PTGS1 and chronic obstructive pulmonary disease: In this pathway, we observed up-regulation of the metabolites (20-HETE, 5-HETE, LTA4, 20-OH-LTB4, LXA4 and PGE2) and metabolic enzymes (LTA4H (leukotriene A4 hydrolase), PTGS2 (prostaglandin-endoperoxide synthase 2)) in COPD rats and down-regulation of the metabolites (5-HETE, LTA4, LTB4, and LXA4) and metabolic enzymes (PTGS1/2/3) involved in APL-treated rats.