Circulating YKL-40 level in COPD patients and its correlations with clinical parameters

Abstract

Objective To analyse the relationship of chitin enzyme protein-40 (YLK-40) levels with the severity of chronic obstructive pulmonary disease (COPD) and clinical parameters, and to discuss the clinical significance of YLK-40 in COPD. Methods There were 80 COPD patients included 40 stable COPD patients, 40 acuteexacerbation of COPD patients and 20 healthy subjects were collected from April 2016 to June 2017 in Department of Respiratory and Critical Care Medicine of Jiangsu Province Hospital.The circulating levels of YKL-40, IL-6, and VEGF in 80 COPD patients′ serums were measured via Enzyme-Linked Immuno Sorbent Assay.Smoking index, body mass index(BMI), symptoms [modified British medical research council (mMRC), chronic obstructive pulmonary diseases assessment test (CAT)], frequency of COPD exacerbations (hospitalization times) and other laboratory parameters including C-reactive protein levels, plasma fibrinogen levels, neutrophil cell counts were also recorded.Then, pulmonary function and imaging examination index (emphysema parameters) of stable COPD patients were measured by pulmonary function instrument and spiral CT.Finally, some relevant factors were analysed in detail by SPSS 20.0 analysis software. Results The serum levels of YKL-40, IL-6, VEGF and neutrophil cell count were significantly higher in COPD patients than in controls (all P 10 packs-year.The levels of YKL-40 positively correlated with the levels of IL-6 (r=0.51, P<0.001) and VEGF (r=0.49, P<0.001), but no correlation was observed with CRP.In stable COPD patients, the serum level of YKL-40 both negatively correlated with forced expiratory volume in the first second percentage of predicted value (r=-0.503, P=0.005) and maximal voluntary ventilation percentage of predicted value (r=-0.463, P=0.010), but it positively correlated with the low attenuation area percentage of lung volume during expiration (r=0.452, P=0.03). However, no correlation was observed with diffusion capacity for carbon monoxide corrected percentage of predicted value. Conclusions YKL-40 participates in the inflammatory response of COPD and is expected to be a reference index for evaluating the severity and guiding treatment of COPD. Key words: Pulmonary disease, chronic obstructive; Interleukin-6; Receptors, vascular endothelial growth factor; YKL-40