Macrophages (Immune Cells) Burn Fat
December 19, 2011 by UPI - United Press International, Inc.
SAN FRANCISCO, Dec. 18 (UPI) — In response to cold, tiny immune cells known as macrophages can switch on the brown fat, inducing it to burn energy to make heat, U.S. researchers say.
Dr. Ajay Chawla, an associate professor at University of California, San Francisco’s Cardiovascular Research Institute, said prior to this research, scientists assumed brown fat metabolism was completely controlled by the brain.
However, the study, published in the journal Nature, suggests the immune system plays a backup role in this process — a legacy, perhaps, of some ancient ancestral creature whose metabolic and immune systems were much more intertwined.
“This is a very important secondary system that the body uses to provide a backup for the thermal stress response,” Chawla, the study leader, said in a statement. “It raises the possibility that we can perhaps modulate this program and enhance it in humans to rev up metabolism.”
The modern human immune system relies on these macrophages to gobble up bacteria, helping to protect people against infection, but macrophages were never known to play a role in metabolism, Chawla said.
The brain monitors the body’s temperature and, in face of extreme cold, releases the hormone norepinephrine, which kick-starts the brown fat, but the research team showed that macrophage cells within the brown fat can also do this directly, Chawla explained.