A potential link between left stellate ganglion and renal sympathetic nerve: An important mechanism for cardiac arrhythmias?

Renal denervation achieves its antiarrhythmic effect through attenuating macrophage activation and neuroinflammation in stellate ganglia in chronic heart failure

AIMS

Renal denervation (RDN) is widely investigated in multiple studies of sympathetically driven cardiovascular diseases. While the therapeutic potential of RDN for ventricular arrhythmia has been reported, the mechanisms responsible for its antiarrhythmic effect are poorly understood. Our recent study showed that macrophage expansion-induced neuroinflammation in the stellate ganglion (SG) was a critical factor for cardiac sympathetic overactivation and ventricular arrhythmogenesis in chronic heart failure (CHF). This study investigates if and how RDN decreases ventricular arrhythmias by attenuating neuroinflammation in cardiac sympathetic postganglionic (CSP) neurons in CHF.

METHODS AND RESULTS

Rat CHF was induced by surgical ligation of the left anterior descending coronary artery (LAD). At 12 weeks after LAD ligation, completed bilateral RDN was achieved by surgically cutting all the visible renal nerves around the renal artery and vein, followed by applying of 70% ethanol around the vessels. Immunofluorescence staining and Western blot data showed that expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) and its receptor-α subunit (GM-CSFRα) in SGs was increased in CHF rats. RDN not only reduced CHF-elevated GM-CSF levels in kidney, serum and SGs, but also attenuated macrophage expansion and neuroinflammation in SGs from CHF rats. Using flow cytometry, we confirmed that RDN reduced the percentage of macrophages in SGs, which is pathologically increased in CHF. RDN also decreased CHF-enhanced N-type Ca2+ currents in CSP neurons and attenuated CHF-elevated cardiac sympathetic nerve activity. ECG data from 24-hour continuous telemetry recording in conscious rats revealed that RDN improved CHF-induced heterogeneity of ventricular electrical activities and reduced the duration of spontaneous ventricular tachyarrhythmias in CHF rats.

CONCLUSIONS

RDN alleviates cardiac sympathetic overactivation and ventricular arrhythmogenesis through attenuating GM-CSF-induced macrophage activation and neuroinflammation within SGs in CHF. This suggests that manipulation of the GM-CSF signaling pathway could be a novel strategy for achieving the antiarrhythmic effect of RDN in CHF.

Impacts of Renal Sympathetic Activation on Atrial Fibrillation: The Potential Role of the Autonomic Cross Talk Between Kidney and Heart

Background

Recent studies have demonstrated that there is a high variability of renal sympathetic nerve density distribution from proximal to distal renal artery segments. The aim of our study was to investigate the roles of renal sympathetic nerve stimulation (RSS) on atrial fibrillation and cardiac autonomic nervous activity.

Methods and Results

Twenty‐eight dogs were randomly assigned to the proximal RSS group (P‐RSS, N=7), middle RSS group (M‐RSS, N=7), distal RSS group (D‐RSS, N=7), and the control group (sham RSS, N=7). RSS was performed using electrical stimulation on the bilateral renal arteries for 3 hours. Effective refractory period and the window of vulnerability were measured at atrial and pulmonary veins sites. Superior left ganglionated plexi (SLGP) and left stellate ganglion (LSG) function and neural activity were determined. C‐fos and nerve growth factor protein expression in the SLGP and LSG were examined. Only P‐RSS (1) caused pronounced blood pressure rises, induced a significant decrease in effective refractory period, and generated a marked increase in cumulative window of vulnerability and effective refractory period dispersion; (2) increased the frequency and amplitude of the neural activity in the SLGP and LSG; (3) increased SLGP and LSG function; and (4) upregulated the level of c‐fos and nerve growth factor expression in the SLGP and LSG.

Conclusions

This study demonstrated that renal sympathetic nerve activation induced by 3 hours of P‐RSS facilitated atrial fibrillation inducibility by upregulating cardiac autonomic nervous activity, suggesting a potential autonomic cross talk between kidney and heart.

Rebuilding a broken heart: lessons from developmental and regenerative biology

In May 2016, the annual Weinstein Cardiovascular Development and Regeneration Conference was held in Durham, North Carolina, USA. The meeting assembled leading investigators, junior scientists and trainees from around the world to discuss developmental and regenerative biological approaches to understanding the etiology of congenital heart defects and the repair of diseased cardiac tissue. In this Meeting Review, we present several of the major themes that were discussed throughout the meeting and highlight the depth and range of research currently being performed to uncover the causes of human cardiac diseases and develop potential therapies.