Polystyrene nanoplastics lead to ferroptosis in the lungs
Yuhao Wu, Junke Wang, Tianxin Zhao, Mang Sun, Maozhu Xu, Siyi Che, Zhengxia Pan, Wu Chun, Lianju Shen
Abstract
It has been shown that polystyrene nanoplastic (PS-NP) exposure induces toxicity in the lungs. This study aims to provide foundational evidence to corroborate that ferroptosis and abnormal HIF-1α activity are the main factors contributing to pulmonary dysfunction induced by PS-NP exposure. Fifty male and female C57BL/6 mice were exposed to distilled water or 100 nm or 200 nm PS-NPs 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 μg/ml, 200 μg/ml and 400 μg/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-1α/HO-1 signaling pathway activity. 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-1α/HO-1 signaling pathway played an important role in regulating ferroptosis in the PS-NP-exposed lung injury. PS-NP exposure caused ferroptosis in bronchial epithelial cells by activating the HIF-1α/HO-1 signaling pathway, and eventually led to lung injury.