New insight into intestinal toxicity accelerated by aged microplastics with triclosan: Inflammation regulation by gut...

The combined toxic effects of microplastics (MPs) and their carried contaminants on organisms have been widely concerned; however, the health risks and its mechanism of "gut microbiota-host metabolism (bile acids, BA)" remain unknown. Herein, Xenopus tropicalis were exposured to aged polystyrene MPs carried triclosan (aPS+TCS) and single (a)PS-MPs & TCS, respectively. The bioaccumulation of TCS in the gut of X. tropicalis was significantly increased in aPS+TCS group, which was 89 % higher than that of PS+TCS group, causing more severe oxidative stress, inflammation and intestinal barrier disruption (leaky gut). The expressions of TNF-α, IL-6 and IL-10 in aPS+TCS group were enhanced by 276 % and 19 % and decreased by 81 %, respectively, compared to that in PS+TCS group. Moreover, co-exposure to aPS+TCS increased the number of Escherichia coli, and reduced levels of DCA and LCA (secondary BAs). Multiomics analysis further revealed that the intestinal toxicity of aPS+TCS to X. tropicalis was mainly influenced by the gut flora, BA metabolism and inflammation-related pathways. Co-exposure may exacerbate inflammation by increasing the blood levels of lipopolysaccharides and inhibiting secondary BA production, which are regulated by the gut microbiota-bile acid axis. This study provides new insights in the potential mechanisms of intestinal damage from pollutant-loaded aged MPs.