Circ_0087199 Depletion Attenuates Lipopolysaccharides-induced Human Periodontal Ligament Cell Injury Through the MiR-527/TLR4 Axis

Background: Circular RNAs participate in the development of periodontitis. The present work aims to reveal the role and mechanism of circ_0087199 in human periodontal ligament cell (PDLC) injury during periodontitis.

Methods: PDLCs were treated with lipopolysaccharides (LPS) to establish a periodontitis cell model. Quantitative real-time polymerase chain reaction was used to detect the expression of circ_0087199, miR-527, toll-like receptor 4 (TLR4). Western blot analysis assay was performed to assess protein expression. Cell viability, proliferation, apoptosis and inflammation were investigated by cell counting kit-8, EdU assay, flow cytometry and enzyme-linked immunosorbent assay, respectively. Oxidative stress was evaluated by malondialdehyde assay kit and superoxide dismutase activity assay kit. The interaction between miR-527 and circ_0087199 or TLR4 was confirmed by a dual-luciferase reporter assay.

Results: Circ_0087199 and TLR4 expression levels were significantly increased, while miR-527 was decreased in the periodontal ligament tissues of periodontitis patients and LPS-stimulated PDLCs when compared with controls. LPS treatment inhibited cell viability and proliferation but induced cell apoptosis, inflammation and oxidative stress, whereas these effects were attenuated after circ_0087199 knockdown. Circ_0087199 bound to miR-527 and regulated LPS-caused PDLC damage by targeting miR-527. Additionally, the overexpression of TLR4, a target gene of miR-527, rescued miR-527 mimic-mediated effects on LPS-treated PDLCs. Further, the regulation of circ_0087199 toward TLR4 involved miR-527.

Conclusion: Circ_0087199 knockdown attenuated LPS-induced apoptosis, inflammation and oxidative stress of PDLCs by regulating the miR-527/TLR4 pathway.