Search

Aim: Periodontitis (PD) is the sixth most prevalent disease around the world and is involved in the development and progression of multiple systemic diseases. Previous studies have reported that PD may aggravate liver injuries. The objective of this study was to investigate whether and how PD affects liver fibrosis. Materials and Methods: Ligature‐induced PD (LIP) was induced in male C57/B6J mice, and sub‐gingival 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 analysed by serum alanine aminotransferase and hepatic hydroxyproline. Picrosirius red and α‐smooth muscle actin (SMA) staining were used to evaluate the 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 analyse the accumulation of immune cells. Mouse microbiota were analysed using 16S rRNA gene sequencing. Results: Mice in 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 liver samples than those of the CCl4 group, suggesting that PD (LIP+PL) aggravated CCl4‐induced hepatic dysfunction and liver fibrosis. Consistently, the expression of fibro‐genic genes and the protein levels of transforming growth factor β were much higher in the CCl4+LIP+PL group than in 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 pro‐inflammatory nuclear factor‐kappa B pathway in the 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 the increase of inflammation and alteration of microbiota in the liver. [ABSTRACT FROM AUTHOR]

Aims This study explored sFasL expression in neurons and the potential role of neuronal sFasL in modulating the microglial phenotypes. Methods In vivo, middle cerebral artery occlusion ( MCAO) was induced in both FasL-mutant ( gld) and wild-type (wt) mice. In vitro, primary cortical neuron or microglia or coculture from wt/ gld mice was subjected to oxygen glucose deprivation ( OGD). sFasL level in the supernatant was evaluated by ELISA. Neuronal-conditioned medium (NCM) or exogenous sFasL was applied to primary microglia with or without FasL neutralizing antibody. Protein expression of JAK2/ STAT3 and NF-κB pathways were determined by Western blot. The effect of microglia phenotype from wt/ gld mice on the fate of ischemic neurons was further elucidated. Results In vivo, compared with wild-type mice, M1 markers ( CD16, CD32 and iNOS) were attenuated in gld mice after MCAO. In vitro, post- OGD neuron released more sFasL. Both post- OGD NCM and exogenous sFasL could trigger M1-microglial polarization. However, this M1 phenotype shift was partially blocked by utilization of FasL neutralizing antibody or gld NCM. Consistently, JAK2/ STAT3 and NF-κB signal pathways were both activated in microglia after exogenous sFasL treatment. Compared with wild-type mice, M1-conditioned medium prepared from gld mice protected neuron against OGD injury. Conclusions Ischemic neurons release sFasL, which contributes to M1-microglial polarization. The underlying mechanisms may involve the activation of JAK2/ STAT3 and NF-κB signaling pathways. [ABSTRACT FROM AUTHOR]