Virus-induced and bacteria-induced exacerbations of chronic obstructive pulmonary disease caused by industrial aerosols or tobacco smoke exposure

Abstract

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are associated with disease progression and increased risk of death. We need to better understand the phenotypes of AECOPD to improve treatment strategies. The main triggers of COPD exacerbations are viral and bacterial infections.The aim is to characterize the viral, bacterial, and viral-bacterial phenotypes of acute exacerbations in patients with COPD caused by industrial aerosol exposure or tobacco smoke.Methods. 180 subjects with established moderate and severe COPD who met the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria, 2020 – 2021, and were hospitalized with AECOPD, were enrolled in this prospective observational study. The virus-induced, bacteria-induced, and virus-bacteria-induced AECOPD strata (n = 60 each) were formed. Each stratum included 30 patients with occupational COPD and 30 patients with COPD caused by tobacco smoke. Virus-induced AECOPDs were diagnosed by PCR of bronchoalveolar fluid. Length of hospital stay, symptoms, lung function, mean pulmonary artery pressure (mPAP), and type of inflammation were assessed. Cox proportional hazard regression was used to examine the relationships.Results. The length of hospital stay was highest in patients with virus-induced and virus-bacteria-induced exacerbations of occupational COPD, being equal to (Me, IQR) 16.5 (14 – 18) and 18 (16 – 20) days. The virus-induced exacerbations in occupational COPD and in COPD caused by tobacco smoke featured the highest bronchodilation coefficient, 10.9 (9.8 – 11,5)% and 9.2 (8.3 – 10.3)%, respectively, decrease in the diffusing capacity of the lungs (DLCO/Va) by 42 (40 – 45)% and 49 (47 – 52)%, increase in mPAP by 44 (39 – 45) и 33 (29 – 38) mmHg, and eosinophilic inflammation with blood eosinophil count of 425 (385 –527) and 350 (310 – 391) cells per μl (р > 0.01). Virus-bacteria-induced AECOPD in occupational COPD and in COPD caused by smoke were characterized by decrease in FEV1 by 40.2 (36.6 – 42.2)% and 31.0 (28.1 – 33.6%), decrease in DLCO/Va by 48 (44 – 50)% and 37 (35 – 41)%, increase in mPA by 43 (38 – 46) and 50 (45 – 54) mmHg, and eosinophilic-neutrophilic inflammation in 63.3 and 66.6% of patients. The mid-range FEV1, highest DLCO/Va, and neutrophilic inflammation were seen in patients with bacteria-induced AECOPD.Conclusion. Exacerbations of occupational COPD are characterized by more severe functional impairment and inflammation with high eosinophil count when these exacerbations have viral origin.