Skeletal muscle inflammation and nitric oxide in patients with COPD

In chronic obstructive pulmonary disease (COPD) the presence of systemic inflammation has been associated with peripheral muscle abnormalities and weight loss. To study whether inflammatory factors are important in these processes, the present study compared the skeletal muscle levels of nitrite, nitrate, nitrotyrosine, neuronal, endothelial and inducible nitric oxide synthases (nNOS, eNOS, and NOS, respectively), and inflammatory markers (tumour necrosis factor (TNF)-alpha, CD154 and CD163) in 15 patients (forced expiratory volume in one second 43 +/- 11 %) and 14 controls. All these markers were also compared between patients with normal and low body weight. Nitrite (12.5 +/- 2.6 versus 17.0 +/- 3.4 mu mol center dot mg(-1) protein), nitrate (20.7 +/- 2.4 versus 24.4 +/- 4.5 mu mol center dot mg(-1) protein) and eNOS (31.9 +/- 4.6 versus 43.6 +/- 7.5 ng center dot mg(-1) protein) were lower in COPD patients than in controls. Nitrotyrosine (25.6 +/- 5.4 versus 6.6 +/- 3.3 ng center dot mg(-1) protein), iNOS expression (32 +/- 9.5 versus 7.16 +/- 2.7 ng center dot mg(-1) protein), TNF-alpha (257 +/- 160 versus 48.3 +/- 4.4 pg center dot mg(-1) protein) and CD163 (6.4 +/- 2.1 versus 0.8 +/- 0.4 ng center dot mg(-1) protein) were higher in COPD patients than in controls. CD154 levels were 15.7 +/- 7.0 ng center dot mg(-1) protein in COPD patients and undetectable in controls. Similar levels of all these markers were observed in COPD patients with normal and low body weight. In conclusion, these findings suggest the presence of an inflammatory process in the muscle tissue of chronic obstructive pulmonary disease patients, and argue in favour of its participation in the pathogenesis of skeletal muscle abnormalities.