Perturbation of gut microbiota plays an important role in micro/nanoplastics-induced gut barrier dysfunction

The widespread of microplastics (MPLs) and nanoplastics (NPLs), collectively abbreviated as M/NPLs, has markedly affected the ecosystem and become a global threat to human health. Multiple investigations have shown that chronic ingestion of M/NPLs injures gut barrier function but the mechanism remains unclear. Herein, this research investigated toxic effects of pristine polystyrene (PS) M/NPLs, negatively charged carboxylated polystyrene M/NPLs (PS-COOH), and positively charged aminated polystyrene M/NPLs (PS-NH2) with two sizes (70 nm and 5 μm in diameter) in mice. Gavage of these PS M/NPLs for 28 days caused obvious injuries to gut tract, leading to decreased expression of tight junction proteins. The toxicity of the M/NPLs ranked as PS-NH2 > PS-COOH > pristine PS. Oral administration of these M/NPLs resulted in marked gut microbiota dysbiosis. The M/NPLs-enriched genera generally contained opportunistic pathogens which are accompanies deteriorated intestinal barrier function, while most M/NPLs-decreased bacteria were beneficial microbes with known tight junction-promoting functions, implicating an important indirect toxic effect of gut microbiota dysbiosis in M/NPLs -induced gut barrier dysfunction. In conclusion, the research highlights the importance of gut microbiota in the toxicity of M/NPLs exposure on gut barrier function, providing novel insights into the adverse effects of M/NPLs exposure on human health.