The aim of the study is to assess if chronic cough leads to injury and remodelling of the airways. We plan to analyse bronchial injury and remodelling in patients with refractory chronic cough lasting longer than 12 month . Assessment of injury mediators will be performed in blood and bronchoalveolar lavage fluid. Remodelling features will be analysed based on chest CT scan and pathologic specimens. Injury of epithelium will be assessed in bronchial biopsy specimens. The relationship between the duration, severity of chronic cough, and bronchial inflammation, damage, remodelling will be analysed.

Cough is a physiological defensive reflex which decreases the risk of aspiration to the lower airways and allows to remove sputum and excessive mucus from the airways. However, in some cases, persisting intensive cough may result in many complications and decrease in patients' quality of life. Damage of the airway epithelium due to infection, chemical or mechanical injury leads to an increase in the frequency or intensity of cough.

The aim of the study is to assess if chronic cough leads to damage and remodelling of the airways. We plan to analyse bronchial injury and remodelling in patients with refractory chronic cough lasting longer than 12 months. Assessment of injury mediators will be performed in blood and BALF. Remodelling will be analysed based on chest CT scan and pathologic specimens. Injury of epithelium will be assessed in pathologic specimens of bronchial biopsy. The relationship between the duration, severity of chronic cough and bronchial inflammation, damage, remodelling will be analysed.

Patients with refractory chronic cough and clinical indications for bronchoscopy (such as: productive cough, mucus plugs or bronchiectasis in chest CT, suspected extensive dynamic airway collapse (EDAC), assessment of eosinophilic airway inflammation when induced sputum could not be obtained, or any suspicion or high risk of malignancy) will be invited to take part in the study.

We plan to enroll 40 non-smoking patients with chronic cough lasting longer than 12 months, who had already been unsuccessfully treated because of cough. Thorough diagnostics of cough reason will be performed. Besides parameters of bronchial inflammation, remodelling and injury will be analysed in serum and BALF. Injury and remodelling will also be assessed in bronchial biopsy and in chest CT.

The results of the study will assess if refractory chronic cough is associated with any type of airway inflammation, bronchial injury or remodeling.

Inclusion criteria for the study group:

1. age between 18 and 75 years,
2. chronic cough of at least one year duration, with no previous treatment (at least 2 previous unsuccessful attempts at pharmacological treatment of cough)
3. negative history of smoking (at least 6 months of abstinence),
4. negative history of treatment with angiotensin-converting enzyme inhibitors (ACEI),
5. normal chest radiograph or with changes not relevant to cough formation,
6. no respiratory tract infections in the past 6 weeks,
7. written consent from the patient to participate in the study.

Exclusion Criteria:

1. patients less than 18 and more than 75 years of age,
2. cough lasting less than 12 months,
3. active smoking or abstinence period of less than 6 months,
4. respiratory tract infection 6 weeks prior to inclusion or at the time of study conduct - retry inclusion after 6 weeks,
5. cancer or interstitial lung disease,
6. contraindications to functional testing, sputum induction or bronchoscopy

In 30 patients referred to the cough clinic for refractory chronic cough lasting more than 6 months