Inflammatory bowel disease occurs when parts of the digestive tract become damaged by prolonged inflammation. The two most common types, Crohn’s disease and ulcerative colitis, are serious chronic illnesses with no known cause. Our research into the causes of inflammation aims to reveal new treatments for inflammatory bowel disease.

Inflammatory bowel disease research at WEHI

Prolonged inflammation in the digestive tract can lead to significant digestive symptoms and other medical problems. Our researchers are studying:

• The cause of intestinal inflammation in inflammatory bowel disease.
• The molecules that initiate and prolong inflammation.
• How inflammation can be turned off to treat Crohn’s disease and ulcerative colitis

What is inflammatory bowel disease?

Inflammatory bowel disease is a condition in which the lining of the digestive tract becomes inflamed and damaged.

The two most common types of inflammatory bowel disease are:

• Ulcerative colitis, in which inflammation is limited to the surface layers of the large bowel (colon).
• Crohn’s disease, which can occur anywhere in the digestive tract from the mouth to the anus, and which inflames the entire thickness of the intestinal wall.

Some people are diagnosed with ‘indeterminate colitis’, when their inflammatory bowel disease cannot be distinguished between ulcerative colitis and Crohn’s disease.

Symptoms of inflammatory bowel disease

The most common symptoms of inflammatory bowel disease are:

• Diarrhoea, often including blood or mucous
• Abdominal pain
• Loss of appetite
• Tiredness
• Fever
• Weight loss

Symptoms can come and go as the disease can flare unpredictably. Sometimes symptoms are severe enough to require treatment in hospital.

Damage to the intestinal wall leads to ulceration and bleeding. People with Crohn’s disease can also experience:

• Narrowing (strictures) of the bowel
• Breaks (perforation) of the bowel
• Tunnels between sections of the bowel or other organs (fistulae)

These complications require medical and sometimes surgical treatment.

In the long-term, people with inflammatory bowel disease are at elevated risk of bowel cancer.

The inflammation in Crohn’s disease and colitis is not limited to the intestine. People often experience problems caused by inflammation in other organs including their eyes, skin, liver and joints.

Australia has one of the highest rates of inflammatory bowel disease in the world, with nearly 85,000 Australians affected. Most people are diagnosed as young adults. There is often a delay between the start of symptoms and a medical diagnosis.

For more information about inflammatory bowel disease, please visit Crohn’s and Colitis Australia.

What causes Crohn’s disease?

Crohn’s disease and ulcerative colitis are inflammatory conditions. This means they are caused by the body’s immune system. Inflammation can protect the body from invading microbes. However in inflammatory bowel disease, unnecessary inflammation is triggered. It continues for long enough to cause damage to the digestive tract.

Inflammatory bowel disease risk factors

It is hard to predict who will develop inflammatory bowel disease. Both genetic and environmental factors are important contributors to inflammatory bowel disease. These probably interact with an unknown ‘trigger’ to cause abnormal inflammation in the digestive tract.

Inflammatory bowel disease is more common in people who are relatives of someone with the condition. Specific genetic changes have been found that increase the risk of developing inflammatory bowel disease.

Crohn’s disease can occur following an infectious gastroenteritis. It is possible that the immune response protecting against infection ends up damaging the intestine. Some research suggests Crohn’s disease may be triggered by the bacterium Mycobacterium avium subspecies paratuberculosis (related to the bacterium that causes tuberculosis).

Environmental and lifestyle influences such as tobacco use and diet as well as alteration in the bacterial composition of the bowel, called the microbiome, also have an effect on the development of Crohn’s disease. Smoking more than doubles the risk of Crohn’s disease.

There is some evidence that living in urban or industrialised areas may increase Crohn’s disease risk, possibly due to differences in diet, gut microbes or the effect of pollution.

How is inflammatory bowel disease treated?

For most people, inflammatory bowel diseases are lifelong illnesses. Treatments aim to reduce inflammation and improve symptoms to enable a good quality of life.

For people with severe ulcerative colitis, the entire large bowel can be surgically removed. This cures the disease, but other health issues can remain. Crohn’s disease cannot be cured.

Treatments for people with inflammatory bowel disease may include:

• Medications, such as steroids, to reduce inflammation
• ‘Biologic’ medications that block the specific molecules that allow inflammation to occur
• Antibiotics
• Surgery to remove areas of severe inflammation, or to repair damage

Dietary modification is sometimes recommended for people with inflammatory bowel disease. Nutritional deficiencies are common, especially when inflammation is present, so adequate nutrition is important.