Effect of Maxing Shigantang on Airway Injury and EGFR Expression in Asthma Model Rats / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo explore the optimal formula of Maxing Shigantang in regulating epidermal growth factor receptor（EGFR）expression and alleviating airway injury in asthmatic rats and to reveal the underlying mechanism. MethodSD male rats were randomly divided into normal group, model group, dexamethasone group (5×10-4 g·kg-1) and Maxing Shigantang 1∶0.5, 1∶1, 1∶2 groups (group A, B, C, 10 g·kg-1), with 8 rats in each group. The other groups except the normal group received nebulization of 2% acetylcholine chloride and 0.4% histamine phosphate for the modeling of asthma. One hour before modeling， the normal group and the model group were given the same amount of normal saline， and the other groups were given the same amount of corresponding drugs， once a day for 7 days. On the 7th day， the model was established and the incubation period of asthma was recorded. The rats were then immediately anesthetized， and arterial blood and tracheal tissue were collected. Enzyme-linked immunosorbent assay （ELISA） was employed to detect the levels of interleukin-2 （IL-2）， interleukin-4 （IL-4）， and tumor necrosis factor-α （TNF-α） in serum. Pathological sections were prepared for the observation of the pathological changes of tracheal tissues and the ultrastructure of epithelial cells in each group. Terminal-deoxynucleotidyl transferase-mediated nick-end labeling （TUNEL） was adopted to detect epithelial cell apoptosis， and in situ hybridization and Western blot were employed to determine the mRNA and protein levels of epidermal growth factor receptor （EGFR）， respectively. ResultCompared with the model group， groups A， B and C prolonged the incubation period of asthma （P<0.05，P<0.01）. Compared with the control group， the model group showed declined IL-2 level （P<0.01）， risen IL-4 and TNF-α levels （P<0.05，P<0.01）， increased airway pathology score， collagen volume fraction， and airway epithelial cell apoptosis index （P<0.01）， and up-regulated mRNA and protein levels of EGFR in trachea tissue （P<0.01）. Compared with the model group， group A showed increased IL-2 level （P<0.05） and declined IL-4 （P<0.05，P<0.01） level， and group B showed declined IL-4 level （P<0.05）. The level of TNF-α in groups A， B， and C declined compared with that in the model group （P<0.01）. Maxing Shigantang repaired the tracheal tissue to different degrees （P<0.05）. Among the three groups， group A inhibited tracheal fibrosis （P<0.05） and had the most significant effect of repairing the ultrastructural changes of airway epithelial cells. Groups A， B and C all inhibited the apoptosis of airway epithelial cells （P<0.05）. All the three groups inhibited the up-regulation of EGFR mRNA level （P<0.05，P<0.01）， and groups B and C inhibited the up-regulation of EGFR protein level （P<0.05，P<0.01）. ConclusionMaxing Shigantang can inhibit the abnormal changes of airway epithelial structure， alleviate airway injury， and can down-regulate the expression of EGFR in the tracheal tissue of asthma model rats. In this study， the optimal compatibility of Maxing Shigantang to repair airway epithelial injury in asthmatic rats was group A， with the Ephedrae Herba-Armeniacae Semen Amarum-Glycyrrhizae Radix et Rhizoma-Gypsum Fibrosum ratio of 1∶0.5∶4∶1.