Cytokine-induced prostaglandin E2 production and cyclooxygenase-2 expression in dental pulp cells:: downstream calcium signalling via activation of prostaglandin EP receptor

Aim To determine whether (i) proinflammatory cytokines stimulate prostaglandin E-2 (PGE(2)) production and cyclooxygenase (COX) gene expression in dental pulp cells, and (ii) pulp cells that express different prostaglandin E-2 receptor (EP) isoforms and their activation by PGE(2) leads to downstream Ca2+ signalling. Methodology Cultured human dental pulp cells were exposed to interleukin (IL)-1 beta and tumour necrotic factor-alpha (TNF-alpha). The expression of COX-1 and COX-2 was measured with reverse transcriptase-polymerase chain reaction (RT-PCR). The production of PGE(2) was measured using an enzyme-linked immunosorbent assay. Expression of prostaglandin EP receptor isoforms was studied by RT-PCR, whereas fura-2 fluorescence was used to measure calcium mobilization. The Kruskal-Wallis test and Wilcoxon sum rank test with Bonferroni correction were used for statistical analysis. Results Interleukin-1 beta and TNF-alpha stimulate PGE(2) production of human dental pulp cells (P < 0.05). IL-1 beta stimulated the COX-2 but not COX-1 mRNA expression. Pulp cells express mainly EP2, EP3 and EP1 receptors as analysed by RT-PCR. PGE(2) (0.25-2 mu mol L-1) stimulated the Ca2+ mobilization as indicated by increase in fura-2 fluorescence. Conclusions Interleukin-1 beta and TNF-alpha may stimulate PGE(2) production in dental pulp cells. Activation of prostaglandin EP receptors in dental pulp cells by PGE(2) may induce Ca2+ signalling to regulate cellular biological activity during inflammation.