Nano polystyrene microplastics could accumulate in Nile tilapia (Oreochromis niloticus): Negatively impacts on the intestinal and liver health through water exposure.

Microplastics (MPs) have become a significant concern for their potential toxicity. However, the correlation between the size of plastic particles and their toxicity remains inconclusive. Here, we investigate the toxic effects of different sizes (80 nm, 800 nm, 8 µm and 80 µm) polystyrene MPs (PS-MPs) on the model organism Nile tilapia (Oreochromis niloticus). The results of bioluminescent imaging indicate that the 80 nm PS-MPs are more likely to invade the body. H&E staining shows severe damage on the intestinal villi and distinct hepatic steatosis in the 80 nm group. EdU labeling shows that the proliferation activity of intestinal and liver cells reduces significantly in the 80 nm group. The gut microbiome analysis shows a severe imbalance of gut microbiota homeostasis in the 80 nm group. The analysis of liver transcriptomics and metabolomics shows that the liver lipid metabolism is disordered in the 80 nm group. In conclusion, this study confirms that the 80 nm PS-MPs are more likely to induce intestinal and liver toxicity. All the above lay the foundation for further study on the pathological damage of MPs to other organisms.