RESUMO
Wnt5a has been found recently to be involved in inflammation regulation through a mechanism that remains unclear. Immunohistochemical staining of infected human dental pulp and tissue from experimental dental pulpitis in rats showed that Wnt5a levels were increased. In vitro, Wnt5a was increased 8-fold in human dental pulp cells (HDPCs) after TNF-α stimulation compared with control cells. We then investigated the role of Wnt5a in HDPCs. In the presence of TNF-α, Wnt5a further increased the production of cytokines/chemokines, whereas Wnt5a knockdown markedly reduced cytokine/ chemokine production induced by TNF-α. In addition, in HDPCs, Wnt5a efficiently induced cytokine/chemokine expression and, in particular, expression of IL-8 (14.5-fold) and CCL2 (25.5-fold), as assessed by a Luminex assay. The cytokine subsets regulated by Wnt5a overlap partially with those induced by TNF-α. However, no TNF-α and IL-1ß was detected after Wnt5a treatment. We then found that Wnt5a alone and the supernatants of Wnt5a-treated HDPCs significantly increased macrophage migration, which supports a role for Wnt5a in macrophage recruitment and as an inflammatory mediator in human dental pulp inflammation. Finally, Wnt5a participates in dental pulp inflammation in a MAPK-dependent (p38-, JNK-, and ERK-dependent) and NF-κB-dependent manner. Our data suggest that Wnt5a, as an inflammatory mediator that drives the integration of cytokines and chemokines, acts downstream of TNF-α.
Assuntos
Polpa Dentária/metabolismo , Mediadores da Inflamação/metabolismo , Sistema de Sinalização das MAP Quinases , NF-kappa B/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Wnt/metabolismo , Animais , Quimiocina CCL2/genética , Quimiocina CCL2/metabolismo , Polpa Dentária/patologia , Feminino , Humanos , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Interleucina-8/genética , Interleucina-8/metabolismo , Macrófagos/metabolismo , Macrófagos/patologia , Masculino , NF-kappa B/genética , Proteínas Proto-Oncogênicas/genética , Ratos , Ratos Wistar , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/metabolismo , Proteínas Wnt/genética , Proteína Wnt-5aRESUMO
Both bone morphogenetic protein 2 (BMP2) and the wingless-type MMTV integration site (WNT)/ß-catenin signalling pathway play important roles in odontoblast differentiation and dentinogenesis. Cross-talk between BMP2 and WNT/ß-catenin in osteoblast differentiation and bone formation has been identified. However, the roles and mechanisms of the canonical WNT pathway in the regulation of BMP2 in dental pulp injury and repair remain largely unknown. Here, we demonstrate that BMP2 promotes the differentiation of human dental pulp cells (HDPCs) by activating WNT/ß-catenin signalling, which is further mediated by p38 mitogen-activated protein kinase (MAPK) in vitro. BMP2 stimulation upregulated the expression of ß-catenin in HDPCs, which was abolished by SB203580 but not by Noggin or LDN193189. Furthermore, BMP2 enhanced cell differentiation, which was not fully inhibited by Noggin or LDN193189. Instead, SB203580 partially blocked BMP2-induced ß-catenin expression and cell differentiation. Taken together, these data suggest a possible mechanism by which the elevation of ß-catenin resulting from BMP2 stimulation is mediated by the p38 MAPK pathway, which sheds light on the molecular mechanisms of BMP2-mediated pulp reparative dentin formation.