Abstract 124: Angiotensin-(1-12) Immunoneutralization: A New Approach To Hypertension Treatment

There is a critical need to identify new therapeutic targets and treatments, given emerging data documenting the limited effectiveness of current antihypertensive drugs to have a marked impact in preventing target organ damage and cardiovascular death. While monoclonal antibodies (mAb) are revolutionizing the treatment of human diseases, including severe hypercholesterolemia, their applicability to long-term hypertension control remains unexplored. Identification of angiotensin-(1-12) [Ang-(1–12)] as a non-renin-dependent substrate for Ang II generation in rodents and humans led us to engineer a mAb directed against the C-terminus of human Ang-(1–12) [h-Ang-(1-12)] sequence. We utilized a model of hypertension expressing the human angiotensinogen (AGT) gene in the rat genome [TGR(hAGT)L1623 rats] to address the effectiveness of endogenous h-Ang-(1–12) immunoneutralization in controlling the elevated blood pressure and reversing hypertension-induced target organ damage. Acute delivery of the h-Ang-(1–12) mAb (30 mg/Kg, i.v.) in anesthetized hypertensive transgenic rats induced a prompt arterial pressure fall (M ± SE: -18 ± 6/-16 ± 3 mm Hg, n=7; p< 0.001) in the absence of corresponding heart rate changes. The antihypertensive effect of the h-Ang-(1-12) mAb triggered a rise in plasma renin concentrations (from 107 ± 24 to 381 ± 260 ng/mL/h) that was inversely correlated with the fall in mean arterial pressure (r= -0.92, p< 0.001). Prior intravenous delivery of aliskiren fumarate (3-5 mg/Kg, i.v.) while inducing a fall in arterial pressure did not mask the antihypertensive action of the h-Ang-(1-12) mAb. Extension of these acute effects of the h-Ang-(1-12) mAb to awake instrumented transgenic hypertensive rats given consecutive daily doses of the mAb (30 mg/Kg, i.m. x 4 -5 days, n=7) documented a trend for significant statistical drops in daytime blood pressure and no changes in heart rate. We conclude that Ang-(1–12) is an endogenous Ang II forming substrate participating in the control of arterial pressure in a humanized model of high blood pressure and that selective immunoneutralization of this alternate substrate is a promising and novel therapeutic approach to treat hypertension and prevent its adverse cardiovascular sequelae.