Rationale: COPD patients are largely asymptomatic until the late stages when prognosis is generally poor. In this study, we shifted the focus to pre-COPD and smoking stages, and found enrichment of hypoxia inducible factor (HIF)-3α is in pre-COPD samples. Smoking induced regional tissue hypoxia and emphysema have been found in COPD patients. However, the mechanisms underlying hypoxia especially HIF-3α and COPD have not been investigated. Methods: We performed bulk-RNA sequencing on 36 peripheral lung tissue specimens from non-smokers, smokers, pre-COPD and COPD patients, and using "Mfuzz" algorithm to analysis the dataset dynamically. GSE171541 and EpCAM co-localization analyses were used to explore HIF-3α localization. Further, SftpcCreert2/+R26LSL-Hif3a knock-in mice and small molecular inhibitors in vitro were used to explore the involvement of HIF-3α in the pathophysiology of COPD. Results: Reactive oxygen species (ROS) and hypoxia were enriched in pre-COPD samples, and HIF-3α was downregulated in alveolar epithelial cells in COPD. In vitro experiments using lentivirus transfection, bulk-RNA seq, and RSL3 showed that the activation of the HIF-3α-GPx4 axis inhibited alveolar epithelial cell ferroptosis when treated with cigarettes smoking extracts (CSE). Further results from SftpcCreert2/+R26LSL-Hif3a knock-in mice demonstrated overexpression of HIF-3α inhibited alveolar epithelial cells ferroptosis and prevented the decline of lung function. Conclusion: Hypoxia and oxidation-related damage begins years before the onset of COPD symptoms, suggesting the imbalance and impairment of intracellular homeostatic system. The activation of the HIF-3α-GPx4 axis is a promising treatment target. By leveraging this comprehensive analysis method, more potential targets could be found and enhancing our understanding of the pathogenesis.
Keywords: HIF-3α; emphysema; ferroptosis; hypoxia; pre-COPD.
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