Fig. 1

Morphology and function of mitochondria of non-smokers (n = 10), smokers (n = 8) and COPD patients (n = 15). Representative ultrastructure of mitochondrial morphology in the alveolar type II (ATII) cell of non-smoker, smoker and COPD patient is obtained by Transmission electron microscopy (TEM) (A). Red arrows indicate elongated mitochondria, yellow arrows indicate abnormal mitochondria (mitochondria with impaired membrane and cristae arrangements) and green arrows indicate autophagosomes. The scale bar is 1 μm. Quantification of mitochondrial morphology including area (B), length (C), perimeter (D), circularity index (E), number of mitochondria per cell (F), percentage of abnormal mitochondria (G) and number of autophagosomes (H) is conducted by Image J analysis. The mitochondrial respiratory chain (MRC) complexes I (I), III (J) and V (K) activities are assessed using an activity assay kit, and data are presented as the percentage changes compared to non-smokers. Data are presented as individual and mean values. ^*p < 0.05, ^**p < 0.01, ^***p < 0.001