Asiaticoside Enhances the Osteoblast Potential of LPS-induced Periodontal Ligament Stem Cells through TLR4/NF-κB Pathway

Abstract

Objective: Asiaticoside (AS), an active compound extracted from Centella asiatica, can promote the osteogenic differentiation of human periodontal ligament cells. In this study, we investigated the impact of AS on lipopolysaccharide (LPS)-induced osteoblast differentiation and inflammatory response in human periodontal ligament stem cells (hPDLSCs) and its possible mechanisms. Method: hPDLSCs were treated with LPS to establish a model mimicking periodontitis and then administered with different concentrations of AS (30, 60, and 120 μM). Flow cytometry and CCK-8 were conducted to assess cell apoptosis and proliferation rates, ELISA to detect the levels of inflammatory factors (IL-1β, IL-8, and TNF-α) in the cell supernatant, and Western blot to determine the expression of osteoblast differentiation proteins (Runx2, and OPN) and TLR4/NF-κB signaling pathway proteins (TLR4, MyD88, P65, p-P65) with ALP and Alizarin red staining conducted. Results: LPS induced apoptosis of hPDLSCs, and inhibited proliferation and osteoblast differentiation when increasing the levels of inflammatory factors. However, these alterations were restored upon AS treatment dose-dependently when cell apoptosis decreased, proliferation rate increased, IL-1β, IL-8, TNF- α levels decreased, and osteoblast differentiation enhanced. Additionally, LPS activated the TLR4/NF-κB signaling pathway in hPDLSCs, up-regulating TLR4, MyD88, and p-P65 expression, which was abrogated by AS. Conclusion: AS ameliorates LPS-induced inflammation and apoptosis in hPDLSCs through TLR4/NF- κB pathway and that AS can be expected to become a therapeutic drug for periodontal tissue regeneration treatment.