Polydatin attenuates IL-4/TGF-β-induced bronchial epithelial cell injury by modulating copper homeostasis and cuproptosis via NRIP2/NRF2 axis

Background Cuproptosis-induced bronchial epithelial cell (BEC) injury has been recently identified as a new regulator of airway remodeling under chronic asthma. Polydatin is a natural antioxidant agent; however, whether polydatin exerts anti-asthmatic effects by modulating cuproptosis remains unknown. This study aimed to investigate the protective effects of polydatin against rhIL-4/TGF-β-induced BEC injury and its underlying mechanisms involving copper homeostasis and cuproptosis. Methods An in vitro model of BEC injury was established by stimulating BEAS-2B cells with rhIL-4 (20 ng/mL) and TGF-β (5 ng/mL) for 48 h. For polydatin intervention, cells were co-treated with 50 μM polydatin simultaneously with rhIL-4/TGF-β treatment. Cell viability, cell migration, intracellular copper levels, as well as intracellular and mitochondrial reactive oxygen species (ROS) levels were determined. Moreover, the expression levels of genes involved in copper homeostasis and markers of cuproptosis were examined by qRT-PCR and western blot. The NRIP2/NRF2 axis was investigated as a potential target of polydatin using bioinformatics analysis and NRIP2 knockdown experiments. Results Polydatin significantly alleviated BEC injury upon rhIL-4/TGF-β treatment, characterized by restored cell viability and migration. Intracellular copper levels and ROS levels were significantly increased upon rhIL-4/TGF-β treatment, which could be substantially alleviated by polydatin. Consistently, the expression of copper exporters (ATP7A and ATP7B), and the expression of cuproptosis markers (FDX1 and DLST) were alleviated by polydatin. Furthermore, NRIP2/NRF2 axis was identified as a potential target of polydatin. Transient knockdown of NRIP2 significantly suppressed NRF2 expression. Moreover, the expression pattern of NRIP2 and NRF2 was evidently suppressed by rhIL-4/TGF-β, which could be abolished by polydatin. Conclusion Polydatin protects BEC from rhIL-4/TGF-β-induced injury by activating NRIP2/NRF2 axis to restore copper homeostasis and inhibit cuproptosis. This study provides a novel mechanistic basis for polydatin as a potential therapeutic candidate, though conclusions are limited to an in vitro model of bronchial epithelial cell injury. It should be noted that this study utilized an in vitro BEAS-2B monolayer model, and the conclusions are limited to protection from epithelial cell injury and inhibition of cuproptosis markers rather than reversal of airway remodeling in vivo.