Fight against fat deposits on the abdomen
Immune cells interfere with metabolism
Anna Kerman, XX2 century, based on Medical Xpress: Battling belly fat: Specialized immune cells impair metabolism in aging
In a new study, scientists from Yale University described how the nervous and immune systems interact with each other to control metabolism and inflammatory processes. The results of the work helped the researchers understand why the fat accumulated on the abdomen burns so slowly in older people. The latter circumstance negatively affects the risk of developing chronic diseases. Also, according to scientists, the study pointed to possible therapeutic approaches to solving this problem.
The work was conducted by Vishwa Deep Dixit, Professor of Comparative Medicine and immunobiology. The results are published September 27 in the journal Nature.
In older people, regardless of body weight, fat is deposited on the abdomen, which does not burn as efficiently as in young people. This leads to the accumulation of harmful fat. Until now, it was unknown for what reason this is happening.
In their study, Dixit and his colleagues from Yale University, a health science center in The University of Tennessee (University of Tennessee Health Science Center) and the University of Bonn (Rheinische Friedrich-Wilhelms-Universität Bonn) focused on specialized immune cells – macrophages involved in the immune response to infections. A new type of macrophages was discovered in the laboratory. These cells are located on nerves in the fatty deposits on the abdomen. With age, macrophages become inflamed and interfere with the proper functioning of neurotransmitters (substances that transmit impulses in the nervous system).
The researchers isolated immune cells from the adipose tissue of young and old mice, and then sequenced the genome to figure out what the cause is. "We found that mature macrophages destroy a group of neurotransmitters, catecholamines, so fat cells can no longer supply energy when needed," Dixit said.
The researchers found that after they lowered the content of the NLRP3 inflammasome (a receptor that controls the inflammatory process) in mature macrophages, catecholamines were able to start the fat splitting process again – as in young mice.
"Our key discovery is that immune cells interact with the nervous system to control metabolism," Dixit said. In further experiments, the researchers blocked the enzyme accumulating in mature macrophages, and this returned the fat metabolism in old mice to normal. Dixit noted that this enzyme, monoamine oxidase A, or MAO–A, is suppressed by drugs that are now used to treat depression. "Theoretically, it is possible to reorient these MAO-A inhibitors to improve metabolism in older people," he said. But he also warned that more research is needed to refocus these drugs to work with fat deposits on the abdomen and check their safety.
In future studies, Dixit and his colleagues plan to study immune cells and their interaction with nerves more thoroughly, as well as to find out how neuroimmune "dialogue" affects health and the course of diseases. According to scientists, controlling the inflammatory process in aging immune cells can improve metabolism. It is also possible that it can positively affect the nervous system and the aging process itself.
"The aim of our work is to better understand the interaction of immune cells with nerves and fat cells so that it is possible to reduce fat deposits on the abdomen, improve metabolism and quality of life of older people," said Christina D. Camell, the first author of the study.
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29.09.2017