In a groundbreaking discovery published in Nature on May 28, 2025, Yale School of Medicine researchers have found T cells residing in healthy brains of both mice and humans. This challenges the long-held belief that these immune cells are only present during disease or infection.
The T cells were found to be concentrated in the subfornical organ, a brain region responsible for regulating thirst and hunger. Further investigation revealed that the gut microbiome influences the transport of these T cells to the brain, suggesting a novel form of gut-brain communication. Specifically, altering the gut microbiome in mice affected the presence of T cells in the brain.
Researchers hypothesize that these T cells may signal the body's nutritional status to the brain. Future studies will explore the role of these cells in neurological diseases like multiple sclerosis and Parkinson's disease, potentially opening new avenues for understanding and treating these conditions.