Atrial fibrillation (AF) is highly prevalent in hypertensive patients with
metabolic syndrome and is related to
inflammation and activation of the sympathoadrenergic system. The multi-
ligand Receptor-for-Advanced-Glycation-End-products (RAGE) activates
inflammation-associated tissue remodeling and is regulated by the sympathetic nervous system. Its counterpart, soluble RAGE (sRAGE), serves as anti-inflammatory decoy receptor with protective properties. We investigated the effect of sympathetic modulation by renal
denervation (RDN) on
atrial remodeling, RAGE/sRAGE and RAGE
ligands in
metabolic syndrome. RDN was performed in spontaneously hypertensive obese rats (SHRob) with
metabolic syndrome compared with lean spontaneously hypertensive rats (SHR) and with normotensive non-obese control rats. Blood pressure and heart rate were measured by telemetry. The animals were killed 12 weeks after RDN. Left atrial (LA) and right atrial (RA) remodeling was assessed by histological analysis and
collagen types. Sympathetic innervation was measured by
tyrosine hydroxylase staining of atrial nerve fibers, RAGE/sRAGE, RAGE
ligands,
cytokine expressions and inflammatory infiltrates were analyzed by Western blot and immunofluorescence staining. LA sympathetic nerve fiber density was higher in SHRob (+44%) versus controls and reduced after RDN (-64% versus SHRob). RAGE was increased (+718%) and sRAGE decreased (- 62%) in SHRob as compared with controls. RDN reduced RAGE expression (- 61% versus SHRob), significantly increased sRAGE levels (+162%) and induced a significant decrease in RAGE
ligand levels in SHRob (- 57% CML and - 51%
HMGB1) with reduced pro-inflammatory NFkB activation (- 96%),
IL-6 production (- 55%) and reduced inflammatory infiltrates. This led to a reduction in atrial
fibrosis (- 33%),
collagen type I content (- 72%), accompanied by reduced LA myocyte
hypertrophy (- 21%). Transfection experiments on H9C2 cardiomyoblasts demonstrated that RAGE is directly involved in
fibrosis formation by influencing cellular production of
collagen type I. In conclusion, suppression of renal sympathetic nerve activity by RDN prevents
atrial remodeling in
metabolic syndrome by reducing atrial sympathetic innervation and by modulating RAGE/sRAGE balance and reducing pro-inflammatory and pro-fibrotic RAGE
ligands, which provides a potential therapeutic mechanism to reduce the development of AF.