Dual role of autophagy/mitophagy in chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a common lung disease characterised by progressive, irreversible airflow limitation. Multiple regulatory pathways are involved in COPD pathogenesis. Emerging evidence from clinical and basic medical research has suggested that autophagy-a highly conserved catabolic process mediated under various cellular stress conditions-plays a role in the development and prognosis of COPD. Nevertheless, precise function of autophagy remains debatable owing to its beneficial as well as detrimental consequences. In this review, we summarised the 'double-edged sword' functions of autophagy in COPD and aimed to distinguish and classify these functions on the basis of various factors, such as different airway cell types and autophagy stimulators and modulators. Moreover, we determined the biological-functional consequences of autophagy. In particular, we discussed mitophagy-also termed mitochondrial autophagy-which is a critical process in cellular energy homeostasis. We hope that our findings will shed new light on future therapeutic strategies for COPD.