STAT4 Mediates IL-6 Trans-signaling Ventricular Arrhythmias in High Fat Diet Guinea Pig Heart

Obesity is a major risk factor for the development of life-threatening malignant ventricular tachyarrhythmias (VT) and sudden cardiac death (SCD). Risks may be highest for patients with high levels of the proinflammatory cytokine interleukin (IL)-6. We used our guinea pig model of high-fat diet (HFD) induced Ventricular arrhythmias, that exhibit heightened proinflammatory-like pathology which is also observed in human obesity VT, as well as immunofluorescence, and confocal microscopy approaches to evaluate the pathological IL-6 trans-signaling function and explore the underlying mechanisms. Using blind-stick and electrocardiogram (ECG) techniques, we tested the hypothesis that heightened IL-6 trans-signaling exhibit enhanced Ventricular arrhythmias /SCD incidence and underlying arrhythmia substrates. Remarkably, compared to low-fat (LFD) diet fed controls, HFD promotes phosphorylation of the IL-6 signal transducer and activator of transcription 4 (STAT4) leading to its activation and enhanced nuclear translocation of pSTAT4/STAT4 more than LFD controls and pSTAT3/STAT3 nuclear expression. Overactivation of IL-6 trans-signaling in guinea pigs prolonged the QT interval that resulted in greater susceptibility to VT/SCD with isoproterenol challenge, as also observed with the downstream Janus kinase (JAK) 2 activator. These findings may have potentially profound implications for more effective VT therapy in the vulnerable obese patient population.