CD-NP: a novel engineered dual guanylyl cyclase activator with anti-fibrotic actions in the heart

Abstract

Natriuretic peptides (NPs) are cardioprotective through the activation of guanylyl cyclase (GC) receptors A and B. CD-NP, also known as cenderitide, is a novel engineered NP that was designed to uniquely serve as a first-in-class dual GC receptor agonist. Recognizing the aldosterone suppressing actions of GC-A activation and the potent inhibitory actions on collagen synthesis and fibroblast proliferation through GC-B activation, the current study was designed to establish the anti-fibrotic actions of CD-NP, administered subcutaneously, in an experimental rat model of early cardiac fibrosis induced by unilateral nephrectomy (UNX). Our results demonstrate that a two week subcutaneous infusion of CD-NP significantly suppresses left ventricular fibrosis and circulating aldosterone, while preserving both systolic and diastolic function, in UNX rats compared to vehicle treated UNX rats. Additionally we also confirmed, in vitro, that CD-NP significantly generates the second messenger, cGMP, through both the GC-A and GC-B receptors. Taken together, this novel dual GC receptor activator may represent an innovative anti-fibrotic therapeutic agent.

Figure 1. Natriuretic Peptide Structures.

Amino acid sequence of mature C-type natriuretic peptide (CNP), Dendroaspis natriuretic peptide (DNP) and the designer natriuretic peptide, CD-NP.

Figure 2. Study Timeline.

Experimental protocol of CD-NP (170 ng/kg/min in 5% glucose solution) or Vehicle (5% glucose solution) delivery in Sham or UNX-operated male Wistar rats by subcutaneous (SubQ) osmotic mini-pump.

Figure 3. Natriuretic Peptide Generation of cGMP.

In vitro 3′,5′-cyclic guanosine monophosphate (cGMP) generation in human embryonic kidney 293 cells stably transfected with either the GC-A (upper graph) or GC-B (lower graph) receptor in response to a 10⁻⁶ M dose of CNP (yellow bar), DNP (orange bar) and CD-NP (green bar) compared with no treatment. Values are mean ± SEM. *P<0.05 vs no treatment.

Figure 4. Diastolic Function.

Effect of CD-NP treatment on preserving diastolic function in UNX+CD-NP rats compared to UNX+Vehicle rats. Values are mean ± SEM. *P<0.05 vs Sham+Vehicle and P<0.05 vs UNX+Vehicle.

Figure 5. LV Fibrosis.

Representative histology images at 10x objective magnification of the LV stained with picrosirius red (upper panels) and the quantification of LV fibrosis staining (lower graph) in Sham+Vehicle, UNX+Vehicle and UNX+CD-NP rats. Values are mean ± SEM. *P<0.05 vs Sham+Vehicle and P<0.05 vs UNX+Vehicle.

Figure 6. Plasma Aldosterone

. Effect of CD-NP treatment in suppressing plasma aldosterone in UNX+CD-NP rats compared to UNX+Vehicle rats. Values are mean ± SEM. *P<0.05 vs Sham+Vehicle and P<0.05 vs UNX+Vehicle.