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Anti-Ro52 monoclonal antibodies specific for amino acid 200–239, but not other Ro52 epitopes, induce congenital heart block in a rat model
  1. Aurélie Ambrosi1,
  2. Vijole Dzikaite1,
  3. Jeongsook Park2,
  4. Linn Strandberg1,
  5. Vijay K Kuchroo, DVM3,
  6. Eric Herlenius2,
  7. Marie Wahren-Herlenius1
  1. 1Department of Medicine, Karolinska Institutet, Stockholm, Sweden
  2. 2Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
  3. 3Center for Neurological Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
  1. Correspondence to Marie Wahren-Herlenius, Department of Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden; Marie.Wahren{at}ki.se

Abstract

Background Congenital heart block (CHB) may develop in fetuses of women with anti-Ro/La autoantibodies following placental transfer of maternal autoantibodies and disruption of the fetal atrioventricular (AV) conduction system. Animal models of CHB currently rely on immunisation or transfer of anti-Ro/La antibodies purified from mothers of children with CHB, which does not allow precise identification of the disease-inducing antibody specificity.

Objective To determine the ability of different anti-Ro52 monoclonal antibodies to induce cardiac electrophysiological abnormalities in vivo and affect the calcium homoeostasis of cardiomyocytes in vitro.

Methods Monoclonal antibodies recognising different domains of Ro52 were generated and injected into pregnant rats, and ECG was recorded on newborn pups. Cultures of rat neonatal cardiomyocytes were established to assess the effect of the different anti-Ro52 monoclonal antibodies on calcium homoeostasis.

Results First-degree AV block and bradycardia developed after maternal transfer of antibodies specific for amino acids 200–239 of Ro52 (p200), while pups exposed to antibodies targeting N- or C-terminal epitopes of Ro52 did not show any electrocardiogram abnormalities. Addition of an anti-p200 antibody to cultured cardiomyocytes induced calcium dyshomoeostasis in a time- and dose-dependent manner, while addition of other Ro52 antibodies had no effect.

Conclusion These data for the first time show unambiguously that antibodies specific for amino acids 200–239 of Ro52 can induce cardiac conduction defects in the absence of other autoantibodies, and may therefore be the main initiators of cardiac pathology in the pool of anti-Ro52 antibodies in mothers of children with CHB.

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Footnotes

  • AA and VD contributed equally.

  • Competing interests None.

  • Funding Supported by grants from the Swedish Research Council, the Heart-Lung Foundation, the Stockholm County Council, Karolinska Institutet, the Swedish Rheumatism association, the King Gustaf the 5th 80-year foundation, the Göran Gustafsson Foundation and the Torsten and Ragnar Söderberg Foundation.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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