Francisco Quintana, PhD

Joon-Hyuk Lee, PhD

What helps drive immune attacks and inflammation in multiple sclerosis (MS) within the brain and spinal cord?

Researchers from Mass General Brigham and the Broad Institute of MIT and Harvard, led by Joon-Hyuk Lee, PhD, and supervised by Francisco Quintana, PhD, found an unexpected answer — astrocytes, brain cells long viewed as the nervous system’s support cells.

Using approaches ranging from MS mouse models to single-cell RNA sequencing and direct cell-tracking techniques, the team investigated how astrocytes communicate with immune cells known as T cells during neuroinflammation.

They found a subset of astrocytes that can directly interact with T cells, helping to reactivate them and increasing their inflammatory activity. They also found the communication goes both ways. Signals from T cells activate CD40 on astrocytes, causing them to accumulate lipid droplets that promote inflammatory activity and make the astrocytes more capable of stimulating T cells.

Together, the findings reveal a self-reinforcing cycle where T cells activate astrocytes; and astrocytes become more inflammatory and further activate T cells. In addition, blocking key immune functions in these astrocytes reduced disease severity in the mouse models of MS.

The researchers also analyzed brain tissue from people with MS and identified similar astrocytes, extending the findings beyond preclinical models.

Overall, the study uncovers a previously unrecognized way that astrocytes may help sustain inflammation in MS and highlights targeting the communication between T cells and astrocytes as a potential therapeutic.

Published in Nature on August 5, 2026 | Read the paper: “Antigen presentation by CD40+ MHC-II+ astrocytes 2 promotes CNS autoimmunity(opens in new tab)”

Summary reviewed by: Francisco J. Quintana, PhD, senior author