MTOR and chronic obstructive pulmonary disease: For instance, the Bufei Yishen formula can regulate the Th17/Treg cell balance by activating the adenosine receptor 2a [41, 42], inhibit the mTOR signaling pathway to suppress macrophage M2 polarization and improve airway remodeling in COPD rats [43], inhibit the MAPK signaling pathway to reduce macrophage inflammatory responses [44], activate Nrf2 to suppress oxidative stress and ameliorate COPD-induced airway epithelial cell aging [45], and inhibit the EGFR signaling pathway to protect the airway epithelial cell barrier [46].