Treatment of Pulmonary Hypertension With Angiotensin II Receptor Blocker and Neprilysin Inhibitor Sacubitril/Valsartan

Abstract

Angiotensin II has been implicated in maladaptive RV hypertrophy and fibrosis associated with pulmonary hypertension (PH). Natriuretic peptides decrease RV afterload by promoting pulmonary vasodilation and inhibiting vascular remodeling, but are degraded by neprilysin. We hypothesized that angiotensin receptor blocker and neprilysin inhibitor, Sacubitril/Valsartan (Sac/Val, LCZ696), will attenuate PH and improve RV function by targeting both pulmonary vascular and RV remodeling. PH was induced in rats using the SU5416/hypoxia model (Su/Hx), followed by 6-week treatment with placebo, Sac/Val, or Val alone. There were 4 groups: CON - normoxic animals with placebo (n=18); PH – Su/Hx rats + placebo (n=34); PH + Sac/Val (N=24); and PH + Val (n=16). In animals with PH, treatment with Sac/Val but not Val resulted in significant reduction in RV pressure (mm Hg: PH: 62±4, PH+ Sac/Val: 46±5), hypertrophy (RV/LV+S: PH: 0.74±0.06, PH+ Sac/Val: 0.46±0.06), collagen content(μg/50 μg protein: PH: 8.2±0.3, PH+ Sac/Val: 6.4±0.4), pressures and improvement in RV s′ (mm/s: PH: 31.2±1.8, PH+ Sac/Val: 43.1±3.6) compared to placebo. This was associated with reduced pulmonary vascular wall thickness, increased lung levels of ANP, BNP, and cGMP, and decreased plasma endothelin-1 compared to PH alone. Also, PH + Sac/Val animals had altered expression of PKC isozymes in RV tissue compared PH alone. Sac/Val reduces pulmonary pressures, vascular remodeling as well as RV hypertrophy in a rat model of PH and may be appropriate for treatment of pulmonary hypertension and RV dysfunction.