Regulation of Vascular Cell Adhesion Molecule-1 in Dental Pulp Cells by Interleukin-1β: The Role of Prostanoids

Introduction: Vascular cell adhesion molecule (VCAM-1) plays a critical role in the inflammatory processes by stimulating the recruitment, extravasation, and migration of leukocytes. Its expression and regulation in the dental pulp is not well elucidated. Methods: Primary dental pulp cells were exposed to prostaglandin E-2 (PGE(2)), prostaglandin F-2 alpha (PGF(2 alpha)), or interleukin 1 beta (IL-1 beta) with/without aspirin. VCAM-1 messenger RNA expression was analyzed by reverse transcriptase-polymerase chain reaction. Soluble VCAM-1 (sVCAM-1) in the culture medium was determined by enzyme-linked immunosorbent assay, and the number of viable cells was estimated by (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Results: IL-1 beta induced VCAM-1 gene expression of pulp cells. IL-1 beta also stimulated sVCAM-1 production. The IL-1 beta-induced sVCAM-1 production was not inhibited but rather enhanced by aspirin, a cyclooxygenase (COX) inhibitor. PGE(2) and PGF(2 alpha) decreased the VCAM-1 expression and sVCAM-1 production of pulp cells. U0126 (1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene), a mitogen-activated protein kinase kinase (MEK) inhibitor, attenuated IL-1 beta induced sVCAM-1 production. However, no marked cytotoxicity was noted in these experimental conditions as analyzed by MTT assay. Conclusions: IL-1 beta may be involved in the pulpal inflammatory processes via stimulation of VCAM-1 expression and sVCAM-1 production. This event is not mediated by COX activation and prostanoid production but is associated with MEK signaling. PGE(2) and PGF(2 alpha) may potentially regulate inflammatory processes by the inhibition of VCAM-1. (J Endod 2012;38:774-779)