Expression of factors involved in dental pulp physiopathological processes by nemotic human pulpal fibroblasts

Abstract

Le Clerc J, Tricot-Doleux S, Pellen-Mussi P, P erard M, Jeanne S, P erez F. Expression of factors involved in dental pulp physiopathological processes by nemotic human pulpal fibroblasts. International Endodontic Journal, 51, e94-e106, 2018.Aim To investigate in human dental pulp fibroblasts (HDPF) the expression of factors involved in dental pulp physiopathological processes and in an experimental model of cell activation called nemosis, and to compare the behaviour of pulp cell activation with sound lung fibroblast MRC5, employed as a reference model for nemosis. Methodology Nemotic response was induced in three-dimensional cultures of HDPF and lung fibroblasts. The expressions of molecules involved in physiological (alkaline phosphatase, type I collagen) and in inflammatory processes (IL-6, CXCL8, CCL20, COX-2) were studied using real-time PCR. Concentrations of IL-6 and CXCL8 were analysed during 4 days with ELISA. Nonparametric tests were used to determine statistical differences between groups. Results A significant decrease (P < 0.001) in type I collagen and alkaline phosphatase was observed in MRC5 and HDPF nemotic responses. Although the amounts of mRNA differed between these cell types, there was an increase in CCL20, CXCL8 and COX-2 expression (P < 0.001). Unlike HDPF, MRC5 spheroids displayed significant amounts of IL-6 concentrations and mRNA expression. Notably, increased concentrations of CXCL8 were recorded in all threedimensional cultures compared with monolayers as a function of time (P < 0.05). Conclusion Although the nemotic responses observed were not identical in the pulpal and lung fibroblasts, similarities occurred in the expression of chemokines and cyclooxygenase-2. Nemotic reactions and inflammatory processes in pulp diseases share similarities in terms of the expression of factors. Thus, this in vitro model could constitute a powerful tool to study intercellular relations within the dental pulp and to develop new local treatments to counteract the inflammatory reaction that occurs during pulpitis.

Dental Pulp Fibroblast: A Star Cell

“…Inflammatory reactions are a prerequisite for the migration of progenitor cells involved in pulp repair 3 . An in vitro model of inflammation induced by nemosis verified this 156,157 . In nemosis, normal fibroblasts are induced to form groups, called spheroids, which do not grow but undergo cellular activation and simultaneous programmed cell death 158,159 ; it occurs in DPFs in vitro and could occur in vivo during pulp inflammation 156,160 .…”

“…In nemosis, normal fibroblasts are induced to form groups, called spheroids, which do not grow but undergo cellular activation and simultaneous programmed cell death 158,159 ; it occurs in DPFs in vitro and could occur in vivo during pulp inflammation 156,160 . Nemotic fibroblasts release significant amounts of proinflammatory cytokines, chemokines 156 , cyclooxygenase 2 156,157 , VEGF 156 , and hepatocyte growth factor 160 , triggered through direct cell-to-cell adhesion rather than external stimuli 158,160 . Thus, under experimental conditions, nemotic DPFs could be a source of chemokines and cytokines that induce stem cell migration 160 and proangiogenic factors that induce angiogenic responses from endothelial cells during tissue repair 161 .…”

Vascular endothelial growth factor A/Vascular endothelial growth factor receptor 2 axis promotes human dental pulp stem cell migration via the FAK/PI3K/Akt and p38 MAPK signalling pathways

“…Dental caries is a chronic infectious disease, resulting in enamel and dentine demineralization and subsequent pulp tissue injury (Bowen 2016). As the lesion progresses, caries-related microorganisms penetrate dentinal tubules and induce pulpal tissue inflammation, leading to apoptosis of odontoblasts (Le Clerc et al 2018). During inflammation, the pulp tissue releases a series of chemokines and cytokines through congenital or/and acquired immune responses whist responding to bacterial irritants (Jiang et al 2015).…”

Dental Pulp Fibroblasts Response after Stimulation with HEMA and Adhesive System

“…Some studies have shown that dental pulp fibroblasts can secret many types of cytokines in response to various stimuli in a similar manner to immune and endothelial cells as well as odontoblasts (3). Cytokines are proteins secreted by innate and adaptive immune cells that act stimulating these cells.…”

“…In addition, the cytokines of the CXC subfamily, such as IL-8, growth-related oncogene (GRO) and cell-derived stroma (SDF), are potent chemotactic and neutrophil activators (3). Some studies have shown that dental pulp fibroblasts are real sources of chemokines (1,(3)(4)(5). CXCL8, also called IL-8 is produced by a range of cell types, including neutrophils, monocytes, macrophages, fibroblasts, and keratinocytes.…”