Respiratory viral detection and small airway inflammation in lung tissue of patients with stable, mild COPD.

Background: Viral respiratory tract infections are implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). In lung tissue specimens from patients with stable, mild COPD and from control smokers without airfl ow obstruction, we determined the prevalence and load of nucleic acid from common respiratory viruses and concomitant infl ammation of small airways measuring less than 2-mm in diameter. Methods: Frozen lung tissue obtained from patients with stable, mild COPD (n = 20) and control subjects (n = 20) underwent realtime quantitative PCR (qPCR) for 13 respiratory viruses, and quantitative histology for infl ammation of small airways. The two groups were compared for viral prevalence and load, and airway infl ammation. The relationship between viral load and airway infl ammatory cells was also analyzed. Results: Viral nucleic acid were detected in lung tissue of 18/40 (45.0%) of the individuals studied and included seven co-infections that were characterized by a “dominant virus” contributing to most of the total measured viral load. Lung tissue of COPD patients had a signifi cantly higher prevalence of viral nucleic acid (particularly infl uenza A virus), and increased infl ammation of small airways by macrophages and neutrophils versus controls. In qPCR-positive individuals, linear regression analysis showed a direct correlation between viral load and airway neutrophils, and between infl uenza A virus load and airway macrophages. Conclusion: The lung tissue of patients with stable, mild COPD has a higher prevalence and load of respiratory viruses versus non-obstructed control subjects, and increased infl ammation of small airways. Respiratory viruses may represent potential targets in COPD patient management.