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Abstract

Methacrylate monomers have been identified in aqueous extracts of freshly cured dental fillings. The hypothesis tested presently was that low concentrations of triethyleneglycol dimethacrylate (TEGDMA) and 2-hydroxyethyl methacrylate (HEMA) alone or in combination interfere with the LPS-induced release of cytokines from the macrophage cell line RAW264.7. The cells were exposed to 5–200 μM of monomers for 24 h followed by a 24 h combined exposure to monomers and LPS. TEGDMA reduced LPS-induced release of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), whereas HEMA only reduced IL-1β release. Co-exposure to the two monomers indicated an additive effect. Moreover, the reduced cytokine release persisted for 24 h after termination of the monomer exposure. The LPS-induced activation of proteins in pre-transcriptional signaling pathways (CD14, p-ERK1/2, p-p38, p-JNK, p-IκB-α and p-NFκB-p65) was not altered by monomer exposure, neither were the levels of IL-1β and TNF-α mRNA. However, the LPS-induced level of pro-IL-1β was decreased by the monomer treatment. Thus, HEMA and TEGDMA may interfere with post-transcriptional regulation of synthesis and release of these cytokines. Overall, the results suggest that low concentrations of monomers may cause impaired macrophage responses, and that these effects can persist for up to 24 h after exposure.


Highlights

Low HEMA and TEGDMA levels reduced LPS-induced release of pro-inflammatory cytokines.

Co-exposure to monomers caused additive effects on cytokine release.
HEMA and TEGDMA did not alter mRNA levels of IL-1β and TNF-α.
Monomers could possibly interfere with post-transcriptional regulation of cytokines.
Monomer-induced reduction of cytokine release persisted for 24 h after exposure.

Reference
Dental monomers inhibit LPS-induced cytokine release from the macrophage cell line RAW264.7
Bølling AK, Samuelsen JT, Morisbak E, Ansteinsson V, Becher R, Dahl JE, Mathisen GH
Toxicology Letters 2013; 216: 130-138.