AUG 09, 2017 6:24 PM PDT

Why Tryptophan is Good for the Gut

WRITTEN BY: Kara Marker

Too much inflammation in the gut triggers inflammatory bowel disease (IBD). There are immune cells specifically designed to prevent this, but they can be overwhelmed by inflammatory cells. In a new study from the Washington University School of Medicine published in the journal Science, scientists identify the active ingredient in tryptophan that is responsible for producing tolerance-promoting immune cells in the gut.

 

Gut bacteria, grown on color-changing agar in striking, [with] organic patterns to suggest that bacteria, rather than 'good' or 'bad', should be viewed like the plants around us, where diversity, and balance is key to health. Credit: Nicola Fawcett

The presence of inflammatory cells in the gut is obviously not to cause IBD - it’s to monitor the food we eat that could potentially be harboring pathogens. It’s only when these cells start to outnumber the “tolerant” cells that inhibit inflammation that gut diseases develop, which is why discovering the component responsible for promoting tolerant cells is so important.

Tryptophan is one of eight essential amino acids that make up proteins. It was discovered early in the 20th century, and it’s commonly found in foods like oats, bananas, milk, tuna, cheese, bread, chicken, turkey, peanuts chocolate. The new Science study shows that tryptophan is necessary to trigger the appearance of tolerance-promoting immune cells, and its effect is specific to Lactobacillus reuteri bacteria.

L. reuteri is commonly found in the gut of both humans and mice, and researchers are beginning to learn how this species of bacteria in particular triggers the development of tolerance-promoting immune cells via mouse models. "The more tryptophan the mice had in their diet, the more of these immune cells they had,” explained senior author Marco Colonna, MD.

The scientific journey began when one scientist saw a major difference between two groups of mice that were genetically identical but raised separately: one group had the tolerant immune cells and the other did not. What happened to the one group of mice to trigger the production of these cells?

The next step included sequencing tntestinal DNA from both groups of mice. The results showed six species of bacteria present in the mice with the tolerant immune cells that were mysteriously missing in the other group. Which one was responsible for inducing the production of the immune cells? To find out, researchers introduced - one at a time - each of the species to mice raised to have no gut microbiome, and they found that L. reuteri was the key.

How does L. reuteri do it? Researchers found that an active component, a byproduct of tryptophan metabolism, called indole-3-lactic acid was at the center of production for tolerant immune cells. Further mouse studies confirmed the formula: more tryptophan, more indole-3-lactic acid, more tolerant immune cells.

"The development of these cells is probably something we want to encourage since these cells control inflammation on the inner surface of the intestines," explained Postdoctoral researcher Luisa Cervantes-Barragan, PhD. "Potentially, high levels of tryptophan in the presence of L. reuteri may induce expansion of this population."

Sources: Washington University School of Medicine, International Journal of Tryptophan Researc

About the Author
  • I am a scientific journalist and enthusiast, especially in the realm of biomedicine. I am passionate about conveying the truth in scientific phenomena and subsequently improving health and public awareness. Sometimes scientific research needs a translator to effectively communicate the scientific jargon present in significant findings. I plan to be that translating communicator, and I hope to decrease the spread of misrepresented scientific phenomena! Check out my science blog: ScienceKara.com.
You May Also Like
SEP 27, 2019
Drug Discovery & Development
SEP 27, 2019
AI Exponentially Accelerates Drug Development
Research and development for new drugs is both an expensive and lengthy process, often lasting years, if not decades. With the development of artificial in...
NOV 19, 2019
Microbiology
NOV 19, 2019
Ketogenic Diet Appears to Help Protect Against the Flu
The ketogenic diet forces the body to use stored fat as fuel instead of carbohydrates; the fat gets broken down into ketone bodies....
NOV 20, 2019
Health & Medicine
NOV 20, 2019
Could your bedding make you sick?
Do you use duvets or pillows filled with goose or duck feathers? While indeed cozy, doctors have issued a new warning related to feather filled bedding cal...
NOV 20, 2019
Immunology
NOV 20, 2019
Harnessing the Power of Natural Killer Cells to Fight Cancer
Manipulating the immune system’s population of natural killer cells could bolster therapies targeting cancer. A new study saw positive results invest...
JAN 19, 2020
Immunology
JAN 19, 2020
Overactive Immune Gene May Cause Schizophrenia
A windy road links excessive activity of the “C4” gene to the development of schizophrenia. Researchers begin to study C4 activity as part of n...
FEB 06, 2020
Drug Discovery & Development
FEB 06, 2020
Potential Cure for Coronavirus Found in Thailand
Doctors in Thailand have successfully treated people affected by the coronavirus via a new drug cocktail made out of antiviral, flu and HIV medication. Alt...
Loading Comments...