Release of prostaglandin E2, IL-6 and IL-8 from human oral epithelial culture models after exposure to compounds of dental materials

A three-dimensional human tissue model based on TR146 cells isolated from a squamous cell carcinoma of the buccal mucosa was used to test for the release of the proinflammatory molecules prostaglandin E2 (PGE2), interleukin 6 (IL-6), and interleukin 8 (IL-8) after exposure to nickel chloride (NiCl2), cobalt chloride (COCl2), palladium chloride (PdCl2), and triethylene glycol dimethacrylate (TEGDMA). These compounds have documented adverse biological effects in vitro. The release of PGE2 from the tissue culture models was inversely correlated with cell viability (MTT assay). Toxic concentrations of NiCl2 and CoCl2 induced the release of PGE2 by factors of about 200-300 compared to controls, but PdCl2 which was nontoxic enhanced PGE2 levels about 10-fold. TEGDMA, however, did not stimulate PGE2 release. None or weakly toxic concentrations of Ni and Co chloride induced IL-6 and IL-8 release by a factor of 5-10 compared to controls. The amounts of IL-6 were induced 25- to 30-fold by PdCl2 under physiological conditions, and IL-8 levels were also slightly enhanced. Nontoxic TEGDMA concentrations induced IL-6 levels 5-fold, but IL-8 amounts increased only slightly. We conclude that a steep rise of PGE2 is closely associated with cytotoxicity. On the other hand, the specific induction of IL-6 occurs at much lower concentrations. Therefore, the measurement of this cytokine may be included as another parameter in evaluating the biological activity of dental materials under nontoxic experimental conditions in vitro.