Gut microbes may be key to treat ulcerative colitis

Scientists have linked a missing gut microbe to ulcerative colitis and have opened the door to a potential new treatment.

Gut microbes
Researchers have discovered a missing family of microbes in some people which may explain ulcerative colitis.

A team of scientists from California’s Stanford University School of Medicine have identified a gut microbe that is absent in some individuals. This finding may be crucial to understanding why some people develop ulcerative colitis.

The thesis appears in Cell Host & Microbe journal.

The scientists hope that new and more effective treatments for ulcerative colitis may be produced by replacing the function of this missing microbe.

Ulcerative colitis

The National Diabetes and Digestive and Kidney Diseases Institute states that ulcerative colitis is a form of inflammatory bowel disease.

This causes inflammation and sores in a person’s large intestine, which can lead to abdominal pain, weight loss, pus- or blood-containing diarrhea and other complications.

The symptoms of ulcerative colitis can range from mild to severe, and currently there is no cure. Instead, therapies aim to keep the disease in remission for as long as possible.

Treatment usually begins with medications, but surgery may be needed if these don’t work.

23–45 per cent of people with ulcerative colitis will potentially need surgery, according to the Crohn’s and Colitis Foundation of America.

Surgery requires the complete removal of colon and rectum from a human. The surgeon will then build either a stoma that serves as an outer pouch to store intestinal contents, or an ileoanal reservoir that is a J-shaped pouch at the end of the small intestine that performs the same function.

Scientists have not been sure until now why ulcerative colitis is affecting certain people and not others. The new research from the Stanford team indicates that the lack of specific gut microbes may be a key reason.

Bile acids

Those people who undergo surgery to develop the J-shaped pouch for ulcerative colitis will then see the inflammation and the associated symptoms return.

Interestingly, people with family adenomatous polyposis (FAP) genetic condition, which also requires a J-shaped pouch to be created, rarely experience those inflammatory symptoms.

The investigators wanted to find out why that was the case. To do so, two groups of participants were compared, one with FAP and the other with ulcerative colitis, finding any significant differences between them.

They considered the presence of a form of bile acid in the intestines, which was much greater in those with FAP than in those with ulcerative colitis, to be a significant difference.

These biliary acids form a normal part of a balanced intestine and help break down fats.

Gut microbes

Bacteria transform certain bile acids into secondary bile acids in the intestines.

The scientists were able to identify a specific family of bacteria called ruminococcaceae that was underrepresented in those with colitis ulcerosa.

Bacteria from ruminococcaceae are the main type of microbe that converts primary bile acids to secondary bile acids.

As the study’s associate professor and senior author Dr. Aida Habtezion notes: “All healthy people have Ruminococcaceae in their intestines. But members of the family were substantially reduced in the[ ulcerative colitis] pouch patients.”

The investigators, in helping to validate their results, found that stool samples from FAP participants converted primary bile acids into secondary bile acids, while samples from those with ulcerative colitis did not.

The team then gave the mice that had ulcerative colitis supplements to replace any missing secondary bile acids. The decreased inflammation as well as mice’s typical colitis symptoms.

“This research will help us understand the disease better,” Dr Habtezion says.

We hope it also leads to our being able to treat it with a naturally produced metabolite that’s already present in high amounts in a healthy gut.”

– Dr. Aida Habtezion

The team is now running a clinical trial to find out if an acid replacement will help people with ulcerative colitis, to get to that level.

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