The role of noninvasive methods in assessing airway inflammation and structural changes in asthma and COPD

The aim of our study was to assess the role of non-invasive methods in assessing airway inflammation and structural changes in asthma and COPD.

The study was conducted on patients attending outpatient and inpatient department of TB and Chest Diseases and Department of Pathology at our hospital from January 2006 to August 2007. 50 asthmatic and 46 COPD patients were selected. A detailed history and clinical examination, routine laboratory investigations, pulmonary function testing, Chest X-ray PA and lateral view, HRCT Thorax, biochemical and cellular analysis of sputum was carried out in all cases. Quality control and procedures of pulmomary function test were performed according to the European Respiratory Society guidelines.

Bronchial wall thickening, bronchiectasis and air trapping correlated well with disease severity in asthmatics while all abnormal HRCT finding correlate well with disease severity in COPD patients. The levels of MMP-9 and TIMP-1 increased significantly with increasing disease severity in both asthmatic and COPD groups. The MMP-9/TIMP-1 ratio decreased with increasing disease severity in both groups. The major source of MMP-9 in human lungs is macrophages, neutrophils and eosinophils. Macrophages and neutrophils were also the source of TIMP-1.

Asthma and COPD are characterised by an imbalance between MMP-9 and TIMP-1. COPD patients showed a higher prevalence of HRCT findings which correlate with their lower MMP-1/TIMP-1 ratio than asthmatics supporting fact that the destruction and fibrosis of alveolar walls are more prominent in COPD. MMP-9/TIMP-1 ratio is associated with magnitude of HRCT findings in asthma and COPD and suggests that level of these markers reflect the extent of structural changes of airway.