Colon Health May Rely on Gut Bacteria

Written By:Elizabeth Mendes

Bacteria aren’t all bad. Research is increasingly showing that many of the bacteria living in the human body – there are trillions of them – are actually really good for people.

One important role for these gut bacteria: helping to keep the colon clean. The right mix of gut bacteria contributes to a healthy digestive system and colon. The wrong kinds of bacteria, or too few of the good ones, may lead to, or fail to protect against, inflammation or other types of cell damage that can bring about cancer.

Chronic inflammation in the colon – such as that seen in people who have ulcerative colitis or Crohn’s disease – is strongly linked to colorectal cancer. Uncovering why certain individuals develop such inflammation and cancer – and how gut bacteria fit in – is what University of Michigan immunology researcher Grace Chen, M.D., Ph.D., is currently investigating.

Chen, with the help of an American Cancer Society research grant, is taking a close look at how the body’s immune system responds – or doesn’t – to injury in the colon. “There is emerging data that gut bacteria are helpful in controlling immune responses to promote healing of the gut,” Chen says. An improper immune response could lead to cancer-inducing inflammation.

Putting the Gut Bacteria Theory to the Test

Gut Bacteria Large

Chen is studying the relationship between the immune system, inflammation, and gut bacteria and colon cancer in mice. To test the importance of gut bacteria in all of this, Chen studies how mice with no gut bacteria – called germ-free mice – react to a colon injury compared with how mice with a normal bacteria community react.

Chen’s initial experiments have shown that the germ-free mice were unable to heal the injury she caused to their colon. The lack of gut bacteria appears to impair wound healing and cause fewer immune cells to be recruited to the part of the colon that needs to be repaired – leading to unchecked inflammation and the development of tumors. When provoked with the same type of injury to the colon, the mice with normal gut bacteria were less likely to develop tumors. This suggests that under these conditions, gut bacteria were protecting against colon cancer.

Searching for the Right Cocktail of Bacteria to Bring to the Masses

Chen is now trying to figure out which specific bacteria strains are the ones helping to limit tumor growth. She tests this by giving the germ-free mice different types of bacteria – and varying combinations of bacteria – and seeing how the mice then react to the same type of colon injury. Her results are looking promising so far. “We have developed a cocktail of bacteria that almost completely prevent any tumor development in the germ-free mice,” Chen says. Her next step is to figure out why this particular cocktail of bacteria suppresses tumor growth.

Although in the early stages, Chen hopes that down the road, her findings could help inform strategies for helping people prevent colon cancer. This might take the form of a probiotic, a product with live good bacteria, or a prebiotic, which provides food for good bacteria you already have, says Chen.

“I am hoping it would be a bacterial product that everyone could use because prevention is the key to reducing colon cancer because treatment for this cancer remains challenging.”

Read more about this topic: Certain Cancer Drugs May Need Gut Bacteria to Work

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