Hongyan Wen1, Yang Liu2, Jinchan Li2, Dandan Wei2, Dandan Liu2, Fangfang Zhao2. 1. Department of Rheumatology, Shanxi Medical University, the Second Hospital of Shanxi Medical University, Taiyuan, Shanxi Province, China. wenhongyan0509@aliyun.com. 2. Department of Rheumatology, Shanxi Medical University, the Second Hospital of Shanxi Medical University, Taiyuan, Shanxi Province, China.
Abstract
OBJECTIVES: To explore the inhibitory effect and mechanism of 1,25-dihydroxy vitamin D3 (l,25(OH)2D3) on receptor activator of nuclear factor-κB ligand (RANKL) expression in fibroblast-like synoviocytes (FLSs) and osteoclastogenesis induced by interleukin (IL)-22 in patients with rheumatoid arthritis (RA). METHODS: Fibroblast-like synoviocytes from patients with rheumatoid arthritis (RA-FLSs) were cultured and stimulated for RANKL expression with IL-22 in the absence or presence of various concentrations of l,25(OH)2D3, and JAK-2 inhibitor or p38 MAPK inhibitor at the optimised time point of IL-22 treatment. The level of RANKL messenger RNA (mRNA) or protein was measured using real-time polymerase chain reaction (RT-PCR) or western blot method. To assess the impact of l,25(OH)2D3 on osteoclastogenesis, isolated monocytes were activated by M-CSF and RANKL or cocultured with FLSs stimulated by IL-22 in the presence or absence of l,25(OH)2D3 and those inhibitors. TRAP-positive cells as differentiated osteoclasts were stained for alkaline phosphatase. RESULTS: FLSs stimulated with IL-22 for 72 hours were used in further experiment because of the highest expression of RANKL at this time point. The expression of RANKL mRNA and protein in IL-22-stimulated FLSs were significantly inhibited by 1 nM of 1,25(OH)2D3 (p<0.05). Interestingly, this inhibition was reversed by inhibitor of JAK-2/STAT-3 or p38 MAPK/NF-κB signalling. In monocytes cocultured with IL-22-stimulated FLSs in the presence of exogenous RANKL and M-CSF, 1,25(OH)2D3 could block the process of osteoclastogenesis by JAK-2/STAT-3 or p38 MAPK/NF-κB signalling. CONCLUSIONS: 1,25(OH)2D3 may exert inhibitory effect on osteoclastogenesis of RA-FLSs by down-regulating RANKL expression, which could be mediated by IL-22 through JAK-2/STAT-3 and p38 MAPK/NF-κB signalling.
OBJECTIVES: To explore the inhibitory effect and mechanism of 1,25-dihydroxy vitamin D3 (l,25(OH)2D3) on receptor activator of nuclear factor-κB ligand (RANKL) expression in fibroblast-like synoviocytes (FLSs) and osteoclastogenesis induced by interleukin (IL)-22 in patients with rheumatoid arthritis (RA). METHODS: Fibroblast-like synoviocytes from patients with rheumatoid arthritis (RA-FLSs) were cultured and stimulated for RANKL expression with IL-22 in the absence or presence of various concentrations of l,25(OH)2D3, and JAK-2 inhibitor or p38 MAPK inhibitor at the optimised time point of IL-22 treatment. The level of RANKL messenger RNA (mRNA) or protein was measured using real-time polymerase chain reaction (RT-PCR) or western blot method. To assess the impact of l,25(OH)2D3 on osteoclastogenesis, isolated monocytes were activated by M-CSF and RANKL or cocultured with FLSs stimulated by IL-22 in the presence or absence of l,25(OH)2D3 and those inhibitors. TRAP-positive cells as differentiated osteoclasts were stained for alkaline phosphatase. RESULTS: FLSs stimulated with IL-22 for 72 hours were used in further experiment because of the highest expression of RANKL at this time point. The expression of RANKL mRNA and protein in IL-22-stimulated FLSs were significantly inhibited by 1 nM of 1,25(OH)2D3 (p<0.05). Interestingly, this inhibition was reversed by inhibitor of JAK-2/STAT-3 or p38 MAPK/NF-κB signalling. In monocytes cocultured with IL-22-stimulated FLSs in the presence of exogenous RANKL and M-CSF, 1,25(OH)2D3 could block the process of osteoclastogenesis by JAK-2/STAT-3 or p38 MAPK/NF-κB signalling. CONCLUSIONS:1,25(OH)2D3 may exert inhibitory effect on osteoclastogenesis of RA-FLSs by down-regulating RANKL expression, which could be mediated by IL-22 through JAK-2/STAT-3 and p38 MAPK/NF-κB signalling.