Attenuation of Porphyromonas Gingival Lipopolysaccharide-Induced Periodontal Ligament Stem Cells Injury and Inflammation by Blocking Cell Pyroptosis

Periodontitis is a chronic inflammation of periodontal tissue, and programmed cell death plays an important role in chronic periodontitis induced by P. gingivalis. Studies have shown that the increased expression of pyroptosis-related NLRP3 inflammasome and the pro-inflammatory cytokines IL-1 beta and IL-18 in gingivitis, invasive periodontitis, and chronic periodontitis patients. The present study aimed to investigate whether the inhibition of pyroptosis could protect porphyromonas gingival lipopolysaccharide (pg-LPS)-induced human periodontal ligament stem cells (hPDLSCs) injury and inflammation. The hPDLSCs were treated with pg-LPS and ATP in the presence of caspase1/4 inhibitor VX765. The cell proliferation and survival were assessed by CCK-8, the osteogenic differentiation capacity was evaluated by Alkaline Phosphatase (ALP) assay and alizarin red staining. Then, cell apoptosis, cleavage of gasdermin D (GSDMD) and generation of inflammatory cytokines were estimated. Lastly, western blotting was used to detect the expression of potential target proteins. Results showed that the treatment of pg-LPS plus ATP significantly inhibited the proliferation, survival and osteogenic differentiation of hPDLSCs, while inducing cell apoptosis, pyroptosis and inflammation. However, the presence of VX765 partially recovered the cell proliferation, survival and osteogenic differentiation. At the same time, VX765 inhibited cell apoptosis, cleavage of GSDMD and generation of inflammatory cytokines. Besides, the expression of related proteins including Bax, Bcl-2, cleaved (c)-caspase3, c-caspase4, c-caspase1, Toll Like Receptor 4, High Mobility Group Box 1 (HMGB1) and NLRP3 was all rescued by VX765. In conclusion, our results revealed that the blocking of cell pyroptosis could protect hPDLSCs from pg-LPS-induced injury. Therefore, the application of pyroptosis inhibitor may be a valuable therapeutic approach for treating periodontitis.