Elevated plasma cytochrome c levels in patients with chronic obstructive pulmonary disease

Apoptosis and inflammation are involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). Mitochondrial damage-associated molecular patterns (DAMPs) are released during cell apoptosis and cause inflammation. Cytochrome c (CYC) is an important mitochondrial DAMP and participates in the process of apoptosis, but the relationship between circulating CYC levels and COPD remains unclear. 54 COPD patients and 36 healthy controls were included in the present study. Basic characteristics along with plasma CYC and systemic inflammatory factors were collected and analysed in all subjects. In addition, the COPD patients were required to complete the COPD assessment test (CAT). CYC was detected in 40.74% of COPD patients but was undetectable in 30 (83.3%) of 36 healthy individuals. The levels of CYC were higher in COPD compared with controls, and associated inversely with FEV1% predicted (r = -0.321, P = 0.018) and FEV1/FVC (r = -0.353, P = 0.009). A positive correlation was found between levels of CYC and CAT score (r = 0.463, P = 0.000). However, no correlations were found between CYC levels and inflammatory biomarkers, pack-years or body mass index (BMI). Our study showed that plasma levels of CYC were elevated in COPD patients and correlated with lung function and CAT score, suggesting that CYC may play a role in COPD.