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

Abstract

Objective: 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.

Methods: Enzyme-linked immunosorbent assay were utilized to detect the CX3CL1 protein in serum separately from 64 patients with COPD and 53 healthy controls.

Results: 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 < 0.05). Correlation analysis indicated that serum CX3CL1 in COPD smokers was negatively correlated with FEV₁/FVC (justified r = -0.319, P < 0.001), FEV₁/Pre (justified r = -0.476, P < 0.001), FEV₃/FVC (justified r = -0.354, P < 0.001), MMEF25-75/Pre (justified r = -0.428, P < 0.001), but positively correlated with CRP (justified r = 0.331, P < 0.001) and MMP-12 (justified r = 0.352, P < 0.001). However, our results showed no significant correlation between serum CX3CL1 of COPD smokers and the diffusing capacity of the lung for carbon monoxide (DLCO) (justified r = 0.0397, P = 0.6025), but a positive correlation with COPD assessment test (CAT) scores (justified r = 0.367, P < 0.001). Finally, through multivariate linear analysis, statistical results demonstrated age (β = -0.2694, P = 0.005), FEV₁/Pred (β = -0.2653, P = 0.003), CRP (β = 0.1427, P = 0.0478) and MMP-12 (β = 0.430, P < 0.001) are independent parameters associated with CX3CL1.

Conclusion: The results demonstrated that elevated circulating CX3CL1 level is associated with the systemic inflammation, small airway obstruction, and CAT scores in COPD patients, suggesting that CX3CL1 may play crucial roles in the pathogenesis of COPD. Blocking CX3CL1 might prevent the progression of chronic obstructive pulmonary disease.

Keywords: COPD assessment test (CAT); CX3CL1; Chronic obstructive pulmonary disease (COPD); Small airway obstruction; Systemic inflammation.