Scientists have discovered that regulatory T cells, a type of white blood cell, constantly move throughout the body looking for and repairing damaged tissue.
It was believed that regulatory T cells exist as multiple populations restricted to specific parts of the body.
Now, researchers have found that they roam around the body as a single large population of cells and target areas of inflammation, which destroys nerves and leads to a loss of movement.
Researchers at the University of Cambridge say this discovery of “new rules of the immune system” could improve the treatment of inflammatory diseases such as multiple sclerosis (MS).
“We’ve uncovered new rules of the immune system. This ‘unified healer army’ can do everything - repair injured muscle, make your fat cells respond better to insulin, and regrow hair follicles,” said Adrian Liston, a professor at the Department of Pathology at the University of Cambridge, in apress release.
“To think that we could use it in such an enormous range of diseases is fantastic: it’s got the potential to be used for almost everything,” he added.
‘Unified healer army’
Effector T cells such as cytotoxic and helper T cells are known to fight infection by directly and indirectly attacking viruses and bacteria, triggering an immune response.
Most symptoms of infections, such as COVID-19, are due to the body’s immune system attacking the virus, rather than the virus itself.
After the peak of the virus, regulatory T cells should turn off the immune response.
“They initiate a healing response this makes them a really powerful cell type to combat any inflammatory condition or any autoimmune disease,” Liston said.
But in some people, the process can be inefficient, leading to chronic problems.
The new finding could make it possible to use a drug to specifically shut down the immune response, for example, in the lungs, allowing the immune system in the rest of the body to continue to function normally.
Current treatments akin to ‘hitting the body with a sledgehammer’
Researchers say most anti-inflammatory drugs taken as oral tablets or as injections are administered to the whole body even though it’s just one organ that needs to be treated.
They hope their finding could change this with higher, more targeted doses of drugs and more rapid results.
“Now that we know these regulatory T cells are present everywhere in the body, in principle we can start to make immune suppression and tissue regeneration treatments that are targeted against a single organ – a vast improvement on current treatments that are like hitting the body with a sledgehammer,” Liston said.
However, in baseline states, there are only a small number of these regulatory T cells in the tissues that help block, repair and initiate healing. Therefore they can’t always calm the inflammation effectively.
"We're really lucky that the regulatory T cells are a renewable resource. They are made in an organ called the thymus that sits just above our heart, and they can constantly produce more of these cells throughout our life,” Liston said.
Liston says the source of these cells, the thymus, gets smaller as people get stressed, sick, or pregnant. It also gets smaller with age.
“So there is a finite cap, but they will be cells continually generated throughout our life," Liston added.
Now the research team says it is trying to enhance these in patients who have an inflammatory condition in an organ.
The team believes a viral vector can be used to inject DNA, making a potent drug that increases the population of regulatory T cells.
In the case of MS, where the immune system mistakenly attacks the protective covering of nerves, this injection would go to the brain.
“In multiple sclerosis, you've got this inflammatory process that is going on inside the brain that is causing damage to the central nervous system and to signalling from the brain to the muscles. This is all coordinated by the immune system,” said Liston.
“If you get regulatory T cells to go into the brain, they can shut down the inflammation and they can also initiate a healing response," Liston added.
So far the study published in the journal Immunity has only been conducted in animal models like mice.
Researchers have analysed regulatory T cells in 48 different tissues in mice and successfully moved regulatory T cells, using a drug they developed, to a specific part of the body, activating them to turn off the immune response and promote healing in just one organ or tissue.
There will need to be many more safety studies before a drug trial can be proposed for humans.
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