Koo HK, et al. - Researchers ascertained whether or not the destruction of the terminal and transitional bronchioles (the first generation of respiratory airways) occurs before, or in parallel with, emphysematous tissue destruction. In mild and moderate chronic obstructive pulmonary disease (COPD), a pathological feature is small airways disease. As per data, patients with mild or moderate COPD may require the early intervention for disease modification.

Methods

• Experts in this cross-sectional analysis applied a novel multiresolution CT imaging protocol to tissue samples obtained using a systematic uniform sampling method to obtain representative unbiased samples of the whole lung or lobe of smokers with normal lung function (controls) and patients with mild COPD (Global Initiative for Chronic Obstructive Lung Disease [GOLD] stage 1), moderate COPD (GOLD 2), or very severe COPD (GOLD 4).
• Lobectomy and pneumonectomy was conducted in the patients with GOLD 1 or GOLD 2 COPD and smokers with normal lung function, while patients with GOLD 4 COPD had undergone lung transplantation.
• They used the lung tissue samples for stereological assessment of the number and morphology of terminal and transitional bronchioles, airspace size (mean linear intercept), and alveolar surface area.

Results

• As per data, out of the 34 patients included in this study, 10 were controls (smokers with normal lung function), 18 patients had GOLD 1 COPD, 8 had GOLD 2 COPD, and 6 had GOLD 4 COPD with centrilobular emphysema.
• There were 262 lung samples provided by the 34 lung specimens.
• The number of terminal bronchioles decreased by 40% in patients with GOLD 1 COPD (p=0·014) and 43% in patients with GOLD 2 COPD (p=0·036), the number of transitional bronchioles decreased by 56% in patients with GOLD 1 COPD (p=0·0001) and 59% in patients with GOLD 2 COPD (p=0·0001), and alveolar surface area decreased by 33% in patients with GOLD 1 COPD (p=0·019) and 45% in patients with GOLD 2 COPD (p=0·0021) vs control smokers.
• Results demonstrated a correlation of these pathological changes with lung function decline.
• Significant loss of terminal and transitional bronchioles was demonstrated in lung samples from patients with GOLD 1 or GOLD 2 COPD that had a normal alveolar surface area.
• Thickened walls and narrowed lumens were seen in remaining small airways, which become more obstructed with increasing COPD GOLD stage.