Abstract
Objectives: To determine whether the combination of resolvin E1 (RvE1) and lipoxin A4 (LXA4) could promote resolution of pulpitis and to investigate the mechanism. Materials and methods: Preliminary screening was first conducted in four specialized pro-resolving mediators (SPMs). Real-time quantitative polymerase chain reaction, western blotting, enzyme-linked immunosorbent assay and double-immunofluorescence labelling were employed to assess the expression of RelA, SIRT1, SIRT6, SIRT7 and pro-inflammatory factors. Dental pulp fibroblasts (DPFs) were transfected with siRNA to assess the biological role of SIRT7. A pulpitis model was utilized to evaluate the in vivo curative effect. Results: Preliminary results showed that RvE1 and LXA4 reduced the expression of RelA more markedly than other two SPMs. Both RvE1 and LXA4 treatment downregulated nuclear factor kappa B (NF-κB) activation and increased the expression of SIRT1, SIRT6 and SIRT7, more so in combination than alone. Double-immunofluorescence labelling showed that SIRT7 co-localized with p-p65 and Ac-p65 in the nucleus. Inhibiting ChemR23 and ALX reversed the expression of RelA mRNA, p-p65 and Ac-p65 proteins, pro-inflammatory factors, SIRT1, SIRT6 and SIRT7. Silencing SIRT7 significantly increased p-p65 and Ac-p65 protein levels and decreased SIRT1 and SIRT6 expression. In vivo experiments showed that combined administration of RvE1 and LXA4 promoted pulpitis markedly to resolution. Conclusions: Combination of RvE1 and LXA4 effectively inhibited NF-κB activation by upregulating SIRT7 expression in DPFs, leading to reduced production of pro-inflammatory factors and promotion of pulpitis resolution.