A new study reveals how brain inflammation from infections and neurodegenerative diseases causes muscle weakness by releasing the IL-6 protein. Researchers found that IL-6 travels from the brain to muscles, reducing their energy production and function.
NeuroScience via Washington University School of Medicine in St. Louis (WUSTL)
Extracts
Infections and neurodegenerative diseases cause inflammation in the brain. But, for unknown reasons, patients with brain inflammation often develop muscle problems that seem to be independent of the central nervous system.
Now, researchers at Washington University School of Medicine in St. Louis have revealed how brain inflammation releases a specific protein that travels from the brain to the muscles and causes a loss of muscle function.
The study, in fruit flies and mice, also identified ways to block this process, which could have implications for treating or preventing the muscle wasting sometimes associated with inflammatory diseases, including bacterial infections, Alzheimer’s disease and Long Covid.
The study is published July 12 in the journal Science Immunology.
We are interested in understanding the very deep muscle fatigue that is associated with some common illnesses. Our study suggests that when we get sick, messenger proteins from the brain travel through the bloodstream and reduce energy levels in skeletal muscle. This is more than a lack of motivation to move because we don’t feel well. These processes reduce energy levels in skeletal muscle, decreasing the capacity to move and function normally.
Senior Author Aaron Johnson, PhD, an associate professor of developmental biology
The study pinpoints potential targets for preventing or treating muscle weakness related to brain inflammation. The researchers found that IL-6 activates what is called the JAK-STAT pathway in muscle, and this is what causes the reduced energy production of mitochondria.
In the meantime, we hope our study encourages more clinical research into this pathway and whether existing treatments that block various parts of it can help the many patients who experience this type of debilitating muscle fatigue.
Senior Author Aaron Johnson, PhD, an associate professor of developmental biology