EFFECTS OF SUBCHRONIC EXPOSURE TO POLYSTYRENE NANOPLASTICS ON THE MOUSE SMALL INTESTINE

Nanoplastics (NPs) are being used increasingly in cosmetics, personal care products, foods, automotive products, and cleaning products, as well as being by-products of some industrial processes. The aim of this study was to examine the effects of a subchronic exposure of NPs on various biological systems, using mice as a model. Adult male mice were administered 500 nm polystyrene (PS) NPs at 0.15 mg/day and 1.5 mg/day for 60 days, to mimic subchronic exposure to NPs. Control mice received water. The small intestines were separated into three regions: duodenum, jejunum, and ileum. Hematoxylin and eosin (H&E) staining was performed to evaluate histopathology, and RNA-Seq was conducted on tissues from all three regions. H&E staining revealed few effects on the duodenum, but increasingly pronounced disruption and epithelial alterations in the jejunum and ileum, respectively. RNA-Seq analysis of controls compared to the high-dose (HD; 1.5 mg/day) group supported these observations. The number of differentially expressed genes (DEGs) was low (19) in the duodenum, higher in the jejunum (114 DEGs), and significantly greater in the ileum (4982 DEGs) suggesting differential sensitivity of the different regions of the small intestine. Genes associated with immune response, ion transport, and junctional proteins were among the groups of genes most differentially expressed. These results demonstrate the potentially harmful effects of PS NPs on the small intestine of mice and that the sensitivity to NPs increases along the intestine.