Structural insight into hormone recognition by the natriuretic peptide receptor-A.

Atrial natriuretic peptide (ANP) plays a central role in the regulation of blood pressure and volume. ANP activities are mediated by natriuretic peptide receptor-A (NPR-A), a single-pass transmembrane receptor harboring intrinsic guanylate cyclase activity. This study investigated the mechanism underlying NPR-A-dependent hormone recognition through the determination of the crystal structures of the NPR-A extracellular hormone-binding domain complexed with full-length ANP, truncated mutants of ANP, and dendroaspis natriuretic peptide (DNP) isolated from the venom of the green Mamba snake, Dendroaspis angusticeps. The bound peptides possessed pseudo-two-fold symmetry, despite the lack of two-fold symmetry in the primary sequences, which enabled the tight coupling of the peptide to the receptor, and evidently contributes to guanylyl cyclase activity. The binding of DNP to the NPR-A was essentially identical to that of ANP; however, the affinity of DNP for NPR-A was higher than that of ANP owing to the additional interactions between distinctive sequences in the DNP and NPR-A. Consequently, our findings provide valuable insights that can be applied to the development of novel agonists for the treatment of various human diseases.

The Natriuretic Peptide System: A Single Entity, Pleiotropic Effects.

In the modern scientific landscape, natriuretic peptides are a complex and interesting network of molecules playing pleiotropic effects on many organs and tissues, ensuring the maintenance of homeostasis mainly in the cardiovascular system and regulating the water-salt balance. The characterization of their receptors, the understanding of the molecular mechanisms through which they exert their action, and the discovery of new peptides in the last period have made it possible to increasingly feature the physiological and pathophysiological role of the members of this family, also allowing to hypothesize the possible settings for using these molecules for therapeutic purposes. This literature review traces the history of the discovery and characterization of the key players among the natriuretic peptides, the scientific trials performed to ascertain their physiological role, and the applications of this knowledge in the clinical field, leaving a glimpse of new and exciting possibilities for their use in the treatment of diseases.

A State of Natriuretic Peptide Deficiency.

Measurement of natriuretic peptides (NPs) has proven its clinical value as biomarker, especially in the context of heart failure (HF). In contrast, a state of partial NP deficiency appears integral to several conditions in which lower NP concentrations in plasma presage overt cardiometabolic disease. Here, obesity and type 2 diabetes have attracted considerable attention. Other factors-including age, sex, race, genetics, and diurnal regulation-affect the NP "armory" and may leave some individuals more prone to development of cardiovascular disease. The molecular maturation of NPs has also proven complex, with highly variable O-glycosylation within the biosynthetic precursors. The relevance of this regulatory step in post-translational propeptide maturation has recently become recognized in biomarker measurement/interpretation and cardiovascular pathophysiology. An important proportion of people appear to have reduced effective net NP bioactivity in terms of receptor activation and physiological effects. The state of NP deficiency both entails a potential for further biomarker development and could also offer novel pharmacological possibilities. Alleviating the state of NP deficiency before development of overt cardiometabolic disease in selected patients could be a future path for improving precision medicine.

Treatment of murine colitis by Saccharomyces boulardii secreting atrial natriuretic peptide.

Inflammatory bowel disease is a lifelong disorder that involves chronic inflammation in the small and large intestines. Current therapies, including aminosalicylates, corticosteroids, and anti-inflammatory biologics, can only alleviate the symptoms and often cause adverse effects with long-term usage. Engineered probiotics provide an alternative approach to treat inflammatory bowel disease in a self-renewable and local delivery fashion. In this work, we utilized a yeast probiotic Saccharomyces boulardii for this purpose. We developed a robust method to integrate recombinant genes into the Ty elements of S. boulardii. Stable yeast cell lines that secreted various anti-inflammatory proteins, including IL-10, TNFR1-ECD, alkaline phosphatase, and atrial natriuretic peptide (ANP), were successfully created and investigated for their efficacies to the DSS-induced colitis in mice through oral administration. While IL-10, TNFR1-ECD, and alkaline phosphatase did not show therapeutic effects, the ANP-secreting S. boulardii effectively ameliorated the mouse conditions as reflected by the improvements in body weight, disease activity index, and survival rate. A post-mortem examination revealed that the ANP-treated mice exhibited significant downregulations of TNF-α and IL-1ß and an upregulation of IL-6 in colon tissues. This observation is consistent with the previous reports showing that TNF-α and IL-1ß are responsible for initiating the pathogenesis, whereas IL-6 plays a protective role in colitis. Overall, we demonstrated that S. boulardii is a safe and robust vehicle for recombinant protein delivery in the gastrointestinal tract, and ANP is a potential anti-inflammatory drug for colitis treatment. KEY MESSAGES: Recombinant genes can be robustly integrated into the transposable elements of S. boulardii. Oral administration of S. boulardii secreting IL-10 or TNF-α inhibitor did not exert therapeutic effects for DSS-induced colitis in mice. Atrial natriuretic peptide-secreting S. boulardii effectively ameliorated the murine colitis as reflected by improved body weight, disease activity index, and survival rate. The ANP-treated mice exhibited decreased mRNA levels of TNF-α and IL-1ß and an increased mRNA level of IL-6 in colon tissues.

Function and regulation of corin in physiology and disease.

Atrial natriuretic peptide (ANP) is of major importance in the maintenance of electrolyte balance and normal blood pressure. Reduced plasma ANP levels are associated with the increased risk of cardiovascular disease. Corin is a type II transmembrane serine protease that converts the ANP precursor to mature ANP. Corin deficiency prevents ANP generation and alters electrolyte and body fluid homeostasis. Corin is synthesized as a zymogen that is proteolytically activated on the cell surface. Factors that disrupt corin folding, intracellular trafficking, cell surface expression, and zymogen activation are expected to impair corin function. To date, CORIN variants that reduce corin activity have been identified in hypertensive patients. In addition to the heart, corin expression has been detected in non-cardiac tissues, where corin and ANP participate in diverse physiological processes. In this review, we summarize the current knowledge in corin biosynthesis and post-translational modifications. We also discuss tissue-specific corin expression and function in physiology and disease.

Dual-peptide functionalized acetalated dextran-based nanoparticles for sequential targeting of macrophages during myocardial infarction.

The advent of nanomedicine has recently started to innovate the treatment of cardiovascular diseases, in particular myocardial infarction. Although current approaches are very promising, there is still an urgent need for advanced targeting strategies. In this work, the exploitation of macrophage recruitment is proposed as a novel and synergistic approach to improve the addressability of the infarcted myocardium achieved by current peptide-based heart targeting strategies. For this purpose, an acetalated dextran-based nanosystem is designed and successfully functionalized with two different peptides, atrial natriuretic peptide (ANP) and linTT1, which target, respectively, cardiac cells and macrophages associated with atherosclerotic plaques. The biocompatibility of the nanocarrier is screened on both macrophage cell lines and primary macrophages, showing high safety, in particular after functionalization of the nanoparticles' surface. Furthermore, the system shows higher association versus uptake ratio towards M2-like macrophages (approximately 2-fold and 6-fold increase in murine and human primary M2-like macrophages, respectively, compared to M1-like). Overall, the results demonstrate that the nanosystem has potential to exploit the "hitchhike" effect on M2-like macrophages and potentially improve, in a dual targeting strategy, the ability of the ANP peptide to target infarcted heart.

Assessment of Targeted Nanoparticle Assemblies for Atherosclerosis Imaging with Positron Emission Tomography and Potential for Clinical Translation.

Nanoparticles have been assessed in preclinical models of atherosclerosis for detection of plaque complexity and treatment. However, their successful clinical translation has been hampered by less than satisfactory plaque detection and lack of a general strategy for assessing the translational potential of nanoparticles. Herein, nanoparticles based on comb-co-polymer assemblies were synthesized through a modular construction approach with precise control over the conjugation of multiple functional building blocks for in vivo evaluation. This high level of design control also allows physicochemical properties to be varied in a controllable fashion. Through conjugation of c-atrial natriuretic factor (CANF) peptide and radiolabeling with 64Cu, the 64Cu-CANF-comb nanoparticle was assessed for plaque imaging by targeting natriuretic peptide clearance receptor (NPRC) in a double-injury atherosclerosis model in rabbits. The prolonged blood circulation and enhanced binding capacity of 64Cu-CANF-comb nanoparticles provided sensitive and specific imaging of NPRC overexpressed in atherosclerotic lesions by positron emission tomography at intervals during the progression of the disease. Ex vivo tissue validation using autoradiography and immunostaining on human carotid endarterectomy specimens demonstrated specific binding of 64Cu-CANF-comb to human NPRC receptors. Taken together, this study not only shows the potential of NPRC-targeted 64Cu-CANF-comb nanoparticles for increased sensitivity to an epitope that increases during atherosclerosis plaque development but also provides a useful strategy for the general design and assessment of the translational potential of nanoparticles in cardiovascular imaging.

Human Atrial Natriuretic Peptide in Cold Storage of Donation After Circulatory Death Rat Livers: An Old but New Agent for Protecting Vascular Endothelia?

BACKGROUND: Current critical shortage of donor organs has increased the use of donation after circulatory death (DCD) livers for transplantation, despite higher risk for primary nonfunction or ischemic cholangiopathy. Human atrial natriuretic peptide (hANP) is a cardiovascular hormone that possesses protective action to vascular endothelia. We aimed to clarify the therapeutic potential of hANP in cold storage of DCD livers. METHODS: Male Wistar rats were exposed to 30-minute warm ischemia in situ. Livers were then retrieved and cold-preserved for 6 hours with or without hANP supplementation. Functional and morphological integrity of the livers was evaluated by oxygenated ex vivo reperfusion at 37°C. RESULTS: hANP supplementation resulted in significant reduction of portal venous pressure (12.2 ± 0.5 versus 22.5 ± 3.5 mm Hg, P < 0.001). As underlying mechanisms, hANP supplementation significantly increased tissue adenosine concentration (P = 0.008), resulting in significant upregulation of endothelial nitric oxide synthase and significant downregulation of endothelin-1 (P = 0.01 and P = 0.004 vs. the controls, respectively). Consequently, hANP significantly decreased transaminase release (P < 0.001) and increased bile production (96.2 ± 18.2 versus 36.2 ± 15.2 µL/g-liver/h, P < 0.001). Morphologically, hepatocytes and sinusoidal endothelia were both better maintained by hANP (P = 0.021). Electron microscopy also revealed that sinusoidal ultrastructures and microvilli formation in bile canaliculi were both better preserved by hANP supplementation. Silver staining also demonstrated that hANP significantly preserved reticulin fibers in Disse space (P = 0.017), representing significant protection of sinusoidal frameworks/architectures. CONCLUSIONS: Supplementation of hANP during cold storage significantly attenuated cold ischemia/warm reperfusion injury of DCD livers.

Pharmacokinetic and Pharmacodynamic Profiles of Glyco-Modified Atrial Natriuretic Peptide Derivatives Synthesized Using Chemo-enzymatic Synthesis Approaches.

Atrial natriuretic peptide (ANP) exerts beneficial pharmacological effects in the treatment of various cardiovascular disorders, such as acute congestive heart failure (ADHF). However, the clinical use of ANP is limited to the continuous intravenous infusion owing to its short half-life (2.4 ± 0.7 min). In the present study, we conjugated the glyco-modified ANP with a monoclonal antibody (mAb) or an Fc via chemo-enzymatic glyco-engineering using EndoS D233Q/Q303L. The most potent derivative SG-ANP-Fc conjugate extended the half-life to 14.9 d and the duration of blood pressure lowering effect to over 28 d. This new biologic modality provides an opportunity to develop outpatient therapy after ADHF.

Midregional pro-atrial natriuretic peptide, an important member of the natriuretic peptide family: potential role in diagnosis and prognosis of cardiovascular disease.

Midregional pro-atrial natriuretic peptide (MR-proANP), first isolated in 1981, is a novel peptide with multiple biological functions, especially within the cardiovascular system. This peptide plays an important role in many processes, including natriuresis, diuresis, and other physiological and pathophysiological pathways in the human body. Several electronic databases (PubMed, EBSCO, Scopus, and ScienceDirect) were analyzed in the present literature review. The aim of this study was to elucidate the wide roles of MR-proANP, which can be analyzed because of the development of a new sandwich immunoassay, and to determine the possible diagnostic and prognostic implications of MR-proANP on cardiovascular disease and other disorders. The studies discussed in this literature review provide valuable data on the role of ANP in the pathogenesis, diagnostic process, prognosis, and potential therapeutic strategies for disease. Although ANP is mainly associated with cardiovascular disease, it may be used as a biomarker in diabetology, neurology, and metabolic disorders.

Atrial natriuretic peptide modified oleate adenosine prodrug lipid nanocarriers for the treatment of myocardial infarction: in vitro and in vivo evaluation.

PURPOSE: Myocardial infarction is a major cause of mortality and heart failure worldwide. One of the most effective methods of this injury is direct delivery of cardioprotective drugs to ischemia-reperfusion (IR) myocardium. The aim of the present study was to fabricate an adenosine (Ade) prodrug-based, atrial natriuretic peptide (ANP)-modified nanosystem for the treatment of myocardial infarction. MATERIALS AND METHODS: Oleate adenosine prodrug (Ade-OA) and ANP-distearoylphosphatidylethanolamine-polyethylene glycol were synthesized. ANP-modified Ade-loaded lipid nanocarriers (ANP Ade/LNCs) were then self-assembled by using solvent evaporation method. In vitro drug release in the presence of plasma was evaluated. In vivo inhibition effect on infarct size, tissue distribution, and pharmacokinetics were investigated in rats with ischemic myocardium after intravenous injection. RESULTS: In vivo inhibition effect on infarct size, tissue distribution, and pharmacokinetics studies in acute myocardial infarction (AMI) rats showed that ANP Ade/LNCs exhibited better efficiency than non-modified Ade/LNCs and free Ade in all respects. CONCLUSION: These results indicated that the ANP Ade/LNCs can be used as a promising system for the treatment of cardiovascular diseases.

Distribution and co-localization of diversified natriuretic peptides in the eel heart.

Atrial and B-type natriuretic peptides (ANP and BNP) are cardiac hormones important for cardiovascular and body fluid regulation. In some teleost species, an additional member of the natriuretic peptide family, ventricular NP (VNP), has been identified. In this study, we examine tissue distribution of these three NPs in the eel heart. Quantitative real-time PCR showed that anp is almost exclusively expressed in atria, bnp equally in atria and ventricles and vnp three-fold more in ventricles than in atria. The amount of bnp transcript overall in the heart was 1/10 those of anp and vnp. There was no difference in transcript levels between freshwater and seawater-acclimated fishes. Immunohistochemistry using specific antisera and in situ hybridization using gene-specific probes showed that NP signals were detected in most atrial and ventricular myocytes with some regional differences in density. Because of high sequence similarity of the three NPs, each of the three NP antisera individually was pre-incubated with 10-8 M of the other two non-targeted cardiac NPs to increase the specificity. A few atrial myocytes contained all three NPs in the same cell. Immuno-electron microscopy identified many dense-core vesicles containing ANP in atria and VNP in ventricles and some vesicles contained both ANP and VNP as demonstrated using pre-absorbed antisera. Based on these data and those of previous studies, we suggest that in eels ANP is secreted from atria in a regulatory pathway and VNP from ventricles in a constitutive pathway. In addition, VNP, not BNP, is the principal ventricular hormone in eels.

[Atrial natriuretic hormones and metabolic syndrome: recent advances]. / Hormones natriurétiques et syndrome métabolique : mise au point.

Natriuretic peptides are a group of hormones including atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), C type (CNP), urodilatin and guanilyn. ANP (half-life: 2-4 min), is secreted by the atrium, BNP (half-life: 20 min) by the ventricle, CNP by the vascular endothelium, urodilatin by the kidney and guanylin by the intestine. These natriuretic peptides prevent water and salt retention through renal action, vasodilatation and hormonal inhibition of aldosterone, vasopressin and cortisol. These peptides also have a recently demonstrated metabolic effect through an increase of lipolysis, thermogenesis, beta cell proliferation and muscular sensitivity to insulin. Blood levels of these natriuretic peptides depend on "active NPR-A receptors/clearance NPR-C receptors", the last ones being abundant on adipocytes. Therefore, natriuretic peptides act as adipose tissue regulator and constitute a link between blood pressure and metabolic syndrome. They are used as markers and treatment of cardiac failure. Other applications are on going. BNP and NT-proBNP (inactive portion de la pro-hormone) are used as markers of cardiac failure since they have a longer half-life than ANP. BNP decrease is quicker and more important than that one of NT-ProBNP in case of improvement of cardiac failure. Chronic renal insufficiency and beta-blockers increase BNP levels. BNP measurement is useless under treatment with neprilysine inhibitors such as sacubitril, one of the neutral endopeptidases involved in catabolism of natriuretic peptides. The association sacubitril/valsartan is a new treatment of chronic cardiac failure, acting through the decrease of ANP catabolism.

The T2238C Human Atrial Natriuretic Peptide Molecular Variant and the Risk of Cardiovascular Diseases.

Atrial natriuretic peptide (ANP) is a cardiac hormone which plays important functions to maintain cardio-renal homeostasis. The peptide structure is highly conserved among species. However, a few gene variants are known to fall within the human ANP gene. The variant rs5065 (T2238C) exerts the most substantial effects. The T to C transition at the 2238 position of the gene (13-23% allele frequency in the general population) leads to the production of a 30-, instead of 28-, amino-acid-long α-carboxy-terminal peptide. In vitro, CC2238/αANP increases the levels of reactive oxygen species and causes endothelial damage, vascular smooth muscle cells contraction, and increased platelet aggregation. These effects are achieved through the deregulated activation of type C natriuretic peptide receptor, the consequent inhibition of adenylate cyclase activity, and the activation of Giα proteins. In vivo, endothelial dysfunction and increased platelet aggregation are present in human subjects carrying the C2238/αANP allele variant. Several studies documented an increased risk of stroke and of myocardial infarction in C2238/αANP carriers. Recently, an incomplete response to antiplatelet therapy in ischemic heart disease patients carrying the C2238/αANP variant and undergoing percutaneous coronary revascularization has been reported. In summary, the overall evidence supports the concept that T2238C/ANP is a cardiovascular genetic risk factor that needs to be taken into account in daily clinical practice.

A potent and selective natriuretic peptide receptor-3 blocker 11-mer peptide created by hybridization of musclin and atrial natriuretic peptide.

The natriuretic peptide (NP) system is a critical endocrine, autocrine, and paracrine system and has been investigated for potential use against cardiovascular and metabolic diseases. The clearance of NPs is regulated by the proteolysis of neutral endopeptidase (NEP) and by endocytosis via natriuretic peptide receptor-3 (NPR3). A linear NPR3-selective peptide, [Cha8]-ANP(7-16)-NH2 (1), showed potent binding affinity for NPR3 but poor predicted chemical stability due to its free thiol group. A 12-mer peptide (9) without a thiol group was designed by the hybridization of two NPR3-binding peptides: a linear ANP fragment peptide analog and musclin, a murine member of the bHLH family of transcription factors, possessed high binding affinity and strict selectivity for NPR3. To increase the proteolytic resistance of 9, amino acid substitutions at the cleavage sites led to hydroxyacetyl-[d-Phe5,d-Hyp7,Cha8,d-Ser9,Hyp11,Arg(Me)14]-ANP(5-15)-NHCH3 (23), showing high and selective binding affinity for NPR3 over NPR1 and excellent stability in mouse serum. Compound 23 increased intracellular cGMP concentrations in primary cultured adipocytes, and continuous administration induced substantial plasma cGMP elevation in mice, suggesting its potential to clarify the physiological role of NPR3 and its therapeutic application.

The 3-nitro-2-pyridinesulfenyl group: synthesis and applications to peptide chemistry.

The 3-nitro-2-pyridinesulfenyl chloride, commonly abbreviated as Npys-Cl, was among the first stable heterocyclic sulfenyl halides to be isolated. After its discovery, the Npys group was widely used as a protecting group for the amines, alcohols and thiols. Herein, we have reviewed some of the aspects of the Npys-Cl moiety, and its most promising recent uses are summarized, from the stability of the Npys protection of amines, hydroxyls and thiols and removal conditions for potential applications in peptide synthesis, to one of its most successful applications for the formation of mixed disulfides. Indeed, Npys protects thiols and acts as an activator for disulfide bond formation, thereby facilitating thiol/disulfide exchange to the corresponding disulfides. The selectivity and mild reaction conditions opened up a wide range of applications in chemical biology as well. Finally, some of the most recent developments regarding the synthesis and applications of solid-phase Npys derivatives are discussed. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.

Atrial natriuretic peptide-conjugated chitosan-hydrazone-mPEG copolymer nanoparticles as pH-responsive carriers for intracellular delivery of prednisone.

A chitosan-hydrazone-mPEG (CH-Hz-mPEG) copolymer which is stable at extracellular pH and cleaves at slightly acidic intracellular pH was synthesized and characterized. Blank polymeric nanoparticles (B-PNPs) and prednisone-loaded polymeric nanoparticles (P-PNPs) were then formulated by dialysis/precipitation method. The cell-specific ligand, atrial natriuretic peptide (ANP) was then conjugated to P-PNPs (ANP-P-PNPs) by a coupling reaction. Particle size and morphological analyses revealed uniform spherical shape of PNPs. In vitro pH dependent degradation of PNPs was investigated. Drug release profile of ANP-P-PNPs indicated a slow release of prednisone at pH 7.4, but a rapid release at pH 5.0 due to the cleavage of hydrazone linkage. Cytotoxicity studies demonstrated greater compatibility of B-PNPs compared to ANP-P-PNPs. Cellular internalization of ANP-P-PNPs was higher than P-PNPs owing to receptor-mediated endocytosis. The results from this investigation support the hypothesis that chitosan based ANP-P-PNPs could act as an intracellular pH-responsive and targeted drug delivery system.

Lumican-null mice are susceptible to aging and isoproterenol-induced myocardial fibrosis.

With aging and stress, the myocardium undergoes structural remodeling, often leading to fibrosis. The purpose of this study is to examine whether lumican, one of the class II small leucine-rich proteoglycans, has a protective role in cardiac remodeling and fibrosis. In attempts to elucidate the hypothesis that lumican may have a protective role in cardiac remodeling and fibrosis, we compared the cardiac phenotypes of young (3-month-old) and elder (6-month- and 12-month-old) lumican-null (Lum-/-) mice. Extra-cellular matrix remodeling and apoptosis are examined to determine the roles of lumican on age-dependent cardiac fibrosis induced by isoproterenol. Compared to wild type littermates, Lum-/- mice exhibited higher mortality due to significantly impaired systolic function, which was associated with an increase of atrial natriuretic peptide (ANP) secreted by the ventricles in response to excessive stretching of myocytes. Masson's Trichrome and silver stains showed significantly more severe ventricle fibrosis in Lum-/- mice. Interestingly, rate of cell death mediated via apoptosis illustrated by the expression of caspase 3 and TUNEL assay was lower in Lum-/- mice after isoproterenol infusion. In addition, Lum-/- mice exhibited higher levels of TGF-ß, collagen I/III, and membrane-type matrix metalloproteinase-1 (MT1-MMP/MMP-14) during cardiac remodeling. This study shows that alternations of lumican might be implicated in the pathogenesis of cardiac fibrosis and suggests lumican as novel targets for cardiac fibrosis therapy. Further studies are required to define the mechanism by which lumican modulates cardiac remodeling.

Redox Activity of Copper(II) Complexes with NSFRY Pentapeptide and Its Analogues.

The influence of cation-π interactions on the electrochemical properties of copper(II) complexes with synthesized pentapeptide C-terminal fragment of Atrial Natriuretic Factor (ANF) hormone was studied in this work. Molecular modeling performed for Cu(II)-NSFRY-NH2 complex indicated that the cation-π interactions between Tyr and Cu(II), and also between Phe-Arg led to specific conformation defined as peptide box, in which the metal cation is isolated from the solvent by peptide ligand. Voltammetry experiments enabled to compare the redox properties and stability of copper(II) complexes with NSFRY-NH2 and its analogues (namely: NSFRA-NH2, NSFRF-NH2, NSAAY-NH2, NSAAA-NH2, AAAAA-NH2) as well as to evaluate the contribution of individual amino acid residues to these properties. The obtained results led to the conclusion, that cation-π interactions play a crucial role in the effective stabilization of copper(II) complexes with the fragments of ANF peptide hormone and therefore could control the redox processes in other metalloproteins.

Design and Modular Construction of a Polymeric Nanoparticle for Targeted Atherosclerosis Positron Emission Tomography Imaging: A Story of 25% (64)Cu-CANF-Comb.

PURPOSE: To assess the physicochemical properties, pharmacokinetic profiles, and in vivo positron emission tomography (PET) imaging of natriuretic peptide clearance receptors (NPRC) expressed on atherosclerotic plaque of a series of targeted, polymeric nanoparticles. METHODS: To control their structure, non-targeted and targeted polymeric (comb) nanoparticles, conjugated with various amounts of c-atrial natriuretic peptide (CANF, 0, 5, 10 and 25%), were synthesized by controlled and modular chemistry. In vivo pharmacokinetic evaluation of these nanoparticles was performed in wildtype (WT) C57BL/6 mice after (64)Cu radiolabeling. PET imaging was performed on an apolipoprotein E-deficient (ApoE(-/-)) mouse atherosclerosis model to assess the NPRC targeting efficiency. For comparison, an in vivo blood metabolism study was carried out in WT mice. RESULTS: All three (64)Cu-CANF-comb nanoparticles showed improved biodistribution profiles, including significantly reduced accumulation in both liver and spleen, compared to the non-targeted (64)Cu-comb. Of the three nanoparticles, the 25% (64)Cu-CANF-comb demonstrated the best NPRC targeting specificity and sensitivity in ApoE(-/-) mice. Metabolism studies showed that the radiolabeled CANF-comb was stable in blood up to 9 days. Histopathological analyses confirmed the up-regulation of NPRC along the progression of atherosclerosis. CONCLUSION: The 25% (64)Cu-CANF-comb demonstrated its potential as a PET imaging agent to detect atherosclerosis progression and status.