Stimulating 'beige' fat might help treat obesity

A new study in mice may help identify new methods to treat obesity and metabolic disorders in the future.
The study revealed the mechanism through which cytokines — immune cell signaling molecules — promote the production of beige fat, thus reducing obesity and other metabolic disorders.
Administering the cytokine interleukin-25 to mice on a high-fat diet prevented them from developing obesity and improved their responsiveness to insulin.

Obesity is a major risk factor for various metabolic disorders and cardiovascular diseases.

According to the World Health Organization (WHO), today, most of the world’s population lives in countries where obesity kills more people than malnutrition.

The prevalence of obesity has significantly increased in adults in the past few decades. As such, researchers are engaged in finding new ways to understand and potentially treat obesity.

A new study, which appears in the open-access journal PLOS Biology found that high levels of a cytokine — interleukin-25 — promotes the production of beige fat cells.

The study’s results might help find new ways to treat obesity and other metabolic disorders.

Significance of beige fat in humans

Not all fat stored in the body is harmful to health. Typically, there are two types of fat tissue: brown and white.

Brown fat helps turn food into heat, whereas white fat is responsible for storing calories; thus, an excess of white fat contributes to obesity.

However, scientists have discovered another type of fat cell in human adults, known as beige fat. Typically, these cells burn energy in a similar way to brown fat rather than storing it like white fat.

How do beige cells burn energy?

Beige fat cells, or adipocytes, are present in white adipose tissue. They can perform functions similar to both white and brown adipocytes. Generally, they act like white cells by storing energy.

However, when exposed to cold temperatures, they behave like brown cells and dissipate energy by creating heat.

Interleukin-25

In this recent study, the researchers fed mice with a high fat diet. They found that when they administered the cytokine interleukin-25, the animals gained less weight and demonstrated improved glucose metabolism and insulin sensitivity.

The researchers also showed that exposure to a cold environment was associated with increased levels of interleukin-25 signaling.

Zhonghan Yang, one of the study’s authors, told Medical News Today, “Our findings demonstrated that IL-25 induced beige fat via macrophage, improved homeostasis, and decreased glucose disposal and insulin resistance.”

The author further explored the pathway and found that IL-25 induced beige fat formation by releasing IL-3 and IL-4 and promoting the activation of macrophages. Those macrophages boosted the release of the neurotransmitter norepinephrine, which instructs beige cells to burn energy.

Implications and the future

Although the researchers conducted the study in mice, Yang told MNT that, “considering the conserved nature of IL-4 and sympathetic nerves between humans and mice, our study is likely to be generalizable to humans.”

On asking about the potential implications of the study, Dr. Mir B. Ali, a general and bariatric surgeon at Memorial Care Center for Obesity at Orange Coast Medical Center in Fountain Valley, CA, who was not involved in the study, told MNT:

“The potential clinical implication of this study is that we can stimulate the body to increase production of beige fat, which in turn would burn more calories.”

“One way that beige fat is increased is by the application of cold to the body, especially around the neck and shoulders,” explained Dr. Ali. “This is very uncomfortable for most people. Potentially a medication that causes cytokine release could be an easier way to accomplish this.”

However, Dr. Ali remains cautious about the near-term implications, adding: “Although these very early results seem promising, I do not see them replacing current methods for weight loss in the near future. A great deal more investigation is needed to prove its efficacy before we can potentially see this therapy applied to humans.”

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