Differences in Airway Inflammation in Patients with Fixed Airflow Obstruction Due to Asthma or Chronic Obstructive Pulmonary Disease

Abstract

To determine whether patients with fixed airflow obstruction have distinct pathologic and functional characteristics depending on a history of either asthma or chronic obstructive pulmonary disease (COPD), we characterized 46 consecutive outpatients presenting with fixed airflow obstruction by clinical history, pulmonary function tests, exhaled nitric oxide, sputum analysis, bronchoalveolar lavage, bronchial biopsy, and high-resolution computed tomography chest scans. Subjects with a history of COPD (n = 27) and subjects with a history of asthma (n = 19) had a similar degree of fixed airflow obstruction (FEV1: 56 +/- 2 versus 56 +/- 3% predicted) and airway hyperresponsiveness (PC20FEV1: 2.81 [3.1] versus 1.17 [3.3]). Subjects with a history of asthma had significantly more eosinophils in peripheral blood, sputum, bronchoalveolar lavage, and airway mucosa; fewer neutrophils in sputum and bronchoalveolar lavage fluid; a higher CD4+/CD8+ ratio of T cells infiltrating the airway mucosa; and a thicker reticular layer of the epithelial basement membrane. They also had significantly lower residual volume, higher diffusing capacity, higher exhaled nitric oxide, lower high-resolution computed tomography scan emphysema score, and greater reversibility to bronchodilator and steroids. In conclusion, despite similar fixed airflow obstruction, subjects with a history of asthma have distinct characteristics compared with subjects with a history of COPD and should be properly identified and treated.

Does leptin play a cytokine-like role within the airways of COPD patients?

“…Therefore, the current authors hypothesised that the leptin-leptin receptor system might be upregulated in the airway mucosa and that such a system may be involved in the regulation of the number and phenotype of T lymphocytes in the bronchial mucosa of COPD subjects. In smokers and COPD patients the colocalisation of leptin and leptin-receptor expression with pertinent inflammatory cells was assessed [18]. The apoptotic status of inflammatory cells was also demonstrated and the cells that expressed leptin and leptin-receptors were detected.…”

Which Pulmonary Function Tests Best Differentiate Between COPD Phenotypes?

“…9 Using a composite clinical picture to assign 19 as asthma and 27 as COPD, they sought to identify which clinical features, including PFTs, were best at distinguishing the 2 conditions. COPD patients were more likely than asthma patients to have smoked tobacco (24 1 after inhaled corticosteroid (3.6% predicted vs 12.1% predicted, P Ͻ .01), and higher CT emphysema score (3.6 vs 0.6, P Ͻ .05).…”

“…9 Table 3 identifies that inflammatory markers, such as eosinophilia in sputum and bronchoalveolar lavage fluid, and exhaled nitric oxide, were better than PFT-based tests at distinguishing COPD from asthma. These data, taken together, suggest that PFT phenotypes alone do not adequately distinguish COPD from asthma, and composite clinical phenotypes perform better.…”

“…First, some patients with an FEV 1 /FVC below the lower limit of normal (the defining characteristic of obstructive lung disease 4 ) have asthma rather than COPD, as shown in the Fabbri et al study discussed earlier. 9 Another implication of this question is what is the importance of Stage I COPD? According to the GOLD guidelines, Stage I COPD (mild COPD) is defined by mild air flow obstruction (FEV 1 /FVC Ͻ 0.70 with FEV 1 Ͼ 80% predicted) and sometimes, but not always, chronic cough and sputum production.…”

Intérêt de la mesure de l’inflammation en clinique dans l’asthme

“…Une large étude de population a montré que la mesure du FE NO était un complément utile au tests de provocation bronchique dans la détection de l'asthme [86] . Le FE NO aide au diagnostic différentiel entre asthme et BPCO [87] chez les patients avec une obstruction respiratoire fixée témoignant d'un remodelage.…”