Clinical and pathological characteristics of CRS with nasal polyps in patients with asthma-COPD overlap

Bronchial asthma (BA) and Chronic Obstructive Pulmonary Disease (COPD) have been considered as independent diseases, but in recent years, Asthma and COPD Overlap (ACO), which combines characteristics of BA and COPD, has been defined. Chronic rhinosinusitis (CRS) with nasal polyps and BA, both caused by similar type 2 inflammation, often coexist and are considered to have a "one airway, one disease" relationship. In ACO, airway inflammatory cells of BA (eosinophils and CD4⁺ lymphocytes) and COPD (neutrophils, CD8+ lymphocytes and macrophages) coincide, theoretically leading to steroid resistance compared to BA alone. Based on the "one airway, one disease" concept, we hypothesized that clinical and pathological characteristics of CRS differs depending on its comorbidity with ACO or with BA alone.

Sixty-two CRS patients with BA who underwent endoscopic surgery for CRS with nasal polyp at our hospital between January 2014 and December 2022 were included in this study, and were followed at our hospital until December 2023. The patients were categorized by pulmonologists into 21 patients of CRS-ACO and 41 patients of CRS-BA according to the Japanese guidelines for the Management of ACO 2018. We compared recurrence-free period of nasal polyps between these two groups. Nasal polyps from CRS-ACO (n = 11) and CRS-BA (n = 13) those who consented to this study were subjected to histologic examination and the numbers of eosinophils, and cell positive for CD4, CD8, elastase (a marker for neutrophils), and CD163 (a marker for macrophages) were counted.

CRS-ACO had a significantly faster recurrence time, compared to the recurrence time in CRS-BA, and was a risk factor for recurrence. Nasal polyps from CRS-ACO and CRS-BA those who consented to this study were subjected to histologic examination. Elastase, CD8, and CD163 positive cell numbers were significantly higher in CRS-ACO than in CRS-BA patients.

CRS-ACO patients were prone to recurrence of nasal polyps, and the pathology of nasal polyps in CRS-ACO patients were significantly infiltrated with neutrophilic inflammatory cells. CRS-ACO patients revealed inflammatory cell infiltration in the upper airway (nasal polyps) and similar cell types was confirmed to coexist in the lower airway, suggests the possibility of a "one airway, one disease" concept, not only in BA, but also in ACO as well.