Abstract P231: Macrophage Neutrophil Gelatinase-associated Lipocalin Has A Critical Role In Aldosterone-induced Renal Fibrosis Via The Ccl5-il4 Pathway.

Abstract

Introduction: Neutrophil Gelatinase-Associated Lipocalin (NGAL) (or lipocalin 2) is a novel mineralocorticoid biotarget in the cardiovascular system. NGAL is also described as an acute renal lesion biomarker and NGAL serum concentration is associated with the severity of renal damages patients with a chronic kidney disease (CKD). Lipocalin2 (Lcn2) gene invalidation in a CKD mouse model protects from proteinuria and renal lesions. Objective: We hypothesized that the NGAL from macrophages promotes expression of chemoattractant molecules involved in renal lesions induced by mineralocorticoid excess. Methods: The role of Lcn2 was analyzed using full Lcn2 knock out mice (NGAL KO) challenged with uni-Nephrectomy, Aldosterone 200μg/kg/day, Salt 1% (NAS model) during 6 weeks. Assessment of CCL5/IL4 in kidney fibrosis were studied using maraviroc administration (50mg/kg/d in chow diet) or by injections of anti-IL4 antibody (600μg/week). Results: NAS induced a significant increase in the expression (relative values, mean±SEM, compared to 1 in the control samples, p&lt0.05) of extracellular matrix proteins such as collagen I (2.35±0.33), α-SMA (2.04±0.44) and fibronectin (3.38±0.42) in the kidney of WT mice associated with interstitial kidney fibrosis (6.49±0.70). These modifications were fully prevented by NGAL deletion. Expression of macrophages markers F4/80 , CD80 and CD86 was increased (5.11±0.46, 4.84±0.19 and 5.22±0.45 respectively) in WT NAS mice and partly prevented in NGAL KO mice. Macrophages isolated from NGAL KO or WT mice were co-treated with aldosterone (10 -8 M) and NaCl (40mM). In WT macrophages, expression of Lcn2 (2.81±0.30) and the CCL5 chemokine (2.48±0.32) was increased. The increase of CCL5 was prevented in NGAL KO macrophages. Such as total deletion of NGAL, CCL5 receptor blockade improved renal fibrosis and high level of Th2 CD4 + cell markers induced by NAS. Neutralization of IL4 Th2 cytokine in NAS mice injected with anti-IL4 antibody blunted kidney fibrosis and overexpression of profibrotic proteins such as collagen I, α-SMA and fibronectin. Conclusion: NGAL produced by macrophages plays a critical role in renal interstitial fibrosis through CCL5/IL4 pathways in mice exposed to mineralocorticoid excess.