Extending the vitamin D pathway to vitamin D3 and CYP27A1 in periodontal ligament cells

Abstract

Background: In periodontal connective tissue cells, the vitamin D pathway has been elucidated, and vitamin D3 in the main storage form, 25-hydroxy vitamin D3 (25[OH]D3), and the functional form, 1,25-dihydroxy vitamin D3 (1,25[OH]2D3), have been found to induce the expression of human cationic antimicrobial protein (hCAP-18)/LL-37. Moreover, synergistic effects between Toll-like receptor agonists and 25(OH)D3 have been reported. This research aimed at extending the vitamin D pathway to vitamin D3 and CYP27A1 in human periodontal ligament cells (hPDLCs) to further explore its function in periodontal inflammatory reaction. Methods: Vitamin D3 was used to stimulate hPDLCs in the presence or absence of Porphyromonas gingivalis lipopolysaccharide (Pg-LPS). Conversely, CYP27A1 RNA interference was performed to further validate the findings. The mRNA expression of hCAP-18 was determined with real-time polymerase chain reaction. Monocyte chemotactic protein-1 (MCP-1) and interleukin-8 (IL-8) were also detected. The cell supernatant levels of LL-37 were detected with enzyme-linked immunosorbent assay. Results: Vitamin D3 significantly enhanced the generation of hCAP-18/LL-37. A combination of Pg-LPS and vitamin D3 significantly promoted hCAP-18/LL-37 expression. When the expression of CYP27A1 was knocked down with RNA interference, the induction of hCAP-18/LL-37 expression was significantly inhibited. Therefore, the mRNA levels of MCP-1 and IL-8 in hPDLCs were significantly decreased through the vitamin D pathway. Conclusion: The vitamin D pathway from vitamin D3 to hCAP-18/LL-37 exists in hPDLCs, and CYP27A1 might be involved in periodontal immune defense.