The effect of polystyrene nanoplastic on ion channels and mucus secretion – insights from Caco-2 cell model

Abstract

Plastic pollution is an escalating global concern, as the degradation of plastic waste generates micro- and nanoplastics that can be ingested by living organisms and interact with the intestinal epithelial barrier. However, the effects of nanoplastics on human intestinal epithelial function, particularly with respect to transepithelial ion transport, remain insufficiently understood. To better understand the effects of nanoplastics on the intestinal epithelium, we aimed to investigate the impact of 100 nm polystyrene nanoplastics (PS-NPs) on mucus secretion, ion transport, and epithelial integrity in the human intestinal epithelial cell line Caco-2. The cellular response to nanoplastic exposure was assessed by measuring cytotoxicity, transepithelial electrical resistance (TEER), and cell migration. Transepithelial ion transport was assessed in Ussing chamber system on treated and untreated Caco-2 cell monolayers, and the activity of specific ion-channels was analysed using selective pharmacological modulators. Despite some alterations, nanoplastic exposure did not exert marked cytotoxic effects, changes in barrier integrity, and in cell migration. Ion transport analysis revealed decreased CFTR activity and enhanced CaCC activity in nanoplastic-treated cell monolayers. Nanoplastic exposure also induced an increase in mucus secretion. These findings suggest that polystyrene nanoplastics modulate intestinal epithelial ion transport and stimulate mucus secretion, which may be associated with TMEM16A activation. This response may represent a protective mechanism of intestinal epithelial cells against nanoplastic exposure.