MONOCYTE DERIVED CYTOKINES INDUCE ENDOTHELIAL DYSFUNCTION IN PATIENTS WITH PRIMARY ALDOSTERONISM

Abstract

Objective: Due to aldosterone excess and its pleotropic effects patients with primary aldosteronism (PA) are exposed to high rates of cardiovascular events. Endothelial dysfunction, as a part of vascular disease, is one of the earliest changes related to high cardiovascular risk and monocytes are the main immune cells participating in the development of vascular wall damage. Therefore, we ought to compare endothelial function between PA patients and healthy controls. Next, we wanted to estimate, if monocytes are able to induce endothelial dysfunction solely by their secretome. Design and method: 13 healthy controls and 42 PA patients received flow mediated dilation measurements (FMD). Later, monocytes were isolated from 8 PA patients and 6 healthy individuals and placed in cell culture. 24 hours later supernatants were collected for cytokine measurements using Human Cytokine 17-plex Assay (Bio-rad). Effects of monocyte derived cytokines on endothelial function were assessed using wire Myograph (Danish Myo Technology). Pre-contraction was induced by norepinephrine (1μM) (Sigma) followed by cumulative concentration response curve to carbachol (0.3μM-300μM) (Sigma). Results: FMD was significantly lower among PA patients (6.3(3.8-8.1)% vs 10.5 ± 3%, p < 0.05). Furthermore, monocytes from patients with PA secreted significantly higher concentrations of following cytokines and growth factors than healthy controls: G-CSF, IFN-gamma, TNF-alfa, IL-6, IL-10, IL-8, IL-17, and MCP-1. Especially concentrations of IL-6 (388 (351-580)pg/ml vs 36(4-268)pg/ml, p < 0.05) and TNF-alfa (95(48-135)pg/ml vs 17(5-41)pg/ml, p < 0.05) were much higher among PA patients. Incubation of mouse thoracic aorta with this monocyte secretome for 24 hours revealed stronger vascular contraction than using supernatant from healthy controls. In pre-constricted murine aortas, maximal dilation of 87.9 ± 11% was reached using aortas incubated in PA monocyte secretome whereas a dilation of 90.9 ± 9.1% was reached in controls. Indeed, carbachol EC50 for aortas incubated in monocyte secretome derived from healthy controls was 1.0mkM and 1.9mkM for PA patients. Conclusions: PA patients demonstrate endothelial dysfunction measured by FMD. Moreover, monocytes isolated from these patients are characterized by high secretion of pro-inflammatory cytokines which induce endothelial dysfunction, one of mechanisms triggering vascular dysfunction among these patients.