Cardiorenal Syndrome: Role of Arginine Vasopressin and Vaptans in Heart Failure

Arginine vasopressin induces ferroptosis to promote heart failure via activation of the V1aR/CaN/NFATC3 pathway

Arginine vasopressin (AVP) is a key contributor to heart failure (HF), but the underlying mechanisms remain unclear. In the present study, a mouse model of HF and human cardiomyocyte (HCM) cells treated with dDAVP are generated in vivo and in vitro, respectively. Hematoxylin and eosin (HE) staining is used to evaluate the morphological changes in the myocardial tissues. A colorimetric method is used to measure the iron concentration, Fe 2+ concentration and malondialdehyde (MDA) level. Western blot analysis is used to examine the protein levels of the V1a receptor (V1aR), calcineurin (CaN), nuclear factor of activated T cells isoform C3 (NFATC3), glutathione peroxidase 4 (GPX4) and acyl-CoA synthase long chain family member 4 (ACSL4). Immunoprecipitation (IP) and luciferase reporter assays are performed to determine the interaction between NFATC3 and ACSL4. Both in vivo and in vitro experiments reveal that the V1aR-CaN-NFATC3 signaling pathway and ferroptosis are upregulated in HFs, which are verified by the elevated protein levels of V1aR, CaN, NFATC3 and ACSL4; reduced GPX4 protein level; and enhanced Fe 2+ and MDA levels. We further find that inhibiting NFATC3 by suppressing the V1aR/CaN/NFATC3 pathway via V1aR/CaN inhibitors or sh-NFATC3 not only alleviates HF but also inhibits AVP-induced ferroptosis. Mechanistically, sh-NFATC3 significantly reverses the increase in AVP-induced ACSL4 protein level, Fe 2+ concentration, and MDA level by directly interacting with ACSL4. Our results demonstrate that AVP enhances ACSL4 expression by activating the V1aR/CaN/NFATC3 pathway to induce ferroptosis, thus contributing to HF. This study may lead to the proposal of a novel therapeutic strategy for HF.

Identification of Shared Signature Genes and Immune Microenvironment Subtypes for Heart Failure and Chronic Kidney Disease Based on Machine Learning

Background

A complex interrelationship exists between Heart Failure (HF) and chronic kidney disease (CKD). This study aims to clarify the molecular mechanisms of the organ-to-organ interplay between heart failure and CKD, as well as to identify extremely sensitive and specific biomarkers.

Methods

Differentially expressed tandem genes were identified from HF and CKD microarray datasets and enrichment analyses of tandem perturbation genes were performed to determine their biological functions. Machine learning algorithms are utilized to identify diagnostic biomarkers and evaluate the model by ROC curves. RT-PCR was employed to validate the accuracy of diagnostic biomarkers. Molecular subtypes were identified based on tandem gene expression profiling, and immune cell infiltration of different subtypes was examined. Finally, the ssGSEA score was used to build the ImmuneScore model and to assess the differentiation between subtypes using ROC curves.

Results

Thirty-three crosstalk genes were associated with inflammatory, immune and metabolism-related signaling pathways. The machine-learning algorithm identified 5 hub genes (PHLDA1, ATP1A1, IFIT2, HLTF, and MPP3) as the optimal shared diagnostic biomarkers. The expression levels of tandem genes were negatively correlated with left ventricular ejection fraction and glomerular filtration rate. The CIBERSORT results indicated the presence of severe immune dysregulation in patients with HF and CKD, which was further validated at the single-cell level. Consensus clustering classified HF and CKD patients into immune and metabolic subtypes. Twelve immune genes associated with immune subtypes were screened based on WGCNA analysis, and an ImmuneScore model was constructed for high and low risk. The model accurately predicted different molecular subtypes of HF or CKD.

Conclusion

Five crosstalk genes may serve as potential biomarkers for diagnosing HF and CKD and are involved in disease progression. Metabolite disorders causing activation of a large number of immune cells explain the common pathogenesis of HF and CKD.

Combination Diuretic Therapy to Counter Renal Sodium Avidity in Acute Heart Failure: Trials and Tribulations

In contrast to significant advances in the management of patients with chronic heart failure over the past few years, there has been little change in how patients with acute heart failure are treated. Symptoms and signs of fluid overload are the primary reason for hospitalization of patients who experience acute decompensation of heart failure. Intravenous loop diuretics remain the mainstay of therapy in this patient population, with a significant subset of them showing suboptimal response to these agents leading to incomplete decongestion at the time of discharge. Combination diuretic therapy, that is, using loop diuretics along with an add-on agent, is a widely applied strategy to counter renal sodium avidity through sequential blockade of sodium absorption within renal tubules. The choice of the second diuretic is affected by several factors, including the site of action, the anticipated secondary effects, and the available evidence on their efficacy and safety. While the current guidelines recommend combination diuretic therapy as a viable option to overcome suboptimal response to loop diuretics, it is also acknowledged that this strategy is not supported by strong evidence and remains an area of uncertainty. The recent publication of landmark studies has regenerated the interest in sequential nephron blockade. In this article, we provide an overview of the results of the key studies on combination diuretic therapy in the setting of acute heart failure and discuss their findings primarily with regard to the effect on renal sodium avidity and cardiorenal outcomes.

Predictive Value of Plasma Copeptin Level in Children with Acute Heart Failure

We investigated the ability of copeptin level to predict adverse outcome in pediatric heart failure (HF) and correlated copeptin level with various clinical and echocardiographic data. This cohort study was carried out on forty children with clinical picture of acute HF as the patient group and forty healthy children of matched age and sex as the control group. Echocardiographic examination and plasma copeptin level were performed for all included children at admission. Patients were followed up for 6 months for mortality or readmission. Plasma copeptin level was significantly higher in the patient group (16.2 ± 5) pmol/L compared to the control group (4.1 ± 2.3) pmol/L, P ˂0.001. Moreover, copeptin level was positively correlated with Ross classification, being the highest in patients with class IV (19.6 ± 3.9) pmol/L compared to those with class III (15.2 ± 4) pmol/L and class II (10.4 ± 1.5) pmol/L. Copeptin levels were significantly higher in patients with bad prognosis (21.2 ± 4.1) pmol/L compared to those with good prognosis (14.5 ± 4.1) pmol/L, P ˂0.001. Copeptin level had a significant positive correlation with age, heart rate, respiratory rate, and ROSS classification. On the contrary, copeptin level had a significant negative correlation with left ventricular fraction shortening and diastolic function. Copeptin at cut-off value of ≥ 19.5 pmol/L yielded a sensitivity of 75% and a specificity of 93% to predict adverse outcome in children with HF. Plasma copeptin level has a good prognostic value to predict adverse outcome in pediatric heart failure. Moreover, copeptin correlate well with the severity of pediatric HF.

Right Heart Function in Cardiorenal Syndrome

PURPOSE OF REVIEW

Since CRS is critically dependent on right heart function and involved in interorgan crosstalk, assessment and monitoring of both right heart and kidney function are of utmost importance for clinical outcomes. This systematic review aims to comprehensively report on novel diagnostic and therapeutic paradigms that are gaining importance for the clinical management of the growing heart failure population suffering from CRS.

RECENT FINDINGS

Cardiorenal syndrome (CRS) in patients with heart failure is associated with poor outcome. Although systemic venous congestion and elevated central venous pressure have been recognized as main contributors to CRS, they are often neglected in clinical practice. The delicate hemodynamic balance in CRS is particularly determined by the respective status of the right heart. The consideration of hemodynamic and CRS profiles is advantageous in tailoring treatment for better preservation of renal function. Assessment and monitoring of right heart and renal function by known and emerging tools like renal Doppler ultrasonography or new biomarkers may have direct clinical implications.

Combination of tolvaptan and valsartan improves cardiac and renal functions in doxorubicin-induced heart failure in mice

Heart failure (HF) is often complicated by renal dysfunction. Tolvaptan and valsartan are two well-known agents for the treatment of HF. However, the role of tolvaptan/valsartan combination on HF with renal dysfunction remains unclear. To establish a mice model with HF with renal dysfunction, mice were intraperitoneally injected with doxorubicin (Dox). Echocardiogram was applied to assess the left ventricular function. Additionally, serum aldosterone (ALD) and angiotensin II (Ang II) level in mice were determined by ELISA. Meanwhile, western blot assay was used to evaluate the expressions of B cell lymphoma-2 (Bcl-2), Bcl-2 associated X (Bax) and cleaved caspase 3 in the heart and kidney tissues of mice. In this study, we found that compared to tolvaptan or valsartan alone treatment group, tolvaptan/valsartan combination obviously improved the left ventricular ejection fraction (LVEF) and the left ventricular fractional shortening (LVFS), and reduced serum ALD and Ang II level in Dox-treated mice. Additionally, tolvaptan/valsartan combination significantly prevented the inflammation and fibrosis of heart and kidney tissues in Dox-treated mice. Meanwhile, tolvaptan/valsartan combination notably inhibited the myocardial and renal cell apoptosis in Dox-treated mice via upregulation of Bcl-2 and downregulation of Bax and cleaved caspase 3, compared to the single drug treatment. Collectively, tolvaptan/valsartan combination could improve cardiac and renal functions, as well as prevent the fibrosis, inflammation and apoptosis of heart and kidney tissues in Dox-treated mice. Taken together, combining tolvaptan with valsartan might be a promising approach to achieve enhanced therapeutic effect for treatment of HF with renal dysfunction.

Demystifying hyponatremia: A clinical guide to evaluation and management

Hyponatremia (serum sodium <135 mEq/L) is a frequent electrolyte abnormality complicating the clinical care of hospitalized patients. Hyponatremia has been associated with an increased risk of mortality. Hyponatremia can be seen in patients with euvolemia, hypovolemia, or hypervolemia. Evaluation of hyponatremia relies on clinical assessment and estimation of serum sodium, urine electrolytes, and serum and urine osmolality in addition to other case-specific laboratory parameters. In addition, point-of-care ultrasonography is an important adjunct to physical assessment in estimation of volume status. Understanding the pathophysiology of the underlying process can lead to a timely diagnosis and appropriate management of hyponatremia.

Serum Osmolarity and Vasopressin Concentration in Acute Heart Failure-Influence on Clinical Course and Outcome

Neurohormone activation plays an important role in Acute Heart Failure (AHF) pathophysiology. Serum osmolarity can affect this activation causing vasopressin excretion. The role of serum osmolarity and vasopressin concentration and its interaction remain still unexplored in AHF. The objective of our study was to evaluate the relationship of serum osmolarity with clinical parameters, vasopressin concentration, in-hospital course, and outcomes in AHF patients. The study group consisted of 338 AHF patients (male (76.3%), mean age of 68 ± 13 years) with serum osmolarity calculated by the equation: 1.86 × sodium [mmol/L] + (glucose [mg/dL]/18) + (urea [mg/dL]/2.8) + 9 and divided into osmolarity quartiles marked as: low: <287 mOsm/L, intermediate low: 287−294 mOsm/L, intermediate high: 295−304 mOsm/L, and high: >304 mOsm/L. There was an increasing age gradient in the groups and patients differed in the occurrence of comorbidities and baseline clinical and laboratory parameters. Importantly, analysis revealed that vasopressin presented a linear correlation with osmolarity (r = −0.221, p = 0.003) and its concentration decreased with quartiles (61.6 [44.0−81.0] vs. 57.8 [50.0−77.3] vs. 52.7 [43.1−69.2] vs. 45.0 [30.7−60.7] pg/mL, respectively, p = 0.034). This association across quartiles was observed among de novo AHF (63.6 [55.3−94.5] vs. 58.0 [50.7−78.6] vs. 52.0 [46.0−58.0] vs. 38.0 [27.0−57.0] pg/mL, respectively, p = 0.022) and was not statistically significant in patients with acute decompensated heart failure (ADHF) (59.5 [37.4−80.0] vs. 52.0 [38.0−74.5] vs. 57.0 [38.0−79.0] vs. 50.0 [33.0−84.0] pg/mL, respectively, p = 0.849). The worsening of renal function episodes were more frequent in quartiles with higher osmolarity (4 vs. 2 vs. 13 vs. 11%, respectively, p = 0.018) and patients that belonged to the quartiles with low and high osmolarity were characterized more often by incidence of worsening heart failure (20 vs. 9 vs. 10 vs. 22%, respectively, p = 0.032). There was also a U-shape distribution in relation to one-year mortality (31 vs. 19 vs. 23 vs. 37%, respectively, p = 0.022). In conclusion, there was an association of serum osmolarity with clinical status and both in-hospital and out-of-hospital outcomes. Moreover, the linear dependence between vasopressin concentration and serum osmolarity in the AHF population was identified and was driven mainly by patients with de novo AHF which suggests different pathophysiological paths in ADHF and AHF de novo.

Predictive Value of Urinary Aquaporin 2 for Acute Kidney Injury in Patients with Acute Decompensated Heart Failure

Acute kidney injury (AKI) is frequently encountered in people with acute decompensated heart failure (ADHF) and is associated with increased morbidity and mortality. Early detection of a urinary biomarker of kidney injury might allow a prompt diagnosis and improve outcomes. Levels of urinary aquaporin 2 (UAQP2), which is also associated with several renal diseases, are increased with ADHF. We aimed to determine whether UAQP2 predicted AKI in patients with ADHF. We conducted a prospective observation study in the coronary care unit (CCU) in a tertiary care university hospital in Taiwan. Individuals with ADHF admitted to the CCU between November 2009 and November 2014 were enrolled, and serum and urinary samples were collected. AKI was diagnosed in 69 (36.5%) of 189 adult patients (mean age: 68 years). Area under the receiver operating characteristic curve (AUROC) of biomarkers was evaluated to evaluate the diagnostic power for AKI. Both brain natriuretic peptide and UAQP2 demonstrated acceptable AUROCs (0.759 and 0.795, respectively). A combination of the markers had an AUROC of 0.802. UAQP2 is a potential biomarker of AKI in CCU patients with ADHF. Additional research on this novel biomarker is required.

Hyponatraemia in heart failure: time for new solutions?

Hyponatraemia is very common in heart failure (HF), especially in decompensated patients. It is associated with increased mortality and morbidity and considered a marker of advanced disease. Recognition of hyponatraemia and its causes may help guide treatment strategy. Historically, therapy has primarily focused on water restriction, decongestion with loop diuretics in case of volume overload (dilutional hyponatraemia) and sodium repletion in case of depletion. In this review, we summarise the potential benefits of established and emerging HF therapies on sodium homeostasis, with a focus on dual vasopressin antagonists, angiotensin receptor-neprilysin inhibitors, sodium-glucose cotransporter 2 inhibitors and hypertonic saline, and propose a potential therapeutic approach for hyponatraemia in HF.

Emerging Treatments of Cardiorenal Syndrome: An Update on Pathophysiology and Management

Cardiorenal syndrome refers to combined cardiac and renal dysfunction that adversely impacts both organs and is also associated with severe clinical outcomes. The pathophysiology is believed to be multifactorial and complex. Increased central venous pressure and intra-abdominal pressure, overactivation of the Renin-Angiotensin-Aldosterone System (RAAS), systemic illnesses like sepsis, amyloidosis, diabetes are important factors in developing the cardiorenal syndrome. Our review article attempts to review the pathophysiology and treatment aspect of cardiorenal syndrome and explores potential therapeutic strategies that can be adopted for the management.

We searched PubMed, EMBASE, Google Scholar for relevant articles using different keywords and Medical Subject Headings, and finalized 38 articles to be included in our study. Cardiorenal syndrome management aims to eliminate venous congestion and fluid retention, which leads to improved cardiorenal status. This is usually achieved using pharmacologic agents like diuretics, vasodilators, inotropes, angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin II receptor blockers (ARBs), neprilysin inhibitors, and extracorporeal methods like ultrafiltration. The use of therapeutic agents such as sodium-glucose co-transporter 2 inhibitors and tolvaptan (a vasopressin V2 receptor antagonist), and cardiac resynchronization therapy has also been shown to have potential benefits in managing the disease. These agents can be instrumental in the management and require large-scale clinical trials specifically aimed at improving cardiorenal outcomes based on severity and type of cardiorenal syndrome.

Apela inhibits systemic and renal inflammatory reactions in mice with type I cardiorenal syndrome

This study investigated the effect of apela on renal function and anti-inflammatory effect on whole body and kidney tissue in mice with type I cardiorenal syndrome (CRS). The murine type I CRS model was established and apela was subcutaneously infused for two weeks. Cardiac and renal functions were evaluated by echocardiography and blood biochemistry, respectively. The systemic and renal inflammatory responses were examined with molecular biological and histological methods. Human renal glomerular endothelial cells (RGECs) were used to evaluate the adhesion effect of monocytes in vitro. Compared to mice from the control group (CRS + vehicle), the plasma levels of N-terminal pro-brain natriuretic peptide, blood urea nitrogen and creatinine were significantly decreased, while the mean left ventricular ejection fraction was increased in apela-treated CRS mice at the 4th week. The expression of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) in the circulation and kidney was decreased in apela-treated mice compared with control mice, and apela improved cardio-renal pathology in mice with type I CRS. Additionally, Apela significantly suppressed the expression of MCP-1, TNF-α, intercellular adhesion molecule-1 and vascular intercellular adhesion molecule-1 in RGECs induced by angiotensin II (Ang II), and inhibited the promoting effect of Ang II on the adhesion of THP-1 cells to RGECs. Western blot results showed that the expression of phosphorylated nuclear factor kappa B (phospho-NFκB) in CRS mice was increased, but the expression of phospho-NFκB was down-regulated after apela treatment. Furthermore, apela significantly inhibited the Ang II-mediated increase in phospho-NFκB expression in RGECs in vitro, but the administration of an apelin peptide jejunum receptor (APJ) inhibitor blocked the inhibitory effect of apela. This study revealed that apela improves cardiorenal function and reduces systemic and renal inflammatory response in type I CRS mice and the apela/APJ system may alleviate renal inflammatory responses by inhibiting the NFκB signalling pathway.

Diastolic dysfunction and impaired cardiac output reserve in dysmetabolic nonhuman primate with proteinuria

BACKGROUND

Cardiorenal complications are common in patients with dysmetabolism and diabetes. The present study aimed to examine if a nonhuman primate (NHP) model with spontaneously developed metabolic disorder and diabetes develops similar complications to humans, such as proteinuria and cardiac dysfunction at resting condition or diminished cardiac functional reserve following dobutamine stress echocardiography (DSE).

METHODS AND RESULTS

A total of 66 dysmetabolic and diabetic cynomolgus (Macaca fascicularis) NHPs were enrolled to select 19 NHPs (MetS) with marked metabolic disorders and diabetes (fasting blood glucose: 178 ± 18 vs. 61 ± 3 mg/dL) accompanied by proteinuria (ACR: 134 ± 34 vs. 1.5 ± 0.4 mg/mmol) compared to 8 normal NHPs (CTRL). Under resting condition, MetS NHPs showed mild left ventricular (LV) diastolic dysfunction (E/A: 1 ± 0.06 vs. 1.5 ± 0.13), but with preserved ejection fraction (EF: 65 ± 2 vs. 71 ± 3%) compared to CTRL. DSE with an intravenous infusion of dobutamine at ascending doses (5, 10, 20, 30 and 40 μg/kg/min, 7 min for each dose) resulted in a dose-dependent increase in cardiac function, however, with a significantly diminished magnitude at the highest dose of dobutamine infusion (40 μg/kg/min) in both diastole (E/A: -12 ± 3 vs. -38 ± 5%) and systole (EF: 25 ± 3 vs. 33 ± 5%) as well as ~42% reduced cardiac output reserve (COR: 63 ± 8 vs. 105 ± 18%, p < 0.02) in the MetS compared to CTRL NHPs.

CONCLUSION

These data demonstrate that MetS NHPs with cardiorenal complications: proteinuria, LV diastolic dysfunction and preserved LV systolic function under resting conditions displayed compromised cardiac functional reserve under dobutamine stress. Based on these phenotypes, this NHP model of diabetes with cardiorenal complications can be used as a highly translational model mimic human disease for pharmaceutical research.

Aquaporins and diseases pathogenesis: From trivial to undeniable involvements, a disease-based point of view

Aquaporins (AQPs), as transmembrane proteins, were primarily identified as water channels with the ability of regulating the transmission of water, glycerol, urea, and other small-sized molecules. The classic view of AQPs involvement in therapeutic plan restricted them and their regulators into managing only a narrow spectrum of the diseases such as diabetes insipidus and the syndrome of inappropriate ADH secretion. However, further investigations performed, especially in the third millennium, has found that their cooperation in water transmission control can be manipulated to handle other burden-imposing diseases such as cirrhosis, heart failure, Meniere's disease, cancer, bullous pemphigoid, eczema, and Sjögren's syndrome.

Deciphering key genes in cardio-renal syndrome using network analysis

Cardio-renal syndrome (CRS) is a rapidly recognized clinical entity which refers to the inextricably connection between heart and renal impairment, whereby abnormality to one organ directly promotes deterioration of the other one. Biological markers help to gain insight into the pathological processes for early diagnosis with higher accuracy of CRS using known clinical findings. Therefore, it is of interest to identify target genes in associated pathways implicated linked to CRS. Hence, 119 CRS genes were extracted from the literature to construct the PPIN network. We used the MCODE tool to generate modules from network so as to select the top 10 modules from 23 available modules. The modules were further analyzed to identify 12 essential genes in the network. These biomarkers are potential emerging tools for understanding the pathophysiologic mechanisms for the early diagnosis of CRS. Ontological analysis shows that they are rich in MF protease binding and endo-peptidase inhibitor activity. Thus, this data help increase our knowledge on CRS to improve clinical management of the disease.

HEP-Net opinion on the management of ascites and its complications in the setting of decompensated cirrhosis in the resource constrained environment of Pakistan

Approximately one half of patients develop ascites within 10 years of diagnosis of compensated cirrhosis. It is a poor prognostic indicator, with only 50% surviving beyond two years. Mortality worsens significantly to 20% to 50% at one year if the ascites becomes refractory to medical therapy. Pakistan has one of the highest prevalence of viral hepatitis in the world and patients with ascites secondary to liver cirrhosis make a major percentage of both inpatient and outpatient burden. Studies indicate that over 80% of patients admitted with ascites have liver cirrhosis as the cause.

This expert opinion suggests proper assessment of patients with ascites in the presence of underlying cirrhosis. This expert opinion includes appropriate diagnosis and management of uncomplicated ascites, refractory ascites and complicated ascites (including spontaneous bacterial peritonitis (SBP) ascites, hepatorenal syndrome (HRS) and hyponatremia. The purpose behind this expert opinion is to help consultants, postgraduate trainees, medical officers and primary care physicians optimally manage their patients with cirrhosis and ascites in a resource constrained setting as is often encountered in a developing country like Pakistan.

An Update on the Pathophysiology and Treatment of Cardiorenal Syndrome

Cardiorenal syndrome (CRS) encompasses various disorders of the heart and kidneys; dysfunction of one organ leads to acute or chronic dysfunction of the other. It incorporates the intersection of heart-kidney interactions across several mediums, hemodynamically, through the alterations in neurohormonal markers, and increased venous and renal pressure, all of which are hallmarks of its clinical phenotypes. This article explores the epidemiology, pathology, classification and treatment of each type of CRS.

Over-expression of arginine vasopressin in magnocellular neurosecretory cells of hypothalamus and its potential relationship with development of diabetic nephropathy

INTRODUCTION

We aimed to assess our hypothesis that the expression changes of arginine vasopressin (AVP) in the magnocellular neurosecretory cells (MNCs) of hypothalamus and V2 receptor for AVP (RVP) in kidney may contribute to the pathogenesis of diabetic nephropathy (DN).

MATERIAL AND METHODS

Twenty-five male Wistar rats were randomly assigned to the control group and the diabetes mellitus (DM) group. Periodic acid-Schiff (PAS) staining and electron microscopy were used for morphological studies. Immunohistochemical staining for glial fibrillary acidic protein (GFAP) is standard for visualization of reactive astrocytes in the hypothalamus. Hypothalamus was used for immunofluorescence of AVP. Kidney was used for immunohistochemical staining of RVP. Quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) was used for quantitative determinations of AVP mRNA in hypothalamus and RVP mRNA in kidney. Western blot was used to measure the protein expression of AVP in hypothalamus and RVP in kidney.

RESULTS

Morphological studies showed abnormalities in kidney and hypothalamus in the DM group. The number of neurons and the gray value of astrocytes in hypothalamus in the DM group were markedly decreased. The expression level of AVP in hypothalamus and the expression level of RVP in kidney of DM rats were significantly increased. The positive correlations between the proteinuria and expression (mRNA and protein) of AVP, proteinuria and expression (mRNA and protein) of RVP, and the expression of AVP and RVP levels were found.

CONCLUSIONS

AVP was upregulated in the MNCs of hypothalamus and RVP was upregulated in kidney in streptozotocin-induced DM rats, indicating their potential roles in the development of DN.

Hyponatremia in Heart Failure: Pathogenesis and Management

Hyponatremia is a very common electrolyte abnormality, associated with poor short- and long-term outcomes in patients with heart failure (HF). Two opposite processes can result in hyponatremia in this setting: Volume overload with dilutional hypervolemic hyponatremia from congestion, and hypovolemic hyponatremia from excessive use of natriuretics. These two conditions require different therapeutic approaches. While sodium in the form of normal saline can be lifesaving in the second case, the same treatment would exacerbate hyponatremia in the first case. Hypervolemic hyponatremia in HF patients is multifactorial and occurs mainly due to the persistent release of arginine vasopressin (AVP) in the setting of ineffective renal perfusion secondary to low cardiac output. Fluid restriction and loop diuretics remain mainstay treatments for hypervolemic/dilutional hyponatremia in patients with HF. In recent years, a few strategies, such as AVP antagonists (Tolvaptan, Conivaptan, and Lixivaptan), and hypertonic saline in addition to loop diuretics, have been proposed as potentially promising treatment options for this condition. This review aimed to summarize the current literature on pathogenesis and management of hyponatremia in patients with HF.

Antidiuretic Hormone and Serum Osmolarity Physiology and Related Outcomes: What Is Old, What Is New, and What Is Unknown?

CONTEXT

Although the physiology of sodium, water, and arginine vasopressin (AVP), also known as antidiuretic hormone, has long been known, accumulating data suggest that this system operates as a more complex network than previously thought.

EVIDENCE ACQUISITION

English-language basic science and clinical studies of AVP and osmolarity on the development of kidney and cardiovascular disease and overall outcomes.

EVIDENCE SYNTHESIS

Apart from osmoreceptors and hypovolemia, AVP secretion is modified by novel factors such as tongue acid-sensing taste receptor cells and brain median preoptic nucleus neurons. Moreover, pharyngeal, esophageal, and/or gastric sensors and gut microbiota modulate AVP secretion. Evidence is accumulating that increased osmolarity, AVP, copeptin, and dehydration are all associated with worse outcomes in chronic disease states such as chronic kidney disease (CKD), diabetes, and heart failure. On the basis of these pathophysiological relationships, an AVP receptor 2 blocker is now licensed for CKD related to polycystic kidney disease.

CONCLUSION

From a therapeutic perspective, fluid intake may be associated with increased AVP secretion if it is driven by loss of urine concentration capacity or with suppressed AVP if it is driven by voluntary fluid intake. In the current review, we summarize the literature on the relationship between elevated osmolarity, AVP, copeptin, and dehydration with renal and cardiovascular outcomes and underlying classical and novel pathophysiologic pathways. We also review recent unexpected and contrasting findings regarding AVP physiology in an attempt to explain and understand some of these relationships.

Hyponatraemia in heart failure

Hyponatraemia is common in heart failure (HF). It is estimated that over 20% of patients admitted to hospital with HF have hyponatraemia. It has also been repeatedly shown to be a surrogate marker of increased morbidity and mortality in this specific population. This review focuses on the pathophysiology of hyponatraemia through the activation of neurohormonal cascades in HF, the clinical implications of sustained hyponatraemia and treatment options in the management of this challenging phenomenon.

Neurohormonal, Endocrine, and Immune Dysregulation and Inflammation in Cardiorenal Syndrome

“Organ crosstalk” is the complex physiological communication between different body systems, and it is necessary for the optimal equilibrium and functioning of the organism. In particular, heart and kidney function is tightly connected, and interplay between these two organs occurs through a vast array of dynamic and bidirectional mechanisms. The term cardiorenal syndrome (CRS) indicates an interaction between the heart and kidneys in acute and chronic disease settings. In all types of CRS, multiple pathophysiological processes are implicated in the initiation and progression of organ injury. In addition to hemodynamic parameters, endothelial injury, immunological imbalance, cell death, inflammatory cascades, oxidative stress, neutrophil migration, leukocyte trafficking, caspase-mediated apoptosis, extracellular vesicles, small noncoding RNAs, and epigenetics play pivotal roles in the development of CRS. In this review, we will focus on neurohormonal, endocrine, and immune dysregulation and inflammation as mechanisms involved in the pathogenesis of CRS.

Correlation between miRNA target site polymorphisms in the 3' UTR of AVPR1A and the risk of hypertension in the Chinese Han population

We aimed to study the relationship between rs11174811 and rs3803107 single nucleotide polymorphisms (SNPs) in miRNA target sites of the 3' UTR in the arginine vasopressin receptor 1a gene (AVPR1A) and the risk of hypertension in the Chinese Han population. The genotypes at rs11174811 and rs3803107 were analyzed by direct sequencing in 425 Chinese Han patients with hypertension and 425 healthy subjects. AVPR1A expression was investigated by transfecting miR-526b, miR-375, and miR-186 mimics into human umbilical vein endothelial cells (HUVECs) containing AVPR1A rs11174811 CC, CA/AA and AVPR1A rs3803107 GG, GA/AA genotypes. The A alleles of rs11174811 (adjusted OR = 1.424, 95% CI: 1.231-1.599, P<0.001) and rs3803107 (adjusted OR = 1.222, 95% CI: 1.092-1.355; P=0.001) were high risk factors for hypertension. Plasma levels of miR-526b, miR-375, and miR-186 were higher in the study group than in the control group (P<0.001). The expression levels of AVPR1A mRNA in AVPR1A rs11174811 and rs3803107 mutant HUVECs were higher than those in wild-type cells (t = 8.811, 4.068 and P=0.001, 0.015, respectively). The single nucleotide polymorphisms rs11174811 and rs3803107 in the AVPR1A gene are associated with an increased risk of hypertension in the Chinese Han population. This may be related to the effect of these variants on the regulation of AVPR1A expression by miRNAs.

Tolvaptan for Volume Management in Heart Failure

Volume management in acute decompensated and chronic heart failure (HF) remains a significant challenge. Although progress has been made in the development of mortality-reducing neurohormonal regimens in the reduced ejection fraction population, no clinical trial has yet demonstrated anything more than symptomatic relief or biomarker reduction with pharmacotherapeutic volume-based interventions made in the acutely decompensated individual or those with evolving outpatient congestion. As the number of patients with HF continues to grow, in addition to HF-related hospitalizations, identifying therapies that have the potential to aid in diuresis more safely and efficaciously is paramount to decreasing inpatient length of stay and preventing unnecessary admissions. More recently, a significant amount of research has been dedicated to the use of vasopressin antagonists, specifically tolvaptan, as adjunctive therapy to loop and thiazide diuretics. Although these agents do not seem to have a pervasive role in fluid management in the acute decompensated and chronic HF populations, they are effective tools to have available for specific clinical situations. This review summarizes the literature surrounding the use of tolvaptan for volume management in congestive HF, as well as offering practical guidance for use of this agent.

Hemodynamic and Hormonal Effects of Tolvaptan for Heart Failure

Tolvaptan (TLV) is a diuretic agent administrated for heart failure (HF) only in Japan. Many clinical findings have been obtained from the accumulation of clinical experience, and the administration of TLV reportedly avoids causing a reduction in the renal function. In addition, TLV has been reported to exert effects other than diuresis. The early start of TLV after hospitalization shortens the length of the hospital stay, and continuous TLV after discharge extends the period until re-hospitalization of HF patients. TLV is thought to function via vasopressin V2 receptor antagonism. However, no significant differences in the long-term prognosis were noted between the group using TLV and not using TLV in the Endovascular Valve Edge-to-Edge Repair Study (EVEREST) trial, and effects other than diuresis are not useful for all HF patients. Therefore, it is necessary to identify patients who may experience effects other than diuresis with TLV administration. The accumulation of more patients and findings from further large-scale clinical trials will be necessary in order to clarify these points.

New therapies for the treatment of heart failure: a summary of recent accomplishments

Despite continuous efforts to prevent cardiovascular diseases (CVDs), heart failure prevails as the number one cause of death in developed countries. To properly treat CVDs, scientists had to take a closer look at the factors that contribute to their pathogenesis and either modernize current pharmaceuticals or develop brand new treatments. Enhancement of current drugs, such as tolvaptan and omecamtiv mecarbil, sheds new light on already-known therapies. Tolvaptan, a vasopressin antagonist, could be adopted in heart failure therapy as it reduces pre- and afterload by decreasing systolic blood pressure and blood volume. Omecamtiv mecarbil, which is a myosin binding peptide, could aid cardiac contractility. The next generation vasodilators, serelaxin and ularitide, are based on naturally occurring peptides and they reduce peripheral vascular resistance and increase the cardiac index. In combination with their anti-inflammatory properties, they could turn out to be extremely potent drugs for heart failure treatment. Cardiotrophin has exceeded many researchers’ expectations, as evidence suggests that it could cause sarcomere hypertrophy without excessive proliferation of connective tissue. Rapid progress in gene therapy has caused it to finally be considered as one of the viable options for the treatment of CVDs. This novel therapeutic approach could restore stable heart function either by restoring depleted membrane proteins or by balancing the intracellular calcium concentration. Although it has been set back by problems concerning its long-term effects, it is still highly likely to succeed.

The clinical application value of the plasma copeptin level in the assessment of heart failure with reduced left ventricular ejection fraction: A cross-sectional study

This study aimed to evaluate the clinical applicability of the plasma copeptin level to assess heart failure with reduced left ventricular ejection fraction (HFrEF).One hundred thirty-one patients with HFrEF, 127 patients with heart failure with preserved left ventricular ejection fraction (HFpEF), and 119 healthy candidates were involved. The basic data and examination results of patients were collected. The heart function of the patients with HFrEF and HFpEF were graded on the basis of the criteria of New York Heart Association (NYHA) classification. The plasma copeptin and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were tested using enzyme-linked immunosorbent assays (ELISAs).The copeptin and NT-proBNP levels were higher in the HFrEF group than in the HFpEF group. The copeptin and NT-proBNP values increased as the NYHA grade increased in the patients with HFrEF. However, for the patients with HFpEF, the copeptin levels did not change markedly as the NYHA grade increased. The copeptin levels were positively correlated with the NT-proBNP levels in the patients with HFrEF; however, there was no correlation between the copeptin and NT-proBNP values in the patients with HFpEF.Copeptin is involved in the process of progression in patients with HFrEF and the copeptin values might be useful for HFrEF prediction and assessment in the clinic.

Efficacy of oral tolvaptan versus 3% hypertonic saline for correction of hyponatraemia in post-operative patients

Background and Aims:

Hyponatraemia is frequent in post-operative patients and may be corrected with hypertonic saline (HTS). Oral tolvaptan is used to treat hypervolaemic or euvolaemic hyponatraemia. This study was performed to assess the efficacy of oral tolvaptan in correcting postoperative hyponatraemia compared to HTS.

Methods:

This prospective, randomised study was conducted in 40 symptomatic patients with serum sodium level ≤130 mEq/L. In Group H (n = 20), 3% HTS was infused at 20–30 mL/h aiming for correction of 6 mEq/L/day. Group T received oral tolvaptan 15 mg on the 1^st day. If daily correction was <4 mEq/L, the dose was increased by 15 mg/day to a maximum of 45 mg. The primary outcome was serum sodium concentration 48 hours after starting treatment. Paired t-test was used to compare changes in sodium levels.

Results:

Baseline sodium and values at 12, 24 and 48 h were comparable in both groups. At 72 h, Group T had significantly higher sodium levels as compared to Group H (133.4 ± 1.9 vs. 131.3 ± 2.4 mEq/L). Intragroup analysis had shown a significant increase in sodium levels from baseline values in both groups at 12, 24, 48 and 72 h. Group H had a significantly lower potassium level and lower negative fluid balance on day 3.

Conclusion:

Oral tolvaptan and 3% HTS were equally effective in correcting hyponatraemia at 48 hours, but serum sodium levels were higher at 72 hours after oral tolvaptan.