Chronic administration of lipopolysaccharide and proteases induces periodontal inflammation and hepatic steatosis in rats

Background: Epidemiologic studies suggest a relationship between periodontitis and liver diseases. A rat periodontitis model was used to investigate whether a causal relationship exists between periodontitis and liver diseases. Methods: Fourteen male Wistar rats (8 weeks old) were divided into two groups: a periodontitis group in which Escherichia coli lipopolysaccharide (LPS) and Streptomyces griseus proteases were applied into the gingival sulcus for 8 weeks, and a control group using pyrogen-free water instead. After blood samples were collected, periodontal tissues and liver specimens were analyzed. Results: Chronic administration of LPS and proteases to the gingival sulcus induced periodontitis and liver injury, including steatosis with inflammation and sinusoidal fibrosis. Apoptosis, enhanced concentration of 8-hydroxydeoxyguanosine, and activated production of tumor necrosis factor-alpha in liver were observed in the periodontitis group, with increased gingival inflammation, serum LPS, and reactive oxygen species. Conclusion: Periodontal inflammation in a rat model induced fatty liver disease through increased serum LPS.