MAR 06, 2017 01:17 PM PST

"Guardian Angels" of the Immune System Hindered By Obesity

WRITTEN BY: Kara Marker

A specific type of immune cells take charge of defending fat tissue from microbes and maintaining homeostatic tissue remodeling, making sure there is just the right amount of pro-inflammatory macrophages, another type of immune cell. But for a person who is obese, these cells lose their ability to keep the immune system in check.

"Guardian" immune cell activity changes in response to eating habits.

"All people have fat, even if they are not obese,” explained study leader Lydia Lynch, Professor at Trinity College London and Harvard Medical School. “Fat is found around almost all tissues in our body, and all fat has its own immune system, which we are only recently learning about.”

In addition to storing energy via adipocytes, adipose tissue also acts as an endocrine organ, regulating metabolic homeostasis. The so-called “guardian” immune cells that regulate inflammatory macrophages are called adipose type one innate lymphoid cells (ILCs), and they live in fat cells in adipose tissue. These ILCs regulate the balance of macrophages in adipose tissue, eliminating them at certain times according to certain physiological conditions.

“They essentially guard against inflammation when macrophages are too numerous in fat,” Lynch explained. “This function is unique as immune cells are not generally supposed to kill other healthy immune cells in non-pathological conditions."

Natural killer cells, a type of ILC, “know” when not to kill healthy immune cells thanks to protein sequences on their cell surfaces that indicate their healthy “status.” However, cancer cells typically do not have these protein sequences, so natural killer cells destroy them. When they are unable to function due to obesity, ILCs fail to recognize the “I’m healthy” protein sequences.

ILCs function properly at first, but as obesity progresses the ILC population fades away and they stop killing macrophages to keep them in check. Then, an accumulation of pro-inflammatory macrophages leads to obesity-related inflammation.

"We know that macrophages enter fat at the onset of obesity and that they likely do a protective job cleaning up as much excess fat as they can,” Lynch said. “However, as obesity progresses, these macrophages get overwhelmed by the workload and turn inflammatory, which leads to more severe obesity and further complications like diabetes."

Lynch’s new study, published in Immunity, demonstrates the implications of metabolic changes in adipose tissue in response to diet changes. As scientists begin to understand more about how what we eat impacts our immune systems, the opportunity for new prevention and treatment plans for metabolic diseases like obesity grows.

Sources: Trinity College Dublin, The Journal of Immunology, The American Journal of Clinical Nutrition

About the Author
  • I am a scientific journalist and enthusiast, especially in the realm of biomedicine. I am passionate about conveying the truth in scientific phenomena and subsequently improving health and public awareness. Sometimes scientific research needs a translator to effectively communicate the scientific jargon present in significant findings. I plan to be that translating communicator, and I hope to decrease the spread of misrepresented scientific phenomena! Check out my science blog: ScienceKara.com.
You May Also Like
MAY 31, 2018
Immunology
MAY 31, 2018
Immunosuppressant Drugs to Prevent Parkinson's Disease
Certain immune activity could be increasing a person’s risk of developing Parkinson’s disease (PD), but immunosuppressant drugs might solve the...
JUL 18, 2018
Immunology
JUL 18, 2018
Immunotherapy Increases Survival of Melanoma Brain Metastases Patients
Use of Checkpoint Blockade Immunotherapy increases survival rates in Melanoma Brain Metastases patients, with a 4-year survival rate increase from 11.1% to 28.1%...
JUL 31, 2018
Immunology
JUL 31, 2018
The Immune Systems Molecular Alphabet
Lab-designed nucleic acid nanoparticles elicit varied and specific immune response from immune cells based on shape, size, and formulation of each particle....
AUG 02, 2018
Immunology
AUG 02, 2018
Chronic Infections Outsmart the Immune System
Chronic parasitic infection shown to take advantage of a mechanism to sustain infection and induce death of white blood cells essential to immune response....
AUG 22, 2018
Immunology
AUG 22, 2018
Immune Response Runs on the Body Clock
Immune cell functions such as inflammation are dictated by your bodies circadian rhythm, responding daily to external stimuli on a 24 hour schedule....
AUG 29, 2018
Immunology
AUG 29, 2018
Immune System Prioritizes Response when Faced with Multiple Threats
The Innate Immune response prioritizes lung infection and cell repair over other threats in both infants and adults....
Loading Comments...