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

Abstract

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 Ca(2+) signalling.

Methodology: Cultured human dental pulp cells were exposed to interleukin (IL)-1beta 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-1beta and TNF-alpha stimulate PGE(2) production of human dental pulp cells (P < 0.05). IL-1beta 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 micromol L(-1)) stimulated the Ca(2+) mobilization as indicated by increase in fura-2 fluorescence.

Conclusions: Interleukin-1beta 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 Ca(2+) signalling to regulate cellular biological activity during inflammation.