL-1β did not affect COX-2 expression in a concentration-dependent manner compared to media control. Treatment with indomethacin or NS392 significantly decreased TNFα-induced COX-2 expression coupled with decreased PGE2 production and MMP-9 expression. In addition, anti-TNFα decreased HMGB1 release level, PGE2 production and MMP-9 expression, which support a critical role for TNFα-induced TNF Receptor (TNFR) activation for these effects. Overall, our results support treatment approaches in RA that attenuate the effects of TNFα-induced TNFR stimulation on MMP-9 and PGE2 production with HMGB1 release for a more efficacious therapy.