Microplastic’s Effects on Gene Expression and Microflora of Mice Colon in Health and Acute Colitis

Due to the growing pollution of the environment with a microplastic (MP), the problem of MP impact on human health is relevant. MP is considered to contribute to the development of inflammatory bowel diseases. Therefore, we assessed the effect of long-term MP consumption on the expression of genes associated with the colon barrier function and on the luminal microflora composition in healthy mice and in mice with acute colitis. The effect of MP was modeled by replacing drinking water with a 10 mg/L suspension of 5 µm polystyrene particles for six weeks. To model acute colitis, 1% sodium dextran sulfate was added to the drinking water from day 36 to day 40 of the experiment. In healthy mice, MP caused an increase in the mRNA expression of transmembrane mucin Muc3, tight junction proteins Cldn4 and Cldn7, pro-apoptotic factor Bax, and anti-apoptotic factor Bcl2, which generally indicates the activation of synthetic processes in the intestinal epithelium. This is an adaptive response. An increase in the representation of the genus Aestuariispira was observed in the microflora. In colitis with MP consumption, the mRNA expression of Cldn4 and Bax, and the Bax/Bcl2 ratio were lower, and expression of Muc13 was higher than in colitis without MP. The content of bacteria from 24 genera in the microflora differed.