In some people with certain genetic features narcolepsy can be triggered by a protein called hypocretin and part of a protein from the swine flu virus H1N1.
The finding helped back up the theory of "molecular mimicry," which is the idea that immune responses to a pathogen could cause "autoimmunity," (when the immune system attacks its host cells), a Stanford University Medical Center news release reported.
The study suggested narcolepsy, which is characterized by sudden sleepiness and muscle weakness, is actually an autoimmune disease; it occurs when the immune system accidently attacks brain cells that create the "wakefulness" protein called hypocretin.
"The relationship between H1N1 infection, vaccination and narcolepsy gave us some very interesting insight into possible causes of the condition," Emmanuel Mignot, MD, PhD, professor of psychiatry and behavioral sciences said. "In particular, it strongly suggested to us that T cells of the immune system primed to attack H1N1 can occasionally also cross-react with hypocretin and somehow cause the destruction of hypocretin-producing neurons."
The study could help medical researchers get a step closer to finding an effective intervention in narcolepsy as well as new tests to diagnose the condition.
The team also found a connection between a pandemic H1N1 vaccine used in Europe in 2009 and a breakout of narcolepsy cases in Scandinavia the year after.
"This study will shape the next decade of research into narcolepsy. It will focus investigators on immune-mediated mechanisms of neuronal death, which ultimately may shed light on other autoimmune diseases, particularly of the brain," Elizabeth Mellins, MD, an immunology researcher and professor of pediatrics at Stanford said. "By giving us a new way to think about how neurons in these patients die, it also suggests new therapeutic approaches that we would not have considered if we hadn't learned that this is an autoimmune disease."
Narcolepsy affects about on in 3,000 people and there are few successful treatments for the condition.
