1. LNK/SH2B3 loss of function increases susceptibility to murine and human atrial fibrillation.
- Author
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Murphy MB, Yang Z, Subati T, Farber-Eger E, Kim K, Blackwell DJ, Fleming MR, Stark JM, Van Amburg JC, Woodall KK, Van Beusecum JP, Agrawal V, Smart CD, Pitzer A, Atkinson JB, Fogo AB, Bastarache JA, Kirabo A, Wells QS, Madhur MS, Barnett JV, and Murray KT
- Subjects
- Animals, Female, Humans, Male, Benzylamines pharmacology, Genetic Predisposition to Disease, Heart Rate drug effects, Inflammation Mediators metabolism, Intracellular Signaling Peptides and Proteins genetics, Intracellular Signaling Peptides and Proteins metabolism, Mitochondria, Heart metabolism, Mitochondria, Heart pathology, Mitochondria, Heart drug effects, Oxidative Stress drug effects, Phenotype, Signal Transduction, Tumor Necrosis Factor-alpha metabolism, Tumor Necrosis Factor-alpha genetics, Action Potentials drug effects, Adaptor Proteins, Signal Transducing genetics, Adaptor Proteins, Signal Transducing metabolism, Atrial Fibrillation metabolism, Atrial Fibrillation physiopathology, Atrial Fibrillation genetics, Disease Models, Animal, Interleukin-1beta metabolism, Interleukin-1beta genetics, Mice, Inbred C57BL, Mice, Knockout, Myocytes, Cardiac metabolism, Myocytes, Cardiac drug effects, Myocytes, Cardiac pathology
- Abstract
Aims: The lymphocyte adaptor protein (LNK) is a negative regulator of cytokine and growth factor signalling. The rs3184504 variant in SH2B3 reduces LNK function and is linked to cardiovascular, inflammatory, and haematologic disorders, including stroke. In mice, deletion of Lnk causes inflammation and oxidative stress. We hypothesized that Lnk-/- mice are susceptible to atrial fibrillation (AF) and that rs3184504 is associated with AF and AF-related stroke in humans. During inflammation, reactive lipid dicarbonyls are the major components of oxidative injury, and we further hypothesized that these mediators are critical drivers of the AF substrate in Lnk-/- mice., Methods and Results: Lnk-/- or wild-type (WT) mice were treated with vehicle or 2-hydroxybenzylamine (2-HOBA), a dicarbonyl scavenger, for 3 months. Compared with WT, Lnk-/- mice displayed increased AF duration that was prevented by 2-HOBA. In the Lnk-/- atria, action potentials were prolonged with reduced transient outward K+ current, increased late Na+ current, and reduced peak Na+ current, pro-arrhythmic effects that were inhibited by 2-HOBA. Mitochondrial dysfunction, especially for Complex I, was evident in Lnk-/- atria, while scavenging lipid dicarbonyls prevented this abnormality. Tumour necrosis factor-α (TNF-α) and interleukin-1 beta (IL-1β) were elevated in Lnk-/- plasma and atrial tissue, respectively, both of which caused electrical and bioenergetic remodelling in vitro. Inhibition of soluble TNF-α prevented electrical remodelling and AF susceptibility, while IL-1β inhibition improved mitochondrial respiration but had no effect on AF susceptibility. In a large database of genotyped patients, rs3184504 was associated with AF, as well as AF-related stroke., Conclusion: These findings identify a novel role for LNK in the pathophysiology of AF in both experimental mice and humans. Moreover, reactive lipid dicarbonyls are critical to the inflammatory AF substrate in Lnk-/- mice and mediate the pro-arrhythmic effects of pro-inflammatory cytokines, primarily through electrical remodelling., Competing Interests: Conflict of interest: K.T.M. has a pending patent application, and A.K. is a co-inventor on US Patent # 14/232,615, both with Metabolic Technologies, Inc. and Vanderbilt University., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
- Published
- 2024
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