HEMA-induced oxidative stress inhibits NF-κB nuclear translocation and TNF release from LTA- and LPS-stimulated immunocompetent cells.

Objective: The release of inflammatory cytokines from antigen-stimulated cells of the immune system is inhibited by resin monomers such as 2-hydroxyethyl methacrylate (HEMA). Although the formation of oxidative stress in cells exposed to HEMA is firmly established, the mechanism behind the inhibited cytokine secretion is only partly known. The present investigation presents evidence regarding the role of HEMA-induced oxidative stress in the secretion of the pro-inflammatory cytokine TNFα from cells exposed to the antigens LTA (lipoteichoic acid) or LPS (lipopolysaccharide) of cariogenic microorganisms using BSO (L-buthionine sulfoximine) or NAC (N-acetyl cysteine) to inhibit or stabilize the amounts of the antioxidant glutathione.

Functions of transcription factors NF-κB and Nrf2 in the inhibition of LPS-stimulated cytokine release by the resin monomer HEMA.

Objective: Resin monomers like 2-hydroxyethyl methacrylate (HEMA) interfere with effects induced by stressors such as lipopolysaccharide (LPS) released from cariogenic microorganisms. In this study, mechanisms underlying monomer-induced inhibition of the LPS-stimulated secretion of inflammatory cytokines from immunocompetent cells were investigated.

Methods: Secretion of pro-inflammatory cytokines TNF-α, IL-6 and the anti-inflammatory IL-10 from RAW264.

Flavin-containing enzymes as a source of reactive oxygen species in HEMA-induced apoptosis.

Objective: Oxidative stress induced by compounds of dental composites like 2-hydroxyethyl methacrylate (HEMA) due to excess formation of reactive oxygen species (ROS) disturbs vital cell functions leading to apoptosis. The sources of ROS in cells exposed to resin monomers are unknown. The present study investigates functions of flavin-containing ROS and RNS (reactive nitrogen species) producing enzymes in cells exposed to HEMA.

Interaction between LPS and a dental resin monomer on cell viability in mouse macrophages.

Objective: Lipopolysaccharide (LPS) from cariogenic microorganisms and resin monomers like HEMA (2-hydroxyethyl methacrylate) included in dentin adhesive are present in a clinical situation in deep dentinal cavity preparations. Here, cell survival, expression of proteins related to redox homeostasis, and viability of mouse macrophages exposed to LPS and HEMA were analyzed with respect to the influence of oxidative stress.

Methods: Cell survival of RAW264.

Activation of the Nrf2-regulated antioxidant cell response inhibits HEMA-induced oxidative stress and supports cell viability.

Oxidative stress due to increased formation of reactive oxygen species (ROS) in target cells of dental resin monomers like 2-hydroxyethyl methacrylate (HEMA) is a major mechanism underlying the disturbance of vital cell functions including mineralization and differentiation, responses of the innate immune system, and the induction of cell death via apoptosis. Although a shift in the equilibrium between cell viability and apoptosis is related to the non-enzymatic antioxidant glutathione (GSH) in HEMA-exposed cells, the major mechanisms of adaptive antioxidant cell responses to maintain cellular redox homeostasis are still unknown. The present study provides insight into the induction of a communicating network of pathways under the control of the redox-sensitive transcription factor Nrf2, a major transcriptional activator of genes coding for enzymatic antioxidants.

2-Hydroxyethyl methacrylate-induced apoptosis through the ATM- and p53-dependent intrinsic mitochondrial pathway.

Resin monomers of dental composites like 2-hydroxyethyl methacrylate (HEMA) disturb cell functions including responses of the innate immune system, mineralization and differentiation of dental pulp-derived cells, or induce cell death via apoptosis. The induction of apoptosis is related to the availability of the antioxidant glutathione, although a detailed understanding of the signaling pathways is still unknown. The present study provides insight into the causal relationship between oxidative stress, oxidative DNA damage, and the specific signaling pathway leading to HEMA-induced apoptosis in RAW264.

Function of MAPK and downstream transcription factors in monomer-induced apoptosis.

The resin monomer triethylene glycol dimethacrylate (TEGDMA) disrupts vital cell functions, and the production of oxidative stress is considered a common underlying mechanism. The precise signaling pathways, however, that initiate monomer-induced effects, which disturb responses of the innate immune system, inhibit dentin mineralization processes, or induce apoptosis in target cells in vitro are still unknown. The present study provides insight into the causal relationship between TEGDMA-induced apoptosis and the activation of MAPK and transcription factors downstream using pharmacological inhibitors of the ERK1/2, p38 and JNK pathways.

Activation of stress-regulated transcription factors by triethylene glycol dimethacrylate monomer.

Triethylene glycol dimethacrylate (TEGDMA) is a resin monomer available for short exposure scenarios of oral tissues due to incomplete polymerization processes of dental composite materials. The generation of reactive oxygen species (ROS) in the presence of resin monomers is discussed as a common mechanism underlying cellular reactions as diverse as disturbed responses of the innate immune system, inhibition of dentin mineralization processes, genotoxicity and a delayed cell cycle. Yet, the signaling pathway through a network of proteins that finally initiates the execution of monomer-induced specific cell responses is unknown so far.

Resin monomer-induced differential activation of MAP kinases and apoptosis in mouse macrophages and human pulp cells.

Triethylene glycol dimethacrylate (TEGDMA) is a resin monomer which is released from polymerized dental composite materials. It induced apoptosis in various target cells or inhibition of LPS-induced cytokine production in cells of the immune system after prolonged exposure. In these tissues, mitogen-activated protein kinases (MAPK) regulate signal transduction pathways that support cell survival and cytokine synthesis.