Abstract: Objective　To evaluate the effects of chronic intermittent hypoxia (CIH) on lung tissue structure and function by establishing a rat model of CIH to simulate the pathological pattern of obstructive sleep apnea (OSA). To investigate the roles of ferroptosis and endoplasmic reticulum stress (ERS) in CIH-induced lung injury, so as to provide new ideas for the clinical prevention and treatment of OSA related lung diseases.Methods　Eighteen male SD rats were randomly divided into 3 groups with 6 rats in each group, control (CON) group, CIH group, and CIH+Fer-1 (FIH) group. They were exposed to normoxic or CIH environment respectively. From the 5th week, the FIH group was intraperitoneally injected with Fer-1 [2 mg/(kg·d)], and the CON group and CIH group were injected with equal volume of 2% dimethyl sulfoxide (DMSO). At the end of the 8th week, the rats were sacrificed, and HE and Masson staining were used to observe the pathological changes of lung tissue, and TUNEL staining was used to analyze cell apoptosis. According to the kit instructions, the levels of interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), glutathione (GSH), 4-hydroxynonenal (4-HNE), reactive oxygen species (ROS), glutathione peroxidase 4 (GPX4), and Fe2+ were measured. Western blot was used to detect the expression of key proteins in the ERS pathway.Results　Compared with the CON group, the CIH group showed thickening of the alveolar wall, increased infiltration of inflammatory cells in the alveoli, and mild alveolar dilatation in rats. Partial collagen fiber hyperplasia was observed in the pulmonary interstitium, and the number of apoptotic cells was significantly increased, The levels of inflammatory factors (IL-6, IL-1β, and TNF-α) were elevated, Oxidative stress was aggravated (GSH content decreased, 4-HNE content increased), Ferroptosis markers were abnormal (ROS and Fe2+ levels were significantly increased, GPX4 content was decreased), The relative content of eIF2α protein in the ERS pathway was increased(P<0.05). Compared with CIH group, the lung tissue injury and pulmonary fibrosis were alleviated in rats of FIH group, with a significant reduction in the apoptosis rate, Meanwhile, the levels of IL-6 and TNF-α were decreased, and a notable decrease in the levels of 4-HNE, Fe2+, and ROS, whereas the content of GPX4 was increased (P<0.05).Conclusion　Ferroptosis and ERS are involved in CIH-induced lung injury, and Fer-1 effectively alleviates lung injury by inhibiting inflammation, oxidative stress, ERS, and apoptosis.

Key words: chronic intermittent hypoxia, ferroptosis, endoplasmic reticulum stress, lung injury

摘要： 目的　通过构建慢性间歇性低氧(CIH)大鼠模型模拟阻塞性睡眠呼吸暂停(OSA)病理模式,评估CIH对肺 组织结构和功能的影响。探究铁死亡和内质网应激(ERS)在CIH所致肺损伤中的作用,为OSA相关肺部疾病的临 床防治提供新思路。方法　将18只雄性SD大鼠随机分为3组,常氧对照组(CON组)、CIH组、CIH+铁抑素-1 (Fer-1)组(FIH组),每组6只,分别暴露于常氧或CIH环境。第5周起,FIH组腹腔注射Fer-1[2 mg/(kg·d)], CON组和CIH组注射等体积溶剂2%二甲基亚砜(DMSO)。第8周末处死大鼠,使用HE和Masson染色观察肺组织 病理学变化,TUNEL染色分析细胞凋亡情况。根据试剂盒说明书测定白细胞介素-6(IL- 6)、白细胞介素-1β(IL-1β)、 肿瘤坏死因子-α(TNF-α)、丙二醛(MDA)、谷胱甘肽(GSH)、4-羟壬二酸酯(4-HNE)、活性氧(ROS)、谷胱甘肽过氧 化物酶4(GPX4)及Fe2+水平。使用Western blot检测ERS通路关键蛋白表达。结果　与CON组相比,CIH组大鼠 肺泡壁增厚,肺泡炎性细胞浸润增多,肺泡轻度扩张;肺间质可见部分胶原纤维增生,凋亡细胞显著增多;炎性因子 (IL-6、IL-1β和 TNF-α)水平升高;氧化应激加剧(GSH含量下降、4-HNE含量增加);铁死亡标志物异常(ROS和 Fe2+水平显著升高,GPX4含量降低);ERS通路中真核生物起始因子2α(eIF2α)蛋白相对含量升高(P<0.05)。与 CIH组相比,FIH组大鼠肺组织损伤和肺纤维化减轻,细胞凋亡率显著降低;IL-6和TNF-α水平降低;4-HNE、Fe2+和 ROS水平显著降低,GPX4含量升高(P<0.05)。结论　铁死亡和ERS参与CIH引起的肺损伤,Fer-1通过抑制炎 症、氧化应激、ERS和细胞凋亡有效减轻肺损伤。

关键词: 慢性间歇性低氧, 铁死亡, 内质网应激, 肺损伤