Exposure to nanoplastics at a human-relevant dose impairs epithelial cell lineage in murine and human colonoid models

The exponential increase in plastic consumption since the 1960s has led to widespread and increasing environmental contamination worldwide. Nanoplastics generated by plastic fragmentation have become ubiquitous in the human food chain and drinking water. Studies are needed to identify relevant models for human health risk assessment and to enable robust characterization of nanoplastic toxicity to the human intestinal epithelium. Fit-for-purpose polystyrene nanoplastics (nPS) were synthesized without additives or surfactants and then surface-functionalized to mimic environmental aging. The effects of a human-relevant dose of nPS (10 µg mL -1 ) were evaluated in diverse colon epithelial models. In colonoids from healthy mice, transcriptomic analysis identified alterations in the receptor for advanced glycation end products (RAGE) signaling pathway and transmembrane receptor activity. Decreased expression of leucine-rich repeat-containing G protein-coupled receptor 5 ( Lgr5) , a stem cell marker, and increased expression of epithelial cell adhesion molecule ( Epcam) , a pan-epithelial marker, were observed. A similar profile was observed in colonoids from control patients and from patients with colorectal cancer and Crohn's disease and was validated at the protein level for the EPCAM marker. This pattern was associated with impaired differentiation and proliferation across the colonoid types tested. The same pattern was also observed under lipopolysaccharide (LPS)-induced inflammatory conditions. The nPS exerted an anti-inflammatory effect in a LPS-stimulated control colonoid and a pro-inflammatory effect in a LPS-stimulated Crohn’s disease colonoid. This study shows that nPS at a human-relevant dose dysregulates the expression of cell lineage markers in both healthy and diseased human colon tissue and provides new insight into the suitability of the epithelial models used.