DKK1 and TNF-α Affect the Promotion Effect of Berberine on Osteogenic Differentiation of Dental Pulp Stem Cells in Peri-Implantitis

Abstract

Background: Dental pulp stem cells (DPSCs) can improve periodontal tissue regeneration and have significant clinical application value in treating peri-implantitis. The Wnt signaling pathway is crucial for osteogenic differentiation of DPSCs. Berberine (BBR) has been found to promote the viability and differentiation of DPSC, whereas tumor necrosis factor-alpha (TNF-α) is a key factor affecting bone resorption. Additionally, Dickkopf 1 (DKK1) inhibits the Wnt canonical pathway. This study aims to explore how DKK1/TNF-α affects BBR-regulated osteogenic differentiation of DPSCs via the Wnt signaling pathway. Methods: We first evaluated the impact of varying doses of BBR, DKK1, and TNF-α on the viability of DPSCs through Cell Counting Kit-8 (CCK-8) experiments. Subsequently, we assessed the influence of DKK1/TNF-α/BBR on the osteogenic differentiation of DPSCs using alkaline phosphatase (ALP) staining, Alizarin Red staining, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blot techniques. Finally, we investigated the effects of DKK1/TNF-α/BBR on Wnt signaling-related genes and proteins during DPSC osteogenic differentiation using qRT-PCR and Western blot. Results: The results showed that moderate to low concentrations of BBR, DKK1, and TNF-α enhanced the activity of DPSCs, while high concentrations of BBR, DKK1, and TNF-α inhibited DPSC proliferation. BBR promoted the osteogenic differentiation of DPSC by activating the Wnt/β-catenin pathway. DKK1 or TNF-α alone inhibited the promotional effect of BBR, while the combination of DKK1 and TNF-α reduced the inhibitory effect. TNF-α up-regulated the expression of the classical Wnt pathway and down-regulated the expression of the non-classical Wnt pathway. On the other hand, DKK1 inhibited the classical pathway and promoted the non-classical pathway. Conclusions: DKK1 reduced the inhibitory effect of TNF-α on BBR and promoted the osteogenic differentiation of DPSC through the Wnt signaling pathway. These findings provided a reference value for the treatment of bone resorption caused by peri-implantitis.