Human gingival fibroblasts stress response to HEMA: A role for protein kinase C α

Abstract

2-Hydroxyethil methacrylate (HEMA), component of dentin-bonding systems, by diffusing into oral cavity induces a cytotoxic response. HEMA determines reactive oxygen species (ROS) production activating specific signaling pathways, including protein kinases C (PKC). In addition, since a regulation is exerted by various PKCs on nitric oxide synthase (NOS) activation, our aim was to investigate the role of PKCs and the possible interplay with ROS and NO signaling system in human gingival fibroblasts (HGF) response to HEMA. Cultured HGFs were exposed to 3 mM (a subtoxic concentration) HEMA for 0, 24, or 96 h. Each experimental point were processed for flow cytometry, fluorescence microscopy, western blotting, and "in vitro" NOS specific activity analyses. Three millimolar HEMA reduces HGF proliferation less than 50% and increases apoptosis percentage up to 18%. Both ROS production and PKC α expression and activation are also increased 96 h after HEMA exposure. The increased specific activity of iNOS, inflammatory enzyme, accompanied by Bax high expression in HGF response to 96 h HEMA, document the occurrence of an inflammatory and apoptotic response to such agent. Interestingly, a reduced percentage of apoptotic cells and a reduced ROS production are evidenced in the presence of bisindolylmaleide VIII, a PKC α pharmacologic inhibitor. All in all, these results suggest that PKC α can mediate the inflammatory response disclosed by gingival fibroblasts to HEMA released monomers.

pPKC α regulates through integrin β 1 human gingival fibroblasts/Streptococcus mitis adhesion in response to HEMA

“…Based on previous evidence that suggests PKC α as the main PKC expressed by gingival fibroblasts (Cataldi et al . ), the expression of this protein was investigated, which does not significantly change in different experimental conditions, whilst pPKC α expression was more than tenfold higher in the presence of HEMA, bacteria and saliva compared with control sample (Fig. ).…”

“…, Cataldi et al . ). Gingival fibroblasts produce type I, III and V collagens, which serve as scaffolds for numerous associated glycoproteins and proteoglycans of the intercellular matrix.…”

“…Previous studies suggest that PKC α may be the main PKC activated by HEMA in human gingival fibroblasts (Cataldi et al . ). This study investigated the role of PKC α and integrin β 1 response to HEMA treatment in an in vitro coculture model of human gingival fibroblasts (HGFs) and Streptococcus mitis strains (Zara et al .…”

Proliferation and adhesion capability of human gingival fibroblasts onto zirconia, lithium disilicate and feldspathic veneering ceramic in vitro

“…Surface roughness and chemical composition were reported to be able to alter cell adhesion and proliferation, which represent the first steps in the host tissue-biomaterial integration processes 12,13) . In the prosthodontic field, studies on the biological behaviour of gingival fibroblasts in regard to dental materials are significant, as the fibroblasts are involved in the oral soft tissue response to biomaterials [14][15][16][17] ; in particular, gingival fibroblasts take part in the integration process with ceramic materials, being able to integrate or not with biomaterials 18) . The aim of this study is to evaluate, at different experimental times, the cell morphology, proliferation and adhesion potential of HGFs cultured onto three different dental ceramics, i.e.…”

Evaluation in vitro of cytotoxicity of dentinal desensitizing on human gingival fibroblasts.

“…This monomer affects proliferation, apoptosis and cell cycle 25,26 . Aditionally, it has been studied the inflammatory response in gingival fibroblasts, causing an increase in the levels of reactive oxygen species, cyclooxygenase-2, tumor necrosis factor-alpha gene expression and prostaglandin E2 release 27 .…”