title: Association of β1-Adrenergic, M2-Muscarinic Receptor Autoantibody with Occurrence and Development of Nonvalvular Atrial Fibrillation.
abstract: BACKGROUND
  Atrial fibrillation (AF) is the most common sustained arrhythmia and is independently associated with increased risk of stroke and death. Although the exact mechanisms of AF are not completely elucidated, a large number of evidences demonstrate that autoimmunity may play an important role in the initiation, the progression, and the maintenance of AF. In this study, we aimed to compare anti-β1-adrenergic receptor autoantibody (anti-β1-R) and anti-M2-muscarinic receptor autoantibody (anti-M2-R) levels between nonvalvular AF patients and healthy control subjects.
  
  
  METHODS
  The levels of serum anti-β1-R, antinuclear antibodies, and anti-M2-R were measured in both groups by enzyme-linked immunosorbent assay (ELISA). High-sensitivity C-reactive protein (hs-CRP) and interleukin (IL)-6 concentration were measured, respectively, by immunoturbidimetry and chemiluminescence.
  
  
  RESULTS
  Anti-β1-R and anti-M2-R levels were significantly higher in patients with nonvalvular AF than in healthy controls (anti-β1-R 221.11 [132.38-291.69] ng/mL vs 198.14 [125.70-278.40] ng/mL, P < 0.01; anti-M2-R 271.81 [144.99-378.20] ng/mL vs 235.01 [121.53-358.99] ng/mL, P < 0.01). Compared with the control group, the serum levels of IL-6 and hs-CRP were higher in the nonvalvular AF group (IL-6 19.65 ± 5.6 pg/mL vs 6.79 ± 1.09 pg/mL, hs-CRP 6.03 ± 1.35 mg/L vs 2.73 ± 0.63 mg/L, P < 0.05). Antinuclear antibody (ANA) levels were similar between two groups (ANA 10.55 [1.86-271.8] U/mL vs 10.49 [1.303-161.7] U/mL, P > 0.05). The baseline value of serum anti-β1-R (odds ratio [OR]: 13.176, P < 0.001), anti-M2-R (OR: 4.41, P < 0.001), IL-6 (OR: 6.126, P < 0.05) levels, and left atrial diameter (OR: 5.781, P < 0.05) were independent predictors of nonvalvular AF by multivariable analyses.
  
  
  CONCLUSIONS
  We found a significant association between circulating serum anti-β1-R, anti-M2-R, IL-6 levels, and nonvalvular AF. We presume that the autoimmunity and inflammation might take part in electrical remodeling and structural remodeling of left atrium.
authors.affiliation: Department of Cardiology, Zhongshan Affiliated Hospital of Sun Yat-sen University, Zhongshan, Guangdong, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Hu
authors.affiliation: Department of Cardiology, Zhongshan Affiliated Hospital of Sun Yat-sen University, Zhongshan, Guangdong, China.
authors.forename: Yanxiang
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Laboratory Diagnosis, Zhongshan Affiliated Hospital of Sun Yat-sen University, Zhongshan, Guangdong, China.
authors.forename: Sha
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Cardiology, Zhongshan Affiliated Hospital of Sun Yat-sen University, Zhongshan, Guangdong, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Sun
authors.affiliation: Department of Cardiology, Zhongshan Affiliated Hospital of Sun Yat-sen University, Zhongshan, Guangdong, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Liu
authors.affiliation: Department of Cardiology, Zhongshan Affiliated Hospital of Sun Yat-sen University, Zhongshan, Guangdong, China.
authors.forename: Zidi
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Department of Cardiology, Zhongshan Affiliated Hospital of Sun Yat-sen University, Zhongshan, Guangdong, China.
authors.forename: L I
authors.initials: LI
authors.lastname: Feng
mesh_terms: D001281:Atrial Fibrillation / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D015415:Biomarkers / Q000097:blood; D002681:China / Q000453:epidemiology; D018450:Disease Progression; D005260:Female; D006349:Heart Valve Diseases / Q000097:blood / Q000453:epidemiology / Q000276:immunology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D043585:Receptor, Muscarinic M2 / Q000097:blood / Q000276:immunology*; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D043585:Receptor, Muscarinic M2
keywords: anti-M2-muscarinic receptor autoantibody; anti-β1-adrenergic receptor autoantibody; atrial fibrillation; autoimmunity