LPS-induced inflammation potentiates dental pulp stem cell odontogenic differentiation through C5aR and p38

Inflammation is a complex host response to harmful infection or injury, and it seems to play a crucial role in tissue regeneration both positively and negatively. We have previously demonstrated that the activation of the complement C5a pathway affects dentin-pulp regeneration. However, limited information is available to understand the role of the complement C5a system related to inflammation-mediated dentinogenesis. The aim of this study was to determine the role of complement C5a receptor (C5aR) in regulating lipopolysaccharide (LPS)-induced odontogenic differentiation of dental pulp stem cells (DPSCs).

Human DPSCs were subjected to LPS-stimulated odontogenic differentiation in dentinogenic media treated with the C5aR agonist and antagonist. A putative downstream pathway of the C5aR was examined using a p38 mitogen-activated protein kinase (p38) inhibitor (SB203580).

Our data demonstrated that inflammation induced by the LPS treatment potentiated DPSC odontogenic differentiation and that this is C5aR dependent. C5aR signaling controlled the LPS-stimulated dentinogenesis by regulating the expression of odontogenic lineage markers like dentin sialophosphoprotein (DSPP) and dentin matrix protein 1 (DMP-1). Moreover, the LPS treatment increased the total p38, and the active form of p38 expression, and treatment with SB203580 abolished the LPS-induced DSPP and DMP-1 increase.

These data suggest a significant role of C5aR and its putative downstream molecule p38 in the LPS-induced odontogenic DPSCs differentiation. This study highlights the regulatory pathway of complement C5aR/p38 and a possible therapeutic approach for improving the efficiency of dentin regeneration during inflammation.