Under conditions of stress, cells that normally fight infections protect fat from degradation – a mechanism that we could “hack”.
The extra pounds that refuse to go away could have an unsuspected ally in the immune system. Cells that protect us from infections – neutrophils – are activated to prevent excessive degradation of fat tissue when the body is subjected to physiological stressors, such as low temperatures. The mechanism, which in the distant past allowed our ancestors to conserve precious energy, could be exploited to fight metabolic diseases and promote weight loss. The discovery was described on Nature.
A precious deposit
White adipose tissue is a reserve of fat that the body can draw on when the energy required for vital functions exceeds that provided by food: for example, during periods of fasting, or in cases of extreme cold or intense physical exercise. Since excessive fat loss can harm the body, these fat cells are managed with great caution, but until now it was not clear what mechanism regulates their degradation.
The role of neutrophils
To see more clearly, researchers at the University of California at San Diego re-examined mouse models and human genetic data to conclude that, in mice, the activation of the sympathetic nervous system (which prepares the body to respond to stressful or emergency situations) stimulates the influx of neutrophilic white blood cells towards visceral fat cells, the type of white fat that accumulates around internal organs.
There are two signals that recruit neutrophils and push them to rush to the site: the degradation of visceral fat in progress, and the activation of specific inflammatory pathways by adipose cells.
We need this: let’s save it!
Once there, neutrophils produce signals to avoid further loss of fat cells in surrounding tissues: in mice with a deficiency of these cells, the body burns more fat when subjected to metabolic stress. In people with obesity, the genes involved in the fat storage mechanisms described are more active.
For the study authors, targeting this form of protection could suggest new ways to combat obesity and other metabolic problems, such as conditions that result in excessive and unwanted weight loss.
