As their name suggests, regulatory T cells, or Tregs, are a type of white blood cell that actively regulate or suppress the body’s immune response. They stop the immune system from overreacting, keeping it in check by controlling inflammation and protecting against autoimmune diseases in which the immune system mistakenly attacks healthy tissues.
Traditionally, Tregs were thought to be specialist cell populations found only in specific areas of the body. However, a new study by scientists from the University of Cambridge in the UK has overturned traditional thinking, with significant implications for treating a wide range of diseases and injuries that trigger an immune response.
“It’s difficult to think of a disease, injury or injection that doesn’t involve some kind of immune response, and our finding really changes the way we could control this response,” said Professor Adrian Liston from the University’s Department of Pathology and the study’s corresponding author. “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, regrow hair follicles. 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.”
Lymphoid organs are integral parts of the immune system, responsible for producing lymphocytes, a type of white blood cell that includes T cells. T cells begin life in the bone marrow and then move to the thymus, an organ in the upper mid-chest, where they mature into specialized subsets, including Tregs. Once fully matured, T cells are exported to peripheral lymphatic tissues and organs like the spleen, tonsils, and lymph nodes (some move to the bloodstream). It was thought that’s where Tregs stayed, on ‘standby’ until called upon by the immune system.
To test this, the researchers analyzed the Tregs present in 48 different tissues in mice, including lymphoid and non-lymphoid tissues and tissues associated with the gut. They found them in all tissue types, suggesting that Tregs weren’t specialized cell populations confined to lymphoid tissues but moved around the body, executing repair functions in areas that need it.
“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.
Current anti-inflammatory drugs treat the whole body rather than just the inflamed tissues and inhibit the body's entire immune system, making people susceptible to infection. The researchers tested a drug they’d developed previously that, in mice, attracted Tregs to a specific organ or tissue, increased their number, and activated them to suppress the immune response and promote healing. Based on their findings, the researchers say there’s the potential to repair location-specific damage by shutting down the immune response in that area alone.
“By boosting the number of regulatory T cells in targeted areas of the body, we can help the body do a better job of repairing itself or managing immune responses,” said Liston. “There are so many diseases where we’d like to shut down an immune response and start a repair response, for example, autoimmune disease like multiple sclerosis, and even many infectious diseases.”
The researchers are fundraising to set up a spin-out company. In the next few years, they aim to test their findings by undertaking human clinical trials.
The study was published in the journal Immunity.
Source: University of Cambridge