To Explore The Preventive And Therapeutic Effects Of Qiaoqin Qingfei Agent On Cough Variant Asthma Based On Airway Neurogenic Inflammation

Objective:Through ovalbumin induced cough variant asthma（CVA）model in rats,the prevention and treatment effect of Qiaoqin Qingfei agent on CVA model was investigated based on airway neurogenic inflammation.Methods:A total of 48 SD rats were randomly divided into blank control group,model control group,montelukast sodium group(1.05 mg·kg^-1)and high,medium and low dose groups of Qiaoqin Qingfei agent(26,13,6.5 g·kg^-1),with 8 rats in each group.The rat CVA model was established by the method of ovalbumin（OVA）combined with aluminum hydroxide（Al（OH）₃）sensitization and repeated excitation.Rats in model control group and each intervention group were given 1m L 10%OVA and Al（OH）₃ suspension by intraperitoneal injection+subcutaneous injection on the 1st,3rd,5th,7th and 11th days（0.5ml intraperitoneal injection,and the remaining 0.5ml subcutaneous multi-point injection on the back）;The 15th day was atomized with 1%OVA solution for 30min,once a day for 2 weeks.From the second day of sensitization,the drug was administrated intragastric for 28 days.After 4 weeks of treatment,all animals were anesthetized by intraperitoneal injection of 45 mg·kg^-1 sodium pentobarbital,and 1ml of abdominal aorta blood was taken and placed in EDTA anticoagulant tube for blood analysis and detection.The left lung of each rat was exposed,and bronchoalveolar lavage was performed.3ml normal saline was injected into the trachea,repeated aspiration was performed,and broncho alveolar lavage fluid（BALF）was removed.The BALF was centrifuged at 4℃,4000 r/min for 10 min,and the supernatant was taken and stored at-80℃for testing.The right lung was quickly dissected,and the right lung tissue was taken and fixed in 10%neutral formalin solution for hematoxylin-eosin（HE）staining and immunohistochemical detection.Observation indexes:（1）The number and percentage of eosinophilic granulocyte in blood of each group were detected;（2）ELISA was used to detect the contents of tumor necrosis factorα（TNF-α）,nerve growth factor（NGF）and substance P（SP）in alveolar lavage fluid of each group;（3）The pathological changes of lung tissue of rats in each group were observed under HE staining microscope;（4）The protein expression levels of NGF and SP in lung tissues of rats in each group were detected by immunohistochemistry.Results:（1）Eosinophils:Compared with the blank control group,the number and percentage of blood eosinophils in the model control group were significantly increased（P<0.01）;Compared with the model control group,the number and percentage of eosinophilic granulocyte in blood of rats in Qiaoqin Qingfei agent medium-dose and low-dose groups and the montelukast sodium group were significantly decreased（P<0.05）;（2）ELISA:Compared with the blank control group,the content of TNF-αin the alveolar lavage fluid of rats in the model control group was significantly increased（P<0.05）;Compared with the model control group,the content of TNF-αin the alveolar lavage fluid in Qiaoqin Qingfei agent high-dose,medium-dose and low-dose groups and the montelukast sodium group were significantly decreased（P<0.05）.Compared with the blank control group,the contents of NGF and SP in the alveolar lavage fluid in the model control group were increased（P>0.05）;Compared with the model control group,the contents of NGF and SP in the alveolar lavage fluid in Qiaoqin Qingfei agent high-dose,medium-dose and low-dose groups and the montelukast sodium group were significantly decreased（P<0.05）;（3）HE staining:Compared with the blank control group,the model control group observed a large number of inflammatory cell infiltration,structural relaxation of the vascular wall,obvious edema,and necrosis and exfoliation of the epithelial cells of the lung and trachea;Compared with the model control group,the inflammatory cell infiltration in Qiaoqin Qingfei agent high-dose,medium-dose and low-dose groups and the montelukast sodium group were reduced to varying degrees;（4）Immunohistochemistry:Compared with the blank control group,the protein expression levels of NGF and SP in lung tissue of model control group were significantly increased（P<0.01）;Compared with the model control group,the protein expression levels of NGF and SP in lung tissue of Qiaoqin Qingfei agent high-dose,medium-dose and low-dose groups and the montelukast sodium group were significantly decreased（P<0.01）.Conclusions:（1）Qiaoqin Qingfei agent can reduce the infiltration of inflammatory cells,improve the pathological changes of lung tissue,relieve the symptoms of cough variant asthma,so as to play a role in prevention and treatment;（2）Qiaoqin Qingfei agent can effectively reduce the abnormally elevated levels of TNF-α,NGF and SP in CVA state,thus intervening the occurrence and development of airway neurogenic inflammation,reducing airway inflammatory response,and effectively relieving cough variant asthma.