Post by Harvard Medical School

A new study helps explain why exercise can improve neurological symptoms in people with multiple sclerosis. Irisin — a hormone produced by muscles during exercise — reduced clinical symptoms and neuron loss in a mouse model of MS, found a team led by investigators from Harvard Medical School and University Medical Center Hamburg-Eppendorf in Germany. Additionally, when the team deleted the gene encoding irisin, the protective effects of exercise disappeared. The findings suggest that irisin can protect neurons from inflammation-driven neurodegeneration and that it does so by acting directly on the neurons rather than by suppressing the immune system. This uncovers a new way that exercise acts on MS and makes irisin a potential target for future MS therapies. “Our findings strengthen the argument that irisin can help protect neurons in the context of multiple types of neurodegenerative diseases,” said co-senior author Christiane Wrann, HMS associate professor of neurology at Massachusetts General Hospital. Wrann and colleagues previously showed that irisin can improve cognitive function and reduce neuroinflammation in mouse models of Alzheimer’s disease. More research is needed to understand the precise mechanism by which irisin protects neurons. As the effects of exercise on MS are complex and likely involve multiple factors, irisin alone probably does not account for all of exercise’s benefits, the researchers said. Future work will also need to determine whether the findings translate to humans.