Autoantibodies in Pandemrix (R)-induced narcolepsy: Nine candidate autoantigens fail the conformational autoantibody test
AUTOIMMUNITY
Authors: Wallenius, Madeleine; Lind, Alexander; Akel, Omar; Karlsson, Emma; Svensson, Markus; Arvidsson, Elin; Ramelius, Anita; Torn, Carina; Palm, Lars; Lernmark, Ake; Larsson, Helena Elding
Abstract
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 (R). 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/alpha-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 (R) 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. I-125-labelled HCRT1 and HCRT2 were commercially available while S-35-methionine-labelled ppHypocretin, HCRTR2, TRIB2, alpha-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 (R)-induced NT1.
Messenger RNA expression profile of sleep-related genes in peripheral blood cells in patients with chronic kidney disease
CLINICAL AND EXPERIMENTAL NEPHROLOGY
Authors: Kitajima, Shinji; Iwata, Yasunori; Furuichi, Kengo; Sagara, Akihiro; Shinozaki, Yasuyuki; Toyama, Tadashi; Sakai, Norihiko; Shimizu, Miho; Sakurai, Takeshi; Kaneko, Shuichi; Wada, Takashi
Abstract
Various sleep abnormalities, such as delayed sleep onset, frequent awakening and daytime sleepiness, deteriorate the quality of life in patients with chronic kidney disease (CKD), including those on haemodialysis (HD). Although there are some candidate causative molecules in the central nervous system, the contribution of peripheral blood cells (PBCs) remains unclear. In this study, we performed polysomnographic analysis in CKD patients and used PBCs to examine the expression of genes related to sleep and wakefulness states. Polysomnographic analysis was performed in 9 CKD patients and 6 controls. Genes related to sleep and wakefulness were evaluated by RNA microarray in 19 subjects, including CKD patients and control subjects. Polysomnographic analysis revealed that the duration of the rapid eye movement (REM)/non-REM phases during total sleep time was different between CKD patients and healthy controls. In mRNA microarray evaluation, hierarchical clustering analysis showed different patterns of sleep-related gene expression in HD patients. mRNA expression levels of GABA receptor (GABBR2), noradrenaline receptor (ADRA1A), dopamine receptor (DRD1) and histamine receptor (HRH1) showed an inverse correlation with renal function. Moreover, the mRNA expression of orexin and its receptor (HCRTR1 and HCRTR2) was also inversely correlated with renal function. These data indicate that the expression of sleep-related genes in PBCs of CKD patients may be associated with sleep abnormalities.