The regulation of glucose and lipid homeostasis via PLTP as a mediator of BAT-liver communication.

While brown adipose tissue (BAT) is well-recognized for its ability to dissipate energy in the form of heat, recent studies suggest multifaced roles ofBATin the regulation of glucose and lipid homeostasis beyond stimulating thermogenesis. One of the functions involves interorgan communication with metabolic organs, such as the liver, throughBAT-derived secretory factors, a.k.a., batokine. However, the identity and the roles of such mediators remain insufficiently understood. Here, we employed proteomics and transcriptomics in human thermogenic adipocytes and identified previously unappreciated batokines, including phospholipid transfer protein (PLTP). We found that increased circulating levels ofPLTP, via systemic orBAT-specific overexpression, significantly improve glucose tolerance and insulin sensitivity, increased energy expenditure, and decrease the circulating levels of cholesterol, phospholipids, and sphingolipids. Such changes were accompanied by increased bile acids in the circulation, which in turn enhances glucose uptake and thermogenesis inBAT. Our data suggest thatPLTPis a batokine that contributes to the regulation of systemic glucose and lipid homeostasis as a mediator ofBAT-liver interorgan communication.