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

IntroductionVascular 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.MethodsPrimary dental pulp cells were exposed to prostaglandin E2 (PGE2), prostaglandin F2α (PGF2α), or interleukin 1β (IL-1β) 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.ResultsIL-1β induced VCAM-1 gene expression of pulp cells. IL-1β also stimulated sVCAM-1 production. The IL-1β–induced sVCAM-1 production was not inhibited but rather enhanced by aspirin, a cyclooxygenase (COX) inhibitor. PGE2 and PGF2α 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-1β–induced sVCAM-1 production. However, no marked cytotoxicity was noted in these experimental conditions as analyzed by MTT assay.ConclusionsIL-1β 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. PGE2 and PGF2α may potentially regulate inflammatory processes by the inhibition of VCAM-1.