Vitamin-D Induction of Antimicrobial Peptide Genes in Gingival Epithelial Cells

Objectives: Antimicrobial peptides secreted from epithelial cells such as β-defensins and the cathelicidin LL-37 are proposed to play an important role in host defense against colonization by pathogenic bacteria. We recently demonstrated that the active form of Vitamin D, 1,25(OH)₂ Vitamin D₃ could induce expression of LL-37 mRNA, peptide and antibacterial activity in cultured airway epithelial cells. Published reports have demonstrated an association between polymorphisms of the vitamin D receptor (VDR) gene and early-onset periodontitis, and genetic disorders leading to deficiencies in LL-37 exhibit periodontal disease as well. We therefore wished to examine the potential of this compound to similarly affect antimicrobial peptide gene expression in gingival epithelial cells. Methods: Human gingival epithelial cells (GEC) were cultured in the presence of 1,25(OH)₂ Vitamin D₃ under varying conditions. Total mRNA was isolated from the cells, and levels of human β-defensin (hBD) and LL-37 mRNA were determined by quantitative RT-PCR (QPCR), compared with levels of β-2 microglobulin as a constitutive control. Results: 1,25(OH)₂ Vitamin D₃ exhibited a significant time- and dose-dependent induction of LL-37 mRNA levels in GEC. Elevated levels of LL-37 mRNA were seen as early as 6 hours in the presence of 10^-8M 1,25(OH)₂ Vitamin D₃. No effect was seen on β-defensin gene expression. Conclusion: As we observed with airway epithelial cells, GEC are capable of dose- and time-dependent induction of antimicrobial peptide gene expression in response to Vitamin D. These results support the potential for development of Vitamin D or its analogues to augment current therapies for periodontal disease. This research was supported by the Cystic Fibrosis Foundation.