溴化结构域蛋白抑制剂JQ1对哮喘小鼠气道重塑作用机制研究

Mechanism of action of BET bromodomain inhibitor JQ1 in treating airway remodeling in asthmatic mice

摘要:

目的 探讨溴化结构域蛋白抑制剂JQ1对哮喘小鼠气道重塑治疗的分子学机制。方法 将24只小鼠随机分成对照组、OVA诱导哮喘组（OVA组）、JQ1干预哮喘组（JQ1+OVA组）（n=8）。采用OVA致敏/激发制备哮喘小鼠模型，雾化激发前1 h，JQ1+OVA组小鼠经腹腔注射JQ1溶液（50 μg/g）。末次激发24 h后留取支气管肺泡灌洗液（BALF）及肺组织，计算各组BALF中细胞总数及嗜酸性粒细胞百分比，肺组织行病理染色观察各组小鼠肺组织病理改变；采用RT-PCR及Western blot法分别检测小鼠肺上皮间质转化（EMT）过程中钙黏蛋白（E-Cadherin）、波形蛋白（vimentin）mRNA及蛋白水平的表达变化。结果 与对照组比较，OVA组小鼠气道炎性细胞明显浸润，气道壁增厚，黏液渗出增多；BALF中细胞总数增加，嗜酸性粒细胞百分比增多（P < 0.01）。与OVA组比较，JQ1+OVA组小鼠气道炎症反应明显减轻；BALF中细胞总数明显减少，嗜酸性粒细胞百分比降低（P < 0.01）。与对照组比较，OVA组小鼠肺组织气道上皮E-Cadherin mRNA及蛋白表达水平明显下调，vimentin mRNA及蛋白表达水平明显上调（P < 0.01）；与OVA组比较，JQ1+OVA组E-Cadherin mRNA及蛋白表达水平升高，vimentin mRNA及蛋白表达水平下降（P < 0.01）；JQ1+OVA组与对照组上述指标表达水平比较差异无统计学意义（P > 0.05）。结论 OVA哮喘小鼠存在EMT气道重塑；溴化结构域蛋白抑制剂JQ1可降低哮喘小鼠气道炎症，抑制EMT，减轻气道重塑，为哮喘治疗提供了一个潜在的新方向。

Abstract:

Objective To investigate the molecular mechanism of action of BET bromodomain inhibitor JQ1 in treating airway remodeling in asthmatic mice. Methods A total of 24 mice were randomly divided into control group, ovalbumin (OVA)-induced asthma group (OVA group), and JQ1 intervention group (JQ1+OVA group), with 8 mice in each group. OVA sensitization/challenge was performed to establish a mouse model of asthma. At 1 hour before challenge, the mice in the JQ1+OVA group were given intraperitoneal injection of JQ1 solution (50 μg/g). Bronchoalveolar lavage fluid (BALF) and lung tissue samples were collected at 24 hours after the last challenge, and the total number of cells and percentage of eosinophils in BALF were calculated. Pathological staining was performed to observe histopathological changes in lung tissue. RT-PCR and Western blot were used to measure the mRNA and protein expression of E-cadherin and vimentin during epithelial-mesenchymal transition (EMT). Results Compared with the control group, the OVA group had marked infiltration of inflammatory cells in the airway, thickening of the airway wall, increased secretion of mucus, and increases in the total number of cells and percentage of eosinophils in BALF (P < 0.01). Compared with the OVA group, the JQ1+OVA group had significantly alleviated airway inflammatory response and significant reductions in the total number of cells and percentage of eosinophils in BALF (P < 0.01). Compared with the control group, the OVA group had significant reductions in the mRNA and protein expression of E-cadherin and significant increases in the mRNA and protein expression of vimentin (P < 0.01); compared with the OVA group, the JQ1+OVA group had significant increases in the mRNA and protein expression of E-cadherin and significant reductions in the mRNA and protein expression of vimentin (P < 0.01); there were no significant differences in these indices between the JQ1+OVA group and the control group (P > 0.05). Conclusions Mice with OVA-induced asthma have airway remodeling during EMT. BET bromodomain inhibitor JQ1 can reduce airway inflammation, inhibit EMT, and alleviate airway remodeling, which provides a new direction for the treatment of asthma.