Salvianolic Acid C Attenuates LPS-Induced Inflammation and Apoptosis in Human Periodontal Ligament Stem Cells via Toll-Like Receptors 4 (TLR4)/Nuclear Factor kappa B (NF-κB) Pathway

BACKGROUND: Periodontitis is a chronic inflammatory disease that causes gingival detachment and disintegration of alveolar bone. Salvianolic acid C (SAC) is a polyphenol compound with anti-inflammatory and antioxidant activities that is isolated from Danshen, a traditional Chinese medicine made from the roots of Salvia miltiorrhiza Bunge. The aim of this study was to investigate the mechanisms of underlying its protective effects and its inhibition effect on inflammation and apoptosis in human periodontal ligament stem cells (hPDLSCs). MATERIAL/METHODS: LPS-induced hPDLSCs, as a model mimicking an inflammatory process of periodontitis in vivo, were established to investigate the therapeutic effect of SAC in periodontitis. The inflammatory cytokines secretion and oxidative stress status were measured by use of specific commercial test kits. The hPDLSCs viability was analyzed by Cell Counting Kit-8 assay. The cell apoptosis and cell cycle were assayed with flow cytometry. Expressions levels of proteins involved in apoptosis, osteogenic differentiation, and TLR4/NF-κB pathway were evaluated by Western blotting. Alkaline phosphatase (ALP) activity was detected by ALP assay kit and ALP staining. The mineralized nodules formation of hPDLSCs was checked by Alizarin Red S staining. RESULTS: Our results showed that LPS induced increased levels of inflammatory cytokines and oxidative stress and mediated the phosphorylation and nuclear translocation of NF-κB p65 in hPDLSCs. SAC reversed the abnormal secretion of inflammatory cytokines and inhibited the TLR4/NF-κB activation induced by LPS. SAC also upregulated cell viability, ALP activity, and the ability of osteogenic differentiation. The anti-inflammation and TLR4/NF-κB inhibition effects of SAC were reversed by TLR4 overexpression. CONCLUSIONS: Taken together, our results revealed that SAC effectively attenuates LPS-induced inflammation and apoptosis via the TLR4/NF-κB pathway and that SAC is effective in treating periodontitis.