Serum levels of proinflammatory, anti-inflammatory cytokines, and RANKL/OPG in synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome

Objective: To measure the expression of proinflammatory, anti-inflammatory cytokines, and receptor activator NK-κB ligand (RANKL)/osteoprotegerin (OPG) in synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome, and to assess the relationship between those factors and disease activity. Methods: We studied 30 cases of SAPHO syndrome and 15 healthy controls. According to the Visual Analogue Scale (VAS) pain scores and Bath Ankylosing Spondylitis Activity Index (BASDAI), patients were divided into active group and stable group. The serum levels of IFN-γ, TNF-α, TGF-β1, IL-1β, IL-4, IL-6, IL-8, IL-17A, IL-22, RANKL, and OPG were determined by ELISA. Results: The active group IL-6 (2.34 ± 1.31 pg/ml), IL-8 (36.41 ± 12.93 pg/ml), and IL-17A (29.17 ± 4.01 pg/ml) levels were significantly higher than those in the stable group (p < .01) and healthy controls (p < .01). RANKL in active group (73.43 ± 57.07 pg/ml) was significantly higher than the ones in other groups (p < .0001), with increased RANKL/OPG ratio in the active group compared with other groups (p < .05). While the level of TGF-β1 in the active group was significantly lower than that in the stable and control groups (p < .0001). There was no significant difference with clinical significance were found in IFN-γ, TNF-α, IL-1β, IL-4, IL-22, and OPG. Conclusion: In active SAPHO patients, there was an anomaly of proinflammatory and anti-inflammatory cytokines balance in SAPHO syndrome.