Microplastics are detected in human gallstones and have the ability to form large cholesterol-microplastic heteroaggregates

Ubiquitous pollution due to microplastics through the food chain is a major cause of various deleterious effects on the human health. The aim of this study was to determine the existence of microplastics and the internal mechanism of microplastics as accelerators of cholelithiasis. Gallstones were collected from 16 patients after cholecystectomy, and microplastics in the gallstones were detected through laser direct infrared and pyrolysis gas chromatographymass spectrometry examinations. Mice model of gallstone were constructed with or without different diameters of microplastic (0.5, 5 and 50 µm). The affinity between microplastic and cholesterol or bilirubin was tested by co-culturing and qualified using molecular dynamics simulations. Finally, altered gut microbiota among the groups were identified using 16 s rRNA sequencing. The presence of microplastics in the gallstones of all the patients were confirmed. Microplastic content was significantly higher in younger chololithiasis patients (age<50 years). Mice fed a high-cholesterol diet with microplastic drinks showed more severe chololithiasis. In terms of the mechanism, microplastics showed a higher affinity for cholesterol than for bilirubin. Significant alterations in the gut microbiota have also been identified after microplastic intake in mice. Our study revealed the presence of microplastics in human gallstones, showcasing their potential to aggravate chololithiasis by forming large cholesterol-microplastic heteroaggregates and altering the gut microbiota.