Adipocyte-Derived Leptolin Enhances Energy Expenditure and Prevents Obesity

Adipokines are key factors in regulating energy homeostasis. We identified a novel adipokine, which we named leptolin. In humans, leptolin levels in white adipose tissue were positively correlated with exercise and negatively associated with body mass index. Leptolin levels were positively correlated with lipolysis-promoting gene expression. We observed elevated leptolin in serum from athletes and lower leptolin in serum from obese individuals. Leptolin gene-knockout mice exhibited increased adiposity and body weight, and decreased energy expenditure. Transgenic leptolin overexpressing in mice showed obesity-resistant phenotypes. Treatment with leptolin promoted fat mobilization, increased energy expenditure, and reduced body weight, without affecting food-intake or motor activity. Leptolin is a novel adipokine with a capacity to improve metabolic status and may serve as a new therapeutic agent for obesity and metabolic disorders.