Dysfunction of the non-neuronal cholinergic system seems to be involved in the pathophysiology of COPD and to some extent in resistance to corticosteroid therapy; in fact, non-neuronal cholinergic system is over-expressed in corticosteroid-insensitive neutrophils from COPD patients, as evidenced by increases in the expression of muscarinic receptors (M2, M4 and M5), vesicular acetylcholine transporter (VAChT) and choline acetyltransferase (ChAT). This evidence concerns the gene SLC18A3 and chronic obstructive pulmonary disease.