Bowel disease study points to new therapies for lifelong conditions

Treatments for incurable bowel conditions may be a step closer following the discovery of a key molecule associated with disease flare-ups. Researchers say the finding helps to explain the underlying cause of disorders such as Crohn’s disease and ulcerative colitis. The discovery could also lead to new tests to help doctors monitor patients’ condition and help them to tailor treatments accordingly: May 2018

Inflammatory Bowel Disease (IBD) includes Crohn's Disease and Ulcerative Colitis and affects around 300,000 people in the UK. The causes of these debilitating disorders are unknown and there is currently no cure.

Dr Gwo-Tzer Ho and his team looked for factors that might be associated with disease flare-ups by testing blood samples from almost 100 people with IBD. They discovered tiny fragments of DNA in the patients’ blood samples, which were barely present at all in samples from people who did not have the diseases.

These molecules, called mtDNA, are usually found packaged within the mitochondria - energy factories found inside all human cells. Mitochondria are tiny cellular structures and as they are descended from an ancient type of bacteria, they have DNA similar to modern day bacteria.

In healthy people, when mitochondria become damaged, the mtDNA is recycled and disposed of safely by the body. However, as these processes do not work properly in people with IBD, mtDNA can leak from the affected gut into the blood stream.

As the mtDNA is similar to bacterial DNA, this triggers the immune system to react as if there is an infection and an inflammatory response is initiated. This inflammation causes damage to otherwise healthy tissues and is the cause of the symptoms of IBD.

The study found that people with the most severe illness had the highest levels of mtDNA in their blood. This suggests the mtDNA could serve as a useful marker to monitor disease progression and help doctors to prescribe the most appropriate therapies.