<p>Periodontitis is a chronic inflammatory disease characterized by the progressive destruction of tooth-supporting tissues. Despite extensive research, the molecular mechanisms underlying its pathogenesis remain incompletely understood. This study aimed to investigate the role and regulatory mechanisms of miR-221/222-3p in experimental periodontitis. The expression of miR-221/222-3p in lipopolysaccharide (LPS)-stimulated periodontal ligament cells (PDLCs) and ligation-induced rat periodontitis were detected by RT-qPCR. miR-221/222-3p agomir were administrated topically in ligation-induced rat periodontitis. The therapeutic function of both miRNAs were assessed by micro-CT, TRAP staining, and immunohistochemistry. The mechanisms of miR-221/222-3p function in periodontitis were determined by cell assays. miR-221-3p and miR-222-3p expression were both downregulated in LPS-stimulated PDLCs and ligation-induced periodontitis rat. In vitro, miR-221-3p and miR-222-3p could alleviate the inflammatory damage of PDLCs upon LPS stimulation. Mechanically, PAK1 is demonstrated as a target gene of miR-221/222-3p. Additionally, STAT1 signaling pathway is activated by LPS treatment and STAT1 could bind to the upstream region of the miR-221/222-3p promoter and repress their expression. In vivo, miR-221/222-3p agomir rescued the alveolar bone loss, alleviated the infiltration of osteoclasts and the expression of inflammatory cytokines of periodontitis rats. Our results revealed a novel STAT1-miR-221/222-3p-PAK1 axis in the initiation and progression of periodontitis. Specific targeting this signaling pathway may provide a new therapeutic avenue for periodontitis.</p>