Treatment with Rasburicase in Hospitalized Patients with Cardiorenal Syndrome: Old Treatment, New Scenario.

Cardiorenal syndrome (CRS) involves joint dysfunction of the heart and kidney. Acute forms share biochemical alterations like hyperuricaemia (HU) with tumour lysis syndrome (TLS). The mainstay treatment of acute CRS with systemic overload is diuretics, but rasburicase is used in TLS to prevent and treat hyperuricaemia. An observational, retrospective study was performed to assess the effectiveness and safety of a single dose of rasburicase in hospitalized patients with cardiorenal syndrome, worsening renal function and uric acid levels above 9 mg/dL. Rasburicase improved diuresis and systemic congestion in the 35 patients included. A total of 86% of patients did not need to undergo RRT, and early withdrawal was possible in the remaining five. Creatinine (Cr) decreased after treatment with rasburicase from a peak of 3.6 ± 1.27 to 1.79 ± 0.83 mg/dL, and the estimated glomerular filtration rate (eGFR) improved from 17 ± 8 to 41 ± 20 mL/min/1.73 m2 (p = 0.0001). The levels of N-terminal type B Brain Natriuretic Peptide (Nt-ProBNP) and C-reactive protein (CRP) were also significantly reduced. No relevant adverse events were detected. Our results show that early treatment with a dose of rasburicase in patients with CRS and severe HU is effective to improve renal function and systemic congestion, avoiding the need for sustained extrarenal clearance, regardless of comorbidities and ventricular function.

Eplerenone improves hyperglycemia and sympathetic excitation in chronic renocardiac syndrome in rats.

We aimed to assess the efficacy of eplerenone, a steroidal mineralocorticoid receptor antagonist known to reduce blood pressure and mitigate cardiovascular disease (CVD) progression, in retarding the progression of chronic kidney disease (CKD) and CVD in a rat model of type 4 cardiorenal syndrome (CRS). We grouped rats into four experimental categories: sham surgery, sham treatment with eplerenone, nephrectomy without eplerenone (Nx), and nephrectomy with eplerenone (Nx + EP). For the Nx + EP group, rats received five-sixths nephrectomy, inducing CKD and CVD conditions such as renal hypertension and hyperglycemia, and were then treated with eplerenone (100 mg/kg/day, orally) over 4 weeks after an initial 4-week observation period. Heart rate, blood pressure, blood sugar levels, and sympathetic nerve excitation were monitored biweekly. In addition, assessments of renal and cardiac tissues, including evaluation of renal tubulointerstitial injury, glomerular injury, and cardiomyocyte hypertrophy, were conducted at week 8. Eplerenone administration mitigated CKD and CVD progression in the Nx + EP group, evident by improved blood pressure (217.3 ± 5.4 versus 175.3 ± 5.6), blood sugar (121.8 ± 1.3 versus 145.6 ± 6.0) level, reduced sympathetic nerve excitation, and cardiomyocyte hypertrophy compared to the Nx group. However, renal tubulointerstitial injury, glomerular injury, and cardiovascular dysfunction, which were increased in rats with type 4 CRS, did not show significant changes with eplerenone treatment. Our study demonstrated that eplerenone treatment did not exacerbate type 4 CRS but improved blood pressure, blood sugar levels, sympathetic nerve excitation, and cardiomyocyte hypertrophy in this model.

Gualou xiebai decoction ameliorates cardiorenal syndrome type II by regulation of PI3K/AKT/NF-κB signalling pathway.

BACKGROUND: Cardiorenal syndromes type II (CRS2) is a multi-organ ailment that manifests as a combination of cardiac and renal dysfunction, resulting in chronic kidney disease due to chronic cardiac insufficiency. It affects at least 26 million people worldwide, and its prevalence is increasing. Gualou Xiebai Decoction (GXD), a traditional Chinese medicine (TCM) with a rich history of application in the management of coronary artery disease, has been explored for its potential therapeutic benefits in CRS2. Nevertheless, the mechanism by which GXD alleviates CRS2 remains obscure, necessitating further investigation. PURPOSE: The aim of this study was to assess the effects of the ethanolic extract of GXD on CRS2 and to elucidate the underlying mechanism in a rat model of myocardial infarction, offering a potential target for clinical treatment for CRS2. STUDY DESIGN AND METHODS: A rat model of CRS2 was induced by surgical myocardial infarction and treated with GXD for 10 weeks. Cardiac function was assessed using echocardiography, while serum and urine biochemistry were analyzed to evaluate potential cardiac and renal damage. Furthermore, tissue samples were obtained for histological, protein, and genetic investigations. In addition, network pharmacology analysis and molecular docking were utilized to predict the primary active compounds, potential therapeutic targets, and interventional pathways through which GXD could potentially exert its effects on CRS2. Subsequently, these predictions were confirmed in vivo and vitro through various analyses. RESULTS: The current investigation employed echocardiography to exhibit the apparent cardiac remodeling following the induction of myocardial infarction. Damage to the heart and kidneys of CRS2 rats was effectively ameliorated by administration of GXD. The outcomes derived from the analyses of HE and Masson staining indicated that the pathological damage to the heart and kidney tissues of rats in the GXD groups was considerably alleviated. Using network pharmacology analysis, AKT1, IL-6, and TNF-α were identified as plausible therapeutic targets for the treatment of CRS with GXD. Subsequent functional and pathway enrichment analysis of the underlying targets disclosed that the PI3K/AKT/NF-κB signaling pathway may be involved in the mechanism of GXD in the treatment of CRS2. Immunohistochemical, western blot, RT-PCR and immunofluorescence staining were employed to demonstrate that GXD can regulate the PI3K/AKT/NF-κB signaling pathway in the CRS2 rat model. Ultimately, administration of the PI3K/AKT agonist 740Y-P counteracted the effect of diosmetin, which was one of the potential active components of GXD analysed by compound-target-disease network, on p-PI3K and p-AKT in vitro. CONCLUSIONS: The findings of this study suggest that GXD improves cardiac and renal function in CRS2 rats and that the underlying mechanism involves inhibition of the PI3K/AKT/NF-κB pathway.

Cardiorenal damages in mice at early phase after intervention induced by angiotensin II, nephrectomy, and salt intake.

The interconnection of heart performance and kidney function plays an important role for maintaining homeostasis through a variety of physiological crosstalk between these organs. It has been suggested that acute or chronic dysfunction in one organ causes dysregulation in another one, like patients with cardiorenal syndrome. Despite its growing recognition as global health issues, still little is known on pathophysiological evaluation between the two organs. Previously, we established a preclinical murine model with cardiac hypertrophy and fibrosis, and impaired kidney function with renal enlargement and increased urinary albumin levels induced by co-treatment with vasopressor angiotensin II (A), unilateral nephrectomy (N), and salt loading (S) (defined as ANS treatment) for 4 weeks. However, how both tissues, heart and kidney, are initially affected by ANS treatment during the progression of tissue damages remains to be determined. Here, at one week after ANS treatment, we found that cardiac function in ANS-treated mice (ANS mice) are sustained despite hypertrophy. On the other hand, kidney dysfunction is evident in ANS mice, associated with high blood pressure, enlarged glomeruli, increased levels of urinary albumin and urinary neutrophil gelatinase-associated lipocalin, and reduced creatinine clearance. Our results suggest that cardiorenal tissues become damaged at one week after ANS treatment and that ANS mice are useful as a model causing transition from early to late-stage damages of cardiorenal tissues.

Cardiorenal syndrome and iron supplementation-more benefits than risks: a narrative review.

Intravenous iron administration has emerged as a crucial intervention for managing patients with cardiorenal syndrome (CRS) and iron deficiency, with or without the presence of anemia. Multiple studies have demonstrated the benefits of intravenous iron supplementation in improving anemia, symptoms, and functional capacity in patients with HF and iron deficiency. Furthermore, iron supplementation has been associated with a reduction in hospitalizations for HF exacerbation and the improvement of patients' quality of life and clinical outcomes. In addition to its effects on HF management, emerging evidence suggests a potential positive impact on kidney function in patients with CRS. Studies have shown an increase in estimated glomerular filtration rate and improvements in renal function markers in patients receiving intravenous iron therapy, highlighting the potential of this intervention in patients with CRS. This paper reviews the existing literature on the impact of intravenous iron therapy in these patient populations and explores its effects on various clinical outcomes. Future research endeavors are eagerly awaited to further improve our understanding of its clinical implications and optimize patient outcomes.

The potential role of hydrogen sulfide in regulating macrophage phenotypic changes via PINK1/parkin-mediated mitophagy in sepsis-related cardiorenal syndrome.

OBJECTIVE: Sepsis is one of major reasons of cardiorenal syndrome type 5 (CRS-5), resulting in irreversible tissue damage and organ dysfunction. Macrophage has been demonstrated to play key role in the pathophysiology of sepsis, highlighting the need to identify therapeutic targets for modulating macrophage phenotype in sepsis. METHODS AND RESULTS: In this study, a rapid-releasing hydrogen sulfide (H2S) donor NaSH, and a slow-releasing H2S compound S-propargyl-cysteine (SPRC) which is derived from garlic, have been studied for the immune-regulatory effects on macrophages. The NaSH and SPRC showed the potential to protect the heart and kidney from tissue injury induced by LPS. The immunohistochemistry of F4/80+ revealed that the infiltration of macrophages in the heart and kidney tissues of LPS-treated mice was reduced by NaSH and SPRC. In addition, in the LPS-triggered inflammatory cascade of RAW264.7 macrophage cells, NaSH and SPRC exhibited significantly inhibitory effects on the secretion of inflammatory cytokines, production of reactive oxygen species (ROS), and regulation of the macrophage phenotype from M1-like to M2-like. Moreover, autophagy, a crucial process involved in the elimination of impaired proteins and organelles during oxidative stress and immune response, was induced by NaSH and SPRC in the presence of LPS stimulation. Consequently, there was an increase in the number of mitochondria and an improvement in mitochondrial membrane potential. This process was mainly mediated by PINK1/Parkin pathway mediated mitophagy. DISCUSSION: These results demonstrated that the immunoregulatory effects of H2S donors were through the PINK1/Parkin-mediated mitophagy pathway. Overall, our study provided a new therapeutic direction in LPS-induced cardiorenal injury.

Dimethyl Fumarate Ameliorated Cardiorenal Anemia Syndrome and Improved Overall Survival in Dahl/Salt-Sensitive Rats.

Cardiovascular disease, chronic kidney disease, and anemia are known to adversely affect each other. Inflammation is commonly involved in these diseases. Cardiorenal anemia syndrome (CRAS) is the name given to this mutually harmful condition. Dimethyl fumarate (DMF) is a Food and Drug Administration-approved antioxidant and anti-inflammatory agent. The purpose of this study was to investigate the effects of DMF on Dahl/salt-sensitive (DS) rats as a CRAS model. Six-week-old DS rats were divided into three groups: the control group, the high-salt (HS) group, and the HS+DMF group. The HS and HS+DMF groups were fed a high-salt diet (8% NaCl) from 6 weeks of age. In the HS+DMF group, DMF (90 mg/kg per day) was orally administered from 6 to 15 weeks of age. Systolic blood pressure was measured every 2 weeks. The heart and renal injuries were assessed with histopathological analysis. The heart and renal expression of mRNAs was assessed by reverse-transcription polymerase chain reaction. DMF significantly improved overall survival, which was shortened by HS in DS rats. Systolic blood pressure increased in the HS group compared with the control group, and DMF tended to suppress this change. DMF ameliorated the cardiac and renal abnormalities confirmed in the HS group by histopathological analysis. Furthermore, the changes in mRNA expressions associated with disease exacerbation in the HS group were suppressed by DMF. DMF also improved anemia. This study suggests that DMF improves overall survival in DS rats through organ-protective effects and is effective against cardiorenal anemia syndrome. SIGNIFICANCE STATEMENT: Dimethyl fumarate was found to improve overall survival in Dahl/salt-sensitive rats, associated with its ability to ameliorate anemia and induce cardioprotective and renoprotective effects through anti-inflammatory and antifibrotic effects.

[Connotation of Shenqi Pills based on severe cases in cardiovascular care unit and modern pathophysiological mechanism and application of Shenqi Pills for heart failure, renal failure, cardiorenal syndrome, and diuretic resistance in critical care medicine].

Shenqi Pills, first recorded in Essentials from the Golden Cabinet(Jin Kui Yao Lue) from ZHANG Zhong-jing in Han dynasty, have the effect of warming and tonifying the kidney Qi and are mainly used for the treatment of insufficiency of kidney Qi and kidney Yang. According to modern medicine, kidney Qi involves heart function, kidney function, immune function, and so on. The clinical indications of Shenqi Pills include kidney deficiency, abnormal fluid, and abnormal urination, and the last one is classified into little urine, much urine, and dysuria. In clinical settings, Shenqi Pills can be applied for the treatment of heart failure, renal failure, cardiorenal syndrome, and diuretic resistance, as well as endocrine, urological, orthopedic, and other chronic degenerative diseases. Shenqi Pills are ideal prescriptions for the weak constitution and emergency treatment. It is of great value and significance to carry out in-depth research on the connotation of the classic articles by integrating TCM and western medicine based on "pathogenesis combined with pathology and drug properties combined with pharmacology".

[Zhenwu Decoction:connotation interpretation based on severe cases and modern pathophysiological mechanisms and application in treatment of heart failure in critical care unit].

Zhenwu Decoction is recorded in Treatise on Febrile Diseases by an outstanding physician ZHANG Zhong-jing in the Han dynasty. With effect of warming yang, transforming Qi, and promoting urination, Zhenwu Decoction is mainly used to treat edema due to yang deficiency. The studies of the severe and critical cases and the pathophysiological mechanisms have demonstrated that the record of Zhenwu Decoction in Treatise on Febrile Diseases describes the clinical symptoms and therapeutic regimen of acute heart failure. The syndrome treated by this formula may be related to the misdiagnosis and wrong treatment. Due to the difficult distinguishing between cardiogenic dyspnea and pulmonary dyspnea, high doses of Ephedrae Herba may be misused for inducing sweating, which may finally lead to the acute aggravation of heart failure, electrolyte disorder, and pulmonary infection. The syndrome treated by Zhenwu Decoction can illustrate the lack of experience of ancient physicians in treating acute heart failure. The description of "trembling and shivering" may be the clinical manifestation of heart failure, which is an upgraded version of "trembling and shaking" treated by Linggui Zhugan Decoction.(1)In terms of diseases, Zhenwu Decoction is suitable for the treatment of acute or chronic heart failure, cardiorenal syndrome, and diuretic resistance. The decoction is especially suitable for treating whole heart failure, acute heart failure, heart failure with reduced ejection fraction, and heart failure with the syndrome of sold and dampness. In addition, it can be used to treat both type Ⅱ and type Ⅳ cardiorenal syndrome.(2)In terms of symptoms, Zhenwu Decoction can be used for treating chest tightness, palpitations, lower limb edema, difficult urination or increased urine output, fear of cold, pale fat tongue with teeth marks, white and slippery tongue fur, and deep or slow pulse.(3)In terms of the pharmacological mechanism, Zhenwu Decoction treats heart failure following the principle of promoting urination, expanding blood vessels, and invigorating heart in modern medicine. Aconiti Lateralis Radix Praparata is the sovereign herb in the formula, with the recommended dosage of 30-60 g. However, arrhythmia may be caused by high doses of Aconiti Lateralis Radix Praparata, which should be used with concern. In addition to Zhenwu Decoction, Shenqi Pills, Renshen Decoction, Wuling Powder, and Fangji Huangqi Decoction with the effect of invigorating spleen, replenishing Qi, warming Yang, and promoting urination can be used in the recovery stage. The therapy of reinforcing Yang was the last choice for critical cases due to the lack of medical conditions, unclear clinical diagnosis in history, which should be treated objectively now.

Updates in Cardiorenal Syndrome.

Cardiorenal syndrome is a term that refers to a collection of disorders involving both the heart and kidneys, encompassing multi-directional pathways between the 2 organs mediated through low arterial perfusion, venous congestion, and neurohormonal activation. The pathophysiology is complex and includes hemodynamic and neurohormonal changes, but inconsistent findings from recent studies suggest this is very heterogenous disorder. Management for ADHF remains focused on decongestion and neurohormonal blockade to overcome the intense sodium and fluid avidity of the CRS.

Sestrin2 Mediates Metformin Rescued the Age-Related Cardiac Dysfunctions of Cardiorenal Syndrome Type 3.

Acute kidney injury (AKI) leads to acute cardiac injury and dysfunction in cardiorenal syndrome Type 3 (CRS3) through oxidative stress (OS). The stress-inducible Sestrin2 (Sesn2) protein reduces reactive oxygen species (ROS) accumulation and activates AMP-dependent protein kinase (AMPK) to regulate cellular metabolism and energetics during OS. Sesn2 levels and its protective effects decline in the aged heart. Antidiabetic drug metformin upregulates Sesn2 levels in response to ischemia-reperfusion (IR) stress. However, the role of metformin in CRS3 remains unknown. This study seeks to explore how the age-related decrease in cardiac Sesn2 levels contributes to cardiac intolerance to AKI-induced insults, and how metformin ameliorates CRS3 through Sesn2. Young (3-5 months) and aged (21-23 months) C57BL/6J wild-type mice along with cardiomyocyte-specific knockout (cSesn2-/-) and their wild type of littermate (Sesn2f/f) C57BL/6J mice were subjected to AKI for 15 min followed by 24 h of reperfusion. Cardiac and mitochondrial functions were evaluated through echocardiograms and seahorse mitochondria respirational analysis. Renal and cardiac tissue was collected for histological analysis and immunoblotting. The results indicate that metformin could significantly rescue AKI-induced cardiac dysfunction and injury via Sesn2 through an improvement in systolic and diastolic function, fibrotic and cellular damage, and mitochondrial function in young, Sesn2f/f, and especially aged mice. Metformin significantly increased Sesn2 expression under AKI stress in the aged left-ventricular tissue. Thus, this study suggests that Sesn2 mediates the cardioprotective effects of metformin during post-AKI.

Syringaresinol inhibits cardiorenal fibrosis through HSP90 in a cardiorenal syndrome type 2.

BACKGROUND: Syringaresinol processes anti-inflammatory and antioxidative activity. However, the effects of syringaresinol on cardiorenal fibrosis caused by cardiorenal syndrome type 2 (CRS2) are unclear. METHODS: Molecular docking predicted binding activity of syringaresinol to heat shock protein 90 (HSP90). The toxicity of a 4-weeks treatment with 20 mg/kg of syringaresinol was observed by measuring serum pro-inflammatory cytokines levels and by cardiorenal pathology. A CRS2 rad model was established by myocardial infarction using ligation over an 8 week-period. Rats were divided into five groups, including sham, CRS2, pimitespib, syringaresinol, and HSP90 + syringaresinol. Rats were received a 4-weeks daily treatment with 10 mg/kg pimitespib (a HSP90 inhibitor) or 20 mg/kg syringaresinol. Recombinant adeno-associated virus (rAAV) carrying a periostin (PE) promoter driving the expression of wild-type HSP90 (rAAV9-PE-HSP90, 1 × 1011 µg) was treated intravenously once in CRS2 model rats. Cardiorenal function and pathology were assessed. Expressions of HSP90 and TGF-ß1 in the myocardium and kidney were measured by immunohistochemistry and western blotting. RESULTS: Syringaresinol showed good binding activity with HSP90, and no signs of toxicity in rats following treatment. Pimitespib or syringaresinol significantly improved the cardiorenal function and fibrosis in rats with CRS2. Meanwhile, the rAAV9-PE-HSP90 injection obviously blocked the effects of syringaresinol. CONCLUSIONS: Syringaresinol targets HSP90 to suppress CRS2-induced cardiorenal fibrosis, providing a promising therapeutic drug for CRS2.

Dapagliflozin protects the kidney in a non-diabetic model of cardiorenal syndrome.

Cardiorenal syndrome encompasses a spectrum of disorders involving heart and kidney dysfunction, and sharing common risk factors, such as hypertension and diabetes. Clinical studies have shown that patients with and without diabetes may benefit from using sodium-glucose cotransporter 2 inhibitors to reduce the risk of heart failure and ameliorate renal endpoints. Because the underlying mechanisms remain elusive, we investigated the effects of dapagliflozin on the progression of renal damage, using a model of non-diabetic cardiorenal disease. Dahl salt-sensitive rats were fed a high-salt diet for five weeks and then randomized to dapagliflozin or vehicle for the following six weeks. After treatment with dapagliflozin, renal function resulted ameliorated as shown by decrease of albuminuria and urine albumin-to-creatinine ratio. Functional benefit was accompanied by a decreased accumulation of extracellular matrix and a reduced number of sclerotic glomeruli. Dapagliflozin significantly reduced expression of inflammatory and endothelial activation markers such as NF-κB and e-selectin. Upregulation of pro-oxidant-releasing NADPH oxidases 2 and 4 as well as downregulation of antioxidant enzymes were also counteracted by drug treatment. Our findings also evidenced the modulation of both classic and non-classic renin-angiotensin-aldosterone system (RAAS), and effects of dapagliflozin on gene expression of ion channels/transporters involved in renal homeostasis. Thus, in a non-diabetic model of cardiorenal syndrome, dapagliflozin provides renal protection by modulating inflammatory response, endothelial activation, fibrosis, oxidative stress, local RAAS and ion channels.

Cardioprotective effect of abscisic acid in a rat model of type 3 cardio-renal syndrome: Role of NOX-4, P-53, and HSP-70.

Cardiorenal syndrome (CRS) is a complex heart and kidney pathophysiologic disorder that leads to a bidirectional interrelationship between them. Abscisic acid (ABA) is a phytohormone that is present in plants, and is known to regulate fundamental physiological functions. This study aimed to explore the efficacy of ABA in surgically induced-CRS type 3 rats. Rats were randomly and equally divided into four groups. Rats in Group 1 received saline (Sham group), Group 2 included control induced-CRS rats, Group 3 rats (CRS+ABA) included CRS rats treated with ABA and Group 4 (CRS + ABA + Verapamil + propofol) were CRS rats treated with Verapamil, propofol and ABA. The rats were treated with the drugs daily for four weeks. At the end of the study, relative heart weight corrected QT interval (QTc), mean blood pressure (MBP), kidney functions, oxidative stress, NADPH oxidase 4 (NOX4), protein 53 (P53), and heat shock proteins-70 (HSP-70) expression was assessed and recorded. ABA led to a significant shortening of the ventricular action potential duration indicated by QTc. Furthermore, it significantly lowered heart weight, MBP, serum creatinine, NOX-4, and P-53 expression and augmented HSP-70 expression. In contrast, adding calcium channel blockers (CCBs) to ABA mitigated this effect. The results suggested that ABA has a potential protective role in CRS-induced cardiac hypertrophy and arrhythmia that could be mediated through inhibition of P-53, NOX-4, and an increase in HSP-70 expression.

Role of DPP4 and DPP4i in Glucose Homeostasis and Cardiorenal Syndrome.

The objective of the review led to the pursuit of adopting dipeptidyl peptidase-4 inhibitors (DPP4i) as a novel pharmacotherapy in diabetes mellitus (DM) and cardiorenal syndrome (CRS). The CRS is defined as the co-existence of myocardial ischemia with renal failure. At present, the commercially available drugs enhance insulin secretion or action. However, most of the drugs are associated with adverse effects, such as weight gain or hypoglycemia. As a result, newer therapies with better safety and efficacy profiles are being explored. The DPP4 protease enzyme is involved in cardiovascular and renal diseases in association with over-expressed cytokines. The novel characteristic of DPP4i is to control the elevated blood glucose levels in response to nutrient ingestion without causing hypoglycemia. Also, DPP4i are indirectly involved in reducing myocardial ischemia by promoting cardioprotective peptides. They protect the glucagon-like peptide 1 (GLP-1) from the deteriorating effect of the DPP4 enzyme. The GLP-1 receptors (GLP-1R) are abundantly expressed in renal and cardiovascular tissue. The overexpression of GLP-1R will confer protection of the heart and kidney during CRS. DPP4i were found to significantly clear plasma glucose by the simultaneously activating natural thrombolytic system and increasing insulin levels. They can be used in the early stages of the disease, including pre-diabetes or obesity combined with impaired incretin response, while the combination of DPP4i with metformin or thiazolidinediones as insulin sensitizers offers an additional improvement in the treatment of DM. With its positive attributes in a host of associated parameters of interest, DPP4i are studied extensively in the present review.

Eplerenone inhibits the macrophage-to-myofibroblast transition in rats with UUO-induced type 4 cardiorenal syndrome through the MR/CTGF pathway.

Cardiovascular complications are the leading causes of death in patients with chronic kidney disease (CKD), accounting for approximately 50% of deaths. Despite significant advances in the understanding of cardiac disease due to CKD, the underlying mechanisms involved in many pathological changes have not been fully elucidated. In our previous study, we observed severe fibrosis in the contralateral kidney of a 6-month-old rat UUO model. In the present experiment, we also observed severe fibrosis in the hearts of rats subjected to UUO and the macrophage-to-myofibroblast transition (MMT). These effects were inhibited by the mineralocorticoid receptor (MR) blocker eplerenone. Notably, in vitro, aldosterone-activated MR induced the MMT and subsequently promoted the secretion of CTGF, the target of MR, from macrophages; these changes were inhibited by eplerenone. The CTGF also induced the MMT and both the aldosterone and CTGF-induced MMT could be alleviated by the CTGF blocker. In conclusion, our results suggest that targeting the MR/CTGF pathway to inhibit the MMT may be an effective therapeutic strategy for the treatment of cardiac fibrosis.

Klotho relieves inflammation and exerts a cardioprotective effect during renal ischemia/reperfusion-induced cardiorenal syndrome.

BACKGROUND: Renal ischemia and reperfusion injury (IRI) is the main cause of acute kidney injury (AKI). AKI induces the development of cardiac hypertrophy (CH) during cardiorenal syndrome (CRS), and cardiomyocyte calcium mishandling though systemic inflammation after 8 days of renal IRI. Klotho has recently been described as an anti-inflammatory component. Given this, Klotho treatment could prevent or attenuate the inflammation, thereby also preventing electrical cardiac outcomes incurred by CRS. The aim of this study was to investigate the therapeutic role of Klotho in CRS after unilateral renal IRI through its anti-inflammatory action. METHODS: We examined renal tissue structure and function, intracellular Ca2+ dynamics in adult ventricular cardiomyocytes and serum cytokine levels from C57BL/6 mice that suffered unilateral renal IRI by occluding the left pedicle for 60 min and reperfusion for 8 days. The animals were treated with recombinant Klotho protein starting from the day of the surgery, then daily for 8 days. RESULTS: After Klotho treatment for 8 days, the left renal tissue remained damaged, however the renal function was restored due to the right kidney tissue preservation. In parallel, Klotho also prevented an increase in serum interleukin (IL-) 6, IL-1ß, and tumor necrosis factor alpha (TNF-α) levels. CH and low cell contraction were also prevented, as well as a decrease in systolic Ca2+ transients and sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) activity measured as Ca2+ transient decay, an increase in spontaneous Ca2+ release and the incidence of pro-arrhythmic events. CONCLUSIONS: The Klotho treatment showed promise, playing an important role in the pathophysiology of CRS. We were unable to observe a total renoprotective role of the compound in the model; in turn, a cardioprotective role of Klotho was demonstrated through the prevention of hypertrophy and normalization of the Ca2+ cycle dysfunction of cardiomyocytes. We propose that Klotho acts in the cardiorenal syndrome by systematically preventing inflammation and increased FGF23, alleviating cardiac outcomes.

The Kidney in Heart Failure: The Role of Venous Congestion.

Heart failure can lead to renal impairment, an interaction now termed "cardiorenal syndrome." The prevalent physiological explanation for the renal impairment that accompanies heart failure centers around the forward failure hypothesis, which emphasizes the role of left ventricular dysfunction in causing edema, and the backward failure hypothesis, which singles out venous congestion as the dominant mechanism of edema and reduced glomerular filtration rate. In this review, we provide an appraisal on venous congestion, an extremely important contributor that has received little attention. We also summarize the pharmacology of loop diuretics, explain current understanding of diuretic resistance, and address controversies regarding decongestive treatments.

Classic and Novel Mechanisms of Diuretic Resistance in Cardiorenal Syndrome.

Despite the incompletely understood multiple etiologies and underlying mechanisms, cardiorenal syndrome is characterized by decreased glomerular filtration and sodium avidity. The underlying level of renal sodium avidity is of primary importance in driving a congested heart failure phenotype and ultimately determining the response to diuretic therapy. Historically, mechanisms of kidney sodium avidity and resultant diuretic resistance were primarily extrapolated to cardiorenal syndrome from non-heart failure populations. Yet, the mechanisms appear to differ between these populations. Recent literature in acute decompensated heart failure has refuted several classically accepted diuretic resistance mechanisms and reshaped how we conceptualize diuretic resistance mechanisms in cardiorenal syndrome. Herein, we propose an anatomically based categorization of diuretic resistance mechanisms to establish the relative importance of specific transporters and translate findings toward therapeutic strategies. Within this categorical structure, we discuss classic and novel mechanisms of diuretic resistance.

Empagliflozin activates Wnt/ß-catenin to stimulate FUNDC1-dependent mitochondrial quality surveillance against type-3 cardiorenal syndrome.

OBJECTIVES: Cardiorenal syndrome type-3 (CRS-3) is an abrupt worsening of cardiac function secondary to acute kidney injury. Mitochondrial dysfunction is a key pathological mechanism of CRS-3, and empagliflozin can improve mitochondrial biology by promoting mitophagy. Here, we assessed the effects of empagliflozin on mitochondrial quality surveillance in a mouse model of CRS-3. METHODS: Cardiomyocyte-specific FUNDC1-knockout (FUNDC1CKO) mice were subjected to CRS-3 prior to assessment of mitochondrial homeostasis in the presence or absence of empagliflozin. RESULTS: CRS-3 model mice exhibited lower heart function, increased inflammatory responses and exacerbated myocardial oxidative stress than sham-operated controls; however, empagliflozin attenuated these alterations. Empagliflozin stabilized the mitochondrial membrane potential, suppressed mitochondrial reactive oxygen species production, increased mitochondrial respiratory complex activity and restored the oxygen consumption rate in cardiomyocytes from CRS-3 model mice. Empagliflozin also normalized the mitochondrial morphology, mitochondrial dynamics and mitochondrial permeability transition pore opening rate in cardiomyocytes. Cardiomyocyte-specific ablation of FUN14 domain-containing protein 1 (FUNDC1) in mice abolished the protective effects of empagliflozin on mitochondrial homeostasis and myocardial performance. Empagliflozin activated ß-catenin and promoted its nuclear retention, thus increasing FUNDC1-induced mitophagy in heart tissues; however, a ß-catenin inhibitor reversed these effects. CONCLUSIONS: In summary, empagliflozin activated Wnt/ß-catenin to stimulate FUNDC1-dependent mitochondrial quality surveillance, ultimately improving mitochondrial function and cardiac performance during CRS-3. Thus, empagliflozin could be considered for the clinical management of heart function following acute kidney injury.