Non-Alcoholic Fatty Liver Disease Aggravates Periodontitis In Mice

Emerging clinical evidence has established a significant correlation between non-alcoholic steatohepatitis (NASH) and periodontitis severity, yet the causative relationship remains unclear. This study aims to investigate the direct impact of NASH on periodontitis progression and underlying mechanisms in vivo and in vitro. Thirty 7-8-week-old male mice were randomly allocated to receive either standard chow or NASH-inducing diet for 19 weeks before establishing ligature-induced periodontitis. Liver pathology was evaluated by H&E and Masson's trichrome staining, while mandibular bone destruction was assessed through TRAP staining and micro-CT analysis. Immunofluorescence examined macrophage NLRP3 inflammasome activation. In vitro, LPS-primed bone marrow-derived macrophages were treated with palmitic acid/cholesterol plus ATP to activate the NLRP3 inflammasome. Conditioned medium was applied to RANKL-stimulated BMDMs to assess osteoclast differentiation via TRAP staining and F-actin ring assays. NASH-diet-fed mice showed more severe hepatic steatosis and injury than chow-fed controls, with significantly worsened ligature-induced periodontitis, marked by increased alveolar bone loss, inflammatory infiltration, and osteoclast activation. Immunofluorescence revealed enhanced NLRP3 inflammasome activation in alveolar bone macrophages. In vitro studies demonstrated that palmitic acid and cholesterol synergistically activated the NLRP3 inflammasome in macrophages, and their conditioned medium markedly promoted RANKL-induced osteoclast differentiation and F-actin ring formation. These findings demonstrate that NASH significantly accelerates ligature-induced periodontitis progression in mice by promoting NLRP3 inflammasome activation in periodontal macrophages, closely associated with systemically elevated cholesterol and free fatty acid levels.