Punicalagin ameliorates lipopolysaccharide-induced inflammatory response in dental pulp cells via inhibition of the NF-κB/Wnt5a-ROR2 pathway

Abstract

Introduction: Punicalagin (PCG) is a major polyphenolic component with potent anti-inflammatory, anti-atherogenic, anti-cancer, and antioxidant activities. This study aimed to investigate the impact and underlying mechanisms of PCG on lipopolysaccharide (LPS)-induced dental pulpitis. Methods: A rat pulpitis model was constructed, and the infected pulp was covered with a PCG collagen sponge. In vitro, dental pulp cells (DPCs) were isolated, and the effects of LPS and PCG on cell viability were assessed. The expression levels of inflammation-related factors were investigated by qRT-PCR and ELISA. The Nuclear Factor kappa B (NF-κB) transcription factors and Wnt family member 5a-Receptor tyrosine kinase like Orphan Receptor 2 (Wnt5a-ROR2) levels were evaluated by immunofluorescence staining and Western blotting. Results: We demonstrated that the PCG collagen sponge effectively reduced the infiltration of inflammatory cells in the pulp. PCG significantly alleviated the inflammatory response by reducing the mRNA expression levels of IL-1β, IL-6, IL-8, ICAM-1, and VCAM-1 and the secretion of IL-6 and IL-8 in a concentration-dependent manner. Immunofluorescence staining showed that the activation of the NF-κB pathway was hindered by PCG, which affected with the nuclear translocation of P65. PCG reduced the phosphorylation levels of P65 and IκBα and suppressed the expression levels of Wnt5a and ROR2 induced by LPS. The NF-κB inhibitor Bay11-7082 reduced the activation of the NF-κB/Wnt5a-ROR2 pathway and the inflammatory response; the application of PCG significantly augmented this inhibitory effect. Discussion: PCG demonstrated an anti-inflammatory effect in LPS-induced DPCs by targeting the NF-κB/Wnt5a-ROR2 signaling pathway.