Gut microbiota exaggerates triclosan-induced liver injury via gut-liver axis

Triclosan (TCS) is an antimicrobial ingredient that has been widely incorporated in consumer products. TCS can cause hepatic damage by disturbing lipid metabolism, which is often accompanied with gut microbiota dysbiosis. However, the effects of gut microbiota on the TCS-induced liver injury are still unknown. Therefore, we constructed a mouse model based on five-week-old male C57BL/6 mice to investigate the effects of dietary TCS exposure (40 ppm) on liver injury. We found that TCS treatment for 4 weeks dramatically disturbed gut microbiota homeostasis, resulting in overproduction of lipopolysaccharides (LPS) and deficiency of secondary bile acids such as deoxycholic acid (DCA) and lithocholic acid (LCA). In addition, TCS considerably increased intestinal permeability by reducing mucus excretion and expression of tight junction proteins (ZO-1, occludin and claudin 4), which facilitated translocation of LPS. The LPS accumulation in blood contributed to liver injury by triggering the inflammatory response via TLR4 pathway. In summary, this study provides novel insights into the underlying mechanisms of TCS-associated liver injury induced by gut microbiota via the gut-liver axis, and contributes to better interpretation of the health impact of the environmentally emerging contaminant TCS.