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An unexpected discovery made in fat and immune cells in the body could help develop therapies to lose or gain weight with greater accuracy.
The importance of our immune system can never be overstated as it is crucial to how our body regulates itself and prevents illness, but also in keeping our brains healthy and active, too.
So now, a new and surprising discovery made by researchers from Trinity College Dublin (TCD) could help pave the way for targeted therapies that could finally help people lose or gain weight where needed with greater accuracy.
Our understanding of fats can be broken into two categories: white fat is the type that stores the energy from our food, leading to weight gain; and brown fat, which burns white fat to produce heat in the body.
The latter action can be seen in ‘baby fat’ for toddlers or in the protection for adults from the tremendous shock to the system that is hypothermia.
While it is known that both white and brown fat have their own immune systems, how they work has remained a mystery, until now.
In a paper published to Nature Immunology, the team revealed how fat and special immune cells called ‘gd T cells’ are the key cogs in the biological wheel that regulates our body heat and protects us against cold shock.
These immune cells are normally found in barrier sites of the body to protect it from infection, but the team was surprised to find them in fat.
Immune cells (or gd T cells) swarm around fat cells (adipocytes) in fat tissue to regulate their lipid burning versus storage. Image: TCD
Switching fat cells on and off
Unlike other immune cells that traffic in and out of fat, these gd T cells live there all the time, suggesting that they play an important role where they are housed.
When the research team removed the cells from fat tissue in mice, they observed that the rodents were noticeably colder, even at room temperature; when moved to cold environments, they were unable to regulate their temperature.
“Surprisingly, we found that the immune cells in fat respond to cold temperatures. They play an integral part in regulating thermogenesis by ‘turning on’ the burning of white fat or by stimulating the conversion of white fat into brown fat, which generates the heat required to keep us warm in the cold,” explained Prof Lydia Lynch of the team.
“This heat generation happens when the lipids in the white fat are burned up, and, when this occurs, weight loss is the chief side effect.”
By turning white fat into brown fat, the discovery opens the door to a new potential target for therapeutic research in patients.
For people with obesity, activating the biological pathway could make the body convert white fat tissue into brown; meanwhile, switching it off could induce weight gain for others where this is the desirable outcome.
