Autoantibodies in Pandemrix®-induced narcolepsy: Nine candidate autoantigens fail the conformational autoantibody test

• Published in: Autoimmunity (Chur, Switzerland) Vol. 52; no. 4; pp. 185 - 191
• Main Authors: Wallenius, Madeleine, Lind, Alexander, Akel, Omar, Karlsson, Emma, Svensson, Markus, Arvidsson, Elin, Ramelius, Anita, Törn, Carina, Palm, Lars, Lernmark, Åke, Elding Larsson, Helena
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 19-05-2019; Taylor & Francis Group
• Subjects: Adolescent; Adult; Aged; Autoantibodies; Autoantibodies - immunology; Autoantigens - immunology; autoimmunity; Basic Medicine; Child; Clinical Medicine; Female; HLA-DQ beta-Chains - genetics; Humans; hypocretin/orexin; Immunologi inom det medicinska området; Immunology in the medical area; Influenza Vaccines - adverse effects; Klinisk medicin; Male; Mass Vaccination - adverse effects; Medical and Health Sciences; Medicin och hälsovetenskap; Medicinska och farmaceutiska grundvetenskaper; Middle Aged; Narcolepsy - chemically induced; Narcolepsy - immunology; narcolepsy type 1; Pandemrix®-vaccination; Radioligand Assay - methods; Sweden; Young Adult; Sweden; Pandemrix®-vaccination; hypocretin/orexin; Autoantibodies; autoimmunity; narcolepsy type 1
• ISSN: 0891-6934; 1607-842X
• DOI: 10.1080/08916934.2019.1643843

Study objectives: Narcolepsy type 1 (NT1) is a chronic sleep disorder characterized by loss of hypocretin-producing neurons. Increased NT1 incidence was observed in Sweden following mass-vaccination with Pandemrix
®
. Genetic association to HLA DQB1*06:02 implies an autoimmune origin, but target autoantigen remains unknown. Candidate autoantigens for NT1 have previously been identified in solid-phase immunoassays, while autoantibodies against conformation-dependent epitopes are better detected in radiobinding assays. The aims are to determine autoantibody levels against nine candidate autoantigens representing (1) proteins of the hypocretin transmitter system; Preprohypocretin (ppHypocretin), Hypocretin peptides 1 and 2 (HCRT1 and HCRT2) and Hypocretin receptor 2 (HCRTR2); (2) proteins previously associated with NT1; Tribbles homologue 2 (TRIB2), Pro-opiomelanocortin/alpha-melanocyte-stimulating-hormone (POMC/α-MSH) and Prostaglandin D2 Receptor DP1 (DP1); (3) proteins suggested as autoantigens for multiple sclerosis (another HLA DQB1*06:02-associated neurological disease); ATP-dependent Inwardly Rectifying Potassium Channel Kir4.1 (KIR4.1) and Calcium-activated chloride channel Anoctamin 2 (ANO2).
Methods: Serum from post-Pandemrix
®
NT1 patients (n = 31) and their healthy first-degree relatives (n = 66) were tested for autoantibody levels in radiobinding assays separating autoantibody bound from free labelled antigen with Protein A-Sepharose.
125
I-labelled HCRT1 and HCRT2 were commercially available while
35
S-methionine-labelled ppHypocretin, HCRTR2, TRIB2, α-MSH/POMC, DP1, KIR4.1 or ANO2 was prepared by in vitro transcription translation of respective cDNA. In-house standards were used to express data in arbitrary Units/ml (U/ml).
Results: All radiolabelled autoantigens were detected in a concentration-dependent manner by respective standard sera. Levels of autoantibodies in the NT1 patients did not differ from healthy first-degree relatives in any of the nine candidate autoantigens.
Conclusions: None of the nine labelled proteins proposed to be autoantigens were detected in the radiobinding assays for conformation-dependent autoantibodies. The results emphasise the need of further studies to identify autoantigen(s) and clarify the mechanisms in Pandemrix
®
-induced NT1.