LEP and chronic obstructive pulmonary disease: While clinical studies provide supporting evidence to the mouse-model observations indicating the critical role of leptin in ventilatory control (e.g. leptin is a predictor of lung function in various conditions, including asthma [60], heart failure [61] and is negatively correlated with lung volumes in COPD patients [62]) the pathophysiological significance of leptin regarding respiratory function in humans remains to be clarified.