Blood Pressure Lowering and Safety Improvements With Liver Angiotensinogen Inhibition in Models of Hypertension and Kidney Injury

Abstract

566T he discovery and development of renin-angiotensin-aldosterone system (RAAS) inhibitors have established a role of angiotensin II (Ang II) in disease, leading to therapies that are the foundation of treatment for cardiovascular and renal diseases.1 Yet, as effective as RAAS inhibitors have been in the clinic, there is a need to improve the efficacy, safety, and tolerability of this drug class.Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers (ARBs) elicit compensatory pathways resulting in angiotensin reactivation and aldosterone breakthrough such that plasma Ang II and aldosterone return to pretreatment levels or higher. 2,3 This phenomenon may contribute to the suboptimal efficacy of RAAS blockade in patients with resistant hypertension and heart failure. 4,5 Noncanonical pathways of Ang II generation and intracellular RAAS signaling are considered important mechanisms that limit the therapeutic potential of this drug class. 6 AGT (angiotensinogen) is the source of all downstream angiotensin metabolites. The liver is the principal source of circulating AGT, 7-9 although extrahepatic sites of expression, such as in the kidney, have been implicated in the regulation of blood pressure (BP), sodium, and water homeostasis. 10 More aggressive RAAS inhibition, as attempted by combining different classes of RAAS inhibitors, has demonstrated poor clinical utility due in part to adverse effects, such as hyperkalemia, hypotension, and acute renal failure.11 A current hypothesis is that such untoward effects are because of excessive renal RAAS inhibition. 12 Thus, a more effective therapeutic strategy would (1) work upstream of the RAAS enzymes and receptors, thereby avoiding compensatory mechanisms and intracrine signaling that limit therapeutic efficacy, and (2) have limited kidney activity, thereby providing the benefits of aggressive RAAS suppression without provoking renal complications.To this end, we developed a liver-selective AGT antisense oligonucleotide (ASO) that produced potent and durable reductions of liver AGT expression after systemic administration. Liver targeting is achieved by covalent linkage of triantennary N-acetylgalactosamine (GalNAc), a high-affinity ligand for the hepatocyte-specific asialoglycoprotein receptor, to an ASO. This GalNAc-conjugate approach results in enhanced ASO delivery to hepatocytes Abstract-Uncontrolled hypertension is an important contributor to cardiovascular disease. Despite the armamentarium of antihypertensive treatments, there remains a need for novel agents effective in individuals who cannot reach acceptable blood pressure levels. Inhibitors targeting the renin-angiotensin-aldosterone system (RAAS) are widely used but may not optimally inhibit RAAS and demonstrate an acceptable safety profile. Experiments were conducted to characterize a series of AGT (angiotensinogen) antisense oligonucleotides (ASOs) and compare their efficacy and tolerability to traditional RAAS blockade. AGT ASOs which target multiple systemic sites of AGT versus an N...

Targeting angiotensinogen with RNA-based therapeutics

“…invasive delivery via subcutaneous injection and optimization of AGT downregulation, as circulating AGT levels are determined by hepatic synthesis [56,57 & ]. Indeed, by improving liver activity eight-fold, Gal-NAc-conjugation potentiated AGT inhibition of ASOs to maximally 88% in a dose-dependent manner [58]. Interestingly, a reduction of at least 75% was required to simultaneously lower blood pressure, which then remained low for a period of 7-10 days after a single dose.…”

“…2f). Unique to GalNAc-siRNA is its long-lasting effectiveness [22], as opposed to an ASO liver half-life of 2-4 weeks [58]. These findings suggest that, in clinical practice, AGT inhibition mediated by RNAi may not only prevent RAAS reactivation but also improve cardiovascular outcome and therapy adherence because of a sustained and stable single-dose efficacy lasting weeks to months [50 && ].…”

The emerging role of angiotensinogen in cardiovascular diseases

“…Hepatocyte specific Decreased BP; decreased HW/BW Mice subcutaneous injected with GAL-Nac AGT-ASO Decreased plasma and liver AGT conc. Hepatocyte specific Decreased BP Not report Mullick et al (2017) Abbreviations: AGT, angiotensinogen; AngII, angiotensin II; ASO, antisense oligonucleotides; BP, blood pressure; BW, body weight; HW, heart weight; LVW, left ventricular weight; RAS, renin-angiotensin system; shRNA, short hairpin RNA; siRNA, small interfering RNA. XU ET AL.…”

“…Three approaches including ASO, small interfering RNA (siRNA), and adeno‐associated virus (AAV) carrying short hairpin RNA (shRNA) targeting AGT are now available to manipulate the expression of AGT in rodents (Haase et al, 2020; Kimura, Mohuczy, Tang, & Phillips, 2001; Mullick et al, 2017; Tang et al, 1999; Uijl et al, 2019; Yuan et al, 2015). These approaches can efficiently suppress plasma AGT concentration and reduce blood pressure.…”

Whole-Body but Not Hepatic Knockdown of Chemerin by Antisense Oligonucleotide Decreases Blood Pressure in Rats

“…Additionally, recent advances in targeted delivery using the trivalent N-acetylgalactosamine (GalNAc) conjugation have demonstrated improved targeting of the liver (Prakash et al, 2016). GalNAc conjugation on ASOs containing 29-O-methoxyethyl sugar modification (MOE; Gen 2.0) have demonstrated robust liver activity, with little to no activity in adipose tissue (Mullick et al, 2017). Thus, to dissect the role of liver-derived-versus-extrahepatic chemerin, a GalNAc conjugated Gen 2.0 ASO with high specificity for reducing liver chemerin expression was compared with the Gen 2.5 ASO, which potently reduced liver and adipose chemerin expression.…”