Abstract

Bacterial infection caused cell pyroptosis and gingival inflammation contributes to periodontitis progression, and lipopolysaccharide (LPS) is the main infectious agent of gram-negative bacteria, which is reported to be closely associated with gingival inflammation and periodontitis. In this study, the primary human periodontal ligament cells (PDLCs) were isolated, cultured, and exposed to LPS treatment, and the results suggested that LPS suppressed cell viability and promoted pro-inflammatory cytokines’ (IL-1β, IL-18, IL-6, and TNF-α) generation and secretion in the PDLCs and its supernatants in a time- and concentration-dependent manner. Also, we noticed that LPS upregulated NLRP3, Gasdermin D, and cleaved caspase-1 to trigger pyroptotic cell death in the PDLCs. Further experiments identified that glycogen synthase kinase-3β (GSK-3β) was upregulated by LPS treatment, and inhibition of GSK-3β by its inhibitor (GSKI) or GSK-3β downregulation vectors was effective to restore normal cellular functions in LPS-treated PDLCs. Mechanistically, blockage of GSK-3β restrained NLRP3-meidated cell pyroptosis and inflammation, resulting in the recovery of cell viability and inhibition of cell death in PDLCs treated with LPS, which further ameliorated periodontitis progression. Finally, we collected the serum from periodontitis patients and healthy volunteers, and the clinical data supported that those pro-inflammatory cytokines were also upregulated in patients’ serum but not in the healthy participants. Taken together, we concluded that targeting the GSK-3β/NLRP3 pathway mediated cell pyroptosis was effective to attenuate LPS-induced cell death and inflammation in PDLCs, and this study firstly investigated this issue, which broadened our knowledge in this field.