One of the more promising avenues in recent obesity research has been the investigation into the remarkable energy-burning characteristics of a specific type of fat, called brown fat. A new study from researchers at the University of Cambridge has excitingly discovered a blood-based molecule that can both increase the amount of brown fat in the body and activate its calorie-burning processes.
Most of the fat in our bodies is known as white fat, which forms our internal caloric storage system. However, we also hold a second kind of adipose tissue, referred to as brown fat. This type of fat is rich in mitochondria and holds a great deal more blood vessels than regular white fat, allowing it to burn energy at an incredibly high rate.
Brown fat is important in regulating body temperature and is designed to jump into action when an animal gets cold, hence its prominence in hibernating animals. In humans brown fat is found abundantly in babies but until recently it was thought to disappear in older adults as white fat takes over with aging.
Breakthrough research in 2009 revealed brown fat to not only be present in adult humans, but also still active. This discovery supercharged obesity research into hunting for ways to turn white fat brown, and while several impressive studies have found techniques that can trigger the conversion, this may be only half of the problem. It is one thing to simply increase the volume of brown fat in a body, but it is a completely different challenge to find ways to activate calorie burning in that fat.
"There have been a lot of studies that have found molecules that promote brown fat development, but simply increasing the amount of brown fat will not work to treat disease – it has to be able to get enough nutrients and be turned on," explains lead author on the new study, Toni Vidal-Puig.
Vidal-Puig and the University of Cambridge team have been working on ways to activate brown fat for several years. In 2012 the researchers revealed the discovery of a molecule called BMP8b. Mouse studies showed this molecule effectively triggering brown fat's energy-burning mechanisms, and when the gene for BMP8b was deleted from the animals the brown fat essentially ceased functioning.
The new research set out to investigate what effect increasing levels of BMP8b would have on the volume and activity of brown fat in mice. The impressive results revealed that upping the levels of BMP8b actually made white fat browner, a process occasionally referred to as beiging. Perhaps even more importantly though was the discovery that increasing BPM8b resulted in a larger volume of blood vessels and nerve activity in white fat. This suggests the molecule is effective at not only converting white fat to brown, but also helping establish the environment the cells need to effectively burn energy.
Sam Virtue, co-author on the new study, uses an automotive analogy to explain how important this molecule may be to solving the brown fat/white fat problem.
"It's like taking a one liter engine out of a car and sticking in a two liter engine in its place," saysVirtue. "In theory the car can go quicker, but if you only have a tiny fuel pipe to the engine and don't connect the accelerator pedal it won't do much good. BMP8b increases the engine size, and fits a new fuel line and connects up the accelerator!"
At this stage the technique has only been effectively demonstrated in mice, so much more work needs to be done before any kind of anti-obesity treatment is delivered. But, the hypothesis is promising, as BMP8b is found in the blood of humans, suggesting it could be manipulated to stimulate brown fat activity. The next step for the research is to begin investigating BMP8b in humans.
The new study was published in the journal Nature Communications.
Source: University of Cambridge
