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Digestive-Health

Updated 09 September 2020

Scientists may have figured out main cause of inflammatory bowel disease

Inflammatory bowel disease refers to a group of chronic intestinal disorders that can cause pain and infrequent bowel movements.

  • IBD refers to a group of diseases which are caused when the immune system kills off harmless gut bacteria
  • While there are treatments, none of them work long-term
  • Researchers have now discovered the involvement of a T-cell that could lead to better treatments

Inflammatory bowel disease (IBD), not to be confused with irritable bowel syndrome (IBS), is a group of intestinal diseases, which include Crohn’s disease and ulcerative colitis.

It was always understood that these diseases were triggered by an overactive immune system attacking the good bacteria in the intestine instead of potentially harmful pathogens, causing a range of digestive symptoms such as abdominal pain, infrequent bowel movements, bloody stools, nausea and vomiting.

But now, new research suggests that a type of “killer T-cell” may be responsible for IBD, and that may lead to new treatment methods. Although there are several treatments for IBD, none of them works long-term.

What are T-cells?

Our immune systems work through two branches – innate, and adaptive. The innate branch is the first line of defence that quickly kicks in as soon as harmful pathogens such as bacteria or viruses are discovered. This, however, is a generalised response and doesn’t adapt to specific viruses or bacteria in the body.

The adaptive branch works more slowly, but in a more targeted way. T-cells form part of the adaptive immune system and they are mainly divided into CD4+ and CD8+ T-cells. While CD4+ T-cells release cytokines that can induce inflammation, the CD8+ T-cells function by mainly killing any invader cells – and even after a harmful pathogen has been destroyed, they hang around and remember the pathogen, to recognise and kill it in future.

The T-cells and the intestine system

The new research, which was published in the journal Science Immunology, analysed different blood and intestinal samples.

The team discovered that those with ulcerative colitis had higher numbers of T-cells, belonging to the type of CD8+ T-cells that linger in the system. They also release cytokines, which can cause inflammation and tissue damage in the body.

The fact that memory T-cells are so great for vaccines may explain their involvement with autoimmune diseases such as IBD.

The new discovery and future treatments

While there are treatments for IBD, none of these treatments target long-lived memory cells, which is why they don’t work long-term for many people.

According to the researchers, one therapeutic approach may be to target these T-cells. This can, however, lead to side-effects like a suppressed immune system or increased infection.

While this is an exciting prospect for new treatments, more work needs to be done to see how T-cells can be selectively targeted while minimising side-effects.

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