Transfer toxicity of polystyrene microplastics in vivo: Multi-organ crosstalk

The accumulation of microplastics (MPs) within the environment caused serious ecological and health problems. Nevertheless, its systemic toxicity to organisms and its mechanisms lack effective evidence. This study established a model of MP exposure through the gavage of polystyrene (PS)-MPs particles to maternal mice on days 1 to 21 of lactation. The results demonstrated that PS-MPs were distributed widely in maternal mice, occurring mainly in the feces, colon, liver and mammary glands. Further experiments revealed that the gut and blood-milk barriers were disrupted, and pathological injury and inflammatory reactions were observed in the liver, gut, and mammary glands. Metabolomic and metagenome analysis indicated abnormalities in hepatic bile acid metabolism and significant alterations in the gut microbiota after exposure to PS-MPs. These alterations led to increased disruption of the intestine-liver axis. Notably, with fecal microbiota transplantation and antibiotic experiments, we observed that elimination of the intestinal microbiota reduced tissue inflammation and improved gut and blood-milk barrier leakage. These findings demonstrated that PS-MPs exaggerated intestine-liver axis disorders by inducing colonic injury, intestinal ecological dysregulation and abnormal hepatic bile acid metabolism. Furthermore, PS-MPs translocated via the intestine-liver axis and exerted broader toxic effects on mammary tissue. Overall, our study uncovered the transfer toxicity of PS-MPs in mice, proposing the possibility of a gut-liver-mammary axis.