Polystyrene nanoplastics lead to ferroptosis in the lungs

Introduction: It has been shown that polystyrene nanoplastic (PS-NP) exposure induces toxicity in the lungs. Objectives: This study aims to provide foundational evidence to corroborate that ferroptosis and abnormal HIF-1a activity are the main factors contributing to pulmonary dysfunction induced by PS-NP exposure. Methods: Fifty male and female C57BL/6 mice were exposed to distilled water or 100 nm or 200 nm PSNPs via intratracheal instillation for 7 consecutive days. Hematoxylin and eosin (H&E) and Masson trichrome staining were performed to observe the histomorphological changes in the lungs. To clarify the mechanisms of PS-NP-induced lung injury, we used 100 lg/ml, 200 lg/ml and 400 lg/ml 100 or 200 nm PS-NPs to treat the human lung bronchial epithelial cell line BEAS-2B for 24 h. RNA sequencing (RNA-seq) of BEAS-2B cells was performed following exposure. The levels of glutathione, malondialdehyde, ferrous iron (Fe2+), and reactive oxygen species (ROS) were measured. The expression levels of ferroptotic proteins were detected in BEAS-2B cells and lung tissues by Western blotting. Western blotting, immunohistochemistry, and immunofluorescence were used to evaluate the HIF-1a/HO-1 signaling pathway activity. Results: H&E staining revealed substantial perivascular lymphocytic inflammation in a bronchiolocentric pattern, and Masson trichrome staining demonstrated critical collagen deposits in the lungs after PS-NP exposure. RNA-seq revealed that the differentially expressed genes in PS-NP-exposed BEAS-2B cells were enriched in lipid metabolism and iron ion binding processes. After PS-NP exposure, the levels of malondialdehyde, Fe2+, and ROS were increased, but glutathione level was decreased. The expression levels of ferroptotic proteins were altered significantly. These results verified that PS-NP exposure led to pulmonary injury through ferroptosis. Finally, we discovered that the HIF-1a/HO-1 signaling pathway played an important role in regulating ferroptosis in the PS-NP-exposed lung injury. Conclusion: PS-NP exposure caused ferroptosis in bronchial epithelial cells by activating the HIF-1a/HO-1 signaling pathway, and eventually led to lung injury. (c) 2024 The Authors. Published by Elsevier B.V. on behalf of Cairo University. This is an open access article