Immunohistochemical Analysis of Mastocyte Inflammation: A Comparative Study in COPD Associated with Tobacco Smoking and Wood Smoke Exposure

Chronic Obstructive Pulmonary Disease (COPD) exhibits some phenotypic differences between patients with biomass smoke inhalation (COPD-B) and tobacco smoking (COPD-T), as COPD-B is characterized by less emphysema but more airway disease and vascular pulmonary remodeling; these characteristics were related for mast cells in lung tissues for COPD-T. Our objective was to characterize the differences between the number of mast cells in COPD-B and COPD-T patients. METHODS: A cross-sectional study was conducted on lung tissue resections for suspected cancer obtained between 2014 and 2021 from patients with documented COPD due to wood smoke or tobacco exposure. Histological samples were analyzed for mast cell count, CD34 + expression, and structural changes in the lung tissue and pulmonary circulation. RESULTS: 20 histological samples were analyzed, with significant differences found in mast cell count [median 8 (p25-75, 5–11) vs 2 (p75-25, 0–6), p = 0.016) and severe peribronchiolar fibrosis (60% vs 10%, p = 0.04) between COPD-B and COPD-T patients. A positive correlation (spearman rho = 0.879, p > 0.001) was observed between mast cell count and a gradual increase in pulmonary artery diameter. CONCLUSION: Compared with COPD-T, patients with COPD-B exhibit more counts of mast cells in lung tissue and peribronchiolar fibrosis than tobacco smoke-exposed patients, suggesting a pathogenic role of mast cells in COPD-B more than in COPD-T.