Effects of 1,25-dihydroxyvitamin D₃ on Macrophage Cytokine Secretion Stimulated by Porphyromonas gingivalis

Vitamin D is known to be closely associated with periodontitis; however, its exact mechanisms remain to be clarified. The present study aimed to investigate the influence of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) on Porphyromonas gingivalis (Pg)-stimulated cytokine production and the involved signaling pathways in macrophages. The main observation was that 1,25(OH)₂D₃ inhibited Pg-induced interleukin (IL)-6 cytokine expression but up-regulated the expression of anti-inflammatory cytokine IL-10. Further analyses showed that 1,25(OH)₂D₃ decreased p38 mitogen-activated protein kinase (MAPK) and extracellular signal regulated kinase (ERK)1/2 phosphorylation. Inhibited phosphorylation of p38 MAPK and ERK1/2 was associated with decreased level of IL-6 expression, but was not related to increased level of IL-10 expression in macrophages stimulated with Pg. These results suggest that 1,25(OH)₂D₃ might exert its anti-inflammatory effects on Pg-stimulated macrophages partly through its inhibitory effect on the p38 MAPK and ERK1/2 signaling pathway.