5-Methoxyflavone alleviates LPS-mediated lung injury by promoting Nrf2-mediated the suppression of NOX4/TLR4 axis in bronchial epithelial cells and M1 polarization in macrophages.
5-Methoxyflavone alleviates LPS-mediated lung injury by promoting Nrf2-mediated the suppression of NOX4/TLR4 axis in bronchial epithelial cells and M1 polarization in macrophages.
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DOI：
10.1186/s12950-022-00319-6
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发表时间：
2022-11-30
影响因子：
5.1
通讯作者：
Zhou, Beixian
中科院分区：
文献类型：
--
作者：
Liang, Panqiao;Wang, Linxin;Yang, Sushan;Pan, Xiping;Li, Jiashun;Zhang, Yuehan;Liang, Yueyun;Li, Jing;Zhou, Beixian
急性肺损伤（ALI）是由败血症或细菌感染引起的，这是一种危及生命的呼吸系统疾病，在全球范围内导致死亡的主要原因。5-甲氧基黄酮是一种甲基化的黄酮类化合物，因其各种健康益处而受到越来越多的关注。本研究旨在探讨5-甲氧基黄酮对LPS介导的急性肺损伤的潜在作用，并阐明其可能的机制。采用内毒素（LPS）建立小鼠急性肺损伤模型，分别采用H&E染色、免疫荧光和TUNEL法检测肺组织病理变化、信号通路相关蛋白表达和细胞凋亡。MTT法检测细胞活力; ELISA法检测促炎介质蛋白水平;流式细胞术检测ROS水平和M1巨噬细胞极化; Western blotting检测Nrf 2信号通路、NOX 4/TLR 4轴和P-STAT 1的表达。结果表明，5-甲氧基黄酮可抑制LPS诱导的BEAS-2B细胞中NOX 4和TLR 4的表达，抑制下游信号（NF-κB和P38 MAPK）的激活，并显著降低ROS水平和促炎细胞因子（IL-6、TNF-α、MCP-1和IL-8）的水平。此外，我们发现5-甲氧基黄酮的这些作用与其激活Nrf 2的特性有关，阻断Nrf 2可阻止其对NOX 4/TLR 4/NF-κB/P38 MAPK信号通路的抑制作用，从而消除5-甲氧基黄酮的抗炎作用。此外，5-甲氧基黄酮在RAW264.7细胞中的Nrf 2激活特性导致抑制LPS/IFN-γ介导的STAT 1信号传导，从而抑制LPS/IFN-γ诱导的M1巨噬细胞极化和M2巨噬细胞向M1的复极化。在LPS诱导的ALI小鼠模型中，5-甲氧基黄酮给药可改善LPS介导的肺病理变化，增加肺指数（肺/体重比）和上皮细胞凋亡。同时，我们发现5-甲氧基黄酮能有效地抑制过度活跃的信号通路和过量的促炎介质的产生。此外，5-甲氧基黄酮减少LPS介导的M1巨噬细胞极化与肺组织中P-STAT 1活化升高相关。此外，5-甲氧基黄酮改善了LPS攻击小鼠的存活率。这些结果表明，5-甲氧基黄酮可能适合于开发一种新型的治疗ALI的药物。
Acute lung injury (ALI) arises from sepsis or bacterial infection, which are life-threatening respiratory disorders that cause the leading cause of death worldwide. 5-Methoxyflavone, a methylated flavonoid, is gaining increased attention for its various health benefits. In the current study, we investigated the potential effects of 5-methoxyflavone against LPS-mediated ALI and elucidated the corresponding possible mechanism. A mouse model with ALI was established by intratracheal instillation of LPS, and lung pathological changes, signaling pathway related proteins and apoptosis in lung tissues were estimated by H&E staining, immunofluorescence and TUNEL assay, respectively. Cell viability was evaluated by MTT assay; protein levels of pro-inflammatory mediators were measured by ELISA assay; levels of ROS and M1 macrophage polarization were assayed by flow cytometry; the expression of Nrf2 signaling, NOX4/TLR4 axis and P-STAT1 were detected by western blotting. Our results showed that 5-methoxyflavone treatment inhibited LPS-induced expression of NOX4 and TLR4 as well as the activation of downstream signaling (NF-κB and P38 MAPK), which was accompanied by markedly decreased ROS levels and pro-inflammatory cytokines (IL-6, TNF-α, MCP-1, and IL-8) in BEAS-2B cells. Moreover, we revealed that these effects of 5-methoxyflavone were related to its Nrf2 activating property, and blockade of Nrf2 prevented its inhibitory effects on NOX4/TLR4/NF-κB/P38 MAPK signaling, thus abrogating the anti-inflammatory effects of 5-methoxyflavone. Besides, the Nrf2 activating property of 5-methoxyflavone in RAW264.7 cells led to inhibition of LPS/IFN-γ-mediated STAT1 signaling, resulting in suppression of LPS/IFN-γ-induced M1 macrophage polarization and the repolarization of M2 macrophages to M1. In a mouse model of LPS-induced ALI, 5-methoxyflavone administration ameliorated LPS-mediated lung pathological changes, the increased lung index (lung/body weight ratio), and epithelial cell apoptosis. Meanwhile, we found 5-methoxyflavone effectively suppressed the hyperactive signaling pathways and the production of excessive pro-inflammatory mediators. Moreover, 5-methoxyflavone reduced LPS-mediated M1 macrophage polarization associated with elevated P-STAT1 activation in the lung tissues. In addition, 5-methoxyflavone improved the survival of LPS-challenged mice. These results indicated that 5-methoxyflavone might be suitable for the development of a novel drug for ALI therapeutic.
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