Abstract:
Objective
To investigate the relationship between serum Clara cell secretory protein（CC16） expression and lung function and emphysema phenotype in patients with chronic obstructive pulmonary disease （COPD） in the stable stage.
Methods
A cross-sectional study was conducted in 100 patients with stable COPD in which serum CC16 concentrations were measured by enzyme-linked immunosorbent assay（ELISA）. Spearman′s correlation and linear regression were used to test the relationship between CC16 levels and lung function in COPD.
Results
Patients were categorized into 47 cases of non-emphysematous COPD（NE-COPD） and 53 cases of emphysematous COPD （E-COPD） using the Z-score of single breath diffusion of carbon monoxide （TLCO）. Compared with NE-COPD，the emphysema index （EI） ［1.40%（0.95%，1.86%） vs.5.00%（3.13%，8.64%）］was significantly increased in patients with E-COPD （P＜0.05）， whereas， z-score of forceful expiratory volume in the first second （FEV1）/forceful lung capacity （FEV1/FVCz-score）［-2.51（-3.06，-1.97） vs. -2.96（-3.85，-2.25）］， TLCOz-score［-0.89（-1.32，-0.05） vs. -2.79（-4.02， -2.18）］， alveolar volume （VA）z-score［0.01（-0.92，0.84）vs. -1.03（-1.69，-0.36）］， diffusion constant for carbon monoxide（KCO）z-score［-0.78（-1.30，0.06） vs. -2.33（-3.14，-1.41）］，and serum CC16［14.63（8.87，26.74）ng/ml vs.8.90（2.90，14.89）ng/ml］ were significantly reduced （P＜0.05）. After Sperman correlation analysis， serum CC16 level was negatively correlated with EI （Rho=-0.344）； while it was negatively correlated with TLCOz-score（Rho=0.384）， KCOz-score（Rho=0.266）， VAz-score（Rho=0.214）， FEV1/FVCz-score（Rho=0.383） were positively correlated； all P＜0.05. In the subgroups of E-COPD （Rho=0.408）， NE-COPD （Rho=0.379）， the levels of serum CC16 were positively correlated with FEV1/FVCz-score were all positively correlated （P＜0.001）. After correcting for demographics， cardiopulmonary exercise test parameters， medication， and other clinical factors，serum CC16 levels remained significantly correlated with FEV1/FVCz-score in all COPD patients， E-COPD， and NE-COPD subgroups （P＜0.05）.
Conclusion
Serum CC16 level is an important factor associated with lung function and emphysema phenotype in patients with COPD， and low serum CC16 signifies that patients with COPD may have more severe disease and may combine more complex pathological phenotypes with poorer lung function.
Key words:
Chronic obstructive pulmonary disease,
Lung function,
Emphysema phenotype,
Clara cell secretory protein 16
Qile Shen, Qinhua Zhao, Sugang Gong, Jinming Liu, Lan Wang, Hongling Qiu. Relationship between serum CC16 protein expression， lung function and emphysema phenotype in stable COPD patients[J]. Chinese Journal of Lung Diseases(Electronic Edition), 2024, 17(05): 690-695.