World IBD Day 2021: an overview of current research

Today (19 May 2021) marks World IBD Day – an event where organisations from 50 countries across the globe, including Crohn’s and Colitis UK, Guts UK, St Marks Hospital Foundation and Colostomy UK, raise awareness of Inflammatory Bowel Disease (IBD).

What is IBD?

IBD is a term used to describe inflammatory conditions of the gut. Inflammation of any tissue is caused by damage, injury or irritation and can cause redness, pain and swelling. The two main, and most common IBD conditions are Crohn’s Disease and Ulcerative Colitis. People of any age can get IBD, but it is usually diagnosed between the ages of 15 and 40.¹

Ulcerative Colitis is the most common IBD affecting about 1 in 400 people in the UK.² This condition affects only the large colon (large intestine) and causes inflammation and ulceration of the inner lining of the colon which can bleed and produce excess mucus, whereas Crohn’s Disease can affect any part of the gut causing ulcers and can penetrate deeper into the bowel wall. Crohn’s affects around 1 in 700 people in the UK. ² IBD impacts the body’s ability to digest food and can cause many symptoms including pain, cramps, swelling of the stomach, diarrhoea, blood in stools, weight loss and tiredness.

These IBD conditions are chronic meaning they are ongoing and life-long, although many people experience long period of good health with few, or no symptoms interspersed with ‘flare-ups’ where the condition is more active and symptoms more severe. The disease varies greatly between individuals that vary from mild to severe. There is no cure for Crohn’s or Colitis but medication, and in some cases surgery, can provide relief from symptoms. It is estimated that 1 in 5 people with Colitis have severe symptoms that do not improve with medication. This can lead to treatment involving surgery to remove the inflamed bowel. With Crohn’s it is estimated that 60 – 75% of all cases require surgery to help treat complications of the disease. ²

It is still unclear what causes IBD but, like many complex conditions, it is thought to be caused by a combination of factors which include a person’s genetics (it can run in the family), immune system problems or environmental factors such as smoking.

Research into IBD

There are various research studies being conducted that aim to better understand the disease and identify more effective treatments. Much of this research uses animals. Animals are used in research as a ‘model’ of the human body to try and understand a disease, or aspects of a disease. Mice are by far the most popular animal for this research. In 2019, around 23.5k procedures were carried out on mice for basic research on the gastrointestinal system (including liver), another 3.5k for applied research into the gastrointestinal disorders and around 3.5k for the creation of Genetically Altered (GA) mice lines for this purpose.

Scientists can recreate aspects of the disease in mice, such as inflammation of the gut or ulcers on the colon, in various ways including:^{3, 4}

• Inducing inflammation of the gut caused via dosing the mice with a chemical
• Triggering a response from the immune system causing inflammation (often through the use of mice with a deficient immune system or through the manipulation of gut bacteria)
• Genetic manipulation of mice to produce strains which are immunodeficient or develop spontaneous gut inflammation.

Whilst animal models may be contributing some insights into the mechanisms of IBD, for example, this study into the effect of food dye on gut inflammation, no single animal model of IBD is clinically relevant and the outcomes from this knowledge base of animal research are by no means the best path to understanding these diseases.

World IBD Day 2021

On this year’s World IBD Day, we would like to acknowledge and share current research that uses human-relevant methods that make use of human tissue, human data and computer modelling. These techniques have significantly moved on since the development of the first IBD relevant GA mouse model 25 years ago and have the potential to play a role in understanding these diseases better in the future.

Below are links to some interesting, human-relevant technologies and studies that make use of human tissue and organ-on-a-chip technology to study inflammation of the gut:

• Development of a human primary gut-on-a-chip to model inflammatory processes | Scientific Reports (nature.com)
• Using ‘organs-on-a-chip’ to model complicated diseases: A new approach reveals how different tissues contribute to inflammatory diseases such as ulcerative colitis — ScienceDaily
• Advancing Research of Inflammatory Intestinal Diseases | Technology Networks
• Human Colon-on-a-Chip Enables Continuous In Vitro Analysis of Colon Mucus Layer Accumulation and Physiology – PubMed (nih.gov)
• An Organ-on-a-Chip System to Study Anaerobic Bacteria in Intestinal Health and Disease – ScienceDirect
• Organ-on-a-Chip device sheds light on Crohn’s disease (asme.org)

References

1. Inflammatory bowel disease – NHS – NHS (www.nhs.uk)
2. Inflammatory Bowel Disease | Symptoms and Treatment | Patient
3. Mouse Models of Inflammatory Bowel Disease (crownbio.com)
4. Summary of colitis mouse models in IBD research | Taconic Biosciences
5. Two Common Food Dyes Could Be Linked to Inflammatory Bowel Disease Symptoms (gizmodo.com)

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