Injection of recombinant IL-6 protein dose-dependently increased the incidence of spontaneous atrial fibrillation in mice, from 0% at 15 ng/kg to 75% at 180 ng/kg (P=0.005).
RCT
randomly divided
Does recombinant IL-6 injection induce spontaneous atrial fibrillation in mice?
Atrial injection of IL-6 induces spontaneous atrial fibrillation in mice in a dose-dependent manner, suggesting a causal relationship and highlighting IL-6 inhibition as a potential preventive strategy for postoperative AF.
p-value: p=0.005
Abstract Background Cumulative evidence suggests that atrial interleukin-6 (IL-6) may play a significant role in the development of spontaneous postoperative atrial fibrillation (sPOAF) in coronary artery bypass grafting (CABG) patients. Our previous studies found that the IL-6 produced by the atrium is positively related to the development of sPOAF. However, the causal relationship between IL-6 and sPOAF is not established. Purpose This study aims to explore the potential causality between atrial IL-6 and spontaneous AF(sAF), alongside assessing the impact of IL-6 on the electrophysiological properties of atrial myocytes (AM). Methods To determine the causal link between IL-6 and sAF, mice were randomly divided into eight groups: seven receiving injections of varying doses of recombinant IL-6 protein groups (15ng/kg to180ng/kg) into the left atrial wall, and one control group (vehicle). Mice were monitored for sAF for 7 days using implanted telemetry device. At 48 hrs post-injection, the left atrial appendages of another set of mice were collected for analyzing levels of IL-6, Myeloperoxidase (MPO), Transforming Growth Factor-β1 (TGF-β1), and Tumor Necrosis Factor-α (TNF-α). To assess the effect of IL-6 on the electrophysiological characteristics of AM, AMs were isolated from the hearts of 12-week-old mice and divided into experimental and control groups for electrophysiological testing. The experimental group was perfused with extracellular solutions containing 100 ng/mL of IL-6 while the control group was perfused with standard extracellular solutions. The measurements focused on action potential (AP), transient outward potassium current (Ito), and inward rectifier potassium current (Ik1) after a 30-minute perfusion. Results As depicted in Fig. 1A, a dose-response relationship between IL-6 levels and sAF occurrence was observed, with incidence increasing from 0% at 15 ng/kg to 75% at 180 ng/kg (χ²= 16.691, P = 0.005). The injection of IL-6 also induced the production of MPO, TGF-β1, and TNF-α with a dose-dependent effects (Fig. 2). In comparison to control, the AP duration at 90% (APD90) and APD50 of repolarization of atrial myocytes were significantly shortened in IL-6 group (Fig. 1B). For voltages from -10mV to +70mV, atrial myocytes in the IL-6 group showed significantly lower Ito current density than those in the control (Fig. 1C). No significant alterations were observed in the impact of IL-6 on Ik1 current density in atrial myocytes (Fig.1D). Conclusion To the best of our knowledge, this is the first study that experimentally tested the causal relation between IL-6 and sAF. The injection of IL-6 could cause the onset of sAF and produce MPO, TGF-β1, and TNF-α with a significant dose-dependent effect. The effect of IL-6 on inducing sAF might be through its effect on reducing APD and Ito current density in mouse atrial myocytes. This suggests that inhibition of atrial IL-6 might be a potential novel sPOAF prevention strategy.
Wu et al. (Tue,) conducted a rct in spontaneous atrial fibrillation (sAF). recombinant IL-6 protein vs. vehicle was evaluated on occurrence of spontaneous atrial fibrillation (sAF) (p=0.005). Injection of recombinant IL-6 protein dose-dependently increased the incidence of spontaneous atrial fibrillation in mice, from 0% at 15 ng/kg to 75% at 180 ng/kg (P=0.005).