New evidence could explain why stress is a risk factor for autoimmune disease. A recent study in mice reveals that persistent social stress changes gut microbiota, or microorganisms, in ways that can trigger certain immune responses.
Autoimmune conditions develop when the immune system attacks the body's own tissues, organs, and cells. It responds to them as though they were disease-causing bacteria and viruses.
The National Institute of Allergy and Infectious Diseases suggest that there are at least 80 autoimmune diseases, including lupus, rheumatoid arthritis, and type 1 diabetes.
Studies have identified stress as a risk factor for autoimmune disease. However, the mechanism of the link is unclear.
Researchers at Bar Ilan University in Israel have now found that gut bacteria in mice respond to social stress by increasing the number of effector T helper cells, immune cells that play a role in autoimmunity.
They report their findings in a recent paper in the journal mSystems.
"We know that there's strong crosstalk between the immune system and the microbiota," says senior study author and immunologist Orly Avni, Ph.D.
Avni and her team found that persistent social stress changed not only the expression of genes in the mice's gut bacteria but also their composition.
"And the consequent immune response to that threat jeopardized the tolerance to self," she adds.