AUG 29, 2020 1:47 PM PDT

Together, Two Gut Microbes Have a Nasty Effect

WRITTEN BY: Carmen Leitch

The microbes in the human gut play important roles in our physiology, and they can also contribute to disease. But they do not exist on their own; they live together in a large community, and the relationships they have with one another may be just as important as their individual identities.

Multiple sclerosis (MS) is an autoimmune disease in which the insulating sheath surrounding neurons is destroyed, a process called demyelination. It can cause numbness, tremors, and weakness, and can disrupt the ability to walk. Reporting in Nature, researchers from the RIKEN Center for Integrative Medical Sciences (IMS) used a mouse model to show that a specific combination of gut microbes can worsen the symptoms of MS. Together, the microbes encourage the activity of immune cells that attack the brain and spinal cord.

It's known that gut microbes can change the symptoms of multiple sclerosis. In this study, the researchers began to learn more about how that happens.

A mouse model of MS experiences demyelination of the spinal cord as T cells that generate an inflammatory molecule called IL-17A attack the myelin. When these mice were given ampicillin, the demyelination was reduced, and the activation of this kind of T cell was halted.

"We found that treatment with ampicillin, and only ampicillin, selectively reduced activity of T cells that attack an important protein called myelin oligodendrocyte glycoprotein [MOG], which helps myelin stick to neurons," explained study author Hiroshi Ohno of RIKEN IMS.

The researchers harvested immune cells from the small intestines of the model, exposed them to MOG, and measured cytokine levels; they saw that it was only reduced by ampicillin if the T cells were from the small intestine. This suggested that microbes in the small intestine activate MOG-specific T cells that are then able to attack myelin.

They searched for the microbe that was responsible since ampicillin was reducing the symptoms. They found a candidate, OTU002, and tested it. They determined that when their mouse model totally lacked OTU002, they had symptoms that were worse than mice without gut microbes.

Image credit: Max Pixel

"But, there was a problem," said first author Eiji Miyauchi. "Symptoms in the OTU002-only mice were not as bad as those in the regular model mice. This means that the original effect must involve more than one microorganism."

They looked for a bacterium that could react to MOG-specific T cells, and found that Lactobacillus reuteri makes a protein with a region that is similar to one in MOG. Mice that carried both L. reuteri and OTU002 had more severe symptoms than those with only OTU002 mice and were just as bad as the original model mice. When the microbes combine, they unleash a terrible effect.

"Other studies have focused on fecal microbes, or a single microbe, in patients with multiple sclerosis or in model mice," said Miyauchi. "Our data emphasize the necessity of considering the synergistic effects of intestinal microbes on autoimmune diseases and give hope to people looking for effective treatments for multiple sclerosis. But, because gut microbes and T cell binding locations on myelin differ between mouse and human, further studies using human microbes and autoreactive T cells are now needed."

Sources: AAAS/Eurekalert! Via RIKEN, Nature

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
DEC 03, 2020
Space & Astronomy
Health Issues from Spaceflight Caused by Mitochondria
DEC 03, 2020
Health Issues from Spaceflight Caused by Mitochondria
Spending an extended time in space is known to impact various aspects of health, from muscle and bone regeneration to th ...
DEC 08, 2020
Cardiology
The Protein Galectin-1 Could Act as a Prognostic Marker for Coronary Artery Disease
DEC 08, 2020
The Protein Galectin-1 Could Act as a Prognostic Marker for Coronary Artery Disease
The complexity of life works in many ways. Proteins, the primary things doing work in cells, can be modified after being ...
DEC 06, 2020
Cell & Molecular Biology
Free Radicals May Actually be Good for the Brain
DEC 06, 2020
Free Radicals May Actually be Good for the Brain
Reactive oxygen species (ROS) are a type of highly reactive molecule that is thought to be damaging to cellular structur ...
JAN 02, 2021
Cell & Molecular Biology
Putting Cells in Deep Freeze to Reveal Fine Structures in Action
JAN 02, 2021
Putting Cells in Deep Freeze to Reveal Fine Structures in Action
Many types of cells have to be able to move around, such as during the development of the body, or when immune cells hav ...
JAN 05, 2021
Genetics & Genomics
Integrator: A New Type of Transcriptional Control is Discovered
JAN 05, 2021
Integrator: A New Type of Transcriptional Control is Discovered
The study of the genome once seemed like a straightforward process: a specific short sequence of three nucleotide bases ...
JAN 06, 2021
Genetics & Genomics
Junk DNA Helps Control the Body Clock
JAN 06, 2021
Junk DNA Helps Control the Body Clock
Our bodies run on a kind of molecular clock, which helps regulate and time certain functions beyond just waking and slee ...
Loading Comments...