Abstract 69: Role of Neutrophil Gelatinase Associated Lipocalin in Cardiovascular Remodeling Induced by Aldosterone

Abstract

Neutrophil Gelatinase Associated Lipocalin (NGAL) is a circulating protein, member of the lipocalin family, which binds MMP9 and modulates its stability and activity. We have recently shown that NGAL is a primary target of aldosterone/mineralocorticoid receptor (MR) in endothelial cells, vascular smooth muscle cells and cardiomyocytes. We hypothesized that NGAL could be a mediator of aldosterone/MR profibrotic and proinflammatory effects in the cardiovascular system. Wild type (WT) and NGAL Knock Out (KO) mice were subjected to an uni-nephrectomy aldosterone salt challenge (NAS, 200μg/kg/day of aldo, 1% NaCl in tap water) for 4 weeks. Blood pressure (SBP) was measured by tail cuff method. Vascular reactivity was assessed by wire myograph. Cardiovascular fibrosis and inflammation were analyzed by RT-PCR, western blot, immunohistochemistry and ELISA. There was no difference in SBP between NGAL KO mice compared to WT mice in basal condition. With NAS challenge, SBP was increased only in WT (SBP; CT 107±3, CT NAS 133±5, KO 109±3, KO NAS 115±3 mmHg). Ex vivo aortic contraction induced by phenylephrine (Phe) and potassium chloride (KCl) were increased by NAS challenge in WT and KO (Emax Phe; CT 2.28±0.8, CT NAS 10.65±1.3, KO 1.45±0.3, KO NAS 9.32±0.9 mN). Responses to vasodilators (acetylcholine and sodium nitroprussiate) were altered in NAS condition in both groups. Quantification of pro collagen I N-terminal peptide (PINP) in plasma showed an increase of PINP due to NAS treatment in WT that was prevented by NGAL inactivation (CT 83±15, CT NAS 129±10, KO 70±19, KO NAS 59±12 μg/l). In myocardium, NAS treatment increased collagen type I and perivascular fibrosis in WT whereas KO were resistant to fibrosis (Collagen Volume Fraction; CT 19±3, CT NAS 28±2, KO 20±3, KO NAS 20±3 %). In aorta, collagen type I, vascular fibrosis and osteopontin were also increased by NAS in WT. These increases were prevented by NGAL inactivation (CVF; CT 24±4, CT NAS 34±5, KO 21±2, KO NAS 28±2 %). Our results show that NGAL plays a role in aldosterone/MR-mediated hypertension, vascular and cardiac peri-vascular fibrosis and inflammation, but not in vascular dysfunction.