AKT1 and cholesteryl ester measurement: In conclusion, we find 16 potential signaling pathways related to the pathogenesis of AECOPD, including PI3K/Akt signaling pathway, MAPK signaling pathway, and ECM- receptor interaction, et al. Remarkable, we demonstrated, for the first time, that the WNT/β-catenin signaling pathway is decreased in patients with AECOPD and CE mouse model.