Back in 2009, I wrote about Stanford research indicating that narcolepsy is an autoimmune disease, caused when patients’ immune systems kill the neurons that produce the protein hypocretin. A just-published study confirms that finding while also showing that the condition can sometimes be triggered by a similarity between a region of hypocretin and a portion of a protein from the pandemic H1N1 virus. My colleague Krista Conger explains the detailed science behind the work and summarizes its significance in a release:
The study provides some of the most compelling cellular and molecular evidence to date for a scientific concept known as “molecular mimicry.” Mimicry is the idea that the normal immune response to a pathogen, in this case the pandemic 2009 H1N1 influenza virus, can trigger autoimmunity — when the immune system mistakenly attacks healthy components of the body — because of similarity between a pathogen protein and a human protein.
“The relationship between H1N1 infection, vaccination and narcolepsy gave us some very interesting insight into possible causes of the condition,” said Emmanuel Mignot, MD, PhD, professor of psychiatry and behavioral sciences [and director of the Stanford Center for Sleep Sciences and Medicine. “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 new study suggests new ways to try to intervene before complete destruction of the specialized brain cells. Their loss is the hallmark of the disease and leads to its dramatic symptoms. The study also could pave the way to a new blood test to diagnose narcolepsy. And it sheds light on a previously observed association between a pandemic H1N1 vaccine used in Europe in 2009 and an increase in narcolepsy cases in Scandinavia the subsequent year.
Mignot shares senior authorship of the research with immunology researcher Elizabeth Mellins, MD, who told Conger that the findings “will shape the next decade of research into narcolepsy.” The study appears today in Science Translational Medicine.