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

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.