Abstract 382: Studies on the Effect of ACE2 Inhibitors on ACE2-driven Angiotensin Peptides Metabolism in Plasma Using RAS Fingerprinting
There are species differences between the currently used ACE2 inhibitors (MLN-4760 and DX600) that could be critically relevant to the proper interpretation of studies with these compounds. The effect of these inhibitors on ACE2-driven angiotensin peptides formation and degradation has not yet been studied. Accordingly, we examined the ability of MLN-4760 and two conformational variants of DX600 [a linear (L) and a cyclic (C) form] to inhibit human (h) and mouse (m) recombinant (r) ACE2 using a novel ex vivo LC-MS/MS based approach to concomitantly measure several peptides within the RAS system in plasma. Both mrACE2 and hrACE2 (5ug/mL) when added to blood plasma caused a complete disappearance of Ang II and lead to the formation of Ang-(1-7). As a result of the increase in Ang-(1-7) formation, both mrACE2 and hrACE2 lead also to the formation of Ang-(1-5). This reaction was likely driven by ACE which, like other peptidases, is present in plasma ex vivo assay. The effects of hrACE2 and mrACE2 on the above mentioned Ang peptides were inhibited by MLN-4760 at 10-5M and also at lower concentrations (10-6M and 10-7M). Both, L-DX600 and C-DX600 inhibited the effect of hrACE2 on Ang-(1-7) and Ang-(1-5) formation and this effect was also dose-dependent. By contrast, neither L-DX600 nor C-DX600, even at a high concentration (10-5M), prevented the changes on Ang peptides effected by mrACE2. hrACE2 decreased Ang I levels by 60% whereas mrACE2 did it only marginally. Of note, hrACE2 resulted in the formation of Ang-(1-9) from Ang I whereas mrACE2 did not. In conclusion, there are major differences between the known specific inhibitors of ACE2 between hrACE2 and mrACE2. MLN-4760 inhibits both hrACE2 and mrACE2 whereas DX600 inhibits hrACE2 preferentially. DX600 does not prevent mrACE2-driven formation of Ang-(1-7) from Ang II. mrACE2 effectively degrades Ang II forming Ang-(1-7) whereas it has no effect on the formation of Ang-(1-9) from Ang I. RAS “fingerprinting” is a powerful novel approach to simultaneously evaluate quantitatively several angiotensin peptides in plasma and can be used to demonstrate profound differences on the effect of available ACE2 inhibitors on the formation of various angiotensin peptides driven by human and mouse ACE2.
- © 2012 by American Heart Association, Inc.