GCH1 and chronic obstructive pulmonary disease: Specifically, because neutrophils and macrophages are associated with mucin gene expression [9], we hypothesized that plasma proinflammatory chemokines which mobilize neutrophils and macrophages, particularly interleukin-8 (CXCL8), monocyte chemotactic proteins-1 and −3 (CCL2 and CCL7), macrophage derived chemokine (CCL22), and macrophage inflammatory proteins-1α and -1β (CCL3 and CCL4), would correlate with GCH in smokers and ex-smokers with and without COPD.