NANOPLASTICS AND IMMUNITY: INVESTIGATING THE EXTRACELLULAR MATRIX’S INFLUENCE ON MACROPHAGE INTERACTION WITH POLYSTYRENE NANOPARTICLES

Plastics are extensively used worldwide, but their poor biodegradability results in significant environmental pollution. They are categorized by size into nanoplastics (NPs), measuring from 1 nm to 1000 nm, and microplastics, ranging from 1 μm to 5 mm. Both nano- and microplastics can enter the human body through inhalation, consumption of contaminated food and water, or skin exposure via cosmetics and clothing. Once inside the body, plastics may accumulate and potentially contribute to health issues such as respiratory diseases (e.g., lung cancer, asthma), neurological symptoms (e.g., fatigue), and inflammatory bowel disease. Most in vitro studies expose cells to NPs suspended in culture media, demonstrating that nano- and microplastics can induce apoptosis and exhibit genotoxic and cytotoxic effects. In human tissues, NPs not only diffuse through biological fluids but can also become trapped or adsorbed by components of the extracellular matrix (ECM). This interaction might alter ECM properties and influence how cells respond to NPs. Controlled exposure to NPs via the ECM could impact cell behavior and their responses to these particles. In this study, supported by the PRIN 2022 PNRR program, we aim to investigate the role of the cellular microenvironment in macrophage response to nanoplastics embedded within the ECM. We exposed macrophage-like cells derived from the human monocytic THP-1 cell line to ECM-mimicking substrates preloaded with polystyrene NPs. These substrates, designed to replicate the structural, chemical, and physical characteristics of native ECM, were fabricated from polymer, gelatin, and hyaluronic acid (HA) using electrospinning. Preliminary results showed that macrophages adhered to all substrates, especially those containing gelatin, without compromising cell viability up to 48 hours post-seeding. Fluorescence microscopy and flow cytometry confirmed that the embedded nanoparticles remained bioavailable and were effectively internalized by the macrophages. Notably, in this ECM-like configuration, cell viability was affected by the presence of NPs. Furthermore we investigate the macrophage polarization in pro- or anti-inflammatory phenotypes through flow cytometry analysis. This research underscores the necessity for further studies to elucidate the cellular and molecular mechanisms underlying immune cell responses to nanoplastics, which may provide valuable insights into the health impacts of plastic exposure.The authors acknowledge financial support under the National Recovery and Resilience Plan (NRRP), Mission 4, Component 2, Investment 1.1, “Fund for the National Research Program and for Projects of National Interest (NRP)” by the Italian Ministry of University and Research (MUR), funded by the European Union – NextGenerationEU. Project Title: Role of exTRAcellular MAtrix in controlling macrophage cell response to nanomaterials (TRAMA) – CUP D53D23021660001.