Study reveals new role for inflammatory protein in adipose tissue

A new study published in Natural communications shows that the inflammatory protein IL-1β has an important physiological function in adipose tissues. Researchers at Karolinska Institutet have discovered that IL-1β helps the body manage energy storage by signaling cells to transform into new fat cells that can store energy safely.

The study shows that IL-1β, which is generally associated with negative inflammatory effects, plays a previously unknown role in healthy energy storage.

“This could have implications for the development of new therapeutic treatments that take into account the physiological effects of inflammation,” explains Jurga Laurencikiene, associate professor at the Department of Medicine in Huddinge (MedH).

The study was carried out in collaboration with several other laboratories, including the group of Professor Marc Donath at the University of Basel, Switzerland. The researchers used different mouse models and human experimental systems to test their hypothesis, including in vivo genetic manipulations, where the IL-1 receptor (IL1R1) was removed specifically from fat cells or from all cells of the body. This allowed them to see how the absence of this receptor affected fat storage and metabolism in animals.

The researchers also grew fat cell precursors from mice and humans in the laboratory and exposed them to IL-1β. They studied how this molecule influenced the process of transforming these cells into fat cells, particularly during the early stages of their development. Gene expression analysis was used to understand which genes were activated when IL-1β was present, and they found that key genes involved in fat formation were activated.

Researchers have also studied how short bursts of IL-1β, such as those occurring after meals, promote healthy adipose tissue development, while long-term exposure to high levels of IL-1β, common in obesity, disrupts this process. They observed that higher levels of potentially active IL-1β in the adipose tissue of healthy individuals are linked to smaller fat cells, suggesting more efficient production of new fat cells and favorable metabolism.

Importance of results and future research

“Our results highlight the importance of acute physiological inflammation for maintaining metabolic health and it is important to develop more targeted anti-inflammatory treatments that do not interfere with this tissue remodeling function,” explains Kaisa Hofwimmer, postdoctoral researcher at the Department of Medicine, Huddinge.

The researchers plan to test whether IL-1β targets specific subtypes of fat cell precursors and what makes these cell types unique. They also want to continue mechanistic research to understand how chronic exposure to IL-1β at the cellular level fails to induce the formation of new fat cells, even though the cells retain their ability to respond to its inflammatory induction.

This study opens new perspectives on how inflammation can play a positive role in the body’s energy management and metabolism.