Renal Denervation Reduces Postischemic Myocardial Fibrosis by Attenuating M2 Macrophage Polarization

Markus Therre (Homburg/Saar)1, M. Hohl (Homburg/Saar)1, S.-R. Selejan (Homburg/Saar)1, L. Lauder (Homburg/Saar)1, L. Khaldi (Homburg/Saar)1, A. K. D. Huynh (Aachen)2, M. Böhm (Homburg/Saar)1, F. Mahfoud (Homburg/Saar)1

1Universitätsklinikum des Saarlandes Innere Medizin III - Kardiologie, Angiologie und internistische Intensivmedizin Homburg/Saar, Deutschland; 2Uniklinik RWTH Aachen Med. Klinik I - Kardiologie, Angiologie und Internistische Intensivmedizin Aachen, Deutschland


Graphical Abstract

Renal denervation (RDN) has been shown to lower BP in both, the preclinical and clinical setting via modulation of the renal sympathetic nervous system (SNS). The SNS plays a vital role in both activating and limiting immune-inflammatory responses. After myocardial infarction (MI), activation of the SNS induces liberation of inflammatory progenitor cells and monocytes that infiltrate the infarcted myocardium. However, there is no data exploring the correlation between SNS activity, myocardial fibrosis and M2-polarized macrophages.

Material and Methods
In vivo analyses were conducted using 8-week-old Sprague-Dawley rats (n ≥ 6 per group). Myocardial infarction was induced by LAD ligation two days after surgical denervation of both kidneys. Successful RDN was verified by measurement of renal norepinephrine concentration. Six weeks after MI, cardiac function was assessed by small animal MRI imaging and myocardial fibrosis was evaluated by histochemical Sirius Red staining with consecutive polarization microscopy. Cardiac macrophages as well as involved cytokines were investigated by immunochemistry, qPCR, Western Blot (WB) and multiplex analysis. Observed in vivo effects were recapitulated in vitro, using PMA-differentiated THP-1 cells in the presence of isoprenaline and consecutive beta1- or beta2-adrenoceptor (b1- or b2AR) antagonists as a simulation of SNS activity. For characterization of the underlying mechanism qPCR, WB, flow cytometry and multiplex cytokine analyses were carried out, regarding the expression of typical M2 macrophage enzymes, receptors, and cytokines.


Functional MRI analyses found that left ventricular ejection fraction (LVEF) of rats with RDN following MI was with 65 ± 6 % significantly ameliorated compared to animals with MI and Sham-RDN surgery, whose LVEF was 54 ± 7% (p=0.019). Myocardial collagen and profibrotic genes such as TGFb and CTGF increased 5-fold after MI, which was reversed in RDN rats. In RDN rats scar size was reduced by 60 % (p=0.006) compared to MI animals (p<0.05). The amount of fibrosis correlated with the number of CD68+ and CD206+ M2 macrophages, which have been halved in the myocardia of RDN compared to MI rats, respectively (p<0.01). Mechanistically, we showed significant two to threefold upregulation of profibrotic and M2 macrophage gene and protein expression after isoprenaline stimulation. These effects were reversed by co-stimulation with b1AR antagonist CGP, suggesting that SNS activity caused a profibrotic M2 macrophage phenotype via b1AR signaling.


Modulation of SNS activity through RDN in vivo and through b1-AR blockade in vitro reduced fibrosis by attenuating macrophage M2 polarization, thus providing the rationale to further investigate the potential therapeutic effect of RDN in the management of patients with MI.

Diese Seite teilen