Exacerbation of polyethylene microplastics in animal models of DSS-induced colitis through damage to intestinal epithelial cell conjunctions

• Polyethylene microplastics were developed to replicate environmental conditions, fragmentation and oxidation. • PE-MPs aggravated clinical symptoms and inflammation in an animal model of inflammatory bowel disease. • PE-MPs caused damage to tight and adherens junction proteins, affecting gut epithelial integrity. Microplastics are pollutants that occur in various environments and habitats. Inflammatory bowel disease (IBD) is a chronic inflammatory disease accompanied with diarrhea, and the number of patients has increased worldwide. In this study, manufactured fragmented polyethylene-microplastics in the size range of 10–30 ㎛, were oxidized by exposure to ultraviolet light, and then administered to a dextran sodium sulfate-induced colitis mouse model to observe the effects of polyethylene-microplastics on IBD. In the microplastics-treated groups, an increase in disease activity index score, histopathological score, and a decrease in the areas of goblet cells were observed. In addition, the tight junction proteins, ZO-1 and Occludin, were significantly decreased, whereas MPO was significantly increased. Interestingly, E-cadherin, which is an adheren junction, was also decreased, presumably because of the physical effects of microplastics. The results suggest that polyethylene-microplastics worsen IBD and microplastics can affect not only tight junctions, but also adheren junctions.