The effect of Qi'ao Decoction on ovalbumin induced and lipopolysaccharide enhanced severe asthma mice and its mechanism

AIM: To evaluate the effect of Qi'ao Deocoction (QAD) on the inflammation and hyperresponsiveness of asthma mice. METHODS: 120 Balb/C mice were randomly divided into six groups: normal group, model group, dexamethasone group, high dose QAD group, medium dose QAD group and low dose QAD group. The asthma model was reproduced in Balb/C mice sensitized by ovalbumin, challenged by OVA and LPS. The mice of the normal group were sensitized, chanllenged and intranasally instilled by PBS. On day 28-34, 6.7, 13.4 and 26.8 g·kg⁻¹ Qi'ao Decoction were administrated; 0.002 4 g·kg⁻¹ dexamethasone solution was given to the dexamethasone group; normal and model groups were given the same amount of normal saline. Bronchoalveolar lavage fluid, airway hyperresponsiveness, lung histopathology and cytokines were then collected and analyzed. RESULTS: Compared with normal group, total cellular score, the number of macrophages, lymphocytes, eosinophils and neutrophils of model group significantly increased (P < 0.01). Compared with model group, the administration of dexamethasone induced a significant decrease in eosinophils and neutrophils (P < 0.05, P < 0.01). The number of eosinophils, which plays an important role in airway inflammatory reaction of asthma, of the three QAD groups all decreased (P < 0.01). RL before and after Ach (5 mg·mL⁻¹) stimulation in the model group both overtook that in the normal group (P < 0.01). Compared with model group, dexamethasone group, high dose QAD group, medium dose QAD group and low dose QAD group groups all had significantly lower RL before and after Ach stimulation (P < 0.01). Normal pulmonary histopathology was found in the normal group. In the model group, mice exhibited marked increases in inflammatory cell infiltration, mostly including neutrophils and macrophages, perivascular inflammation and thickened alveolus wall (P < 0.01). Dexamethasone application mitigated inflammation around the bronchi (P < 0.05). These histopathological changes were ameliorated in the three decoction groups (P < 0.01, P < 0.05). In addition, alveolus and airway wall lesions of medium dose QAD group and high dose QAD group were reduced, the number of inflammatory cells infiltrated around the walls decreased, no clear degeneration of bronchial epithelial cells was found, and exudates in bronchi declined in different degrees. Compared with normal group, IFN-γ and IL-12 of model group significantly decreased, while IL-4 increased, showing statistic difference (P < 0.05). Compared with model group, IFN-γ and IL-12 level of dexamethasone group went up too, but IL-4 declined (P < 0.05). The level of IFN-γ of medium dose QAD group and high dose QAD group both increased; IL-4 and IL-12 of medium dose group were found significant differences (P < 0.05); but none of the cytokines of low dose QAD group showed statistical significance (P > 0.05). CONCLUSION: QAD can significantly inhibit airway inflammation and airway hyperresponsiveness of mice with severe asthma induced by ovalumin and lipopolysaccharide, adjust the balance of cytokines, and improve lung histopathological condition. So, it exhibits great effect on severe asthma.