Background Radiation-induced lung fibrosis (RILF) is a severe and life-threatening complication of thoracic radiotherapy. Cell death is the key issue in RILF. Ferroptosis is a form programmed cell death implicated in the pathologies of inflammation. This study aimed to investigate the role of ferroptosis in RILF, and the effectiveness and the potential underlying mechanism of ferroptosis inhibitor on RILF. Methods Immunofluorescence, western blot and RT-PCR assays were performed to examine the ferroptosis maker glutathione peroxidase 4 (GPX4) in a mice RILF model. The lung tissue sections were stained with hematoxylin and eosin (H&E), Masson trichrome staining and Sirius-Red staining to evaluate the histopathological changes in RILF mice. Reactive oxygen species (ROS) and hydroxyproline (HYP) in lungs were measured by the relevant kits. The serum levels of inflammatory cytokines (TNF-α, IL-6, IL-10, and TGF-β1) were measured with Elisa. The protein and mRNA levels of GPX4, nuclear factor (erythroid-derived 2)-like 2 (Nrf2), hemeoxygenase-1 (HO1) and quinone oxidoreductase 1 (NQO1) in lungs were examined by western blot and RT-PCR. Results GPX4 levels of the irradiated lungs were significantly down-regulated than the groups with no irradiation, and the ferroptosis inhibitor, liproxstatin-1, increased GPX4 levels significantly in RILF mice. Treatment with liproxstatin-1 lowered the Szapiel and Ashcroft scores significantly, down-regulated the levels of ROS and HYP in lungs and reduced the serum inflammatory cytokines levels in RILF mice. The protein and the mRNA levels of Nrf2, HO1 and NQO1 were up-regulated by liproxsratin-1 in RILF. Conclusions Our data suggested that ferroptosis played a critical role in RILF, ferroptosis inhibitor liproxstatin-1 alleviated RILF via down-regulation of TGF-β1 by the activation of Nrf2 pathway. The effectiveness of ferroptosis inhibition on RILF provides a novel therapeutic target for RILF.

中文翻译：

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Ferroptosis inhibitor 通过下调 TGF-β1 来减轻辐射诱导的肺纤维化 (RILF)。

背景辐射诱发的肺纤维化（RILF）是胸部放射治疗的严重且危及生命的并发症。细胞死亡是 RILF 的关键问题。铁死亡是一种与炎症病理有关的程序性细胞死亡。本研究旨在探讨铁死亡在 RILF 中的作用，以及铁死亡抑制剂对 RILF 的有效性和潜在的潜在机制。方法 进行免疫荧光、蛋白质印迹和 RT-PCR 测定以检查小鼠 RILF 模型中的铁死亡标志物谷胱甘肽过氧化物酶 4 (GPX4)。肺组织切片用苏木精和伊红(H&E)、Masson三色染色和Sirius-Red染色评估RILF小鼠的组织病理学变化。通过相关试剂盒测量肺中的活性氧（ROS）和羟脯氨酸（HYP）。用 Elisa 测量炎症细胞因子（TNF-α、IL-6、IL-10 和 TGF-β1）的血清水平。通过蛋白质印迹和RT-PCR检测肺中GPX4、核因子（红细胞衍生2）样2（Nrf2）、血氧合酶1（HO1）和醌氧化还原酶1（NQO1）的蛋白质和mRNA水平。结果辐照组肺GPX4水平显着低于未辐照组，而铁死亡抑制剂liproxstatin-1显着提高RILF小鼠的GPX4水平。用 liproxstatin-1 治疗显着降低了 Szapiel 和 Ashcroft 评分，下调了 RILF 小鼠肺中 ROS 和 HYP 的水平，并降低了血清炎性细胞因子水平。Nrf2、HO1 和 NQO1 的蛋白质和 mRNA 水平在 RILF 中被 liproxsratin-1 上调。结论 我们的数据表明，铁死亡在 RILF 中起关键作用，铁死亡抑制剂 liproxstatin-1 通过激活 Nrf2 通路下调 TGF-β1 来缓解 RILF。抑制铁死亡对 RILF 的有效性为 RILF 提供了新的治疗靶点。