(HealthDay News) – Narcolepsy may be an autoimmune disease, and in some cases may be triggered by immune reactivity to a flu protein, according to a study published in the Dec. 18 issue of Science Translational Medicine.
Noting that narcolepsy has been linked to the loss of brain cells that produce the wake-promoting neuropeptide hypocretin (HCRT), Alberto K. De la Herran-Arita, MD, from the Stanford School of Medicine in Palo Alto, CA, and colleagues investigated HCRT-derived peptides that bind to human leukocyte antigen DQ0602, which is strongly associated with the disorder.
The researchers identified two HCRT epitopes that activated a subpopulation of CD4+ T cells in patients with narcolepsy but not DQ0602 healthy controls. Administering a 2010 seasonal H1N1 influenza vaccine previously associated with narcolepsy (Pandemrix) to narcolepsy patients increased the frequency of T cells reactive to the two epitopes. Further studies showed that the 2009 H1N1 strain targeted by the vaccine contained an epitope with homology to the two HCRT epitopes linked to narcolepsy.
“Our data indicate the presence of CD4+ T cells that are reactive to HCRT in narcolepsy patients and possible molecular mimicry between HCRT and a similar epitope in influenza pH1N1, pHA1275-287,” De la Herran-Arita and colleagues conclude.
The study was partially funded by GlaxoSmithKline (maker of Pandemrix) and Jazz Pharmaceutical (maker of a narcolepsy treatment). One author has been a paid consultant to both companies. Several authors are named as inventors on patents related to the study.