Experimental periodontitis induces gene expression of proinflammatory cytokines in liver and white adipose tissues in obesity

Background: Recent studies indicated that periodontitis induces systemic low-grade inflammation. The increase in systemic low-grade inflammation induced by periodontitis may alter the effects of obesity on the production of inflammatory molecules, including C-reactive protein (CRP), interleukin (IL)-6, and tumor necrosis factor-alpha (TNF-α), in the liver and white adipose tissue (WAT). The purpose of the present study is to investigate the effects of periodontitis on the expression of proinflammatory cytokines in the liver and WAT in obese Zucker rats. Methods: Obese Zucker rats and their lean litter mates were divided into four groups of six rats each: lean Zucker rats without periodontitis (control group), lean Zucker rats with periodontitis (periodontitis group), obese Zucker rats without periodontitis (obesity group), and obese Zucker rats with peri-odontitis (combination group). Periodontitis was ligature induced for 4 weeks in the periodontitis and combination groups, whereas the other groups were left unligated. Results: At 4 weeks, the gene expression for CRP, IL-6, and TNF-α in the liver and CRP and IL-6 in the WAT of combination groups was significantly higher than in each of the three groups. Serum TNF-α in the periodontitis and obesity groups was significantly higher than in the control group. Serum CRP and TNF-α in the combination group was significantly higher than in each of the three groups. Conclusion: Systemic low-grade inflammation after experimental periodontitis was associated with increased gene expression for hepatic levels of TNF-α and CRP and adipose tissue levels of IL-6 and CRP in the obese-rat model.