New research at Washington University School of Medicine in St. Louis helps illuminate a surprising mind-body connection. In mice, the researchers found that immune cells surrounding the brain produce a molecule that is then absorbed by neurons in the brain, where it appears to be necessary for normal behavior.
The findings, published Sept. 14 in Nature Immunology, indicate that elements of the immune system affect both mind and body, and that the immune molecule IL-17 may be a key link between the two.
“The brain and the body are not as separate as people think,” said senior author Jonathan Kipnis, the Alan A. and Edith L. Wolff Distinguished Professor of Pathology and Immunology and a professor of neurosurgery, of neurology and of neuroscience. “What we’ve found here is that an immune molecule — IL-17 — is produced by immune cells residing in areas around the brain, and it could affect brain function through interactions with neurons to influence anxiety-like behaviors in mice. We are now looking into whether too much or too little of IL-17 could be linked to anxiety in people.”
IL-17 is a cytokine, a signaling molecule that orchestrates the immune response to infection by activating and directing immune cells. IL-17 also has been linked to autism in animal studies and depression in people.