The Preliminary Study On The Expression Of EOS And SP And Its Correlation With Pulmonary Function And AHR In Cough Variant Asthma

Cough variant asthma is a common problem among all ages that frequently goes unrecognized. In recent years lots of scholars pay attention to this disease. A proportion of patients in CVA followed over time develops the classic signs and symptoms of asthma. It is the second cause of chronic cough. This study was undertaken to elucidate the changes of pulmonary function, airway reactivity and allergic mediator and investigate the involvement of eosinophil and neuropeptide in CVA. This research is composed of two parts of experiment. Part I . This experiment explored the changes of index of ventilation function of large (FVC, FEy1, FEV1%) and small (MMF, V50, V25) airways. Bronchial provocation tests (Rrs, Dmin, sGrs) were performed with methacholine and the levels of total serum IgE were measured by chemical luminescence. The conclusions are as below. (1) The pulmonary function of large airways in CVA is normal. Obstruction of large airways was observed in classic asthma to some extent. (2) Patients in CVA and classic asthma have changes in pulmonary function of small airways, which is not related to smoking. That of the former shows a bit less than the later. (3) There is airway hyperresponsiveness in all patients. The mechanism for the manifestation of cough without wheezing in CVA may be a higher wheezing threshold than classic asthma. (4) Total serum IgE titre is not significantly different between CVA and classic asthma, whose levels both are increased. Part II. Three mucosal biopsies were obtained from the right upper lobes using fibreoptic bronchoscope, one of which was stained with HE, one was processed for IHC staining and another for electron microscopy. At the same time bronchial brushing was performed for calculating the numbers of EQS and classified cells. The results are as below. (1) EOS and SP play an important role in CVA. (2) Tissue EQS is all significantly increased in both CVA and classic asthma, but is not different between two diseases. (3) EOS could be the source of SP. (4) Electron microscopy shows morphologic features of EQS degranu- lation and airway remodeling in CVA. In conclusion, CVA is an occult form of asthma whose only symptom or sign is chronic cough, with weaker dysfunction of small airways and higher wheezing threshold. Eosinophilic inflammation and neurogenic inflammation may be involved in the airway inflammation process. Recently developed EQS and SP antagonists used for patients with this disease may be useful tools for therapy.