Apelin protects against abdominal aortic aneurysm and the therapeutic role of neutral endopeptidase resistant apelin analogs

Abstract

Abdominal aortic aneurysm (AAA) remains the second most frequent vascular disease with high mortality but has no approved medical therapy. We investigated the direct role of apelin (APLN) in AAA and identified a unique approach to enhance APLN action as a therapeutic intervention for this disease. Loss of APLN potentiated angiotensin II (Ang II)-induced AAA formation, aortic rupture, and reduced survival. Formation of AAA was driven by increased smooth muscle cell (SMC) apoptosis and oxidative stress inApln−/yaorta and in APLN-deficient cultured murine and human aortic SMCs. Ang II-induced myogenic response and hypertension were greater inApln−/ymice, however, an equivalent hypertension induced by phenylephrine, an α-adrenergic agonist, did not cause AAA or rupture inApln−/ymice. We further identified Ang converting enzyme 2 (ACE2), the major negative regulator of the renin-Ang system (RAS), as an important target of APLN action in the vasculature. Using a combination of genetic, pharmacological, and modeling approaches, we identified neutral endopeptidase (NEP) that is up-regulated in human AAA tissue as a major enzyme that metabolizes and inactivates APLN-17 peptide. We designed and synthesized a potent APLN-17 analog, APLN-NMeLeu9-A2, that is resistant to NEP cleavage. This stable APLN analog ameliorated Ang II-mediated adverse aortic remodeling and AAA formation in an established model of AAA, high-fat diet (HFD) inLdlr−/−mice. Our findings define a critical role of APLN in AAA formation through induction of ACE2 and protection of vascular SMCs, whereas stable APLN analogs provide an effective therapy for vascular diseases.

Development and validation of an LC-MS/MS method for detection and quantification of in vivo derived metabolites of [Pyr1]apelin-13 in humans

“…Building on these findings, further studies could substitute the amino acids at the neprilysin cleavage sites in [Pyr 1 ]apelin-13 with unnatural amino acids to improve its resistance to degradation. Indeed, it was recently shown that infusion of neprilysin resistant apelin-17 in an established mice model of abdominal aortic aneurysm ameliorated the adverse aortic remodelling and aneurysm formation 27 . Such a strategy was also demonstrated to significantly increase the resistance of [Pyr 1 ]apelin-13 and apelin-17 to ACE2 activity 22,23 , suggesting that this could potentially be a mechanism to improve plasma stability of apelin-based therapeutics for clinical indications.…”

“…These studies demonstrated that apelin peptides are very labile in plasma with a half-life of less than 1-5 minutes in vitro [20][21][22][23][24] . This plasma instability has to date been attributed the enzymatic activity of neprilysin 25 and angiotensin converting enzyme II (ACE2) [22][23][24] , and more recently plasma kallikrein 26,27 . Similarly, another recent study reported more rapid degradation of [Pyr 1 ]apelin-13 in rat and mouse plasma when compared to dog, monkey and human plasma in vitro 28 .…”

Are the Clinical Presentations (Phenotypes) of Gitelman’s and Bartter’s Syndromes Gene Mutations Driven by Their Effects on Intracellular pH, Their “pH” Enotype?

“…Ang II-mediates up-regulation of Apelin (APLN), which in turn up-regulates ACE2, leading to conversion of Ang II by ACE2 into the protective Ang 1-7 peptide [14,15]. The APLN pathway has emerged as a major peptide hormone pathway with APLN widely expressed in mammals [16] and ACE2 is an important target of APLN action in the vasculature [17]. The regulatory loop also functions such that apelin 13 is required for ACE2 expression [18][19][20].…”

The Two-Way Switch Role of ACE2 in the Treatment of Novel Coronavirus Pneumonia and Underlying Comorbidities

“…In addition to Ang II, apelin is another catalytic substrate for ACE2 and is considered an inotropic and cardioprotective peptide [ 82 , 83 ]. Among apelin peptides, apelin-13 is the most abundant in human plasma and cardiac tissue, and it exists predominantly under its pyroglutamylated form (Pyr-apelin-13) [ 84 ].…”

“…In ACE2 knockout mice, hypotensive action of Pyr-apelin-13 was enhanced, with higher apelin levels in plasma. In turn, apelin-13, via activation of G protein–coupled receptor, the apelin receptor (APJ), increased ACE2 promoter activity in vitro, and upregulated ACE2 expression in failing hearts in vivo [ 83 ]. Moreover, apelin-13 treatment also increased cardiac contractility and ACE2 levels in AT1R-deficient mice, which demonstrate an antagonistic relationship between the RAS and apelin [ 83 ].…”