MS is characterized by the loss of myelin — the protective coat surrounding nerve fibers — due to a mistargeted immune reaction. The mechanisms underlying the onset of MS, however, are still poorly understood. Now, a team led by researchers at the University of Manitoba, Canada, discovered that the levels of a particular protein, called Nrg-1beta1, decline with MS onset and progression. Using the experimental autoimmune encephalomyelitis (EAE) mouse model, a well-established model for human MS, the researchers found that the levels of Nrg-1beta1 declined within spinal cord lesions as well as in the blood and spleen before the animals showed symptoms (pre-symptomatic stage). That decline continued as the disease progressed.