Multitarget-based cotreatment with cilostazol and celecoxib synergistically suppresses collagen-induced arthritis in mice by enhancing interleukin-10 expression

Abstract Cilostazol exerts potent anti-inflammatory effects and celecoxib, a COX-2 specific inhibitor, improves the unsatisfactory profile of NSAIDs. It was aimed to assess the anti-arthritic potential of celecoxib add-on for cilostazol therapy in collagen induced arthritis (CIA), and to elucidate the implication of interleukin (IL)-10 in the action of cilostazol and celecoxib cotreatment. Cotreatment of RAW 264.7 cells with 10 μM cilostazol and 0.3 μM celecoxib synergistically suppressed RANKL-induced increases in RANK mRNA and protein levels. When cultured in the presence of RANKL for 5 days, RANKL-stimulated expressions of osteoclastogenic genes (OSCAR, DC-STAMP, and cathepsin K mRNA) and the expression of RANK mRNA were markedly elevated. Furthermore, these gene expressions, including that of RANK, were significantly suppressed by cotreatment with cilostazol (10 μM) and celecoxib (0.3 μM). In addition, this co-treatment strongly down-regulated RANKL-induced NFATc1 protein and TRAP activity (key osteoclastogenic factors), and these down-regulations were significantly prevented by pretreating cells with IL-10 neutralizing antibody. Furthermore, increased osteoclast formation and extensive resorption pit formation by bone marrow-derived monocytes obtained from C57BL/6 mice cultured in the presence of M-CSF/RANKL were markedly suppressed by cilostazol and celecoxib cotreatment. Consequently, hindlimb paw thicknesses in DBA/1J CIA mice were significantly reduced by cilostazol (10 mg/kg/d) and celecoxib (5 mg/kg/d) cotreatment. These results were accompanied by synergistic suppression of cartilage depletion and bone erosion and reductions in arthritis scores in the CIA mice. In conclusion, serum IL-10 levels in these mice were markedly increased by cilostazol and celecoxib cotreatment, whereas elevated serum IL-1β levels were markedly reduced. Cotreatment with low-dose cilostazol and celecoxib may ensure the synergistic anti-arthritic potential.