Link shown between Crohn’s disease and virus
A new study reveals that all children with Crohn’s disease that were examined had a commonly occurring virus – an enterovirus – in their intestines. This link has previously not been shown for this chronic inflammatory intestinal disorder. The findings are being published today in the latest issue of the international journal Clinical and Translational Gastroenterology.
These findings need to be confirmed in larger studies, but they are important, as this connection has never been pointed out before. This paves the way for a better understanding of what might be involved in causing the disease, says Alkwin Wanders, one of the scientists behind the study at Uppsala University and Uppsala University Hospital.
In Sweden several thousand adults live with Crohn’s disease, and each year about 100 children and adolescents develop the disorder. The disease affects various parts of the gastrointestinal system and causes symptoms such as stomach aches, diarrhoea, and weight loss – in severe cases fistulas, or strictures in the intestines.
The cause of Crohn’s disease is not known. Mutations in more than 140 genes have been shown to be associated with the disorder, but this genetic connection is not a sufficient explanation. Many of these genes play key roles in the immune defence, which has prompted theories that the disease might be caused by impaired immune defence against various microorganisms. In that case, the disease would be a consequence of interplay between heredity and environment.
Recent research has shown that some of the genes that are strongly linked to the disorder are important for the immune defence against a certain type of viruses that have their genetic material in the form of RNA, so-called RNA viruses. Using this as a point of departure, an interdisciplinary research team was established in Sweden to investigate what role this type of virus plays in the disease.
The research team includes the paediatrician Niklas Nyström, the pathologist Alkwin Wanders, virus researchers Gun Frisk and Oskar Skog, the molecular biologist Mats Nilsson, and the geneticist Ulf Gyllensten at Uppsala University and Uppsala University Hospital, along with cell biologists Jonas Fuxe and Tove Berg the paediatrician Yigael Finkel at Karolinska Institutet in Stockholm.
Crohn’s disease is a long-term condition that causes inflammation of the lining of the digestive system.
Inflammation can affect any part of the digestive system, from the mouth to the back passage, but most commonly occurs in the last section of the small intestine (ileum) or the large intestine (colon).
Common symptoms of Crohn’s disease include:
diarrhoea
abdominal pain
fatigue (extreme tiredness)
weight loss
Over time, inflammation can damage sections of the digestive system, resulting in additional complications, such as narrowing of the colon.
People with Crohn’s disease sometimes go for long periods (weeks or months) without symptoms, or with very mild symptoms. This is known as remission. Remission can be followed by periods where a person’s symptoms flare up and become particularly troublesome.
This unique composition, with complementary clinical and scientific expertise, has been extremely fruitful for our studies, says Alkwin Wanders.
In the present study the researchers investigated whether the RNA virus were present in children with Crohn´s disease. They focused in particular on the prevalence of enteroviruses, a group of RNA viruses that are known to infect the intestinal mucous lining.
The results showed significant amounts of enteroviruses in the intestines of all of the children with Crohn´s disease, whereas the control group had no or only minimal amounts of enteroviruses in their intestines. Similar results were obtained using two different methods. Enteroviruses were found not only in intestinal mucous linings but also in so-called nerve cell ganglia in deeper segments of the intestinal wall. Receptors for a group of enteroviruses were also found in both the intestinal mucous linings and nerve cell ganglia, which may explain how the virus can make its way into the nerve system in the intestine.
Another interesting finding is that the enterovirus could be thought to be stored in nerve cells in the intestine and to spread to different parts of the intestine via nerve fibres. This would explain both the fact that the disease is periodic (comes and goes) and the fact that it often affects multiple segments of the intestines, says Alkwin Wanders.
The present study comprises nine children with advanced Crohn’s disease and fifteen children with incipient Crohn’s disease symptoms. The research now wants to go on to examine larger groups of patients and more control individuals. They also want to pursue experimental research to investigate the link further.
Who is affected by Crohn’s disease?
Crohn’s disease is a rare condition. In the UK it is estimated that for every 100,000 people there will be seven new cases of Crohn’s disease a year. There are currently around 90,000 people living with Crohn’s disease in the UK.
Most cases of Crohn’s disease first develop in people who are between 16 and 30 years of age. A large number of cases also develop in people between the ages of 60 and 80. However, Crohn’s disease can affect people of all ages, including children. It affects slightly more women than men.
Crohn’s disease is more common in white people than in black or Asian people. It is most prevalent among Jewish people of European descent.
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The study was funded by, among others, Uppsala County Council, the Swedish Society for Medical Research, Cancerfonden, Karolinska Institutet, and the Swedish Research Council.
For more information, please contact:
Alkwin Wanders
tel: +46 (0)18-6113818
mobile: +46 (0)76-2269430
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Niklas Nyström
tel: 018-6119473
mobile: +46 (0)73-9878073
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Gun Frisk
mobile: +46 (0)70-2724336
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Jonas Fuxe
tel: +46 (0)8-52487275
mobile: +46 (0)70-7980065
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Yigael Finkel
tel: +46 (0)8-6164354
mobile: +46 (0)70-7197847
Email: .(JavaScript must be enabled to view this email address)