CXCL8 and chronic obstructive pulmonary disease: We selected the following biomarkers: CRP, TNF-α, IL-6, IL-8, alpha-1 antitrypsin (A1AT), fibrinogen, albumin and nitrites/nitrates (NOx), because they have been more widely studied in COPD and they have shown some relationship with either its prognosis and/or the development of cardiovascular complications.