This mysterious type of fat cell may play an important role in heart health, new research suggests
By Jackie Flynn Mogensen edited by Claire Cameron
A mouse aorta with immunofluorescent labeling. In a new study in mice, beige fat is associated with lower blood pressure.
Weslie R. and William H. Janeway Rockefeller University Molecular Metabolism Laboratory
When we think of fat, we most often think of white fat cells, which store excess calories like batteries, insulating and cushioning our muscles, bones and organs. But not all fat is white: Mammals also have brown fat – so named for its rusty color, thanks to a high concentration of iron-rich mitochondria – which does the opposite, burning energy to keep the body warm. And then there’s the beige grease.
First proposed in 2008, beige fat is located in white adipose tissue, but it functions like brown fat, burning energy efficiently when exposed to cold temperatures. In recent years, growing evidence suggests that beige fat may play an important role in heart health.
“There is enough data to say that beige fat is good for human health,” says Bruce Spiegelman, a researcher at the Dana-Farber Cancer Institute and professor of cell biology and medicine at Harvard Medical School, who proposed the existence of beige fat and was first to isolate beige fat cells in 2012. “For me, it’s now established science.”
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A new study published in Science Thursday adds to this evidence: he shows that beige fat helps lower blood pressure in mice. High blood pressure is a risk factor for heart disease and stroke. The study, led by researchers at Rockefeller University, builds on previous work in humans showing a correlation between brown fat and lower blood pressure.
In humans, brown fat is more prevalent in infants and primarily located in the reserves between our shoulder blades. Scientists believe that this fat, like in other mammals, is intended to keep us warm in cold weather. But as we age, most of that brown fat disappears. What researchers call beige fat, on the other hand, is found above our diaphragm, along our neck, and in our upper spine. Like brown fat, it burns energy to release heat when exposed to cold.
In 2021, Paul Cohen, an associate professor at Rockefeller University who studies obesity, published an article showing that people with more brown fat were less likely to have type 2 diabetes, coronary heart disease and high blood pressure. That sparked new questions, Cohen says.
“Is this link between brown fat and hypertension [high blood pressure] just an association? says Cohen, who is also author of the new Science paper. “Or is there a causal relationship? »
Cohen and his colleagues found that mice raised without beige fat had higher blood pressure than mice with this type of fat, evidence of a causal relationship.
“If we simply change the identity of the adipose tissue, we see that the blood pressure of these mice increases,” says Mascha Koenen, a postdoctoral researcher in Cohen’s lab and co-author of the new study.
The team also found that eliminating beige fat influenced the production of an enzyme called QSOX1, which can change blood vessels and increase blood pressure.
This finding is particularly interesting, says Biao Wang, an associate professor at the University of California, San Francisco, who studies the development of adipose tissue. By identifying a mechanism by which beige adipose cells can regulate blood pressure, it opens the door to further studies in humans.
And, Wang says, that raises a new question: “What else can beige fat secrete?” »
Cohen and his colleagues hope the new study will help elucidate how beige and brown fats affect human health. “Hopefully, this type of work will lead to new and more personalized therapies based on a patient’s specific characteristics, which may be better suited to blood pressure control,” Cohen says. Obesity is also correlated with lower levels of brown fat and higher levels of white fat, says Spiegelman, but more research is needed to fully understand why.
As for how to increase levels of beige and brown fat, researchers aren’t entirely sure, but they have a few theories. In rodents, at least, factors such as a healthy diet, exercise and exposure to cold can help “get things moving,” says Spiegelman.
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