title: Provocation of an autoimmune response to cardiac voltage-gated sodium channel NaV1.5 induces cardiac conduction defects in rats.
abstract: OBJECTIVE
  This study sought to test the hypothesis that inducing an autoimmune response against the cardiac sodium channel (NaV1.5) induces arrhythmias.
  
  
  BACKGROUND
  Sporadic evidence supports the concept that autoantibodies may cause cardiac arrhythmias but substantial experimental investigations using in vivo models have been lacking to date. The NaV1.5 is essential for cardiac impulse propagation and its dysfunction has been linked to conduction disease.
  
  
  METHODS
  Rats were immunized with a peptide sequence derived from the third extracellular loop of the first domain of NaV1.5. After 28 days, we evaluated in vivo both the electrical and mechanical parameters of cardiac function. Histopathology, myocardial gene and protein expression were assessed. Whole-cell patch-clamp was used to measure sodium current (INa) density in isolated cardiomyocytes.
  
  
  RESULTS
  NaV1.5-immunized rats had high titers of autoantibodies against NaV1.5. On ECG recording, NaV1.5-immunized animals showed significantly prolonged PR-intervals. During Holter ECG-monitoring we observed repeated prolonged episodes of third-degree atrioventricular and sinoatrial block in every NaV1.5-immunized animal, but not in controls. Immunization had no effect on cardiac function. In comparison to controls, myocardial NaV1.5 mRNA and protein levels were decreased in immunized rats. INa density was reduced in cardiomyocytes incubated with sera from NaV1.5-immunized rats and from patients with idiopathic atrioventricular block (AVB) in comparison to sera from respective controls. In patients with idiopathic AVB, we observed autoantibodies against NaV1.5 that were absent in sera from healthy controls.
  
  
  CONCLUSIONS
  Provocation of an autoimmune response against NaV1.5 induces conductance defects probably caused by a reduced expression level and an inhibition of NaV1.5 by autoantibodies, resulting in decreased INa.
authors.affiliation: Department of Cardiac Surgery, University of Heidelberg, Heidelberg, Germany.
authors.forename: Sevil
authors.initials: S
authors.lastname: Korkmaz
authors.forename: Edgar
authors.initials: E
authors.lastname: Zitron
authors.forename: Anna
authors.initials: A
authors.lastname: Bangert
authors.forename: Claudia
authors.initials: C
authors.lastname: Seyler
authors.forename: Shiliang
authors.initials: S
authors.lastname: Li
authors.forename: Peter
authors.initials: P
authors.lastname: Hegedüs
authors.forename: Daniel
authors.initials: D
authors.lastname: Scherer
authors.forename: Jin
authors.initials: J
authors.lastname: Li
authors.forename: Thomas
authors.initials: T
authors.lastname: Fink
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Schweizer
authors.forename: Evangelos
authors.initials: E
authors.lastname: Giannitsis
authors.forename: Matthias
authors.initials: M
authors.lastname: Karck
authors.forename: Gábor
authors.initials: G
authors.lastname: Szabó
authors.forename: Hugo A
authors.initials: HA
authors.lastname: Katus
authors.forename: Ziya
authors.initials: Z
authors.lastname: Kaya
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000276:immunology*; D001323:Autoantibodies / Q000096:biosynthesis*; D001327:Autoimmune Diseases / Q000276:immunology*; D006329:Heart Conduction System / Q000276:immunology*; D008297:Male; D008969:Molecular Sequence Data; D062554:NAV1.5 Voltage-Gated Sodium Channel / Q000235:genetics / Q000276:immunology*; D011897:Random Allocation; D051381:Rats; D011917:Rats, Inbred Lew
chemical_list: D001323:Autoantibodies; D062554:NAV1.5 Voltage-Gated Sodium Channel; C568322:Scn5a protein, rat
keywords: AVB; ECG; H&E; I(Na); I(to); LV; MMP; Na(V)1.5; SCN5A; TIMP; atrioventricular block; autoantibodies; autoimmunity; cardiac sodium channel; cardiac transient outward potassium current; cardiac voltage-gated sodium channel α-subunit; cardiac voltage-gated sodium channel α-subunit gene; cardiac voltage-gated sodium-channel current; conduction defect; dP/dt(max); dP/dt(min); electrocardiography; hematoxylin and eosin; left ventricular; matrix metalloproteinase; maximal slope of the diastolic pressure decrement; maximal slope of the systolic pressure increment; tissue inhibitor of metalloproteinase