Biotrasformazione ed effetti su cellule epiteliali intestinali di microplastiche di polietilene ad alta densità usando un modello in vitro avanzato di cellule epiteliali intestinali

In the face of escalating environmental concerns, microplastics, defined as plastic particles smaller than 5 millimetres, have become a global pollutant due to their pervasive presence in ecosystems. Their resilience, resistance to degradation, and extensive use in consumer products contribute to their persistence in the environment. As the prevalence of microplastics rises, the potential risks to human health, particularly through ingestion via food and water, have garnered significant attention. The goal of the present study was to investigate the characteristics of high-density polyethylene (HDPE) microplastics under various environmental and physiological conditions and the effect of this kind of microplastics on gut epithelium by using an advanced in vitro model. The size distribution and the surface properties of distribution of HDPE microplastics were assessed in cell culture media (CCM) with or without a pre-treatment with an in vitro simulated digestion by using an optical size analyser and by Electrophoretic Light Scattering (ELS) respectively, while the ability to generate Reactive Oxygen Species (ROS) was evaluated by Electronic Paramagnetic Resonance (EPR) spectroscopy. Oppositely to what is generally observed with inorganic nanoparticles, the size distribution of HDPE microplastics remained constant across all treatments, with only minimal aggregation observed in the gastric portion of the SHDS. The formation of a soft protein corona throughout the simulated digestion process and in the cell media was however observed. As expected, the microplastics did not generate ROS in all conditions. The impact of pristine and transformed HDPE microplastics on gut, was assessed by acute and chronic exposures of HDPE microplastics to simple and advanced intestinal epithelium cell culture models. Parameters such as cell viability, Trans-Epithelial Electrical Resistance (TEER), membrane permeability, production of inflammatory cytokines and ROS were analysed. Remarkably, the majority of cellular responses remained unchanged by respect to control, suggesting a general inertness of the cells to microplastic exposure. However, specific conditions prompted subtle variations in cellular behaviour, warranting further investigation. Overall, this comprehensive study provides valuable insights into the behaviour of HDPE microplastics under diverse environmental and physiological conditions, shedding light on their potential implications for human health and the environment.