A new, powerful player in lipoprotein metabolism: brown adipose tissue.

Important causes for modern epidemics such as obesity, diabetes, and cardiovascular disease are over- and malnutrition. Dietary as well as endogenous lipids are transported through the bloodstream in lipoproteins, and disturbances in lipoprotein metabolism are associated with atherosclerosis, heart disease, and diabetes. Recent findings reveal biological principles-how lipoproteins, in particular triglyceride-rich lipoproteins, are metabolized and what factors regulate their processing. The fate of triglycerides delivered by lipoproteins is quite simple: either they can be stored or they can be utilized for combustion or biosynthetic pathways. In the healthy state, fatty acids derived from triglycerides can be burned in the heart, muscle, and other organs for actual work load, or they can be stored in white adipose tissue. The combination of storage and combustion is realized in brown adipose tissue (BAT), a peripheral organ that was long thought to be only of relevance in small mammals: Recent data however prove that BAT plays an important role in human adults. Here, we will review recent insights on how BAT controls triglyceride clearance and the possible implications for the treatment of chronic diseases caused by lipid mishandling.