Circulating levels of soluble Fas ligand in cachexic patients with COPD are higher than those in non-cachexic patients with COPD

OBJECTIVE: Apoptosis may be involved in the pathophysiology of cachexia in patients with chronic obstructive pulmonary disease (COPD). The purpose of this study is to assess the potential role of the Fas-Fas ligand (FasL) system in cachexic patients with COPD. PATIENTS AND METHODS: We measured the circulating levels of soluble FasL (sFasL), with a newly developed, highly sensitive enzyme-linked immunosorbent assay system in seventy patients with COPD and forty-seven control subjects. RESULTS: The levels of sFasL in the COPD patients were significantly lower than those in the control subjects (46+/-29 vs. 55+/-28 pg/ml; p<0.05), whereas the levels of soluble Fas (sFas) remained unchanged between the two groups. The significant correlation between the levels of sFasL and sFas, observed in the control subjects (r=0.304; p<0.05), was absent in the COPD patients. Cachexic COPD patients with a relatively lower BMI (BMI <20 kg/m(2), n=45) and %fat (%fat <20%, n=34), showed significantly increased levels of sFasL compared to non-cachexic COPD patients with a relatively higher BMI (BMI > or =20 kg/m(2), n=25) and %fat (%fat > or =20%, n=36) (BMI; 51+/-33 vs. 36+/-15 pg/ml; p<0.05. %fat; 55+/-33 vs. 37+/-21 pg/ml; p<0.01), due to the inverse relationships between the body composition measurements and the levels of sFasL observed exclusively in the patients (BMI; r=-0.307; p<0.05. %fat; r=-0.283; p<0.05). CONCLUSION: These results may suggest that the Fas-FasL system does not play a significant role in the potential triggers of enhanced apoptosis leading to skeletal muscle wasting and adipose tissue depletion in cachexic patients with COPD.