The PI3K/AKT/mTOR pathway regulates autophagy to induce apoptosis of alveolar epithelial cells in chronic obstructive pulmonary disease caused by PM2.5 particulate matter

Objective: Many lung diseases are associated with changes in autophagic activity. The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway plays a key regulatory role in autophagy. Our aim was to explore the function of PI3K/AKT/mTOR pathway on autophagy in chronic obstructive pulmonary disease (COPD) caused by particulate matter with a diameter <2.5 µm (PM2.5).

Methods: Male C57BL/6 mice were randomly divided into sham, model, and PI3K inhibitor groups. Mice were exposed to PM2.5 for 4 weeks to establish an in vivo COPD model. Alveolar epithelial cells were stimulated with PM2.5 to establish an in vitro COPD model.

Results: In mice with COPD induced by PM2.5, the PI3K inhibitor PF-04979064 suppressed protein expression of PI3K, p-AKT, and p-mTOR to increase apoptosis of alveolar epithelial cells and reduce autophagy. Short interfering PI3K suppressed the PI3K/AKT/mTOR pathway to induce apoptosis and reduce autophagy of alveolar epithelial cells in an in vitro model of COPD. Activation of PI3K induced the PI3K/AKT/mTOR pathway to reduce apoptosis of alveolar epithelial cells in the in vitro model of COPD by promoting autophagy.

Conclusions: These data demonstrate that PI3K/AKT/mTOR pathway regulates autophagy to induce apoptosis of alveolar epithelial cells in COPD.