Curcumin Modulates Macrophage Polarization Affecting Dental Pulp Cells

To investigate whether curcumin (Cur) exerts anti-inflammatory and reparative properties on inflamed dental pulp cells by modulating macrophage polarization, given the role of macrophage-dental pulp cell interactions in progression and resolution of pulp inflammation. qRT-PCR assessed Cur's effects on polarization-related gene expression in M0 and M1 macrophages. M0 macrophages were polarized to M1, and conditioned medium (CM) from Cur-treated macrophages under different conditions was collected to culture inflamed human dental pulp cells (hDPCs) model in vitro. The expression levels of inflammation-related genes in hDPCs were analyzed via qRT-PCR. Alkaline phosphatase (ALP) activity, mineralization nodule formation, and osteogenic/odontogenic differentiation-related genes expression were measured. Statistical analysis was performed with SPSS 21.0. All data are presented as mean ± standard deviation. One-way ANOVA was performed followed by LSD post- hoc test. Statistical signifcance was set at p < 0.05 (*). Cur treatment for 24 h significantly reduced the mRNA expression level of M1 markers (iNOS, IL-1β, IL-6) and elevated M2 markers (CD206, Arg-1) in M1-polarized macrophages (p < 0.05). Cur-treated macrophage CM markedly decreased inflammatory mediators gene expression (IL-6, IL-1β, COX-2) in hDPCs (p < 0.05), enhanced ALP activity, promoted mineralization nodule formation (p < 0.05), and upregulated osteogenic genes (ALP, RUNX2, OPN) (p < 0.05). Cur suppresses M1 polarization while promoting M2 polarization, reduces inflammatory mediators expression in hDPCs, and enhances their osteogenic/odontogenic differentiation, demonstrating anti-inflammatory and reparative effects.