Gut bacteria's fatty acid boosts immune system, reducing inflammation

Date: Nov-14-2013Researchers in Japan have carried out a mouse study that reveals a mechanism through

which gut bacteria influence the immune system's role in reducing inflammation. The mechanism works via a

fatty acid known as butyrate, which results when the bacteria digest dietary

fiber.

The researchers, led by a group from the RIKEN Center for Integrative Medical Sciences (IMS-RCAI) in Kanagawa, believe their findings make a case for using butyrate to treat inflammatory

bowel diseases, such as Crohn's disease.

There is already evidence that the gut bacteria in patients with inflammatory bowel disease

do not make butyrate, and that they have low levels of the fatty acid in their gut.

But those studies concluded that the reason butyrate helped to reduce inflammation was because

it acted as an energy source for cells lining the colon.

New findings make a case for using butyrate to treat inflammatory bowel diseases, such as Crohn's disease, researchers say.

This new study is the first to suggest an alternative explanation - a molecular mechanism by

which butyrate influences the production of cells that calm down the effect of other cells - by reducing inflammation response.

In a report published in a recent online issue of Nature, the researchers describe how,

by switching on genes ("epigenetic switching") the fatty acid causes the immune system to produce

more regulatory T cells in the gut.

They showed how it acts on precursor or "naïve" T cells to promote their differentiation into

regulatory T cells and that this occurred by changing expression of the genes responsible for

turning the naïve T cells into regulatory T cells.

Potential to treat IBD, allergy and autoimmune disease

The researchers also found that the guts of mice with colitis increased in regulatory T cells, and their

inflammatory symptoms improved after they were given butyrate in their diets.

Study leader Dr. Hiroshi Ohno, of the Laboratory for Epithelial Immunobiology at RIKEN,

says:

"Regulatory T cells are important for the containment of excessive inflammatory responses as

well as autoimmune disorders. Therefore, these findings could be applicable for the prevention and

treatment of inflammatory bowel disease (IBD), allergy and autoimmune disease."

He says butyrate is a natural and safe therapy, plus it is cheap, making it an attractive,

affordable option for both patients and society.

The study adds to an increasing pile of evidence about the important role that gut microbes play

in human health, for better and for worse.

For example, at a recent Society for General Microbiology conference, UK researchers presented

evidence suggesting gut bacteria may

cause cancer by disarming the immune system.

Written by Catharine Paddock PhD

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