Pro-inflammatory enzymes 5-lipoxygenase (5-LO), leukotriene A4 hydrolase (LTA4H), dipeptidyl peptidase 4 (DPP4), and cyclooxygenase-2 (COX-2), and anti-inflammatory enzymes poly(ADP-ribose) polymerase-1 (PARP-1) and histone deacetylase 2 (HDAC2), are connected to COPD and underlying systemic inflammation [2,5,6,7]. This evidence concerns the gene DPP4 and chronic obstructive pulmonary disease.