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

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 three-dimensional 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.