CXCL8 and chronic obstructive pulmonary disease: In the COPDGene cohort, there was a significant association with 5-year decline in FEV1 and IL-6 in subjects who did not have COPD or emphysema and significant association with 5-year decline in FEV1 and IL-8 in subjects who had chronic bronchitis, but no emphysema (Additional file 3).