Key result
Kir3.4 autoantibodies from unexplained AF patients increase AF susceptibility ~2.8-fold in immunized mice.
Why the study?
In line with the emerging field of autoantibody-related cardiac arrhythmias, this study explored whether autoantibodies targeting cardiac ion channels can underlie unexplained AF.
Do autoantibodies targeting the Kir3.4 protein increase susceptibility to unexplained atrial fibrillation?
Case-Control (n=88)
Do autoantibodies targeting the Kir3.4 protein increase susceptibility to unexplained atrial fibrillation?
Effect estimate: 2.8-fold increase
This study provides the first direct evidence of an autoimmune pathogenesis for unexplained atrial fibrillation mediated by Kir3.4 autoantibodies.
May link Kir3.4 autoimmunity to unexplained AF; hypothesis-generating and requires human validation before clinical relevance.
BACKGROUND: Atrial fibrillation (AF) is by far the most common cardiac arrhythmia. In about 3% of individuals, AF develops as a primary disorder without any identifiable trigger (idiopathic or historically termed lone AF). In line with the emerging field of autoantibody-related cardiac arrhythmias, the objective of this study was to explore whether autoantibodies targeting cardiac ion channels can underlie unexplained AF. METHODS: Peptide microarray was used to screen patient samples for autoantibodies. We compared patients with unexplained AF (n=37 pre-existent AF; n=14 incident AF on follow-up) to age- and sex-matched controls (n=37). Electrophysiological properties of the identified autoantibody were then tested in vitro with the patch clamp technique and in vivo with an experimental mouse model of immunization. RESULTS: A common autoantibody response against K ir 3.4 protein was detected in patients with AF and even before the development of clinically apparent AF. K ir 3.4 protein forms a heterotetramer that underlies the cardiac acetylcholine-activated inwardly rectifying K + current, I KACh . Functional studies on human induced pluripotent stem cell–derived atrial cardiomyocytes showed that anti-K ir 3.4 IgG purified from patients with AF shortened action potentials and enhanced the constitutive form of I KACh , both key mediators of AF. To establish a causal relationship, we developed a mouse model of K ir 3.4 autoimmunity. Electrophysiological study in K ir 3.4-immunized mice showed that K ir 3.4 autoantibodies significantly reduced atrial effective refractory period and predisposed animals to a 2.8-fold increased susceptibility to AF. CONCLUSIONS: To our knowledge, this is the first report of an autoimmune pathogenesis of AF with direct evidence of K ir 3.4 autoantibody-mediated AF.
No takes yet. Share an insight, caveat, or question.
Maguy et al. (2023) conducted a case-control in Unexplained Atrial Fibrillation (n=88). Kir3.4 autoantibodies (exposure) vs. Age- and sex-matched controls was evaluated on Susceptibility to atrial fibrillation (2.8-fold increase). Kir3.4 autoantibodies were detected in patients with unexplained atrial fibrillation and predisposed immunized mice to a 2.8-fold increased susceptibility to AF.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: