Figure 5.

Collagen degradation in the adventitia of small airways is associated with loss of alveolar attachments. (A) Representative images of collagen and elastin anchoring fibres (yellow arrows) in alveolar attachments in a lifelong NS subject, patient with GOLD stage II COPD, and a patient with GOLD stage IV COPD. Top row: PicroSirius red-staining under red fluorescence; bottom row: elastin immunofluorescence. Scale bars=20 µm. (B, C) Box and whisker plots show collagen (B) and elastin (C) density in 10 µm zone of outer adventitia in small airways from NS and FS controls and patients with COPD. Boxes represent the IQR, whiskers extend to the most extreme data point which is no more than 1.5 times the IQR from the box, and circles beyond the whiskers are extreme values, the line within the box represents the median. Groups were compared pairwise using Mann-Whitney U test. Estimated p values were Bonferroni-adjusted. The threshold for significance was 0.05. *Significantly different compared with all other groups. (D) Scatter plot showing correlation and best fit line of collagen density in outer adventitia of small airways with alveolar attachments. FS, former smoker; GOLD, Global Initiative for Chronic Obstructive Lung Disease; NS, non-smoker.