A new study in mice has revealed the mechanism through which cytokines – immune cell signalling molecules – promote production of beige fat, hence reducing obesity and other metabolic disorders.
The Chinese study, published in the journal PLOS Biology, found high levels of the cytokine interleukin-25 – following its administration to mice on a high-fat diet – promoted production of beige fat cells and prevented the mice developing obesity while improving their responsiveness to insulin.
There are two main types of fat tissue in humans: brown (which helps turn food into heat) and white (responsible for storing calories); thus an excess of white fat contributes to obesity.
But a third fat type in human adults is known as beige fat; these cells, while present in white adipose tissue, when exposed to cold temperatures can dissipate energy by creating heat in a similar way to brown fat (rather than storing it like white fat).
Chinese study co-author Zhonghan Yang told medicalnewstoday.com: “Our findings demonstrated IL-25 induced beige fat via macrophage, improved homeostasis and decreased glucose disposal and insulin resistance.”
He also noted IL-25 induced beige fat formation by releasing IL-3 and IL-4 and promoting activation of macrophages, which “boosted the release of the neurotransmitter norepinephrine, which instructs beige cells to burn energy”.
He concluded: “Considering the conserved nature of IL-4 and sympathetic nerves between humans and mise, our study is likely to be generalised to humans”.
Asked about potential implications of the study, California surgeon Dr Mir Ali told medicalnewstoday.com: “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.”
