Abstract
Porphyromonas gingivalis (P. gingivalis), the main pathogen responsible for periodontitis, is linked to systemic disorders via the oral-gut axis. Short-chain fatty acids (SCFAs) are vital for gut health, but their role in P. gingivalis-induced gut disorders remains unclear. This study utilized metabolomics and 16 S rRNA sequencing to explore gut microbiota and SCFAs levels in P. gingivalis-induced periodontitis mouse models. Significant changes were observed in gut, including a reduction in SCFAs-producing bacteria, such as Lactobacillus, Ligilactobacillus, Allobucalum, and a notable decrease in Firmicutes and Actinobacteriota. The intestinal permeability tests and histological analyses revealed that periodontitis led to epithelial inflammation, reduced mucin secretion, and compromised gut barrier integrity. In vitro experiments with Caco-2 cells co-cultured with P. gingivalis showed that the bacterium disrupted cellular junctions by impairing autophagy, specifically through the ATG5-LC3 pathway, leading to decreased expression of tight junction proteins and reduced SCFA absorption. Remarkably, rapamycin treatment both in vitro and in vivo restored gut barrier function by enhancing autophagy, increasing tight junction protein expression, and promoting SCFAs absorption via MCT1 and SMCT1, alongside GPR43/GPR109a pathway activation. These findings reveal autophagy's novel role in regulating SCFAs metabolism in P. gingivalis-induced gut dysbiosis, offering insights for preventing and treating periodontitis-related systemic diseases.