Cardiorenal Syndrome Type 1 May Be Immunologically Mediated: A Pilot Evaluation of Monocyte Apoptosis

Chronic kidney disease activates the HDAC6-inflammatory axis in the heart and contributes to myocardial remodeling in mice: inhibition of HDAC6 alleviates chronic kidney disease-induced myocardial remodeling

Chronic kidney disease (CKD) adversely affects the heart. The underlying mechanism and the interplay between the kidney and the heart are still obscure. We examined the cardiac effect using the unilateral ureteral obstruction (UUO)-induced CKD pre-clinical model in mice. Echocardiography, histopathology of the heart, myocardial mRNA expression of ANP and BNP, the extent of fibrotic (TGF-β, α-SMA, and collagen I) and epigenetic (histone deacetylases, namely HDAC3, HDAC4, and HDAC6) proteins, and myocardial inflammatory response were assessed. Six weeks of post-UUO surgery, we observed a compromised left-ventricular wall thickness and signs of cardiac hypertrophy, accumulation of fibrosis associated, and inflammatory proteins in the heart. In addition, we observed a perturbation of epigenetic proteins, especially HDAC3, HDAC4, and HDAC6, in the heart. Pharmacological inhibition of HDAC6 using ricolinostat (RIC) lessened cardiac damage and improved left-ventricular wall thickness. The RIC treatment substantially restored the serum cardiac injury markers, namely creatine kinase-MB and lactate dehydrogenase (LDH) activities, ANP and BNP mRNA expression, and heart histological changes. The extent of myocardial fibrotic proteins, phospho-NF-κB (p65), and pro-inflammatory cytokines (TNF-α, IL-18, and IL-1β) were significantly decreased in the RIC treatment group. Further findings revealed the CKD-induced infiltration of CD3, CD8a, CD11c, and F4/80 positive inflammatory cells in the heart. Treatment with RIC substantially reduced the myocardial infiltration of these inflammatory cells. From these findings, we believe that CKD-induced myocardial HDAC6 perturbation has a deteriorative effect on the heart, and inhibition of HDAC6 can be a promising approach to alleviate CKD-induced myocardial remodeling.

Biomarkers in cardiorenal syndrome, a potential use in precision medicine

Cardiorenal syndrome refers to the interrelated dysfunction of the heart or kidney resulting in a cascade of feedback mechanisms, hemodynamic, neurohormonal, and immunological and/or biochemical feedback pathways causing damage in the other organ. Cardiorenal syndrome is categorized into five clinical subtypes depending on the perceived primary precipitant of organ injury and is associated with high morbidity and mortality. Therefore, the development of tools for the earliest identification of cardiorenal syndrome in hospitalized patients is of extremely high significance to ameliorate the prognosis and outcome of these patients. There is increasing interest in identifying molecules serving as biomarkers, reflecting hemodynamic changes, heart and kidney damage and/or dysfunction and oxidative stress-induced cell damage or changes in the extracellular matrix of both the heart and kidneys. Biomarkers provide important insights into the pathophysiology of cardiorenal syndrome and are invaluable tools to predict the decrease in renal function during cardiac dysfunction and vice versa. Based on the pathophysiological mechanisms of cardiorenal syndrome, we reviewed and evaluated the available literature on serum and urinary biomarkers as predictors of kidney and/or heart injury. In addition, heart- and kidney-specific biomarkers were also evaluated based on their reference to kidney and cardiac (dys)function respectively, and whether they would provide any prediction and prognostication of cardiorenal syndrome. In this article, we discuss the current knowledge on the pathophysiology of different types of cardiorenal syndrome, examine the clinical utility of candidate biomarkers in the early diagnosis of cardiorenal syndrome, and guide treatment by evaluating the respective roles of the involved pathophysiological pathways.

Inflammation Links Cardiac Injury and Renal Dysfunction: A Cardiovascular Magnetic Resonance Study

Background

Inflammation is essential in cardiorenal syndrome, however there is still a lack of evidence proving the interaction between cardiac injury, renal dysfunction and the inflammatory response. This study aimed to illustrate the association between renal dysfunction and cardiac injury with a specific focus on the role of inflammation.

Methods

A single-center, retrospective study included patients with heart failure admitted to the cardiovascular department from September 2019 to April 2022. Patients received cardiovascular magnetic resonance (CMR) imaging (T1 mapping and late gadolinium enhancement (LGE)). Demographic, creatinine and native T1 were analyzed using pearson correlation, linear regression and adjusted for confounders. Interaction and subgroup analysis were performed.

Results

Finally, 50 validated heart failure (HF) patients (age 58.5 ± 14.8 years; 78.0% men) were included. Cardiac global native T1 for the high estimated glomeruar filtration rate (eGFR) group was 1117.0 ± 56.6 ms, and for the low eGFR group was 1096.5 ± 61.8 ms. Univariate analysis identified global native T1 ( β = 0.16, 95% confidence interval (CI): 0.04-0.28, p = 0.014) and C-reactive protein (CRP) ( β = 0.30, 95% CI: 0.15-0.45, p < 0.001) as determinants of creatinine. Multivariable linear regression analysis identified global native T1 ( β = 0.12, 95% CI: 0.01-0.123, p = 0.040) as a determinant of creatinine while age and diabetes were adjusted. Significant interactions between CRP and global native T1 in relation to creatinine level (p for interaction = 0.005) were identified.

Conclusions

Kidney dysfunction was associated with cardiac injury and inflammation, respectively. The interaction between myocardial injury and kidney dysfunction is contingent on the severity of the inflammatory response. Further studies were needed to identify the mechanisms of the inflammatory response in cardiorenal syndrome.

A comprehensive review of acute cardio-renal syndrome: need for novel biomarkers

Cardiorenal syndrome represents a wide-spectrum disorder involving the heart and kidneys as the primary affected organs. India has an increasingly high burden of acute CRS, coinciding with the rise in global statistics. Up to 2022, approximately 46.1% of all cardiorenal patients have been diagnosed with acute CRS in India. Acute CRS involves a sudden deterioration of kidney functionalities, referred to as acute kidney injury (AKI) in acute heart failure patients. The pathophysiology of CRS involves hyperactivation of the sympathetic nervous system (SNS) and the renin-angiotensin-aldosterone system (RAAS) following acute myocardial stress. The pathological phenotype of acute CRS is associated with perturbed inflammatory, cellular, and neurohormonal markers in circulation. These complications increase the risk of mortality in clinically diagnosed acute CRS patients, making it a worldwide healthcare burden. Hence, effective diagnosis and early prevention are crucial to prevent the progression of CRS in AHF patients. Present biomarkers, such as serum creatinine (sCr), cystatin C (CysC), glomerular filtration rate (GFR), blood urea nitrogen (BUN), serum and/or urine neutrophil gelatinase-associated lipocalin (NGAL), B-type natriuretic peptide (BNP), and NT-proBNP, are clinically used to diagnose AKI stages in CRS patients but are limitedly sensitive to the early detection of the pathology. Therefore, the need for protein biomarkers is emerging for early intervention in CRS progression. Here, we summarized the cardio-renal nexus in acute CRS, with an emphasis on the present clinicopathological biomarkers and their limitations. The objective of this review is to highlight the need for novel proteomic biomarkers that will curb the burgeoning concern and direct future research trials.

Systemic delivery of menstrual blood stem cells is more effective in preventing remote organ injuries following myocardial infarction in comparison with bone marrow stem cells in rat

Objectives

Remote organ injury is a phenomenon that could happen following myocardial infarction (MI). We evaluated the potency of menstrual blood stromal (stem) cells (MenSCs) and bone marrow stem cells (BMSCs) to alleviate remote organ injuries following MI in rats.

Materials and Methods

2 × 10⁶ MenSCs or BMSCs were administrated seven days after MI induction via the tail vein. Four weeks after cell therapy, activities of aspartate aminotransferase (AST), urea, creatinine, and Blood Urea Nitrogen (BUN) were evaluated. The level of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 were determined by ELISA assay. The expression of Nuclear Factor-κB (NF-κB) was evaluated by immunohistochemical staining. Apoptosis activity and tissue damage were also determined by TUNEL and H&E staining, respectively.

Results

MenSCs and BMSCs administration caused a significant reduction in AST, urea, and BUN levels compared with the MI group. In addition, systemic injection of MenSCs significantly decreased the IL-1β level compared with BMSCs and MI groups (P<0.05 and P<0.01 respectively). Apoptosis in injured kidneys was noticeably diminished in MenSCs-treated rats compared with BMSCs administrated and MI groups (P<0.05 and P<0.05, respectively). In hepatic tissue, limited numbers of TUNEL-positive cells were detected in all groups. Interestingly, MenSCs therapy evoked inhibition of NF-κB in the kidney strikingly. Although, no significant NF-κB expression was observed in hepatic tissue in any group (P>0.05).

Conclusion

MenSCs are probably more protective than BMSCs on remote organ injuries following MI via decreasing cell death and immunoregulatory properties.

Toward Human Models of Cardiorenal Syndrome in vitro

Heart and kidney diseases cause high morbidity and mortality. Heart and kidneys have vital functions in the human body and, interestingly, reciprocally influence each other’s behavior: pathological changes in one organ can damage the other. Cardiorenal syndrome (CRS) is a group of disorders in which there is combined dysfunction of both heart and kidney, but its underlying biological mechanisms are not fully understood. This is because complex, multifactorial, and dynamic mechanisms are likely involved. Effective treatments are currently unavailable, but this may be resolved if more was known about how the disease develops and progresses. To date, CRS has actually only been modeled in mice and rats in vivo. Even though these models can capture cardiorenal interaction, they are difficult to manipulate and control. Moreover, interspecies differences may limit extrapolation to patients. The questions we address here are what would it take to model CRS in vitro and how far are we? There are already multiple independent in vitro (human) models of heart and kidney, but none have so far captured their dynamic organ-organ crosstalk. Advanced in vitro human models can provide an insight in disease mechanisms and offer a platform for therapy development. CRS represents an exemplary disease illustrating the need to develop more complex models to study organ-organ interaction in-a-dish. Human induced pluripotent stem cells in combination with microfluidic chips are one powerful tool with potential to recapitulate the characteristics of CRS in vitro. In this review, we provide an overview of the existing in vivo and in vitro models to study CRS, their limitations and new perspectives on how heart-kidney physiological and pathological interaction could be investigated in vitro for future applications.

Involvement of Inflammasome Components in Kidney Disease

Inflammasomes are multiprotein complexes with an important role in the innate immune response. Canonical activation of inflammasomes results in caspase-1 activation and maturation of cytokines interleukin-1β and -18. These cytokines can elicit their effects through receptor activation, both locally within a certain tissue and systemically. Animal models of kidney diseases have shown inflammasome involvement in inflammation, pyroptosis and fibrosis. In particular, the inflammasome component nucleotide-binding domain-like receptor family pyrin domain containing 3 (NLRP3) and related canonical mechanisms have been investigated. However, it has become increasingly clear that other inflammasome components are also of importance in kidney disease. Moreover, it is becoming obvious that the range of molecular interaction partners of inflammasome components in kidney diseases is wide. This review provides insights into these current areas of research, with special emphasis on the interaction of inflammasome components and redox signalling, endoplasmic reticulum stress, and mitochondrial function. We present our findings separately for acute kidney injury and chronic kidney disease. As we strictly divided the results into preclinical and clinical data, this review enables comparison of results from those complementary research specialities. However, it also reveals that knowledge gaps exist, especially in clinical acute kidney injury inflammasome research. Furthermore, patient comorbidities and treatments seem important drivers of inflammasome component alterations in human kidney disease.

The Innate Immune System and Cardiovascular Disease in ESKD: Monocytes and Natural Killer Cells

Adverse innate immune responses have been implicated in several disease processes, including cardiovascular disease (CVD) and chronic kidney disease (CKD). The monocyte subsets natural killer (NK) cells and natural killer T (NKT) cells are involved in innate immunity. Monocytes subsets are key in atherogenesis and the inflammatory cascade occurring in heart failure. Upregulated activity and counts of proinflammatory CD16+ monocyte subsets are associated with clinical indices of atherosclerosis, heart failure syndromes and CKD. Advanced CKD is a complex state of persistent systemic inflammation characterized by elevated expression of proinflammatory and pro-atherogenic CD14++CD16+ monocytes, which are associated with cardiovascular events and death both in the general population and among patients with CKD. Diminished NK cells and NKT cells counts and aberrant activity are observed in both coronary artery disease and end-stage kidney disease. However, evidence of the roles of NK cells and NKT cells in atherogenesis in advanced CKD is circumstantial and remains to be clarified. This review describes the available evidence regarding the roles of specific immune cell subsets in the pathogenesis of CVD in patients with CKD. Future research is expected to further uncover the links between CKD associated innate immune system dysregulation and accelerated CVD and will ideally be translated into therapeutic targets.

Panoramic Dominance of the Immune System in Cardiorenal Syndrome Type I

Physiological organ cross-talk is necessary to maintain equilibrium and homeostasis. Heart and kidney are the essences of this equilibrium. Organ failure in either of these organs can perturb the bidirectional communication between them, impinging this unpleasant vascular and cellular milieu on other distant organs. Cardiorenal syndrome (CRS) type I occurs due to acute deterioration of cardiac function, ultimately causing acute kidney injury (AKI). This syndrome is an intricate condition with neurohormonal and inflammatory aspects. Inflammation creates a vicious circle filled with the innate and adaptive immune systems, pro-inflammatory cytokines, chemokines to actuate hemodynamic compromise in CRS type I patients. Pro-inflammatory cytokines not only aggravate fluid retention and venous congestion but also initiate apoptosis and oxidative stress. The immune response's primary motive is to elicit the heart and kidney to produce cytokines, intensifying the inflammatory process. Despite the possible standard of care, patient mortality, treatment cost, readmissions are extreme in CRS type I, and inflammation certainly has critical inferences warranting future research in humans.

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.

Early diagnosis of acute renal injury in patients with acute decompensation of chronic heart failure

AIM

To study the possibilities of previously diagnosing acute renal damage in patients with acute decompensation of chronic heart failure with reduced systolic function using biomarkers of acute renal injury.

MATERIALS AND METHODS

The study included 60 patients (62.0±11.1 years) with HADS (BNP &gt;500 pg/ml) and a reduced left ventricular ejection fraction (LV 27.05% [23.25; 32.75], c FC III-IV NYHA). The level of creatinine, urea, uric acid, albumin in serum was determined in all patients, as well as a number of biomarkers: lipocalin associated with neutrophil gelatinase (NGAL) and cystatin C (CysC) in serum; kidney damage molecule-1 (KIM-1) and angiotensinogen (AGT) in the urine.

RESULTS

AKI is determined based on changes in serum creatinine concentration or diuresis value. The results obtained indicate a high specificity and sensitivity of the use of biomarkers for the diagnosis of AKI in patients with ADHF. NGAL AUC - 0.833 (p&lt;0.001), Se - 82.8%, Sp - 4.2%. CysC AUC - 0.823 (p&lt;0.001), Se - 79.3%, Sp - 74.2%. KIM-1 AUC - 0.782 (p&lt;0.001), Se - 75.9%, Sp - 74.2%. AGT AUC - 0.829 (p&lt;0.001), Se - 82.8%, Sp - 77.4%. In a multifactorial regression analysis, it was found that with NGAL greater than 157.35 ng/ml, the risk of AKI increases 13.1 times (95% CI 1.365-126.431), with an increase in KIM-1, the risk of the development of AKI increases 20.6 times (95% CI 1.802-235.524), and with an increase in AGT more than 14.31 leng/ml, the risk of AKI increases 32.8 times (95% CI 2.752-390.110).

CONCLUSION

Acute kidney injury develops in 48.3% of patients hospitalized with acute decompensation of chronic heart failure. Patients with acute decompensation of chronic heart failure and AKI have significantly higher serum NGAL and CysC, KIM-1 and AGT values in the urine compared with patients without impairing renal function. These biomarkers can serve both for the early diagnosis of acute kidney damage and the prediction of AKI in patients with acute decompensation of chronic heart failure.

Multi-Omics Approach: New Potential Key Mechanisms Implicated in Cardiorenal Syndromes

Cardiorenal syndromes (CRS) include a scenario of clinical interactions characterized by the heart and kidney dysfunction. The crosstalk between cardiac and renal systems is clearly evidenced but not completely understood. Multi-factorial mechanisms leading to CRS do not involve only hemodynamic parameters. In fact, in recent works on organ crosstalk endothelial injury, the alteration of normal immunologic balance, cell death, inflammatory cascades, cell adhesion molecules, cytokine and chemokine overexpression, neutrophil migration, leukocyte trafficking, caspase-mediated induction of apoptotic mechanisms and oxidative stress has been demonstrated to induce distant organ dysfunction. Furthermore, new alternative mechanisms using the multi-omics approach may be implicated in the pathogenesis of cardiorenal crosstalk. The study of “omics” modifications in the setting of cardiovascular and renal disease represents an emerging area of research. Over the last years, indeed, many studies have elucidated the exact mechanisms involved in gene expression and regulation, cellular communication and organ crosstalk. In this review, we analyze epigenetics, gene expression, small non-coding RNAs, extracellular vesicles, proteomics, and metabolomics in the setting of CRS.

Stem cells transplantation positively modulates the heart-kidney cross talk in cardiorenal syndrome type II

INTRODUCTION

We investigated the effects of human amniotic fluid stem cells (hAFS) and rat adipose tissue stromal vascular fraction GFP-positive cells (rSVC-GFP) in a model of cardio-renal syndrome type II (CRSII).

METHODS AND RESULTS

RHF was induced by monocrotaline (MCT) in 28 Sprague-Dawley rats. Three weeks later, four million hAFS or rSVC-GFP cells were injected via tail vein. BNP, sCreatinine, kidney and heart NGAL and MMP9, sCytokines, kidney and heart apoptosis and cells (Cs) engraftment were evaluated. Cell-treated rats showed a significant reduction of serum NGAL and Creatinine compared to CRSII. In both hAFS and rSVC-GFP group, kidney protein expression of NGAL was significantly lower than in CRSII (hAFS p = 0.036 and rSVC-GFP p < 0.0001) and similar to that of controls. In both hAFS and rSVC-GFP treated rats, we observed cell engraftment in the medulla and differentiation into tubular, endothelial and SMCs cells. Apoptosis was significantly decreased in cell-treated rats (hAFS 14.07 ± 1.38 and rSVC-GFP 12.67 ± 2.96 cells/mm²) and similar to controls (9.85 ± 2.1 cell/mm²). TUNEL-positive cells were mainly located in the kidney medulla. Pro-inflammatory cytokines were down regulated in cell-treated groups and similar to controls. In cell-treated rats, kidney and heart tissue NGAL was not complexed with MMP9 as in CRSII group, suggesting inhibition of MMPs activity.

CONCLUSION

Cell therapy produced improvement in kidney function in rats with CRSII. This was the result of interstitial, vessel and tubular cell engraftment leading to tubular and vessel regeneration, decreased tubular cells apoptosis and mitigated pro-inflammatory milieu. Reduction of NGLA-MMP9 complexes mainly due to decrease MMPs activity prevented further negative heart remodeling.

Combination of Amino-Terminal Pro- BNP , Estimated GFR , and High-Sensitivity CRP for Predicting Cardiorenal Syndrome Type 1 in Acute Myocardial Infarction Patients

Background Cardiorenal syndrome type 1 ( CRS 1) as a complication of acute myocardial infarction can lead to adverse outcomes, and a method for early detection is needed. This study investigated the individual and integrated effectiveness of amino-terminal pro-brain natriuretic peptide (Pro-BNP), estimated glomerular filtration rate (eGFR), and high-sensitivity C-reactive protein (CRP) as predictive factors for CRS 1 in patients with acute myocardial infarction. Methods and Results In a retrospective analysis of 2094 patients with acute myocardial infarction, risk factors for CRS 1 were analyzed by logistic regression. Receiver operating characteristic curves were constructed to determine the predictive ability of the biomarkers individually and in combination. Overall, 177 patients (8.45%) developed CRS 1 during hospitalization. On multivariable analysis, all 3 biomarkers were independent predictors of CRS 1 with odds radios and 95% confidence intervals for a 1-SD change of 1.792 (1.311-2.450) for log(amino-terminal pro-brain natriuretic peptide, 0.424 (0.310-0.576) for estimated glomerular filtration rate, and 1.429 (1.180-1.747) for high-sensitivity C-reactive peptide. After propensity score matching, the biomarkers individually and together significantly predicted CRS 1 with areas under the curve of 0.719 for amino-terminal pro-brain natriuretic peptide, 0.843 for estimated glomerular filtration rate, 0.656 for high-sensitivity C-reactive peptide, and 0.863 for the 3-marker panel (all P<0.001). Also, the integrated 3-marker panel performed better than the individual markers ( P<0.05). CRS 1 risk correlated with the number of biomarkers showing abnormal levels. Abnormal measurements for at least 2 biomarkers indicated a greater risk of CRS 1 (odds ratio 36.19, 95% confidence interval 8.534-153.455, P<0.001). Conclusions The combination of amino-terminal pro-brain natriuretic peptide, estimated glomerular filtration rate, and high-sensitivity C-reactive peptide at presentation may assist in the prediction of CRS 1 and corresponding risk stratification in patients with acute myocardial infarction.

Levels of Proinflammatory Cytokines, Oxidative Stress, and Tissue Damage Markers in Patients with Acute Heart Failure with and without Cardiorenal Syndrome Type 1

BACKGROUND

Cardiorenal syndrome type 1 (CRS type 1) is characterized by a rapid worsening of cardiac function leading to acute kidney injury (AKI). Inflammation and oxidative stress seem to play a pivotal role in its pathophysiology. In this in vivo study, we examined the putative role of inflammation and humoral markers in the pathogenesis of the CRS type 1.

METHODS

We enrolled 53 patients with acute heart failure (AHF); 17 of them developed AKI (CRS type 1). The cause of AKI was presumed to be related to cardiac dysfunction after having excluded other causes. We assessed the plasma levels of proinflammatory cytokines (TNF-α, IL-6, IL-18, sICAM, RANTES, GMCSF), oxidative stress marker (myeloperoxidase, MPO), brain natriuretic peptide (BNP), and neutrophil gelatinase-associated lipocalin (NGAL) in AHF and CRS type 1 patients.

RESULTS

We observed a significant increase in IL-6, IL-18, and MPO levels in CRS type 1 group compared to AHF (p < 0.001). We found higher NGAL at admission in the CRS type 1 group compared to the AHF group (p = 0.008) and a positive correlation between NGAL and IL-6 (Spearman's rho = 0.45, p = 0.003) and between IL-6 and BNP (Spearman's rho = 0.43, p = 0.004). We observed lower hemoglobin levels in CRS type 1 patients compared to AHF patients (p < 0.05) and inverse correlation between hemoglobin and cytokines (IL-6: Spearman's rho = -0.38, p = 0.005; IL-18: Spearman's rho = -0.32, p = 0.02).

CONCLUSION

Patients affected by CRS type 1 present increased levels of proinflammatory cytokines and oxidative stress markers, increased levels of tissue damage markers, and lower hemoglobin levels. All these factors may be implicated in the pathophysiology of CRS type 1 syndrome.

Determinants of Monocyte Apoptosis in Cardiorenal Syndrome Type 1

BACKGROUND

Cardiorenal syndrome type 1 (CRS type 1) is characterized by a rapid worsening of cardiac function leading to acute kidney injury (AKI). Its pathophysiology is complex and not completely understood. In this study, we examined the role of apoptosis and the caspase pathways involved.

MATERIAL AND METHODS

We enrolled 40 acute heart failure (AHF) patients, 11 of whom developed AKI characterizing CRS type 1. We exposed the human cell line U937 to plasma from the CRS type 1 and AHF groups and then we evaluated apoptotic activity by annexin-V evaluation, determination of caspase-3, -8 and -9 levels, and BAX, BAD, and FAS gene expression.

RESULTS

We observed significant upregulation of apoptosis in monocytes exposed to CRS type 1 plasma compared to AHF, with increased levels of caspase-3 (p < 0.01), caspase-9 (p < 0.01), and caspase-8 (p < 0.03) showing activation of both intrinsic and extrinsic pathways. Furthermore, monocytes exposed to CRS type 1 plasma had increased gene expression of BAX and BAD (intrinsic pathways) (p = 0.010 for both). Furthermore, strong significant correlations between the caspase-9 levels and BAD and BAX gene expression were observed (Spearman ρ = - 0.76, p = 0.011, and ρ = - 0.72, p = 0.011).

CONCLUSION

CRS type 1 induces dual apoptotic pathway activation in monocytes; the two pathways converged on caspase-3. Many factors may induce activation of both intrinsic and extrinsic apoptotic pathways in CRS type 1 patients, such as upregulation of proinflammatory cytokines and hypoxia/ischemia. Further investigations are necessary to corroborate the present findings, and to better understand the pathophysiological mechanism and consequent therapeutic and prognostic implications for CRS type 1.

The Physiopathology of Cardiorenal Syndrome: A Review of the Potential Contributions of Inflammation

Inter-organ crosstalk plays an essential role in the physiological homeostasis of the heart and other organs, and requires a complex interaction between a host of cellular, molecular, and neural factors. Derangements in these interactions can initiate multi-organ dysfunction. This is the case, for instance, in the heart or kidneys where a pathological alteration in one organ can unfavorably affect function in another distant organ; attention is currently being paid to understanding the physiopathological consequences of kidney dysfunction on cardiac performance that lead to cardiorenal syndrome. Different cardiorenal connectors (renin-angiotensin or sympathetic nervous system activation, inflammation, uremia, etc.) and non-traditional risk factors potentially contribute to multi-organ failure. Of these, inflammation may be crucial as inflammatory cells contribute to over-production of eicosanoids and lipid second messengers that activate intracellular signaling pathways involved in pathogenesis. Indeed, inflammation biomarkers are often elevated in patients with cardiac or renal dysfunction. Epigenetics, a dynamic process that regulates gene expression and function, is also recognized as an important player in single-organ disease. Principal epigenetic modifications occur at the level of DNA (i.e., methylation) and histone proteins; aberrant DNA methylation is associated with pathogenesis of organ dysfunction through a number of mechanisms (inflammation, nitric oxide bioavailability, endothelin, etc.). Herein, we focus on the potential contribution of inflammation in pathogenesis of cardiorenal syndrome.

Epigenetics: a potential key mechanism involved in the pathogenesis of cardiorenal syndromes

Epigenetics is defined as the heritable changes in gene expression patterns which are not directly encoded by modifications in the nucleotide DNA sequence of the genome, including higher order chromatin organization, DNA methylation, cytosine modifications, covalent histone tail modifications, and short non-coding RNA molecules. Recently, much attention has been paid to the role and the function of epigenetics and epimutations in the cellular and subcellular pathways and in the regulation of genes in the setting of both kidney and cardiovascular disease. Indeed, deregulation of histone alterations has been highlighted in a large spectrum of renal and cardiac disease, including chronic and acute renal injury, renal and cardiac fibrosis, cardiac hypertrophy and failure, kidney congenital anomalies, renal hypoxia, and diabetic renal complications. Nevertheless, the role of epigenetics in the pathogenesis and pathophysiology of cardiorenal syndromes is currently underexplored. Given the significant clinical relevance of heart-kidney crosstalk, efforts in the research for new action mechanisms concurrently operating in both pathologies are thus of maximum interest. This review focuses on epigenetic mechanisms involved in heart and kidney disease, and their possible role in the setting of cardiorenal syndromes.

Acute coronary syndrome and acute kidney injury: role of inflammation in worsening renal function

Background

Acute Kidney Injury (AKI), a common complication of acute coronary syndromes (ACS), is associated with higher mortality and longer hospital stays. The role of cytokines and other mediators is unknown in AKI induced by an ACS (ACS-AKI), leading to several unanswered questions. The worsening of renal function is usually seen as a dichotomous phenomenon instead of a dynamic change, so evaluating changes of the renal function in time may provide valuable information in the ACS-AKI setting. The aim of this study was to explore inflammatory factors associated to de novo kidney injury induced by de novo cardiac injury secondary to ACS.

Methods

One hundred four consecutive patients with ACS were initially included on the time of admission to the Coronary Unit of the Instituto Nacional de Cardiología in Mexico City, from February to May 2016, before any invasive procedure, imaging study, diuretic or anti-platelet therapy. White blood count, hemoglobin, NT-ProBNP, troponin I, C-reactive protein, albumin, glucose, Na⁺, K⁺, blood urea nitrogen (BUN), total cholesterol, HDL, LDL, triglycerides, creatinine (Cr), endothelin-1 (ET-1), leukotriene-B4, matrix metalloproteinase-2 and -9, tissue inhibitor of metalloproteinases-1, resolvin-D1 (RvD1), lipoxin-A4 (LXA4), interleukin-1β, −6, −8, and −10 were measured. We finally enrolled 78 patients, and subsequently we identified 15 patients with ACS-AKI. Correlations were obtained by a Spearman rank test. Low-rank regression, splines regressions, and also protein–protein/chemical interactions and pathways analyses networks were performed.

Results

Positive correlations of ΔCr were found with BUN, admission Cr, GRACE score, IL-1β, IL-6, NT-ProBNP and age, and negative correlations with systolic blood pressure, mean-BP, diastolic-BP and LxA4. In the regression analyses IL-10 and RvD1 had positive non-linear associations with ΔCr. ET-1 had also a positive association. Significant non-linear associations were seen with NT-proBNP, admission Cr, BUN, Na⁺, K⁺, WBC, age, body mass index, GRACE, SBP, mean-BP and Hb.

Conclusion

Inflammation and its components play an important role in the worsening of renal function in ACS. IL-10, ET-1, IL-1β, TnI, RvD1 and LxA4 represent mediators that might be associated with ACS-AKI. IL-6, ET-1, NT-ProBNP might represent crossroads for several physiopathological pathways involved in “de novo cardiac injury leading to de novo kidney injury”.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-017-0640-0) contains supplementary material, which is available to authorized users.

Pathophysiology of the cardio-renal syndromes types 1-5: An uptodate

According to the recent definition proposed by the Consensus conference on Acute Dialysis Quality Initiative Group, the term cardio-renal syndrome (CRS) has been used to define different clinical conditions in which heart and kidney dysfunction overlap. Type 1 CRS (acute cardio- renal syndrome) is characterized by acute worsening of cardiac function leading to AKI (5, 6) in the setting of active cardiac disease such as ADHF, while type - 2 CRS occurs in a setting of chronic heart disease. Type 3 CRS is closely link to acute kidney injury (AKI), while type 4 represent cardiovascular involvement in chronic kidney disese (CKD) patients. Type 5 CRS represent cardiac and renal involvement in several diseases such as sepsis, hepato - renal syndrome and immune - mediated diseases.

The Role of Congestion in Cardiorenal Syndrome Type 2: New Pathophysiological Insights into an Experimental Model of Heart Failure

BACKGROUND

In cardiorenal syndrome type 2 (CRS2), the role of systemic congestion in heart failure (HF) is still obscure. We studied a model of CRS2 [monocrotaline (MCT)-treated rats] secondary to pulmonary hypertension and right ventricular (RV) failure in order to evaluate the contribution of prevalent congestion to the development of kidney injury.

METHODS

Ten animals were treated with MCT for 4 weeks until they developed HF. Eleven animals were taken as controls. Signs of hypertrophy and dilatation of the right ventricle demonstrated the occurrence of HF. Brain natriuretic peptide (BNP), serum creatinine (sCreatinine), both kidney and heart neutrophil gelatinase-associated lipocalin (NGAL), matrix metallopeptidase 9 (MMP9), serum cytokines as well as kidney and heart cell death, as assessed by TUNEL, were studied.

RESULTS

Rats with HF showed higher BNP levels [chronic HF (CHF) 4.8 ± 0.5 ng/ml; controls 1.5 ± 0.2 ng/ml; p < 0.0001], marked RV hypertrophy and dilatation (RV mass/RV volume: CHF 1.46 ± 0.31, controls 2.41 ± 0.81; p < 0.01) as well as pleural and peritoneal effusions. A significant increase in proinflammatory cytokines and sCreatinine was observed (CHF 3.06 ± 1.3 pg/ml vs. controls 0.54 ± 0.23 pg/ml; p = 0.04). Serum (CHF 562.7 ± 93.34 ng/ml vs. controls 245.3 ± 58.19 ng/ml; p = 0.02) as well as renal and heart tissue NGAL levels [CHF 70,680 ± 4,337 arbitrary units (AU) vs. controls 32,120 ± 4,961 AU; p = 0.001] rose significantly, and they were found to be complexed with MMP9 in CHF rats. A higher number of kidney TUNEL-positive tubular cells was also detected (CHF 114.01 ± 45.93 vs. controls 16.36 ± 11.60 cells/mm(2); p = 0.0004).

CONCLUSION

In this model of CHF with prevalent congestion, kidney injury is characterized by tubular damage and systemic inflammation. The upregulated NGAL complexed with MMP9 perpetuates the vicious circle of kidney/heart damage by enhancing the enzymatic activity of MMP9 with extracellular matrix degradation, worsening heart remodeling.

Cardiorenal Syndrome Type 1: Activation of Dual Apoptotic Pathways

Cardiorenal syndrome type 1 (CRS1) pathophysiology is complex, and immune-mediated damage, including alterations in the immune response with monocyte apoptosis and cytokine release, has been reported as a potential mechanism. In this study, we examined the putative role of renal tubular epithelial cell (RTC) apoptosis as a pathogenic mechanism in CRS1. In particular, we investigated the caspase pathways involved in induced apoptosis. We enrolled 29 patients with acute heart failure (AHF), 11 patients with CRS1, and 15 controls (CTR) without AHF or acute kidney injury (AKI). Patients who had AKI prior to the episode of AHF or who had any other potential causes of AKI were excluded. Plasma from different groups was incubated with RTCs for 24 h. Subsequently, cell apoptosis, DNA fragmentation, and caspase-3, -8, and -9 activities were investigated in RTCs incubated with AHF, CRS1, and CTR plasma. A p value <0.5 was considered statistically significant. A quantitative analysis of apoptosis showed significantly higher apoptosis rates in CRS1 patients compared to AHF patients and CTR (p < 0.01). This increase in apoptosis was strongly confirmed by caspase-3 levels (ρ = 0.73). Caspase-8 and -9 were significantly higher in CRS1 patients compared to AHF patients and CTR (p < 0.01). Furthermore, caspase-3 levels showed a significantly positive correlation with caspase-8 (ρ = 0.57) and -9 (ρ = 0.47; p < 0.001). This study demonstrated the significantly heightened presence of dual apoptotic disequilibrium in CRS1. Our findings indicated that apoptosis may have a central role in the mechanism of CRS1, and it could be a potential therapeutic target in this syndrome.

Cardiorenal Syndrome Type 1: Renal Dysfunction in Acute Decompensated Heart Failure

OBJECTIVE

To present a review of cardiorenal syndrome type 1 (CRS1).

METHODS

Review of the literature.

RESULTS

Acute kidney injury occurs in approximately one-third of patients with acute decompensated heart failure (ADHF) and the resultant condition was named CRS1. A growing body of literature shows CRS1 patients are at high risk for poor outcomes, and thus there is an urgent need to understand the pathophysiology and subsequently develop effective treatments. In this review we discuss prevalence, proposed pathophysiology including hemodynamic and nonhemodynamic factors, prognosticating variables, data for different treatment strategies, and ongoing clinical trials and highlight questions and problems physicians will face moving forward with this common and challenging condition.

CONCLUSION

Further research is needed to understand the pathophysiology of this complex clinical entity and to develop effective treatments.

The acute cardiorenal syndrome type I: considerations on physiology, epidemiology, and therapy

Acute cardiorenal syndrome, also known as cardiorenal syndrome type 1, is defined as an abrupt worsening of cardiac function that occurs in at least 30 % of patients with acute decompensated heart failure and can lead to the development of acute kidney injury. The changes in renal function that occur in this setting have variable prognostic implications, as both poorer and better outcomes have been reported when renal function worsens during treatment of heart failure decompensation. Furthermore, it remains unclear when worsening renal function is actually a manifestation of true acute kidney injury or simply an indicator of hemoconcentration. Given these gaps in the understanding of the significance of renal function changes in the setting of decompensated heart failure, it is not surprising that studies on the effects of available therapies, including diuretics, vasoactive drugs, and mechanical fluid removal have yielded inconsistent results. The purpose of this review is to analyze critically the current knowledge on the pathophysiology, epidemiology, prognosis, and treatment of acute cardiorenal syndrome.

Oxidative stress: dual pathway induction in cardiorenal syndrome type 1 pathogenesis

Cardiorenal Syndrome Type 1 (Type 1) is a specific condition which is characterized by a rapid worsening of cardiac function leading to acute kidney injury (AKI). Even though its pathophysiology is complex and not still completely understood, oxidative stress seems to play a pivotal role. In this study, we examined the putative role of oxidative stress in the pathogenesis of CRS Type 1. Twenty-three patients with acute heart failure (AHF) were included in the study. Subsequently, 11 patients who developed AKI due to AHF were classified as CRS Type 1. Quantitative determinations for IL-6, myeloperoxidase (MPO), nitric oxide (NO), copper/zinc superoxide dismutase (Cu/ZnSOD), and endogenous peroxidase activity (EPA) were performed. CRS Type 1 patients displayed significant augmentation in circulating ROS and RNS, as well as expression of IL-6. Quantitative analysis of all oxidative stress markers showed significantly lower oxidative stress levels in controls and AHF compared to CRS Type 1 patients (P < 0.05). This pilot study demonstrates the significantly heightened presence of dual oxidative stress pathway induction in CRS Type 1 compared to AHF patients. Our findings indicate that oxidative stress is a potential therapeutic target, as it promotes inflammation by ROS/RNS-linked pathogenesis.

Novel markers and therapies for patients with acute heart failure and renal dysfunction

BACKGROUND

Acute kidney injury complicates decompensated heart failure in ∼33% of cases and is associated with morbidity and mortality; thus, we sought to systematically review this topic in order to summarize novel diagnostic and therapeutic approaches.

METHODS

Structured PubMed searches on these topics were conducted in February 2014 and relevant literature was identified. The PubMed search identified a total of 192 articles that were individually screened for inclusion in this analysis, and 58 were included.

RESULTS

Acute kidney injury, defined by substantial increases in serum creatinine, is associated consistently with prolonged length of stay, rehospitalization, and mortality. Biomarker studies suggested that natriuretic peptides are prognostic for shorter- and longer-term mortality. Novel proteins indicating kidney damage and albumin in the urine are associated with acute kidney injury. The most promising acute pharmacologic treatment appears to be serelaxin, which has been shown to improve acute heart failure symptoms, hemodynamic parameters, and renal function.

CONCLUSIONS

The presence of acute kidney injury results in worse clinical outcomes for patients with acute heart failure. Novel biomarkers and therapies hold the promise of improving both cardiac and renal outcomes in these patients.

Cardiorenal syndrome type 1: a defective regulation of monocyte apoptosis induced by proinflammatory and proapoptotic factors

In this study, we examined the possible immune-mediated mechanisms in cardiorenal syndrome (CRS) type 1 pathogenesis. We enrolled 40 patients with acute heart failure (AHF), 11 patients with CRS type 1 and 15 controls. Plasma from the different groups was incubated with monocytes; subsequently, cell apoptosis was evaluated by DNA fragmentation, caspase activity and cytofluorometric assay. Cytokine quantification in plasma and supernatant was performed by ELISA. Monocytes treated with CRS type 1 plasma showed significantly higher apoptosis compared with those treated with AHF and the controls (p < 0.05). Caspase-3 (CRS type 1: 2.20 ng/ml, IQR 2.06-2.33; AHF: 1.48 ng/ml, IQR 1.31-1.56; controls: 0.71 ng/ml, IQR 0.67-0.81) and caspase-8 levels (CRS type 1: 1.49 ng/ml, IQR 1.42-1.57; AHF: 0.94 ng/ml, IQR 0.84-0.98; controls: 0.56 ng/ml, IQR 0.51-0.58) in cells incubated with plasma from these patients demonstrated a significantly higher concentration. We observed a strong upregulation of plasma IL-6 and IL-18 in CRS type 1 compared with AHF and the controls (p < 0.05). Interestingly, we observed a similar concentration of TNF-α in CRS type 1 and AHF. In CRS type 1 patients, IL-6 (52.13 ng/ml, IQR 47.29-66.83) and IL-18 levels (197.75 ng/ml, IQR 120.80-265.49) in supernatant were significantly higher than in AHF patients (IL-6: 28.79 ng/ml, IQR 19.90-36.10; IL-18: 21.98 ng/ml, IQR 15.98-29.85) and controls (IL-6: 5.02 ng/ml, IQR 4.56-6.44; IL-18: 7.91 ng/ml, IQR 5.57-10.62). These findings suggest the presence of a defective regulation of monocyte apoptosis in CRS type 1 patients and the involvement of an immune-mediated mechanism in the pathophysiology of this syndrome.

The hemodynamic and nonhemodynamic crosstalk in cardiorenal syndrome type 1

The organ crosstalk can be defined as the complex biological communication and feedback between distant organs mediated via cellular, molecular, neural, endocrine and paracrine factors. In the normal state, this crosstalk helps to maintain homeostasis and optimal functioning of the human body. However, during disease states this very crosstalk can carry over the influence of the diseased organ to initiate and perpetuate structural and functional dysfunction in the other organs. Heart performance and kidney function are intimately interconnected, and the communication between these organs occurs through a variety of bidirectional pathways. The cardiorenal syndrome (CRS) is defined as a complex pathophysiological disorder of the heart and the kidneys whereby acute or chronic dysfunction in one organ may induce acute or chronic dysfunction in the other organ. In particular, CRS type 1 is characterized by a rapid worsening of the cardiac function leading to acute kidney injury. This clinical condition requires a more complex management given its more complicated hospital course and higher mortality. A lot of research has emerged in the last years trying to explain the pathophysiology of CRS type 1 which remains in part poorly understood. This review primarily focuses on the hemodynamic and nonhemodynamic mechanisms involved in this syndrome.

Cardiorenal syndrome

Cardiorenal syndrome (CRS) includes a broad spectrum of diseases within which both the heart and kidneys are involved, acutely or chronically. An effective classification of CRS in 2008 essentially divides CRS in two main groups, cardiorenal and renocardiac CRS, based on primum movens of disease (cardiac or renal); both cardiorenal and renocardiac CRS are then divided into acute and chronic, according to onset of disease. The fifth type of CRS integrates all cardiorenal involvement induced by systemic disease. This article addresses the pathophysiology, diagnosis, treatment, and outcomes of the 5 distinct types of CRS.

Heart-kidney crosstalk and role of humoral signaling in critical illness

Organ failure in the heart or kidney can initiate various complex metabolic, cell-mediated and humoral pathways affecting distant organs, contributing to the high therapeutic costs and significantly higher morbidity and mortality. The universal outreach of cells in an injured state has myriad consequences to distant organ cells and their milieu. Heart performance and kidney function are closely interconnected and communication between these organs occurs through a variety of bidirectional pathways. The term cardiorenal syndrome (CRS) is often used to describe this condition and represents an important model for exploring the pathophysiology of cardiac and renal dysfunction. Clinical evidence suggests that tissue injury in both acute kidney injury and heart failure has immune-mediated inflammatory consequences that can initiate remote organ dysfunction. Acute cardiorenal syndrome (CRS type 1) and acute renocardiac syndrome (CRS type 3) are particularly relevant in high-acuity medical units. This review briefly summarizes relevant research and focuses on the role of signaling in heart-kidney crosstalk in the critical care setting.

Cardiorenal syndrome in critical care: the acute cardiorenal and renocardiac syndromes

Heart and kidney disease often coexist in the same patient, and observational studies have shown that cardiac disease can directly contribute to worsening kidney function and vice versa. Cardiorenal syndrome (CRS) is defined as a complex pathophysiological disorder of the heart and the kidneys in which acute or chronic dysfunction in one organ may induce acute or chronic dysfunction in the other organ. This has been recently classified into five subtypes on the basis of the primary organ dysfunction (heart or kidney) and on whether the organ dysfunction is acute or chronic. Of particular interest to the critical care specialist are CRS type 1 (acute cardiorenal syndrome) and type 3 (acute renocardiac syndrome). CRS type 1 is characterized by an acute deterioration in cardiac function that leads to acute kidney injury (AKI); in CRS type 3, AKI leads to acute cardiac injury and/or dysfunction, such as cardiac ischemic syndromes, congestive heart failure, or arrhythmia. Both subtypes are encountered in high-acuity medical units; in particular, CRS type 1 is commonly seen in the coronary care unit and cardiothoracic intensive care unit. This paper will provide a concise review of the epidemiology, pathophysiology, prevention strategies, and selected kidney management aspects for these two acute CRS subtypes.