Fat cells residing underneath skin could help protect people against a wide range of infections, a new study from the University of California, San Diego School of Medicine reports.
Immune system responses appear to be partly influenced by the presence of fat cells under the surface of the skin.
Dermal fat cells, known as adipocytes, were thought to function in the body just for storing energy, but this new research shows they also play a vital role in fighting off infections. The cells were found to produce antimicrobial peptides, able to fight off bacteria and other invaders.
"It was thought that once the skin barrier was broken, it was entirely the responsibility of circulating (white) blood cells like neutrophils and macrophages to protect us from getting sepsis," Richard Gallo, professor and chief of dermatology at UC San Diego School of Medicine, said.
Once an infection enters a wound, it takes time for white blood cells and other immune system agents to mass in the affected region. During this delay, adipocytes protect the body from microbial invaders, by releasing highly-effective anti-microbial agents.
The human immune system is highly complex, relying on numerous types of cells to fight infections. Among the tools used by the human body to stay healthy are neutrophils and monocytes, which attack and consume microbial invaders. Epithelial cells, which line organs, and mast cells, which play a role in allergies, are usually the first on the scene at the site when an infection enters the body.
Mice were infected with staphylococcus aureus, a bacteria which commonly causes skin and soft tissue infections in humans. Researchers found fat cells increased in both size and number at the site of the infection, within hours of exposure. Cathelicidin antimicrobial peptide (CAMP), a form of antimicrobial peptide (AMP), was produced by the dermal fat cells, partially protecting the mice from infection. When researchers studied mice who were unable to produce sufficient quantities of AMPs, particularly CAMP, they found the rodents were highly-susceptible to infectious disease.
Obese human subjects examined by researchers were found to have a greater concentration of CAMP in their bloodstream than those close to average weight.
"The key is that we now know this part of the immune response puzzle. It opens fantastic new options for study. For example, current drugs designed for use in diabetics might be beneficial to other people who need to boost this aspect of immunity," Gallo stated in a press release.
Further tests will be required before clinical development of new drugs based on this research can begin.
Investigation of the role of subcutaneous fat on the immune system was detailed in the journal Science.