Anti-inflammatory effect of pachymic acid promotes odontoblastic differentiation via HO-1 in dental pulp cells

Objectives: Heme oxygenase-1 (HO-1) is contributed to odontoblast differentiation in human dental pulp cells (HDPCs). In this study, pachymic acid from mushroom Formitopsis niagra is examined to determine whether it affects pulpal inflammation and promotes odontogenesis via HO-1 gene expression. Materials and Methods: The HDPCs were given H₂O₂ for inflammation. The anti-inflammatory character and odontoblast differentiation by pachymic acid were analyzed by Western blotting, alkaline phosphatase activity, and alizarin red S staining. To understand the mechanism of pachymic acid via HO-1 induction, the cells were treated with zinc protoporphyrin IX (ZnPP: HO-1 inhibitor). Results: H₂O₂ induced pulp inflammation and disturbed odontoblast differentiation. However, the HDPCs treated with pachymic acid affected anti-inflammatory effect and induction of odontoblast differentiation through increasing HO-1 expression. In addition, pachymic acid has potent cytoprotection and mineralization under H₂O₂ treatment. Furthermore, pachymic acid significantly suppressed nuclear factor-kappa B (NF-κB) translocation into nucleus and induced NE-E2-related factor-2 (Nrf2) translocation into nucleus. Overall, NF-κB and Nrf2 translocation were regulated by the HO-1 pathway. Conclusions: The pachymic acid showed anti-inflammatory function and odontoblast differentiation via HO-1 pathway. These results suggested that pachymic acid may be applicable for prevention of oral inflammation or to improve dentin mineralization against several stresses.