Extracellular Vesicles From LPS‐Treated PDLSCs Induce NLRP3 Inflammasome Activation in Periodontitis

ABSTRACT Objective This study aimed to investigate the effects of lipopolysaccharide (LPS)‐pretreated primary periodontal ligament stem cell (PDLSC)‐derived extracellular vesicles (EVs) (L‐PDLSC‐EVs) on periodontitis. Materials and Methods PDLSCs were obtained from mouse periodontal ligaments via enzymatic digestion. An in vitro inflammatory microenvironment for PDLSCs was established using LPS, and L‐PDLSC‐EVs were isolated through ultracentrifugation and identified. EVs from different treatments were co‐incubated with RAW264.7 macrophages (Mφs) or periodontal ligament fibroblasts (PLFs) and their co‐cultures, whereafter the biological behaviors in Mφs and PLFs were evaluated. Periodontitis mouse models were established to verify the role of L‐PDLSC‐EVs and the mechanisms involved. Results There were no significant changes in the characteristics of L‐PDLSC‐EVs compared with control EVs. L‐PDLSC‐EVs promoted M1‐type Mφ polarization and activated the nucleotide‐binding oligomerization domain, leucine‐rich repeat, and pyrin domain‐containing protein 3 (NLRP3) inflammasome. Furthermore, L‐PDLSC‐EVs promoted PLF cytotoxicity and apoptosis by enhancing the M1 polarization of Mφs. In periodontitis mouse models, L‐PDLSC‐EVs facilitated alveolar bone loss, PLF injury, and inflammatory responses, accompanied by an increased proportion of M1‐type Mφs and reinforced NLRP3 inflammasome activation. Conclusions L‐PDLSC‐EVs promoted PLF injury and exacerbated periodontitis through activating the NLRP3 inflammasome and promoting the polarization of M1‐type Mφs, providing novel insights for the periodontitis progression.