Effect of 1,25( OH )2D3and 20( OH )D3on interleukin‐1β‐stimulated interleukin‐6 and ‐8 production by human gingival fibroblasts

Background and Objective Vitamin D—1,25(OH)2D3or 1,25D3—maintains healthy osseous tissue, stimulates the production of the antimicrobial peptide cathelicidin and has anti‐inflammatory effects, but it can cause hypercalcemia. Evidence links diminished serum levels of 1,25D3 with increased gingival inflammation. Periodontitis progression is associated with increased local production of inflammatory mediators by immune cells and gingival fibroblasts. These include interleukin (IL)‐6, a regulator of osteoclastic bone resorption, and the neutrophil chemoattractantIL‐8, both regulated by signaling pathways, includingNF‐κBandMAPK/AP‐1. The objectives were to determine the effects of 1,25D3 or a non‐calcemic analog, 20‐hydroxyvitamin D3—20(OH)D3or 20D3—onIL‐1β‐stimulatedIL‐6 andIL‐8 production, andNF‐κBandMAPK/AP‐1 activation, by human gingival fibroblasts. Material and Methods Human gingival fibroblasts were incubated ±IL‐1β, with or without exposure to 1,25D3 or 20D3.IL‐6 andIL‐8 in culture supernatants were measured by enzyme‐linked immunosorbent assay.NF‐κB (p65) andAP‐1 (phospho‐cJun) and were measured in nuclear extracts via binding to specific oligonucleotides. Data were analyzed usingANOVAand Scheffe's F procedure for post hoc comparisons. Results IL‐1β‐stimulatedIL‐6 andIL‐8 levels were both significantly inhibited (40%‐60%) (P<.045) by 1,25D3, but not 20D3 (0%‐15% inhibition, not statistically significant). Both 1,25D3 and 20D3 significantly and similarly inhibitedIL‐1β‐stimulated nuclear levels of p65 and phospho‐cJun (P<.02). Conclusion Reduction of the activation ofNF‐κB andAP‐1 alone is not able to inhibit strongly theIL‐1β stimulatedIL‐6 andIL‐8 gene expression. 1,25D3 but not 20D3 may affect some of the many other factors/processes/pathways that in turn regulate the expression of these genes. However, the results suggest that topical application of ligands of the vitamin D receptor may be useful in the local treatment of periodontitis while reducing adverse systemic effects.