Topical Vitamin D Prevents Bone Loss and Inflammation in a Mouse Model.

There is a strong association between vitamin D levels and periodontal disease based on numerous epidemiological studies. We have previously shown that experimental deficiency of serum vitamin D in mice leads to gingival inflammation and alveolar bone loss. Treatment of cultured oral epithelial cells with the active form of vitamin D, 1,25(OH)₂ vitamin D₃ (1,25(OH)₂D₃), inhibits the extracellular growth and intracellular invasion of bacteria associated with periodontal disease. Maintenance of periodontal health may be due in part to the anti-inflammatory activities of vitamin D. Furthermore, this hormone can induce the expression of an antimicrobial peptide in cultured oral epithelial cells. We have shown that oral epithelial cells are capable of converting inactive vitamin D to the active form, suggesting that topical treatment of the oral epithelium with inactive vitamin D could prevent the development of periodontitis. We subjected mice to ligature-induced periodontitis (LIP), followed by daily treatment with inactive vitamin D or 1,25(OH)₂D₃. Treatment with both forms led to a reduction in ligature-induced bone loss and inflammation. Gingival tissues obtained from vitamin D-treated LIP showed production of specialized proresolving mediators (SPM) of inflammation. To examine the mechanism, we demonstrated that apical treatment of 3-dimensional cultures of primary gingival epithelial cells with vitamin D prevented lipopolysaccharide-induced secretion of proinflammatory cytokines and led to a similar production of SPM. Analysis of the oral microbiome of the mice treated with vitamin D showed significant changes in resident bacteria, which reflects a shift toward health-associated species. Together, our results show that topical treatment of oral tissues with inactive vitamin D can lead to the maintenance of periodontal health through the regulation of a healthy microbiome and the stimulation of resolution of inflammation. This strongly supports the development of a safe and effective vitamin D-based topical treatment or preventive agent for periodontal inflammation and disease.