MMP9 and chronic obstructive pulmonary disease: In the progression of COPD, the upregulation of PI3K and its downstream mediators, such as NF-κB and Matrix Metalloproteinase 9 (MMP-9), can excessively enhance the immune response and inhibit the function of proteins that exert antioxidant effects, such as Forkhead Box O (FOXO), and Sirtuin 1 (SIRT1), thereby inducing chronic inflammation (Yanagisawa et al., 2017; Moradi et al., 2021).