The combination of experimental periodontitis and oral microbiota from periodontitis patients aggravates liver fibrosis in mice
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Aims: Periodontitis (PD) is the sixth most prevalent diseases around the world and is involved in the development and progression of multiple systematic diseases. Previous studies have reported that PD may aggravate liver injuries. The objective of this study was to investigate whether and how PD affected liver fibrosis.
Methods: Ligature-induced PD (LIP) was induced in male C57/B6J mice and subgingival plaques (PL) from patients with PD were applied to mouse teeth. Liver fibrosis was induced by carbon tetrachloride (CCl4) injection. The mice were randomly divided into six groups: Oil, Oil +LIP, Oil +LIP+PL, CCl4, CCl4+LIP, and CCl4+LIP+PL. Alveolar bone resorption was evaluated by methylene blue staining. Hepatic function was analyzed by serum alanine aminotransferase and hepatic hydroxyproline. Picrosirius red and α-SMA staining were used to evaluate fibrotic area. RNA sequencing and quantitative RT-PCR were used to measure gene expression. Western blotting was used to measure protein levels. Flow cytometry was used to analyze accumulation of immune cells. Mouse microbiota was analyzed using 16S rRNA sequencing.
Results: Mice of the CCl4+LIP+PL group displayed higher serum alanine aminotransferase and hepatic hydroxyproline, as well as more Picrosirius red-positive and α-SMA-positive areas in livers than those of the CCl4 group, suggesting that PD (LIP+PL) aggravated CCl4-induced hepatic dysfunction and liver fibrosis. Consistently, expression of fibro-genic genes and protein levels of transforming growth factor β were much higher in the CCl4+LIP+PL group compared to the CCl4 group. Flow cytometry revealed that PD increased the accumulation of immune cells, including Kupffer cells, B cells and Th17 cells, in the liver of mice with CCl4 treatment. PD also increased the expression of inflammatory genes and activated proinflammatory nuclear factor-kappa B pathway in livers of CCl4-injected mice. Moreover, PD altered both oral and liver microbiota in CCl4-injected mice.
Conclusions: PD aggravates CCl4-induced hepatic dysfunction and fibrosis in mice, likely through increase of inflammation and alteration of microbiota in livers.
Lan Bai,Yong-Li Wang,Yan-Lin Chen
Zhong-Chen Song,Sheng-Zhong Duan
Lan Bai,Yong-Li Wang,Yan-Lin Chen,Hu-Xiao Li,Shi-Wei Zhu,Yan Liu,Zhong-Chen Song,Sheng-Zhong Duan