Good Bacteria Could Be Used to Fight Gut Diseases, New Research Suggests

Researchers have offered new insight into the role bacteria plays in our digestive system. Getty Images

We've been told for years that looking after our gut bacteria is essential to our health. Now, researchers have shed light on how friendly microbes in our guts behave in research which could one day help to treat digestive diseases.

The so-called good bacteria in our stomachs are part of our microbiota: the name for the microbes which populate the human body. In fact, the microbes in and on our bodies outnumber our own cells by 10 to 1.

Researchers at Baylor College of Medicine wanted to know how microbiota help to reduce inflammation in the gut by working with cells in the immune system.

Harnessing this response to threats could therefore be the basis of treatments for conditions like inflammatory bowel disease, according to the authors of the study, published in the journal Immunity.

An umbrella term for conditions characterized by chronic inflammation in the gastrointestinal tract linked to overzealous immune responses, ulcerative colitis and Crohn's are the two most common forms of inflammatory bowel disease according to the Centers for Disease Control and Prevention.

Dr. Gretchen Diehl, an author of the study and assistant professor of molecular virology and microbiology co-director of the Biology of Inflammation Center at Baylor College of Medicine, explained in a statement: "A significant body of work currently indicates that the microbiota shapes the immune system and helps it to do its job."

"Disease-causing microbes, such as salmonella, evoke a strong inflammatory immune response that is directed at eliminating the microbe. But an inflammatory immune response, especially in the intestine, can be damaging to the healthy tissue. Here we defined a role for the microbiota in modulating the immune response in a way that reduces inflammation and limits the damage it can do to the gut."

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When the immune system of the gut is working correctly, cells called antigen-presenting cells prompt T cells to trigger an inflammatory response to battle unwanted microbes. At the same time, antigen-presenting cells direct anti-inflammatory regulatory T cells to control the response to wanted visitors to the gut such as food.

Microbiota play an important part in this process by telling the antigen-presenting cells to release the anti-inflammatory molecule cytokine IL-10. This balances the response of both types of T cells.

As a result, the gut can fight off infections such as salmonella, but in a way that prevents damage to healthy tissue in the intestine, Professor Diehl said.

To find out more, researchers gave laboratory animals antibiotics to clear their gut bacteria and found antigen-presenting cells did not produce IL-10.

But when their digestive systems were repopulated with bacteria, they found only bacteria which could stick to the epithelial cells of the stomach—which provide a first line of defense against harmful bacteria and viruses—triggered the production of the inflammatory molecule IL-10.

"It's somewhat counterintuitive because microbes that can attach to the intestinal epithelium are thought of as pathogens that can potentially cause disease," Professor Diehl explained.

"But in this case we found that the attachment of bacteria to the epithelium was not causing disease; on the contrary, it was necessary to promote a balanced regulation of the T cell responses and helped protect the gut."

While the results are illuminating, the authors acknowledged their research is in its early days. Further investigation is required to pinpoint how microbes can be harnessed to create a balanced environment in the digestive system, and to replicate their findings in humans.

Professor Diehl said: "A take home message for us is that a healthy microbiota is necessary to allow for a balanced response to not only protect us from infection, but also to limit potential tissue damage as the immune system attempts to eliminate pathogens."

Dr. Julian Marchesi, professor of digestive health at Imperial College London, who was not involved in the study, told Newsweek: "This study makes an exciting contribution to understanding the role of specific types of microbes in the gut and how they influence the host's immune response. The next major step will be to translate this to humans, who have very different types of microbes in their intestines."

This article has be updated with comment from Professor Julian Marchesi.