Anti-Tribbles homolog 2 autoantibodies in Japanese patients with narcolepsy.
OBJECTIVE
Narcolepsy is a sleep disorder characterized by excessive daytime sleepiness and cataplexy. The association with human leukocyte antigen (HLA)-DQB1*0602 and T-cell receptor alpha locus suggests that autoimmunity plays a role in narcolepsy. A recent study reported an increased prevalence of autoantibodies against Tribbles homolog 2 (TRIB2) in patients with narcolepsy. To replicate this finding, we examined anti-TRIB2 autoantibodies in Japanese patients with narcolepsy.


METHODS
We examined anti-TRIB2 autoantibodies against a full-length [35S]-labeled TRIB2 antigen in Japanese patients with narcolepsy-cataplexy (n = 88), narcolepsy without cataplexy (n = 18), and idiopathic hypersomnia with long sleep time (n = 11). The results were compared to Japanese healthy controls (n = 87). Thirty-seven healthy control subjects were positive for HLA-DRB1*1501-DQB1*0602. We also examined autoantibodies against another Tribbles homolog, TRIB3, as an experimental control.


RESULTS
Autoantibodies against TRIB2 were found in 26.1% of patients with narcolepsy-cataplexy, a significantly higher prevalence than the 2.3% in healthy controls. We found that anti-TRIB3 autoantibodies were rare in patients with narcolepsy and showed no association with anti-TRIB2 indices. No significant correlation was found between anti-TRIB2 positivity and clinical information.


CONCLUSIONS
We confirmed the higher prevalence and specificity of anti-TRIB2 autoantibodies in Japanese patients with narcolepsy-cataplexy. This suggests a subgroup within narcolepsy-cataplexy might be affected by an anti-TRIB2 autoantibody-mediated autoimmune mechanism.
Toyoda
Hiromi
H
Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Tanaka
Susumu
S
Miyagawa
Taku
T
Honda
Yutaka
Y
Tokunaga
Katsushi
K
Honda
Makoto
M
D000328:Adult; D001323:Autoantibodies / Q000276:immunology*; D015551:Autoimmunity / Q000276:immunology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000276:immunology*; D007564:Japan; D008297:Male; D009290:Narcolepsy / Q000276:immunology*; D011869:Radioligand Assay / Q000379:methods
D001323:Autoantibodies; D047908:Intracellular Signaling Peptides and Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C489044:TRIB2 protein, human