The role of Interleukin 15 in protein degradation in skeletal muscles in rats of chronic obstructive pulmonary disease.
OBJECTIVE
The present study aimed to investigate the role of Interleukin 15 (IL-15) in protein degradation in skeletal muscle mediated by the ubiquitin-proteasome pathway (UPP) in a rat model of chronic obstructive pulmonary disease (COPD).


METHODS
The COPD model was established in 30 Sprague Dawley (SD) rats through the combination of passive smoking and intratracheal injection of lipopolysaccharide (LPS). The pathological changes in lungs and bronchi of COPD rats (n=30) were compared with that of control rats (n=15). The levels of IL-15 and tumor necrosis factor-α (TNF- α) in the serum, diaphragm, gastrocnemius, and the intercostal muscles were measured using enzyme-linked immunosorbent assay (ELISA), and compared between the COPD and control rats. In addition, the expression of E2-14K, MAFbx, and ubiquitin (Ub) was evaluated using quantitative real-time PCR and western blot and compared between the COPD and control rats.


RESULTS
The levels of IL-15 and TNF-α in the serum, diaphragm, gastrocnemius, and the intercostal muscles in COPD rats were significantly higher than that in control rats. The expression of E2-14K, MAFbx, and ubiquitin (Ub) in the diaphragm, gastrocnemius, and the intercostal muscles in COPD rats was also significantly higher than that in the control rats. In addition, we identified positive correlation between the levels of IL-15 and TNF-α. Positive correlation was also identified between the levels of IL-15 and E2-14K, MAFbx, and Ub.


CONCLUSIONS
Our results suggest that IL-15 inhibited the protein degradation in skeletal muscle in COPD rats, which may be mediated by the TNF-α and UPP pathway.
Department of Geriatrics, Guangzhou First People's Hospital, Guangzhou Medical University Guangzhou 510180, China.
Zhaohui
Z
Liu
Department of Geriatrics, Guangzhou First People's Hospital, Guangzhou Medical University Guangzhou 510180, China.
Wei
W
Fan
Department of Geriatrics, Guangzhou First People's Hospital, Guangzhou Medical University Guangzhou 510180, China.
Jinlong
J
Chen
Department of Geriatrics, Guangzhou First People's Hospital, Guangzhou Medical University Guangzhou 510180, China.
Zhike
Z
Liang
Department of Geriatrics, Guangzhou First People's Hospital, Guangzhou Medical University Guangzhou 510180, China.
Lijun
L
Guan
Chronic obstructive pulmonary disease; IL-15; tumor necrosis factor-α; ubiquitin-proteasome pathway