Study identifies blood protein molecule that may hold obesity-battling potential

29 Nov 2018 --- A new study published in Nature Communications suggests that a protein molecule found in blood, BMP8b, can help treat obesity. Increased levels of BMP8b may promote the functions of “brown” fat which is the kind of fat the body burns for energy. The study was carried out in mice but researchers are hopeful it could be applied in humans too, perhaps with a drug that increases the levels of BMP8b, in turn, treating obesity more effectively.

A team of researchers led by Professor Toni Vidal-Puig of the Wellcome Trust-MRC Institute of Metabolic Science, University of Cambridge, first identified BMP8b in a 2012 study, as a molecule that regulates the activation of brown fat in brain and body tissues. 

They discovered that deleting the gene that produces this protein in mice stopped brown fat from functioning.

The new study, led once more by Professor Vidal-Puig, shows that increasing how much BMP8b mice can produce increases the function of brown fat. Meaning that it could potentially be used to create a new drug that will help increase brown fat in humans too. More research is warranted though on the matter.

“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,” says Professor Vidal-Puig.

The are two types of fat in the body: white and brown. White fat stores calories while brown fat burns energy and promotes weight loss. Obese individuals accumulate fat until it stops functioning and this leads to numerous fat-related conditions, such as diabetes. By increasing the amount of brown fat, therefore, obesity may be treated more effectively.

Fat is made up of cells called adipocytes. In brown fat, adipocytes are rich in mitochondria which give tissue a brown hue. Everyone has some amount of brown fat but newborns and hibernating animals have it in abundance. Yet just having brown fat doesn’t mean much for weight loss unless it is activated. The only known ways to activate it so far, are putting people in the cold to mimic hibernation or drug treatments. However, both methods are unpleasant and hold health risks. 

Using mice bred to produce higher levels of BMP8b in adipose tissue, the researchers found that increasing the protein molecule’s levels converted some white fat into brown and increased in this way the amount of energy burned by the tissue. Additionally, the molecule increased the number of blood vessels and nerves in brown fat.

They also observed that higher levels of BMP8b make tissue more responsive to adrenergic signals, the same pathway target by adrenergic agonist drugs.

Thermogenesis, the process of burning brown fat, may burn up to 3,400 calories per day, which is extremely higher than the daily caloric intake of most people and enough to promote weight loss. 

Co-author Dr. Sam Virtue, from the Institute of Metabolic Science, says: “It's like taking a one-liter engine out of a car and sticking in a two-liter engine in its place. 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.”