Relaxin: A Novel Agent for the Treatment of Acute Heart Failure

Mechanisms and management of edema in pediatric nephrotic syndrome

Edema is the abnormal accumulation of fluid in the interstitial compartment of tissues within the body. In nephrotic syndrome, edema is often seen in dependent areas such as the legs, but it can progress to cause significant accumulation in other areas leading to pulmonary edema, ascites, and/or anasarca. In this review, we focus on mechanisms and management of edema in children with nephrotic syndrome. We review the common mechanisms of edema, its burden in pediatric patients, and then present our approach and algorithm for management of edema in pediatric patients. The extensive body of experience accumulated over the last 5 decades means that there are many options, and clinicians may choose among these options based on their experience and careful monitoring of responses in individual patients.

Peripartum cardiomyopathy

Peripartum cardiomyopathy is now increasingly recognized as a cause of heart failure in the later months of pregnancy and early postpartum period. Clinical diagnosis may be challenging as it closely resembles several common medical and obstetric complications. Complex pathogenesis, unpredictable onset, staggered recovery, and unanticipated fetomaternal risks pose unique challenge to clinicians. Prevalence seems to vary with race, geographic location, and diagnostic criteria. The presence of multiple risk factors substantially elevates the risk of PPCM. Transthoracic echocardiographic examination can exclude the majority of the mimickers. Symptomatic presentation is initially limited to, varying grades of low cardiac output syndrome. Rarely, PPCM begins with decompensated heart failure and cardiovascular collapse. Guideline-directed medical therapy involves graded initiation and titration of heart failure medications while ensuring the fetal and neonatal safety. Anesthetic and obstetric management should be individualized to improve fetomaternal outcomes. However, emergent cesarean delivery may be required in women with decompensated heart failure and cardiovascular collapse. An early institution of mechanical circulatory support has shown to improve outcome. Bromocriptine and other experimental drugs designed to target pathogenic pathway have yielded mixed results. A further change in approach to management requires a comprehensive understanding of pathophysiology and fetomaternal safety profiles of heart failure medications.

Arthrofibrosis of the Ankle

Arthrofibrosis is a common, but often overlooked, condition that imparts significant morbidity following injuries and surgery to the foot and ankle. The most common etiologies are related to soft tissue trauma with subsequent fibrotic and contractile scar tissue formation within the ligaments and capsule of the ankle. This leads to pain, alterations in gait, and ankle dysfunction. Initial treatment often includes extensive physical therapy, however, if severe enough surgical options exist. Although the literature regarding ankle arthrofibrosis is scarce, this review article provides a greater understanding of the pathogenesis of arthrofibrosis and describes the current and future therapeutic options to treat fibrotic joints. Level of Evidence: Level V, expert opinion.

Anthracycline and Peripartum Cardiomyopathies

Anthracycline-associated cardiomyopathy and peripartum cardiomyopathy are nonischemic cardiomyopathies that often afflict previously healthy young patients; both diseases have been well described since at least the 1970s and both occur in the settings of predictable stressors (ie, cancer treatment and pregnancy). Despite this, the precise mechanisms and the ability to reliably predict who exactly will go on to develop cardiomyopathy and heart failure in the face of anthracycline exposure or childbirth have proven elusive. For both cardiomyopathies, recent advances in basic and molecular sciences have illuminated the complex balance between cardiomyocyte and endothelial homeostasis via 3 broad pathways: reactive oxidative stress, interference in apoptosis/growth/metabolism, and angiogenic imbalance. These advances have already shown potential for specific, disease-altering therapies, and as our mechanistic knowledge continues to evolve, further clinical successes are expected to follow.

Cerebral cavernomas in adults and children express relaxin

OBJECTIVE

To shed light on the role of relaxin in cerebral cavernous malformations (CCMs) in adults and children, the authors investigated endothelial cell (EC) expression of relaxin 1, 2, and 3; vascular endothelial growth factor receptor-1 and -2 (VEGFR-1 and -2); Ki-67; vascular geometry; and hemorrhage, as well as the clinical presentation of 32 patients with surgically resected lesions.

METHODS

Paraffin-embedded sections of 32 CCMs and 5 normal nonvascular lesion control (NVLC) brain tissue samples were immunohistochemically stained with antibodies to relaxin 1, 2, and 3; angiogenesis growth factor receptors Flt-1 (VEGFR-1) and Flk-1 (VEGFR-2); and proliferation marker Ki-67. For morphometric analysis, Elastica van Gieson stain was used, and for hemorrhage demonstration, Turnbull stain was used. Data from the pediatric and adult CCMs were compared with each other and with those obtained from the NVLCs. Statistical analyses were performed with Fisher's exact test, the chi-square test, the phi correlation coefficient, and the Student t-test. A p value < 0.05 was considered significant.

RESULTS

Pediatric and adult cavernoma vessels did not significantly differ in diameter. Hemorrhage was observed in CCMs but not in NVLC samples (p < 0.05). There was no difference in expression of Ki-67, VEGFR-1 and -2, and relaxin 1, 2, and 3 in the ECs of pediatric and adult CCMs. The ECs of CCMs were largely negative for relaxin 3 compared to NVLCs (p < 0.05), whereas CCMs, compared to control brain tissue samples, more frequently expressed Flt-1 and relaxin 2 (p < 0.05). Ki-67 was not expressed in the NVLCs, but the difference was not statistically significant. Relaxin 1 and 2 expression and increased expression of VEGFR-1 were associated with a supra- versus infratentorial location (p < 0.05).

CONCLUSIONS

Relaxin 1 and 2 and VEGFR-1 play a role in supratentorial cavernomas. Relaxin 3 may play a physiological role in normal brain vasculature. Relaxin 1 and 3 are also found in normal cerebral vasculature. Relaxin 1, 2, and 3 are associated with increased VEGFR-1 expression.

Intraarticular injection of relaxin-2 alleviates shoulder arthrofibrosis

Arthrofibrosis is a prevalent condition affecting greater than 5% of the general population and leads to a painful decrease in joint range of motion (ROM) and loss of independence due to pathologic accumulation of periarticular scar tissue. Current treatment options are limited in effectiveness and do not address the underlying cause of the condition: accumulation of fibrotic collagenous tissue. Herein, the naturally occurring peptide hormone relaxin-2 is administered for the treatment of adhesive capsulitis (frozen shoulder) and to restore glenohumeral ROM in shoulder arthrofibrosis. Recombinant human relaxin-2 down-regulates type I collagen and α smooth muscle actin production and increases intracellular cAMP concentration in human fibroblast-like synoviocytes, consistent with a mechanism of extracellular matrix degradation and remodeling. Pharmacokinetic profiling of a bolus administration into the glenohumeral joint space reveals the brief systemic and intraarticular (IA) half-lives of relaxin-2: 0.96 h and 0.62 h, respectively. Furthermore, using an established, immobilization murine model of shoulder arthrofibrosis, multiple IA injections of human relaxin-2 significantly improve ROM, returning it to baseline measurements collected before limb immobilization. This is in contrast to single IA (sIA) or multiple i.v. (mIV) injections of relaxin-2 with which the ROM remains constrained. The histological hallmarks of contracture (e.g., fibrotic adhesions and reduced joint space) are absent in the animals treated with multiple IA injections of relaxin-2 compared with the untreated control and the sIA- and mIV-treated animals. As these findings show, local delivery of relaxin-2 is an innovative treatment of shoulder arthrofibrosis.

Peripartum Cardiomyopathy: an Update

Purpose of Review

Peripartum cardiomyopathy (PPCM) is an idiopathic disorder defined as heart failure occurring in women during the last month of pregnancy and up to 5 months postpartum. In this review, we outline recent reports about the disease pathogenesis and management and highlight the use of diagnosis and prognosis biomarkers.

Recent Findings

Novel data strengthen the implication of endothelial function in PPCM pathogenesis. The first international registry showed that patient presentations were similar globally, with heterogeneity in patient management and outcome.

Summary

Despite large improvement in patient management and treatment, there is still a sub-group of women who die from PPCM or who will not recover their cardiac function. Remarkable advances in the comprehension of disease incidence, pathogenesis, and prognosis could be determined with multi-center and international registries.

Clinical Trials

ClinicalTrials.gov Identifier: NCT02590601

Nephrotic Syndrome: Oedema Formation and Its Treatment With Diuretics

Oedema is a defining element of the nephrotic syndrome. Its' management varies considerably between clinicians, with no national or international clinical guidelines, and hence variable outcomes. Oedema may have serious sequelae such as immobility, skin breakdown and local or systemic infection. Treatment of nephrotic oedema is often of limited efficacy, with frequent side-effects and interactions with other pharmacotherapy. Here, we describe the current paradigms of oedema in nephrosis, including insights into emerging mechanisms such as the role of the abnormal activation of the epithelial sodium channel in the collecting duct. We then discuss the physiological basis for traditional and novel therapies for the treatment of nephrotic oedema. Despite being the cardinal symptom of nephrosis, few clinical studies guide clinicians to the rational use of therapy. This is reflected in the scarcity of publications in this field; it is time to undertake new clinical trials to direct clinical practice.

Combined Assessment of Relaxin and B-Type Natriuretic Peptide Improves Diagnostic Value in Patients With Congestive Heart Failure

BACKGROUND

To improve the poor prognosis of congestive heart failure (CHF), early and accurate diagnosis is necessary. Relaxin is an endogenous cardiovascular peptide, and its plasma level is usually increased in patients with CHF. In this pilot study, we aimed to determine the diagnostic value of relaxin and B-type natriuretic peptide (BNP) in patients with and without CHF.

MATERIALS AND METHODS

The plasma level of relaxin was measured by enzyme-linked immunosorbent assay and plasma level of BNP by fluorescence immunoassay. The area under the receiver operating characteristic curve was used to assess the diagnostic value of relaxin and BNP.

RESULTS

We included 81 patients with decompenstated CHF and 36 controls. Plasma levels of relaxin and BNP were both higher in CHF patients than in controls. The correlation between plasma levels of relaxin and BNP and between relaxin or BNP and cardiac function was nonlinear. Relaxin had medium diagnostic value, and BNP had higher value for cardiac function and CHF. At a cutoff of 39.76pg/mL relaxin, sensitivity was 82.7%, specificity 55.6%, sum of the highest positive predictive value 80.5% and negative predictive value 58.8%. Although the diagnostic value was not better for relaxin than BNP, their combined assessment improved the sensitivity and specificity of diagnosis for CHF as compared with BNP alone.

CONCLUSIONS

Combined assessment of relaxin and BNP may improve the diagnosis of decompensated CHF, which may have potential application in the clinic.

Short-Term Administration of Serelaxin Produces Predominantly Vascular Benefits in the Angiotensin II/L-NAME Chronic Heart Failure Model

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Temporary administration of recombinant relaxin-2 (serelaxin) in patients hospitalized with HF was associated with improved mortality 6 months after discharge.

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The specific effects of serelaxin on vascular and myocardial structure and function in HF have not been studied.

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In mice subjected to continuous 28-day heart failure stimulus of AngII and L-NAME, serelaxin was administered for 3 days (days 7 to 9), and both the acute effects during serelaxin infusion and the delayed effects after termination of serelaxin on cardiovascular structure and function were studied.

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Temporary serelaxin improved vascular fibrosis and myocardial capillary density and reduced resistance vessel constriction to potassium chloride during administration. These effects unexpectedly persisted 19 days after discontinuation of serelaxin, despite continued exposure to AngII/L-NAME. Serelaxin did not alter cardiac hypertrophy, geometry, or dysfunction at either time point.

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These findings support that serelaxin predominantly affects vascular structure and function in the setting of HF.

In patients hospitalized with acute heart failure, temporary serelaxin infusion reduced 6-month mortality through unknown mechanisms. This study therefore explored the cardiovascular effects of temporary serelaxin administration in mice subjected to the angiotensin II (AngII)/L-NG-nitroarginine methyl ester (L-NAME) heart failure model, both during serelaxin infusion and 19 days post–serelaxin infusion. Serelaxin administration did not alter AngII/L-NAME-induced cardiac hypertrophy, geometry, or dysfunction. However, serelaxin-treated mice had reduced perivascular left ventricular fibrosis and preserved left ventricular capillary density at both time points. Furthermore, resistance vessels from serelaxin-treated mice displayed decreased potassium chloride–induced constriction and reduced aortic fibrosis. These findings suggest that serelaxin improves outcomes in patients through vascular-protective effects.

Therapies to Reduce Blood Pressure Acutely

Clinicians make frequent treatment decisions regarding acute blood pressure reduction for the critically ill. Key to the decision making process is a balance between reducing arterial wall stress and maintaining perfusion to vital organs. In this article, we review the physiological considerations underlying acute blood pressure management, including the concept of cerebral autoregulation and its adaptations to chronic hypertension. We then discuss available pharmacological interventions suited for reducing blood pressure acutely. We also discuss specific blood pressure targets in common critical illnesses and consider future directions in this therapeutic area.

Production of human pro-relaxin H2 in the yeast Pichia pastoris

Background

Initially known as the reproductive hormone, relaxin was shown to possess other therapeutically useful properties that include extracellular matrix remodeling, anti-inflammatory, anti-ischemic and angiogenic effects. All these findings make relaxin a potential drug for diverse medical applications. Its precursor, pro-relaxin, is an 18 kDa protein, that shows activity in in vitro assays. Since extraction of relaxin from animal tissues raises several issues, prokaryotes and eukaryotes were both used as expression systems for recombinant relaxin production. Most productive results were obtained when using Escherichia coli as a host for human relaxin expression. However, in such host, relaxin precipitated in the form of inclusion bodies and, therefore, required several expensive recovery steps as cell lysis, refolding and reduction.

Results

To overcome the issues related to prokaryotic expression here we report the production and purification of secreted human pro-relaxin H2 by using the methylotrophic yeast Pichia pastoris as expression host. The methanol inducible promoter AOX1 was used to drive expression of the native and histidine tagged forms of pro-relaxin H2 in dual phase fed-batch experiments on the 22 L scale. Both protein forms presented the correct structure, as determined by mass spectrometry and western blotting analyses, and demonstrated to be biologically active in immune enzymatic assays. The presence of the tag allowed to simplify pro-relaxin purification obtaining higher purity.

Conclusions

This work presents a strategy for microbial production of recombinant human pro-relaxin H2 in Pichia pastoris that allowed the obtainment of biologically active pro-hormone, with a final concentration in the fermentation broth ranging between 10 and 14 mg/L of product, as determined by densitometric analyses.

Electronic supplementary material

The online version of this article (doi:10.1186/s12896-016-0319-0) contains supplementary material, which is available to authorized users.

Evolving therapies for the management of chronic and acute decompensated heart failure

PURPOSE

The pharmacology, clinical efficacy, and safety profiles of evolving therapies for the management of chronic heart failure (HF) and acute decompensated heart failure (ADHF) are described.

SUMMARY

HF confers a significant financial burden despite the widespread use of traditional guideline-directed medical therapies such as angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, β-blockers, and aldosterone receptor antagonists, and the rates of HF-related mortality and hospitalization have remained unacceptably high. In response to a demand for novel pharmacologic agents, several therapeutic compounds have recently gained approval or are currently under review by the Food and Drug Administration. Sacubitril-valsartan has demonstrated benefit in reducing cardiovascular mortality and HF-related hospitalizations in clinical trials, while ivabradine and ferric carboxymaltose have proven efficacious in reducing HF-related hospitalizations. Lastly, the role of serelaxin in ADHF is currently under investigation in an ongoing Phase III study. While large, outcome-driven clinical trials are fundamental in informing the clinical application of these therapeutic agents, careful patient selection is imperative to ensuring similar outcomes postmarketing. In addition, optimization of current guideline-directed medical therapy remains essential as new therapies emerge and are incorporated into guideline recommendations. Additional therapeutic agents currently undergoing investigation include bucindolol hydrochloride, cimaglermin alfa, nitroxyl, omecamtiv mecarbil, TRV027, and ularitide. Clinical practitioners should remain abreast of emerging literature so that new therapeutic entities are optimally applied and positive patient outcomes are achieved.

CONCLUSION

Recently introduced agents for the treatment of patients with HF include sacubitril-valsartan, ivabradine, and ferric carboxymaltose. Additional agents worthy of attention include serelaxin and other therapies currently under investigation.

Antifibrotic therapies to control cardiac fibrosis

Cardiac fibrosis occurs naturally after myocardial infarction. While the initially formed fibrotic tissue prevents the infarcted heart tissue from rupture, the progression of cardiac fibrosis continuously expands the size of fibrotic tissue and causes cardiac function decrease. Cardiac fibrosis eventually evolves the infarcted hearts into heart failure. Inhibiting cardiac fibrosis from progressing is critical to prevent heart failure. However, there is no efficient therapeutic approach currently available. Myofibroblasts are primarily responsible for cardiac fibrosis. They are formed by cardiac fibroblast differentiation, fibrocyte differentiation, epithelial to mesenchymal transdifferentiation, and endothelial to mesenchymal transition, driven by cytokines such as transforming growth factor beta (TGF-β), angiotensin II and platelet-derived growth factor (PDGF). The approaches that inhibit myofibroblast formation have been demonstrated to prevent cardiac fibrosis, including systemic delivery of antifibrotic drugs, localized delivery of biomaterials, localized delivery of biomaterials and antifibrotic drugs, and localized delivery of cells using biomaterials. This review addresses current progresses in cardiac fibrosis therapies.

Relaxin-2 and Soluble Flt1 Levels in Peripartum Cardiomyopathy: Results of the Multicenter IPAC Study

OBJECTIVES

This study explored the association of vascular hormones with myocardial recovery and clinical outcomes in peripartum cardiomyopathy (PPCM).

BACKGROUND

PPCM is an uncommon disorder with unknown etiology. Angiogenic imbalance may contribute to its pathophysiology.

METHODS

In 98 women with newly diagnosed PPCM enrolled in the Investigation in Pregnancy Associated Cardiomyopathy study, serum was obtained at baseline for analysis of relaxin-2, prolactin, soluble fms-like tyrosine kinase 1 (sFlt1), and vascular endothelial growth factor (VEGF). Left ventricular ejection fraction (LVEF) was assessed by echocardiography at baseline and 2, 6, and 12 months.

RESULTS

Mean age was 30 ± 6 years, with a baseline of LVEF 0.35 ± 0.09. Relaxin-2, prolactin, and sFlt1 were elevated in women presenting early post-partum, but decreased rapidly and were correlated inversely with time from delivery to presentation. In tertile analysis, higher relaxin-2 was associated with smaller left ventricular systolic diameter (p = 0.006) and higher LVEF at 2 months (p = 0.01). This was particularly evident in women presenting soon after delivery (p = 0.02). No relationship was evident for myocardial recovery and prolactin, sFlt1 or VEGF levels. sFlt1 levels were higher in women with higher New York Heart Association functional class (p = 0.01) and adverse clinical events (p = 0.004).

CONCLUSIONS

In women with newly diagnosed PPCM, higher relaxin-2 levels soon after delivery were associated with myocardial recovery at 2 months. In contrast, higher sFlt1 levels correlated with more severe symptoms and major adverse clinical events. Vascular mediators may contribute to the development of PPCM and influence subsequent myocardial recovery. (Investigation in Pregnancy Associate Cardiomyopathy [IPAC]; NCT01085955).

Towards comprehensive cardiac repair and regeneration after myocardial infarction: Aspects to consider and proteins to deliver

Ischemic heart disease is a leading cause of death worldwide. After the onset of myocardial infarction, many pathological changes take place and progress the disease towards heart failure. Pathologies such as ischemia, inflammation, cardiomyocyte death, ventricular remodeling and dilation, and interstitial fibrosis, develop and involve the signaling of many proteins. Proteins can play important roles in limiting or countering pathological changes after infarction. However, they typically have short half-lives in vivo in their free form and can benefit from the advantages offered by controlled release systems to overcome their challenges. The controlled delivery of an optimal combination of proteins per their physiologic spatiotemporal cues to the infarcted myocardium holds great potential to repair and regenerate the heart. The effectiveness of therapeutic interventions depends on the elucidation of the molecular mechanisms of the cargo proteins and the spatiotemporal control of their release. It is likely that multiple proteins will provide a more comprehensive and functional recovery of the heart in a controlled release strategy.

GPCR signaling and cardiac function

G protein-coupled receptors (GPCRs), such as β-adrenergic and angiotensin II receptors, located in the membranes of all three major cardiac cell types, i.e. myocytes, fibroblasts and endothelial cells, play crucial roles in regulating cardiac function and morphology. Their importance in cardiac physiology and disease is reflected by the fact that, collectively, they represent the direct targets of over a third of the currently approved cardiovascular drugs used in clinical practice. Over the past few decades, advances in elucidation of their structure, function and the signaling pathways they elicit, specifically in the heart, have led to identification of an increasing number of new molecular targets for heart disease therapy. Here, we review these signaling modalities employed by GPCRs known to be expressed in the cardiac myocyte membranes and to directly modulate cardiac contractility. We also highlight drugs and drug classes that directly target these GPCRs to modulate cardiac function, as well as molecules involved in cardiac GPCR signaling that have the potential of becoming novel drug targets for modulation of cardiac function in the future.