Intrarenal Generation of Aldosterone Contributes to Ischemia-Induced Hypertension and Nephropathy in Mice.

BACKGROUND: The past few years have witnessed a significant advancement in aldosterone (Aldo)-targeted therapies for the management of treatment-resistant hypertension and chronic kidney disease, which often exist in tandem. While Aldo is believed to predominantly originate from the adrenal glands, this study provides evidence to support the involvement of intrarenal Aldo biosynthesis in the pathogenesis of ischemic nephropathy and hypertension in a two-kidney, one-clip (2K1C) model. METHODS: We generated inducible renal tubule-specific deletion of C11B2 (RT C11B2 KO) and characterized the phenotype during the 2K1C procedure. We investigated the underlying mechanisms involving the use of mice with collecting duct-specific (pro)renin receptor (CD PRR KO) or renin (CD renin KO). RESULTS: RT C11B2 KO induced a partial blockade of the hypertensive response but a much greater improvement in renal fibrosis and inflammation four weeks post-2K1C. This phenotype was associated with an effective blockade of intrarenal generation of Aldo contrasting to unchanged circulating Aldo concentrations. Furthermore, clipping-induced acute kidney injury was also attenuated 24 hours post-2K1C, at which point blood pressure (BP) did not increase. Similarly, sodium nitroprusside effectively lowered BP in C57BL/6j/2K1C mice but failed to improve renal injury. Additionally, we identified CD) PRR and renin as key upstream regulators of intrarenal Aldo biosynthesis following the 2K1C procedure. CONCLUSIONS: Together, these results support the idea that CD PRR/renin-dependent generation of intrarenal Aldo may play a primary role in the pathogenesis of ischemic nephropathy and a secondary role in hypertension development during renovascular constriction. Therefore, targeting intrarenal Aldo biosynthesis may represent a more effective and safer intervention than existing Aldo-targeted therapy to manage ischemic nephropathy as well as hypertension.