CXCL12 and chronic obstructive pulmonary disease: In particular, we systematically reviewed chemokines modifications associated with COPD (Table 1), and based on the number of preclinical and clinical evidences as well as recent findings, we focus on the CXCL8-CXCR1/2, CXCL9/10/11-CXCR3, CCL2-CCR2, and CXCL12/CXCR4 axes that seem to be clearly associated with COPD pathophysiology.