Abstract Body: Background:
Inflammation increases the risk of cardiac arrhythmias. The proinflammatory cytokine interleukin-17 (IL17A, IL17F, and IL17A/F) has been implicated in cardiovascular disease. Our pilot data suggest that IL17A activates stress-response kinase JNK2 contributing to enhanced arrhythmogenesis. The molecular and electrophysiological relationship between IL17 and JNK2 in arrhythmogenesis remains unknown.
Objectives:
We hypothesize that IL17 activates a signaling cascade converging on the pro-arrhythmic kinase JNK2, thereby driving arrhythmogenic Ca²⁺ dysregulation.
Methods:
Atrial and ventricular cardiomyocytes from adult male and female New Zealand White rabbits (n=16) were treated with IL17A, IL17F, or IL17A/F (5ng/mL; 16-24 h). A JNK2 inhibitor (JNK2i; 40nM), CaMKII inhibitor AIP (1μM), or IL17A-receptor-neutralizing antibody (424LTS; 8μg/mL) were applied 1h prior to IL17 exposure. Tetracaine-sensitive SR Ca²⁺ leak and pacing-induced delayed afterdepolarizations (DADs) were assessed using confocal Ca²⁺ imaging and patch clamp. Protein phosphorylation was assessed by immunoblotting.
Results:
IL17A markedly increased SR Ca²⁺ leak and DADs in atrial and ventricular myocytes (ΔF/F₀=0.12±0.01 vs 0.40±0.05; p<0.01). These effects were abolished by JNK2- or CaMKII-specific inhibition (p<0.01). IL17A increased activation of JNK and CaMKII (p<0.05), but not ERK and p38; these changes were prevented by JNK2 inhibition, supporting JNK2 as a key downstream effector of IL17A. IL17 receptor blockade with 424LTS prevented IL17A-induced JNK2 and CaMKII activation and eliminated SR Ca²⁺ leak (p<0.01), supporting JNK2 activation downstream of IL17A in driving Ca²⁺-triggered arrhythmic activity. IL17A/F produced approximately 50% of the IL17A response, whereas IL17F alone was ineffective, suggesting IL17A as the dominant arrhythmogenic ligand. Additionally, IL17A increased phosphorylation of TAK1 and MKK7 (indicating enhanced activation; p<0.05), whereas 424LTS abolished these changes (p<0.05). Immunoblotting, together with transcriptional signature connectivity analysis using the LINCS database, supported a strong relationship among IL17 receptor, TAK1, and JNK2, suggesting a regulatory role of TAK1 and MKK7 in JNK2 activation. All findings were consistent across sexes and cardiac chambers.
Conclusions:
IL17A drives arrhythmogenic Ca²⁺ dysregulation via a TAK1-MKK7-JNK2-CaMKII cascade, suggesting a potential therapeutic target in inflammation-driven arrhythmogenesis.