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Intestinal bacteria - for better or for worse

Every year around 400 Swedes fall ill with Crohn’s disease; an incurable inflammation of the intestines that primarily afflicts young people and which can lead to diarrhoea, severe pain, and stomach sores. Johan Dabrosin Söderholm, professor of Surgery, has been researching the illness since the 1990s. He spoke on “Cutting-Edge Research” (Forskning i Framkant) on Thursday.

Johan Dabrosin Söderholm.Awareness is growing regarding the importance of intestinal flora for our health. New discoveries in research show how intestinal bacteria influence the genesis of everything from arteriosclerosis to obesity.  Söderholm hasn’t ruled out that intestinal flora can also be a factor in the development of Crohn’s.

“Most likely it’s a question of a combination, where food, lifestyle, and genetic conditions play a role,” he says.

The human intestinal system contains upwards of a kilogram (2.2 pounds) of bacteria. They’re needed for things like food digestion, but there are also potential pathogens that can cause everything from vomiting to inflammatory bowel disease. The latter affects around 1,200 Swedes every year; a third of them develop Crohn’s.

In the East Swedish province of Östergötland around a thousand people suffer from the disease, which requires lifelong medical treatment. Common symptoms include fever, stomach pains, and weight loss.

When the intestinal walls are inflamed and scar tissue is formed, they become even thicker, which can make it difficult for food to pass. Fistulas can also form in different places, as can sores inside the stomach.

“In some cases bowel surgery is required, but our studies show the inflammation is back within three years,” Söderholm says.

The cause of Crohn’s is still unclear, despite the disease having been known since 1932. The prevailing theory is that the body’s immune defence system goes on the attack against the bacterial flora in the intestine. No one knows whether this is owing to a fault in the immune system, changes in the bacterial flora, or some other trigger factor.

 “We’ve been able to see that there’s a disturbance in the intestinal barrier, which means that the epithelium lets through a greater amount of bacteria. What we’re doing now is looking at how this transmission occurs. Among other things, we’re collaborating with a French research group on looking at how a specific group of E. coli bacteria get through the intestinal barrier in Crohn’s.”

Apart from his research job, Söderholm also works as chief physician in the surgical division at Linköping University Hospital , where he primarily meets patients with inflammatory bowel diseases. He became interested in the subject in his 20s when he worked as a paramedic in a surgical division at a now-defunct hospital in Stockholm.

“One group of patients affected me greatly. I met people who were my own age suffering from a severe, incurable disease. The people I met needed surgery and some of them would get colostomy bags in their 20s. I remember I was really touched,” he says.

Inflammatory bowel diseases primarily affect Western countries; it’s been long known that long-term stress is a risk factor for falling ill. Earlier this year, Söderholm’s research group was able to show what happens on the cell level in the intestine with ulcerative colitis, which is in the same group of diseases, and how stress can worsen the inflammation.

As regards Crohn’s disease, the connection is not as clear. “On the other hand we know that smoking doubles the risk of being afflicted with the disease,” he says.

Medical treatment has improved in recent years, but a cure is so far not yet in sight. On the other hand, one of the group’s studies from last year showed that something as simple as the fibre from plantains (bananas) strengthens the intestinal barrier against bacteria.

“But that’s something that could possibly reduce the risk of illness in the population in general, or to prevent the inflammation from recurring after surgery. It’s not enough when you’ve already become sick,” Söderholm says.

Text: Karin Allander

  • Johan Dabrosin Söderholm lectures in Cutting-Edge Research Thursday, December 1, at 3:30 PM in Victoriasalen, Entrance 7, 10th floor, Hospital campus.
  • Read more about Johan Dabrosin Söderholm.


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Last updated: 2012-12-10