Objectives: Cough variant asthma (CVA) is the main cause of obstinate cough. This study aimed to observe the therapeutic effect of Xiaochuan pill on CVA in a rat model, and to explore the mechanisms.
Methods: The rats were sensitized and challenged with 4% ovaibumin (OA) and 2% Al(OH)3 to establish the CVA models. They were treated with Xiaochuan pill (at the dose of 0.9, 1.8, 3.6 g/kg) or montelukast sodium once a day for 14 days. After 7 and 14 days of intervention, 5 and 10 rats were randomly selected from each group to collect bronchoalveolar lavage fluid (BALF), trachea, and lungs. The number of white blood cells (WBC) and eosinophils (EOS), and the levels of IL-1β, TNF- α, and IFN-γ in BALF were detected. Histopathological examination of lung tissue was performed to observe the histomorphological changes. The expressions of TLR4, MyD88, NF-κBp65, and p-p65 in lung tissue were detected by Western blotting.
Results: The numbers of WBC and EOS in BALF of CVA rats were significantly decreased by Xiaochuan pill (P<0.05 or P<0.01). The hyperplasia of tracheal, bronchial mucosa and the infiltration of inflammatory cells in lung were alleviated obviously. After 14 d of intervention, high dose of Xiaochuan pill significantly increased the level of IFN- γ (P<0.01), reduced the levels of IL-1β (P<0.05) and TNF-α (P<0.05), and decreased the expressions of TLR4, MyD88, p65, and p-p65 (P<0.05 or P<0.01).
Conclusions: Xiaochuan pill exerts the significant therapeutic effect on obstinate cough in rats. The mechanism of action may be related to the regulation of TLR4-MyD88-NF-κBp65 signaling pathway as well as the inflammation and immune response.
目的: 咳嗽变异性哮喘是顽固性咳嗽的主要病因。观察哮喘丸对咳嗽变异性哮喘大鼠的治疗效果，并进一步探讨其作用机制。方法: 选用4%鸡蛋清白蛋白和2%的Al(OH)3共同致敏大鼠，建立咳嗽变异性哮喘大鼠模型。模型大鼠分别灌胃给予低、中、高剂量(0.9，1.8，3.6 g/kg)哮喘丸或孟鲁司特钠，每天1次，连续14 d，并于干预7，14 d后从各组分别随机取5，10只大鼠用于采集支气管肺泡灌洗液(bronchoalveolar lavage fluid，BALF)和气管、肺组织。对BALF中的白细胞及嗜酸性粒细胞计数；采用ELISA试剂盒检测各组大鼠BALF中IFN-γ，IL-1β，TNF-α的水平；对各组大鼠肺组织行病理学检查，观察其组织形态学变化；采用蛋白质印迹法检测各组大鼠肺组织中TLR4，MyD88，NF-κBp65和p-p65的蛋白质表达。结果: 哮喘丸能明显减少变异性哮喘模型大鼠BALF中白细胞及嗜酸性粒细胞的数目(P<0.05或P<0.01)，并能改善气管及支气管黏膜上皮增生和肺组织炎症细胞浸润程度；干预14 d，与模型对照组比较，哮喘丸高剂量组IFN-γ水平明显升高(P<0.01)，IL-1β和TNF-α水平明显降低(均P<0.05)，大鼠肺组织TLR4，MyD88，p-p65及p65的蛋白质表达水平均明显降低(P<0.05或P<0.01)。结论: 哮喘丸对大鼠顽固性咳嗽具有治疗作用，其作用机制可能与调控气道TLR4-MyD88-NF-κBp65信号通路，调节炎症和免疫反应有关。.
Keywords: TLR4-MyD88-NF-κBp65 signaling pathway; Xiaochuan pill; cough variant asthma; obstinate cough.