0214 : Mineralocorticoid Receptor (MR) activation induces the expression of Neutrophil Gelatinase-Associated Lipocalin (NGAL) in dendritic cells in vitro and during the aldosterone-dependent hypertension

Abstract

Inadequate activation of the Mineralocorticoid Receptor (MR) promotes hypertension, inflammation and fibrosis. Neutrophil Gelatinase- Associated Lipocalin (NGAL), a pro-inflammatory/fibrotic glycoprotein, is a target of MR-genomic upregulation in cardiovascular cells, and is increased in immune cells during inflammation. Recently, we have demonstrated that NGAL is crucial for hypertensive effects of aldosterone-salt (NAS) challenge in mice. The specific cell types that modulate the NGAL production during Aldosterone (Aldo)-dependent hypertension are unknown. The aim was to characterize the NGAL expression in mouse immune cells, and to study the effect of MR activation on the NGAL and pro-inflammatory cytokines expression in dendritic cells (DCs). Male C57Bl6 mice were treated in groups Sham and NAS (200μg/kg/d, 28 days). Peripheral blood mononuclear cells (PBMC) were isolated, and CD4 + , CD8 + T cells, B cells, DCs and Macrophages (Mø) were sorted from spleen. DCs and Mø were cultured from WT and NGAL-KO mice and treated with Aldo (100nM) or vehicle for 24hrs. NGAL and cytokines mRNAs abundance was measured by qRT-PCR. NAS mice presented high systolic blood pressure (123 mmHg vs. Sham 101±6 mmHg, p<0.05), cardiac and renal hypertrophy. Additionally, NAS treatment induced a selective increase in the recruitment of activated- CD8 + cells, B cells and granulocytes in lymph nodes. NGAL abundance was higher in PBMC, DCs and Mø, which were further increased in NAS mice (<3-fold vs. Sham, p<0.05 mRNA). In vitro MR activation by Aldo in DCs, but not in Mø, induced an upregulation of NGAL and of cytokines involved in the adaptive immune response: TGF-β1 and IL-23p19 (n=4, p<0.05). Interestingly, the NGAL absence in DCs prevented this overexpression. The MR activation and their subsequent NGAL induction in DCs could play a pivotal role in the inflammation observed during the Aldodependent hypertension.