Increased levels of inflammatory biomarker CX3CL1 in patients with chronic obstructive pulmonary disease

•Expression level of serum CX3CL1 was elevated in stable COPD smokers.•Cytokine CX3CL1 well correlated with systemic inflammation, small airway obstruction, and CAT scores in COPD patients.•There was no significant correlation between serum CX3CL1 and DLCO in stable COPD patients. To investigate the concentration of CX3CL1 in serum of patients with chronic obstructive pulmonary disease (COPD), and to evaluate the associations between the CX3CL1 level and systemic inflammation, small airway obstruction, and COPD assessment test (CAT) scores in COPD patients. Enzyme-linked immunosorbent assay were utilized to detect the CX3CL1 protein in serum separately from 64 patients with COPD and 53 healthy controls. Compared with healthy non-smokers, healthy smokers and COPD non-smokers, serum CX3CL1 protein levels were significantly elevated in COPD smokers (258.33 ± 56.27 pg/mL versus 177.32 ± 43.21 pg/mL, 185.64 ± 47.03 pg/mL, and 226.55 ± 51.79 pg/mL, P