Qian Yao, Fang Chenchen, Wang Beibei, Xu Zhixiao, Yu Wenkai, Gritsiuta Andrei I, Chen Chengshui, Dong Nian, Chen Junjie
Key Laboratory of Interventional Pulmonology of Zhejiang Province, Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.
Department of Pathology, Taizhou Central Hospital (Taizhou University Hospital), Taizhou, China.
J Thorac Dis. 2024 Dec 31;16(12):8724-8742. doi: 10.21037/jtd-2024-2013. Epub 2024 Dec 28.
It has been proposed that repeated exposure of bronchial epithelial cells to atmospheric particulate matter (PM) could disrupt airway epithelial integrity and lead to epithelial-to-mesenchymal transition (EMT) and ultimately airway remodeling. The molecular mechanisms underlying PM-related bronchial epithelial EMT have not yet been elucidated. The aim of this research is to clarify the molecular mechanism of EMT upon PM exposure.
Using an mouse model of PM-induced airway inflammation and an model of PM-stimulated bronchial epithelial cells, we clarified the role of haptoglobin (HP) in PM-induced bronchial epithelial EMT. The expression of HP in lung tissues was evaluated by immunohistochemistry (IHC). Western blotting (WB) and immunofluorescence staining were used to analyze EMT-related protein expression and the relevant signaling pathways in the changes in lung tissues and bronchial epithelial cells upon PM exposure. HP small interfering RNA (siRNA) was used to implement the interference of endogenous HP.
experiments showed elevated HP expression in the bronchial epithelium upon PM exposure. IHC and WB showed that E-cadherin expression was decreased, and vimentin expression was increased in bronchial epithelial cells. Moreover, WB results showed that the phosphorylation levels of signal transducer and activator of transcription 3 (STAT3) and extracellular regulated protein kinases (ERK) were elevated in the lung parenchymal tissue of mice. The results of molecular mechanism experiments showed that compared with those of the control group, the phosphorylation levels of STAT3 and ERK in the PM group increased progressively with higher concentrations of PM and longer stimulation durations. BEAS-2B cells were pretreated with stattic (STAT3 inhibitor) and/or U0126 (ERK inhibitor), and it was found that either stattic or U0126 inhibited PM-induced reduction of E-cadherin expression and elevation of vimentin expression, and the inhibitory effect was most significant when both inhibitors were pretreated simultaneously. Through transfection of BEAS-2B cells with HP siRNA, WB results showed that HP siRNA partially reversed the PM-induced reduction in E-cadherin expression and elevation of vimentin expression, in addition to the reduction in the phosphorylation levels of the STAT3 and ERK.
HP is an important mediator of PM-induced EMT in bronchial epithelial cells and promotes PM-induced EMT in bronchial epithelial cells through activation of the STAT3 signaling pathway and the ERK signaling pathway. Inhibition of HP expression attenuates PM exposure-induced EMT in bronchial epithelial cells.
有人提出，支气管上皮细胞反复暴露于大气颗粒物（PM）中可能会破坏气道上皮的完整性，导致上皮-间质转化（EMT），最终引起气道重塑。PM相关的支气管上皮EMT的分子机制尚未阐明。本研究的目的是阐明PM暴露后EMT的分子机制。
利用PM诱导气道炎症的小鼠模型和PM刺激支气管上皮细胞的模型，我们阐明了触珠蛋白（HP）在PM诱导的支气管上皮EMT中的作用。通过免疫组织化学（IHC）评估肺组织中HP的表达。蛋白质免疫印迹法（WB）和免疫荧光染色用于分析PM暴露后肺组织和支气管上皮细胞中EMT相关蛋白的表达及相关信号通路。使用HP小干扰RNA（siRNA）对内源性HP进行干扰。
实验表明，PM暴露后支气管上皮中HP表达升高。免疫组织化学和蛋白质免疫印迹法显示，支气管上皮细胞中E-钙黏蛋白表达降低，波形蛋白表达增加。此外，蛋白质免疫印迹法结果显示，小鼠肺实质组织中转录信号转导子和激活子3（STAT3）及细胞外调节蛋白激酶（ERK）的磷酸化水平升高。分子机制实验结果表明，与对照组相比，PM组中STAT3和ERK的磷酸化水平随着PM浓度的升高和刺激时间的延长而逐渐增加。用Stattic（STAT3抑制剂）和/或U0126（ERK抑制剂）预处理BEAS-2B细胞，发现Stattic或U0126均可抑制PM诱导的E-钙黏蛋白表达降低和波形蛋白表达升高，且两种抑制剂同时预处理时抑制作用最为显著。通过用HP siRNA转染BEAS-2B细胞，蛋白质免疫印迹法结果显示，HP siRNA除了降低STAT3和ERK的磷酸化水平外，还部分逆转了PM诱导的E-钙黏蛋白表达降低和波形蛋白表达升高。
HP是PM诱导支气管上皮细胞EMT的重要介质，通过激活STAT3信号通路和ERK信号通路促进PM诱导的支气管上皮细胞EMT。抑制HP表达可减轻PM暴露诱导的支气管上皮细胞EMT。
