Unexplained weight loss, which commonly occurs in patients with chronic obstructive pulmonary disease(COPD), is important because weight loss is an independent risk factor of mortality and morbidity in these patients. Leptin is known to play an important role in regulating body weight. In addition, the tumor necrosis factor(TNF-α) might also play a potential role in the weight loss experienced in chronic wasting disease. The aim of this study was to determine the influence of plasma leptin and the circulating TNF-α system to the difference in the body compositions in patients with COPD.

Spirometry, body composition analysis and the plasma concentrations of leptin, TNF-α and a soluble TNF receptor 55, 75 were measured in 31 patients with chronic bronchitis and 10 patients with emphysema. The COPD subtype was classified by the transfer coefficient of carbon monoxide, DLco/VA.

The circulating levels of leptin were significantly lower in those patients with emphysema(108.5±39.37pg/ml) than those with chronic bronchitis(180.9±57.7pg/ml). The circulating levels of sTNF-R55 were significantly higher in the emphysema patients(920.4±116.4pg/ml) than in those with chronic bronchitis(803.2±80.8pg/ml). There was no relationship between the circulating leptin levels and the activated TNF system in patients with chronic bronchitis and emphysema. However, the circulating leptin levels correlated well with the BMI and fat mass in both patient groups.

These results suggest that the weight loss noted in emphysema patients may be associated with the activation of the TNF-α system rather than the plasma leptin level.