Activation of RANKL and MMP Production by Endothelin Signaling in Cultured Periodontal Fibroblasts

Abstract

Periodontitis is a group of inflammatory diseases that affect the tissues surrounding and supporting the teeth. These diseases progressively cause the loss of the alveolar bone and the periodontal ligaments, which can lead to dental exfoliation. Endothelin signaling via the activation of the endothelin‐A receptor (Ednra) by endothelin‐1 (Edn1) is a pathway that may play a role in the disease since the expression of the receptor and ligand is elevated in the periodontal tissues of patients with periodontitis. Using cultured primary periodontal fibroblasts (HPFs), we investigated whether Ednra activation by Edn1 alters the expression of factors involved in the destruction of the periodontium. HPFs were obtained from the extracted teeth of consenting healthy non‐smoking patients with institutional board review approval. The HPFs were treated with 20 and 100nM Edn1for 6 and 24 hours. The osteoclast‐activating factor RANKL and members of the matrix metalloproteinase (MMP) family were examined by western blotting. Edn1 treatment stimulated the production of MMP1, MMP8 and RANKL in a dose‐ and time‐dependent manner; blocking Ednra function with the specific antagonist TBC3214 inhibited the response. Stimulation of Ednra by Edn1 activated phospholipase C. In turn the enzyme activated the ERK MAP kinase‐dependent pathway to increase the MMP1 protein levels, and also activated an independent pathway for RANKL, likely involving NFAT activity. These results support the theory that endothelin signaling, <em style=”mso‐bidi‐font‐style: normal; via the activation of Ednra, stimulates the destruction of the periodontal tissues associated with periodontitis by promoting the expression of MMPs and RANKL.