Proteasome activity related with the daily physical activity of COPD patients

Abstract

Background

COPD is a debilitating disease that affects patients’ daily lives. One’s daily physical activity (DPA) decreases due to multifactorial causes, and this decrease is correlated with a poor prognosis in COPD patients. Muscle wasting may at least be partly due to increased activity of the ubiquitin proteasome pathway and apoptosis.

Methods

This study investigated the relationships among DPA, circulating proteasome activity, and protein carbonyl in COPD patients and healthy subjects (HSs). This study included 57 participants (42 patients and 15 healthy subjects). Ambulatory DPA was measured using actigraphy, and oxygen saturation was measured with a pulse oximeter.

Results

COPD patients had lower DPA, lower 6 min walking distance (6MWD), lower delta saturation pulse oxygenation (SpO₂) during the 6MWT, and lower delta SpO₂ during DPA than HSs. COPD patients had higher proteasome activity and protein carbonyl than HSs. Circulating proteasome activity was significantly negatively correlated with DPA (r=−0.568, P<0.05) in COPD patients, whereas delta SpO₂ during the 6MWT was significantly positively correlated with proteasome activity (r=0.685, P<0.05) in HSs. Protein carbonyl was significantly negatively correlated with the body mass index (r=−0.318, P<0.05), mid-arm circumference (r=0.350, P<0.05), calf circumference (r=0.322, P<0.05), forced expiratory volume in the first second (r=-0.441, P<0.01), and 6MWD (r=−0.313, P<0.05) in COPD patients. Our results showed no significant difference in inflammatory markers (interleukin-6 and tumor necrosis factor-α) or ubiquitin between the two groups.

Conclusion

COPD patients had lower DPA levels and higher circulating proteasome activity than HSs, and a negative correlation of DPA with circulating proteasome activity.

Keywords:

• chronic obstructive pulmonary disease
• circulating proteasome
• daily physical activity
• protein carbonyl
• anthropometric indicator

Acknowledgments

The authors wish to thank the patients and personnel of the hospital unit for their cooperation during the course of this study. The authors wish to thank Ms Yi-Syuan Lin and Mr Lu-Wei Kuo for their technical assistance with this research.

The study was supported by grants from the Taipei Medical University (TMU102-AE1-B45, TMU103-AE1-B31) and Taipei Medical University-Shuang Ho Hospital (103TMU-SHH-01–4, 103TMU-SHH-01–2, and 104TMU-SHH-24).

Author contributions

Kang-Yun Lee and Tzu-Tao Chen conceived the idea, designed, carried out the study, and performed the statistical analysis. Ling-Ling Chiang, Hsiao-Chi Chuang, Po-Hao Feng, Wen-Te Liu, and Kuan-Yuan Chen assisted in subject recruiting and helped to carry out the study. Shu-Chuan Ho directed the statistical analysis, data interpretation, and was the main writer of the manuscript. All authors contributed toward data analysis, drafting and revising the paper and agree to be accountable for all aspects of the work. All authors have read and approved the final version of the manuscript for publication.

Disclosure

The authors report no conflicts of interest in this work.