Mechanism and Dynamics of Bronchial Hyper-reactivity to Methacholine in Distal Airway on Obese Patients With Asthma
Condition: Asthma
MeSH terms: Asthma; Bronchial Hyperreactivity
Study type: Observational

Summary: 
      New insights of small airway contribution to asthma have been gained. Poor levels of control
      and recurrent exacerbations were shown to have the phenotypic counterpart of asthma with
      predominant small airway involvement. Very few pathological specificities were identified at
      this site: mast cells infiltration was suggested as the specific inflammatory change when
      compared to the proximal airways.Biomarkers in asthma are still complex to validate,
      especially in the blood, since compartmentalisation is intense in the lung and the airways, a
      property attributed to the filtering role of the lung to maintain homeostasis. Over the last
      few years, Fraction exhaled Nitric Oxide (FENO) was developed as a non-invasive and indirect
      reflection of airway eosinophilic inflammation]. In the blood, peripheral eosinophil counts
      were shown as a correct T helper 2 (TH2)-phenotype identifier but not perfectly related to
      airway eosinophilic infiltration. Club cell secretory protein (SCGB1A1) levels have been
      shown to have some relevance in asthma, chronic obstructive pulmonary disease (COPD), BOS,
      sarcoidosis, and lung cancer.A biomarker for small airway disease in asthma may improve the
      management of the disease, identify areas of therapeutic resistance and constitute a
      therapeutic guidance tool. In this study, investigators aimed to assess small airway
      involvement in asthmatic women as far as they could. For this purpose, investigators analysed
      trends in air trapping by acquiring expiratory CT slices at each dose during a
      bronchoprovocation test with metacholine. Biomarkers were subsequently tested and confronted
      to clinical and demographical characteristics in their ability to predict the small airway
      involvement index obtained at CT.
    

Detailed description: 
      Patients will be recruited in the respiratory department of University Hospital in
      Montpellier (France) from June 2012 to March 2014. All patients are asthmatics, in order to
      avoid any gender-related biases, investigators decided to include only women. All
      participants had normal range spirometry, specifically regarding forced expiratory volume.
      Each patient will undergo a bronchial provocation test coupled with a thoracic CT scan.
      Bronchial and alveolar Nitric Oxyde will also be measured, a blood sample will be obtained in
      order to measure biomarker concentrations, and the patients will be asked to answer the
      validated Asthma Control Questionnaire in order to quantify asthma control.
    

Intervention name(s): metacholine provocation test and CT-scan low dose
Intervention type(s): Other
Intervention description(s): Investigators perform a metacholine provocation test where expiratory CT slices were acquired at each dose
Observational model: Case-Control
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Patients will be recruited in the respiratory department of University Hospital in
        Montpellier (France) from June 2012 to March 2014. All patients are asthmatics, in order to
        avoid any gender-related biases, investigators decided to include only women. All
        participants had normal range spirometry, specifically regarding forced expiratory volume.
      
Keywords: Airways; asthma; overweight