Tunicamycin Aggravates Endoplasmic Reticulum Stress and Airway Inflammation via PERK-ATF4-CHOP Signaling in a Murine Model of Neutrophilic Asthma

<b>Introduction</b>: Endoplasmic reticulum (ER) stress has been considered to be an important regulator of airway inflammation in the pathogenesis of bronchial asthma, but the mechanism of ER stress involved in neutrophilic asthma remain not fully understood. <b>Methods</b>: Tunicamycin is a mixture of homologous nucleoside antibiotics, which is used to induce ER stress. In the present study, Tunicamycin was administered to mouse bronchial epithelial cells and a neutrophilic asthma model (OVA_LPS-OVA mice), and ER stress indicators and inflammatory cytokines were measured by Western blotting and Elisa. <b>Results</b>: Tunicamycin not only induced ER stress in mouse bronchial epithelial cells, but also increased expression of inflammation indicators such as IL-6, IL-8, and TNF-α via PERK-ATF4-CHOP signaling. Additionally, the phosphorylation of PERK and the expression levels of ATF4 and CHOP proteins and inflammatory cytokines (IL-6, IL-8 and TNF-α) were elevated in the lung tissue of OVA_LPS-OVA mice. Administering tunicamycin further increased protein expression levels of ER stress indicators and inflammatory cytokines, and resulted in more severe asthma phenotypes in OVA_LPS-OVA mice, suggesting that PERK-ATF4-CHOP signaling is associated with airway inflammation in neutrophil-dominant asthma. <b>Conclusions</b>: These data support the emerging notion that regulation of ER stress could be strongly associated with the development of neutrophilic asthma.

**引言**：内质网应激（Endoplasmic Reticulum Stress，ER stress）被认为是支气管哮喘发病过程中气道炎症的重要调控因子，但内质网应激参与嗜中性粒细胞性哮喘的具体机制仍未完全阐明。**方法**：衣霉素（Tunicamycin）是一类同源核苷类抗生素混合物，常用于诱导内质网应激。本研究中，研究者将衣霉素施用于小鼠支气管上皮细胞与嗜中性粒细胞性哮喘模型（OVAₗₚₛ-OVA小鼠），并通过蛋白质印迹法（Western blotting）与酶联免疫吸附实验（Elisa）检测内质网应激指标与炎症因子水平。**结果**：衣霉素不仅可在小鼠支气管上皮细胞中诱导内质网应激，还可通过PERK-ATF4-CHOP信号通路上调IL-6、IL-8、TNF-α等炎症指标的表达。此外，OVAₗₚₛ-OVA小鼠肺组织中PERK的磷酸化水平、ATF4与CHOP蛋白的表达量，以及IL-6、IL-8、TNF-α等炎症因子水平均显著升高。给予衣霉素可进一步增强内质网应激指标与炎症因子的蛋白表达水平，并使OVAₗₚₛ-OVA小鼠的哮喘表型更为严重，这表明PERK-ATF4-CHOP信号通路与嗜中性粒细胞主导型哮喘的气道炎症密切相关。**结论**：本研究数据支持这一新兴观点：内质网应激的调控与嗜中性粒细胞性哮喘的发生发展密切相关。