Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Anhui Medical University, 230022 Hefei, Anhui, China; Key Laboratory of Respiratory Disease Research and Medical Transformation of Anhui Province, The First Affiliated Hospital of Anhui Medical University, 230022 Hefei, Anhui, China.
Key Laboratory of Respiratory Disease Research and Medical Transformation of Anhui Province, The First Affiliated Hospital of Anhui Medical University, 230022 Hefei, Anhui, China; Emergency Department, The First Affiliated Hospital of Anhui Medical University, 230022 Hefei, Anhui, China.
Int Immunopharmacol. 2022 Aug;109:108782. doi: 10.1016/j.intimp.2022.108782. Epub 2022 Apr 23.
Acute lung injury (ALI)/ acute respiratory distress syndrome (ARDS) is featured by intensive inflammatory responses and oxidative stress, which lead to cytokine storms and pyroptosis. Here, we aimed to investigate whether melatonin was capable of alleviating LPS-induced ALI via activating the nuclear factor erythroid 2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) signaling axis and inhibiting pyroptosis. Mice were injected with melatonin (30 mg/kg) intraperitoneally for consecutive five days before LPS instillation intratracheally, and human alveolar epithelial cell (AECⅡ) A549 cell lines and murine macrophages Raw264.7 cell lines were pretreated with melatonin (400 μM) before LPS (10 μg/ml) stimulation. The result demonstrated that LPS induced obvious lung injury characterized by alveolar damage, neutrophil infiltration and lung edema as well as the reduction of the survival rate of mice, which were totally reversed by melatonin pretreatment. Mechanistically, melatonin pretreatment activated nuclear factor erythroid2-related factor (Nrf) 2 signaling, subsequently, drove antioxidant pathways including significant increases in the expression of Nrf2, HO-1, NQO1, Mn-SOD and Catalase in vivo and in vitro. Simultaneously, melatonin inhibited ROS and MDA overproduction, iNOS expression as well as TNF-α and IL-1β expression and release. Furthermore, melatonin inhibited LPS-induced pyroptosis by reversing the overexpression of NLRP3, Caspase-1, IL-1β, IL-18 and GSDMD-N, as well as LDH release and TUNEL-positive cells in A549 cells and Raw264.7 cells. Overall, the current study suggests that melatonin exerts protective roles on LPS-induced ALI and pyroptosis by inhibiting NLRP3-GSDMD pathway via activating Nrf2/HO-1 signaling axis.
急性肺损伤（ALI）/急性呼吸窘迫综合征（ARDS）的特征是强烈的炎症反应和氧化应激，这导致细胞因子风暴和细胞焦亡。在这里，我们旨在研究褪黑素是否能够通过激活核因子红细胞 2 相关因子 2/血红素加氧酶 1（Nrf2/HO-1）信号通路和抑制细胞焦亡来缓解脂多糖（LPS）诱导的 ALI。在 LPS 气管内滴注前，连续 5 天每天给小鼠腹腔注射褪黑素（30mg/kg），然后用褪黑素（400μM）预处理人肺泡上皮细胞（A549）A549 细胞系和鼠巨噬细胞 Raw264.7 细胞系，再用 LPS（10μg/ml）刺激。结果表明，LPS 诱导明显的肺损伤，特征为肺泡损伤、中性粒细胞浸润和肺水肿，以及小鼠存活率降低，这些均被褪黑素预处理完全逆转。从机制上讲，褪黑素预处理激活核因子红细胞 2 相关因子（Nrf）2 信号，随后驱动抗氧化途径，包括体内和体外 Nrf2、HO-1、NQO1、Mn-SOD 和 Catalase 的表达显著增加。同时，褪黑素抑制 ROS 和 MDA 过度产生、iNOS 表达以及 TNF-α和 IL-1β的表达和释放。此外，褪黑素通过逆转 NLRP3、Caspase-1、IL-1β、IL-18 和 GSDMD-N 的过度表达，以及 A549 细胞和 Raw264.7 细胞中 LDH 释放和 TUNEL 阳性细胞，抑制 LPS 诱导的细胞焦亡。总的来说，本研究表明，褪黑素通过激活 Nrf2/HO-1 信号通路抑制 NLRP3-GSDMD 通路，对 LPS 诱导的 ALI 和细胞焦亡发挥保护作用。
