Small interfering RNA targeting CD81 decreased the expression of tumor necrosis factor-alpha and synoviolin in SW982 cells

Rheumatoid arthritis (RA), one of the most common articular diseases, is characterized by chronic inflammation, hyperproliferation of synovial cells, and bone destruction. CD81, which belongs to a family of cell-surface proteins (tetraspanin), is known to be up-regulated in RA synoviocytes. Recently, we showed the therapeutic effect of using small interfering RNA in targeting CD81 (CD81 siRNA) for RA. Here we show how tumor necrosis factor-alpha (TNF-α) can induce the expression of synoviolin, which is decreased by the addition of CD81 siRNA in SW982 cells. In addition, CD81 siRNA decreases the expression of TNF-α in SW982 cells, suggesting that TNF-α stimulates the expression of synoviolin via CD81. Furthermore, knock down of CD81 by the addition of CD81 siRNA decreases the expression of TNF-α, and TNF-α-induces expression of synoviolin in direct and indirect ways. These results in SW982 cells might explain the therapeutic effect of CD81 siRNA in animal models.