Cyclooxygenase-2-derived prostaglandin E2 is involved in vascular endothelial growth factor production in interleukin-1α-stimulated human periodontal ligament cells

Prostaglandin E-2, which exerts its actions via EP receptors (EP1, EP2, EP3 and EP4), is a bioactive metabolite of arachidonic acid produced by cyclooxygenase-1 and/or cyclooxygenase-2. Interleukin-1 alpha induces prostaglandin E-2 production via cyclooxygenase-2 in human periodontal ligament cells. Vascular endothelial growth factor is a key regulator of physiologic as well as pathologic angiogenesis and has been indicated to be involved in the pathology of periodontal diseases. In the present study, we investigated whether interleukin-1 alpha induced vascular endothelial growth factor production in human periodontal ligament cells and whether cyclooxygenase-2-derived prostaglandin E-2 regulated interleukin-1 alpha-induced vascular endothelial growth factor production. Human periodontal ligament cells were obtained from extracted teeth of periodontally healthy subjects. After pre-incubation with a nonselective cyclooxygenase-1/2 inhibitor, indomethacin or a selective cyclooxygenase-2 inhibitor (NS-398), periodontal ligament cells were treated with or without interleukin-1 alpha, prostaglandin E-2, various EP receptor agonists and dibutyryl cAMP (a cAMP analogue). The levels of vascular endothelial growth factor and prostaglandin E-2 in the culture supernatant were measured by enzyme-linked immunosorbent assay. The vascular endothelial growth factor mRNA expression was evaluated by semiquantitative reverse transcription-polymerase chain reaction. Interleukin-1 alpha induced vascular endothelial growth factor production in a dose-dependent and time-dependent manner. The interleukin-1 alpha-induced vascular endothelial growth factor mRNA and protein expression was inhibited to the same extent by indomethacin and NS-398. Indomethacin and NS-398 completely inhibited interleukin-1 alpha-induced prostaglandin E-2 production. Exogenous prostaglandin E-2, butaprost (an EP2 receptor agonist) and dibutyryl cAMP abolished the inhibitory effect of indomethacin on interleukin-1 alpha-induced vascular endothelial growth factor production. We suggest that interleukin-1 alpha induced vascular endothelial growth factor production via cyclooxygenase-2-derived prostaglandin E-2 in human periodontal ligament cells. The interleukin-1 alpha/prostaglandin E-2 pathway might regulate vascular endothelial growth factor production in periodontal lesions.