The angiotensin II type 1 receptor-neprilysin inhibitor LCZ696 blocked aldosterone synthesis in a human adrenocortical cell line

A recent clinical study indicated that an angiotensin II (Ang II) type 1 (AT(1)) receptor-neprilysin inhibitor (ARNi) designated LCZ696 (sacubitril/valsartan, as combined sodium complex) was superior to enalapril at reducing the risks of death and hospitalization due to heart failure. Therefore, we investigated the possible mechanisms of the beneficial effect of LCZ696, in which the inhibition of neprilysin enhances atrial natriuretic peptide (NP) or brain NP (ANP or BNP)-evoked signals that can block Ang II/AT(1) receptor-induced aldosterone (Ald) synthesis in human adrenocortical cells. The binding affinity of valsartan +LBQ657 (active moiety of sacubitril) to the AT(1) receptor was greater than that of valsartan alone in an AT(1) receptor-expressing human embryonic kidney cell-based assay. There was no difference in the dissociation from the AT(1) receptor between valsartan +LBQ657 and valsartan alone. In Ang II-sensitized human adrenocortical cells, ANP or BNP alone, but not LBQ657 or valsartan alone, significantly decreased Ald synthesis. The level of suppression of Ald synthesis by ANP or BNP with LBQ657 was greater than that by ANP or BNP without LBQ657. The suppression of ANP was blocked by inhibitors of regulator of G-protein signaling proteins and cyclic GMP-dependent protein kinase. The inhibition of neprilysin did not change the mRNA levels of the AT(1) receptor, ANP receptor A, regulator of G-protein signaling protein, renin or 3 beta-hydroxysteroid dehydrogenases. In conclusion, the inhibition of neprilysin by LBQ657 enhances the NP-evoked signals that can block Ang II/AT(1) receptor-induced Ald synthesis in human adrenocortical cells.