Characteristics of airway inflammation in patients with the emphysema phenotype of chronic obstructive pulmonary disease

Objective To evaluate the characteristics of airway inflammation in patients with the emphysema phenotype of chronic obstructive pulmonary disease (COPD).Methods Fifty-two outpatients with stable COPD were examined.For each subject,the clinical data were collected,and HRCT scanning and lung function tests were performed.Sputum cells were counted and the supernants were processed for measurement of IL-6,IL-8,TNF-α,VEGF,MMP-9 and TIMP-1.The subjects were divided into 2 groups:an emphysema group (n =29) and a non-emphysema group (n =23) based on the HRCT emphysema index (EI).Results There was no difference between the 2 groups in sex,age,body mass index,time course of cough and wheeze,and smoking (all P ＞0.05).FEV1 ％pred,DLCO％pred,and DLCO/VA％ pred were significantly decreased in the emphysema group as compared to the nonemphysema group [(48.21± 13.44)％ vs (57.04± 12.61)％,P =0.019; (48.57± 16.76)％ vs (65.64±12.48)％,P=0.001;(59.52±15.33)％ vs (82.99±16.31) ％,P＜0.001],but RV/TLC and RV％pred were significantly increased in the emphysema group [(53.86± 10.98)％ vs (44.93 ±6.72)％,P =0.003;(129.95±18.88)％ vs (118.77±13.16)％,P =0.037].The number and the percentage of sputum eosinophils were higher in the emphysema group [0.05 (0.00,0.13) × 109/L vs 0.00(0.00,0.01) × 109/L,P =0.032;0.50(0.00,2.00)％ vs 0.00(0.00,0.25)％,P =0.033].Moreover,the percentage of sputum eosinophils was positively correlated with emphysema index (B =1.248,P =0.007).However,there was no difference between the 2 groups in the number or percentage of sputum neutrophils,lymphocytes and macrophages.The sputum level of TNF-αtended to be higher in the emphysema group as compared to the non emphysema group [221.72(100.00,351.57) ng/L vs 144.85(54.51,269.16) ng/L,P =0.063],but the levels of IL-8,IL-6,VEGF,MMP-9,TIMP-1 and the ratio of MMP 9/TIMP-1 were not different between groups.Conclusions Patients with the emphysema phenotype of COPD in this study tended to have higher airway eosinophils and TNF-α,suggesting a differenct inflammatory profile which needed to be further explored. Key words: Chronic obstructive pulmonary disease;  Phenotype;  Emphysema;  Airway inflammation