This is illustrated by the changes observed during COPD exacerbations whereby the numbers of sputum neutrophils and the levels of C-X-C motif chemokine ligand 8 (CXCL8), interleukin-17A (IL-17A), TNF-α, and IL-1β are increased compared to the stable state [52–54]. This evidence concerns the gene IL17A and chronic obstructive pulmonary disease.