Stressed-Out Bacteria May Trigger Autoimmune Response

American Society for Microbiology.

Stressful life events most likely contribute to autoimmune diseases, but scientists don’t have a deep understanding of the underlying chain of events. 

A study on mice published this week in mSystems suggests that the gut microbiota may play a significant role in that connection. Researchers found that the onset of stress caused changes in the intestinal bacteria that, in turn, stimulated the activity of immune cells in a way that increased the likelihood that the body would attack itself.

The factors behind autoimmune diseases, conditions in which the body’s immune defense attacks its own tissues and systems, can be difficult to pin down. That’s partly because these diseases vary in severity and presentation. They include multiple sclerosis, lupus, rheumatoid arthritis, juvenile diabetes, scleroderma, and pulmonary fibrosis. 

The National Institutes of Health estimates that more than 20 million people in the United States have autoimmune diseases, the vast majority of whom are women.

In the study published in mSystems, immunologist Orly Avni, PhD, at Bar Ilan University, worked with graduate student Michal Werbner and other collaborators to investigate environmental risks, like psychological and social stress, because those offer opportunities for potential treatment.

“We know that there’s strong cross talk between the immune system and the microbiota,” Avni said. An important step in understanding how stress may lead to autoimmune conditions, she said, is to identify the genetic responses of bacteria. Her group’s study showed that social stress changed both the composition and transcriptional patterns in the microbiota. “And the consequent immune response to that threat jeopardized the tolerance to self,” she said.

The study shows that gut bacteria can sense and respond to social stress, but Avni notes that researchers need to better understand how that long-lasting interaction works between bacteria and their hosts.
 

“It’s not enough to study the composition, or the increase or decrease of a species,” she said. “We also have to understand how the microbiota sense us, and how they change their 'behavior' accordingly.”

 That knowledge, she added, could potentially lead to tailored microbial interventions that could dampen autoimmunity and additional stress-inducible illness.

Read the full article with the explanation of how the study was carried out.

Reference
Social-Stress-Responsive Microbiota Induces Stimulation of Self-Reactive Effector T Helper Cells. Michal Werbner, Yiftah Barsheshet, Nir Werbner, Mor Zigdon, Itamar Averbuch, Oren Ziv, Boris Brant, Evan Elliott, Shachaf Gelberg, Moran Titelbaum, Omry Koren, Orly Avni. msystems, July/August 2019 Volume 4 Issue 4 e00292-18, DOI: 10.1128/mSystems.00292-18.