Effect of the emphysema subtypes of patients with chronic obstructive pulmonary disease on airway inflammation and COTE index

The aim of the present study was investigate the association of the severity of emphysema of patients with chronic obstructive pulmonary disease (COPD) with airway inflammation and the COPD-specific comorbidity test (COTE) index. A total of 94 patients with COPD were divided into four groups according to the severity of their emphysema; in each patient, comorbidities were recorded and inflammatory biomarkers, including MMP-9 and TIMP-1 were determined in circulating blood. The unbalanced proportion of MMP-9 and its inhibitor, TIMP-1, led to the airway inflammation and lung remodeling in the patients with COPD. A total of 80.85% of the patients had emphysema of different degrees. The quantity of male patients and the smoking index in the three emphysema groups were significantly higher than those in the non-emphysema group (F=7.67 and 5.42, P<0.05). The level of the predicted percent offorced expiratory volume in 1 sec in the non-emphysema group were significantly higher than those in the emphysema group (4.33; P<0.05), and the level of D-dimer in the non-emphysema group was significantly lower than that in the mild and moderate emphysema groups (F=9.38, P<0.05). The low-attenuation area score was negatively correlated with inhaled bronchodilators (r=-0.240, P=0.007) but positively correlated with the frequency of acute exacerbations in the previous year (r=0.211, P=0.001). In terms of treatment, the use of systemic hormone therapy in the emphysema group was more frequent than that in the non-emphysema group (F=6.21, 12.92 and 4.08, P<0.05). The level of MMP-9 was significantly higher in COPD patients with >3 comorbidities, a COTE index of 4 and cardiovascular disease as well as coronary heart disease (t=6.40, 2.53, 3.65 and 2.90, P<0.05). The level of MMP-9 was positively correlated with the neutrophilic granulocyte percentage, the number of comorbidities and the COTE index (r=0.193, 0.402 and 0.311, P<0.01). The severity of emphysema in patients with COPD was correlated with the persistence of inflammatory factors in the circulating blood and the frequency of acute exacerbations. It was indicated that MMP-9 has a critical role in numerous comorbidities of COPD.