In particular, Liu et al. reported that the IL-15 expression was increased in the diaphragm, intercostal muscles, and gastrocnemius muscles of COPD rats; moreover, the mRNA and protein levels of ubiquitin-conjugating enzyme E2 (14k), MAFbx, and Ub were significantly higher in the treatment group than in the control group. This evidence concerns the gene IL15 and chronic obstructive pulmonary disease.