Ferroptosis in alveolar and bronchial epithelial cells is one of the main mechanisms underlying the development of chronic obstructive pulmonary disease (COPD). Sodium pyruvate (NaPyr) is a natural antioxidant in the body, exhibiting anti-inflammatory and antioxidant activities. NaPyr has been used in a Phase II clinical trial as a novel therapy for COPD; however, the mechanism underlying NaPyr-mediated therapeutic benefits in COPD is not well understood. We aimed to assess the protective effects of NaPyr and elucidate its potential mechanism in cigarette smoke extract (CSE)-induced ferroptosis.To minic the inflammatory response and ferroptosis triggered by cigarette smoke in COPD in an invitro cell based system, we expose a human bronchial epithelial cells to CSE. To minic the inflammatory response and ferroptosis triggered by cigarette smoke in COPD in an invitro cell based system, the A549 (human lung carcinoma epithelial cells) and BEAS-2B (bronchial epithelial cells) cell lines were cultured, followed by treatment with CSE. To measure cellular viability and iron levels, we determined the levels of malondialdehyde (MDA), glutathione (GSH), reactive oxygen species (ROS), mitochondrial superoxide (MitoSOX), membrane potential (MMP), and inflammatory factors (tumor necrosis factor [TNF] and interleukin [IL]-8), and examined CSE-induced pulmonary inflammation and ferroptosis. To clarify the molecular mechanisms of NaPyr in COPD therapy, we performed western blotting and real-time PCR (qPCR) to determine the expression of glutathione peroxidase 4 (GPX4), nuclear factor E2-related factor 2 (Nrf2), and cyclooxygenase 2 (COX2). We found that NaPyr effectively mitigated CSE-induced apoptosis and improved apoptosis induced by erastin, a ferroptosis inducer. NaPyr significantly decreased iron and MDA levels and increased GSH levels in CSE-induced cells. Furthermore, NaPyr suppressed ferroptosis characteristics, such as decreased levels of ROS, MitoSOX, and MMP. NaPyr significantly increases the expression levels of GPX4 and Nrf2, indicating that activation of the GPX4/Nrf2 axis could inhibit ferroptosis in alveolar and bronchial epithelial cells. More importantly, NaPyr inhibited the secretion of downstream inflammatory factors, including TNF and IL-8, by decreasing COX2 expression levels to suppress CSE-induced inflammation. Accordingly, NaPyr could mitigate CSE-induced ferroptosis in alveolar and bronchial epithelial cells by activating the GPX4/Nrf2 axis and decreasing COX2 expression levels. In addition, NaPyr reduced the secretion of inflammatory factors (TNF and IL-8), affording a novel therapeutic candidate for COPD.

中文翻译：

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丙酮酸钠通过 GPX4/Nrf2 轴对香烟烟雾提取物诱导的肺泡和支气管上皮细胞铁死亡发挥保护作用

肺泡和支气管上皮细胞的铁死亡是慢性阻塞性肺病（COPD）发展的主要机制之一。丙酮酸钠 (NaPyr) 是体内的天然抗氧化剂，具有抗炎和抗氧化活性。NaPyr 已作为 COPD 的新型疗法用于 II 期临床试验；然而，NaPyr 介导的 COPD 治疗益处的机制尚不清楚。我们的目的是评估 NaPyr 的保护作用，并阐明其在香烟烟雾提取物 (CSE) 诱导的铁死亡中的潜在机制。为了在体外细胞系统中减少慢性阻塞性肺病 (COPD) 中香烟烟雾引发的炎症反应和铁死亡，我们暴露了人支气管上皮细胞至 CSE。为了在体外细胞系统中观察慢性阻塞性肺病中香烟烟雾引发的炎症反应和铁死亡，培养了 A549（人肺癌上皮细胞）和 BEAS-2B（支气管上皮细胞）细胞系，然后用 CSE 处理。为了测量细胞活力和铁水平，我们测定了丙二醛（MDA）、谷胱甘肽（GSH）、活性氧（ROS）、线粒体超氧化物（MitoSOX）、膜电位（MMP）和炎症因子（肿瘤坏死因子）的水平。 TNF] 和白细胞介素 [IL]-8)，并检查了 CSE 诱导的肺部炎症和铁死亡。为了阐明 NaPyr 在 COPD 治疗中的分子机制，我们进行了蛋白质印迹和实时 PCR (qPCR) 来测定谷胱甘肽过氧化物酶 4 (GPX4)、核因子 E2 相关因子 2 (Nrf2) 和环氧合酶 2 的表达。环氧合酶2）。我们发现 NaPyr 有效减轻 CSE 诱导的细胞凋亡，并改善由erastin（一种铁死亡诱导剂）诱导的细胞凋亡。NaPyr 显着降低 CSE 诱导细胞中的铁和 MDA 水平，并增加 GSH 水平。此外，NaPyr 抑制铁死亡特征，例如 ROS、MitoSOX 和 MMP 水平降低。NaPyr 显着增加 GPX4 和 Nrf2 的表达水平，表明 GPX4/Nrf2 轴的激活可以抑制肺泡和支气管上皮细胞的铁死亡。更重要的是，NaPyr 通过降低 COX2 表达水平来抑制下游炎症因子（包括 TNF 和 IL-8）的分泌，从而抑制 CSE 诱导的炎症。因此，NaPyr 可以通过激活 GPX4/Nrf2 轴并降低 COX2 表达水平来减轻 CSE 诱导的肺泡和支气管上皮细胞铁死亡。此外，NaPyr 还可以减少炎症因子（TNF 和 IL-8）的分泌，为 COPD 提供了一种新的治疗候选药物。