The Role of Dendritic and Endothelial Cells in Cardiorenal Syndrome

The Need to Identify Novel Markers for Early Renal Injury in Cardiorenal Syndrome

The term "Cardiorenal Syndrome" (CRS) refers to the complex interplay between heart and kidney dysfunction. First described by Robert Bright in 1836, CRS was brought to its modern view by Ronco et al. in 2008, who defined it as one organ's primary dysfunction leading to secondary dysfunction in the other, a view that led to the distinction of five different types depending on the organ of primary dysfunction and the temporal pattern (acute vs. chronic). Their pathophysiology is intricate, involving various hemodynamic, neurohormonal, and inflammatory processes that result in damage to both organs. While traditional biomarkers have been utilized for diagnosing and prognosticating CRS, they are inadequate for the early detection of acute renal damage. Hence, there is a pressing need to discover new biomarkers to enhance clinical outcomes and treatment approaches.

Cardiorenal syndrome: Plasmonic biosensors

Cardiorenal syndrome (CRS) is defined as a broad spectrum of conditions encompassing both the heart and kidneys in which acute or chronic heart disorder may induce acute or chronic tubular injury in the kidneys and vice versa. Early diagnosis allows timely intervention and attenuates disease progression. Two well-established biomarkers, neutrophil gelatinase-associated lipocalin (NGAL) and brain (B-type) natriuretic peptide (BNP), are reflective of impaired cardiac and kidney function associated with poor prognosis in various cardiac disorders, including heart failure and coronary artery disease. Given the ongoing contribution of CRS to the high morbidity and mortality post-MI, early risk stratification and preventive measures are highly significant. In this review, we examine Surface Plasmon Resonance (SPR) optical biosensors for detection of these biomarkers and discuss potential implications of this highly sensitive and specific technology in CRS detection, treatment and outcomes.

Factors predicting acute kidney injury in patients after abdominal aortic aneurysm repair

INTRODUCTION

Postoperative acute kidney injury (AKI) is one of the most frequent complications in abdominal aortic aneurysm (AAA) patients after open and endovascular aortic aneurysm repair. AKI decreases the efficiency of kidney function, allowing accumulation of waste products in the body, and an imbalance of water, acid and electrolytes in the body. As a result, the functioning of various organs throughout the body is affected. These effects may raise the cost of treatment, length of stay, and mortality rate.

OBJECTIVE

This study aims to examine the predictive factors of AKI - preoperative of estimated glomerular filtration rate (eGFR), preoperative of hemoglobin level, types of abdominal aortic aneurysms repair, and intraoperative of cardiac arrhythmias - after open and endovascular aortic repair among AAA patients within 72 h.

METHODS

This is a retrospective study of 196 patients with AAA after elective open and endovascular aortic aneurysm repair within the first 72 h who met the inclusion criteria recruited from a tertiary care hospital in Bangkok, Thailand. Postoperative AKI after elective open and endovascular aortic repair among AAA patients is defined by the 2012 Kidney Disease Improving Global Outcomes (KDIGO) Clinical Practice Guidelines.

RESULTS

A total of 196 AAA patients, 75.5% were male with an average age of 75.12 years (SD = 8.45). Endovascular aortic aneurysm repair was used more frequently than open aortic aneurysm repair (64.8% vs 35.2%) and 37.2% of the AAA patients had intraoperative cardiac arrhythmias. The occurrence of AKI among the AAA patients after abdominal aortic aneurysm repair within 72 h was 54.1%. The AKI rate of EVAR patients was 69.8% while the AKI rate for OAR patients was 30.2%. The preoperative estimated glomerular filtration rate (eGFR) and hemoglobin level were found to jointly predict AKI and explain 32.2% of the variance (Nagelkerke R2 = 0.322, p < .05). However, the type of abdominal aortic aneurysms repair and intraoperative cardiac arrhythmias did not correlate with the incidence of AKI in AAA repair patients. The predictive factors for AKI among AAA patients after aortic aneurysm repair were preoperative eGFR < 60 mL/min/1.73 m2 (OR = 4.436, 95% CI: 2.202-8.928, p < .001) and preoperative hemoglobin level between 8.1-10.0 g/dL (OR = 4.496, 95% CI: 1.831-11.040, p = .001).

CONCLUSION

Preoperative eGFR < 60 mL/min/1.73 m2 and preoperative hemoglobin level between 8.1-10.0 g/dL were the predictive factors for AKI among AAA patients after both open and endovascular AAA repair. Therefore, healthcare providers should be aware of and monitor signs of AKI after surgery in AAA patients, especially those undergoing EVAR with lower eGFR and hemoglobin levels.

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.

Hepatocardiorenal syndrome in liver cirrhosis: Recognition of a new entity?

Emerging evidence and perspectives have pointed towards the heart playing an important role in hepatorenal syndrome (HRS), outside of conventional understanding that liver cirrhosis is traditionally considered the sole origin of a cascade of pathophysiological mechanisms directly affecting the kidneys in this context. In the absence of established heart disease, cirrhotic cardiomyopathy may occur more frequently in those with liver cirrhosis and kidney disease. It is a specific form of cardiac dysfunction characterized by blunted contractile responsiveness to stress stimuli and altered diastolic relaxation with electrophysiological abnormalities. Despite the clinical description of these potential cardiac-related complications of the liver, the role of the heart has traditionally been an overlooked aspect of circulatory dysfunction in HRS. Yet from a physiological sense, temporality (prior onset) of cardiorenal interactions in HRS and positive effects stemming from portosystemic shunting demonstrated an important role of the heart in the development and progression of kidney dysfunction in cirrhotic patients. In this review, we discuss current concepts surrounding how the heart may influence the development and progression of HRS, and the role of systemic inflammation and endothelial dysfunction causing circulatory dysfunction within this setting. The temporality of heart and kidney dysfunction in HRS will be discussed. For a subgroup of patients who receive portosystemic shunting, the dynamics of cardiorenal interactions following treatment is reviewed. Continued research to determine the unknowns in this topic is anticipated, hopefully to further clarify the intricacies surrounding the liver-heart-kidney connection and improve strategies for management.

New Insight in Cardiorenal Syndrome: From Biomarkers to Therapy

Cardiorenal syndrome consists in the coexistence of acute or chronic dysfunction of heart and kidneys resulting in a cascade of feedback mechanisms and causing damage to both organs associated with high morbidity and mortality. In the last few years, different biomarkers have been investigated with the aim to achieve an early and accurate diagnosis of cardiorenal syndrome, to provide a prognostic role and to guide the development of targeted pharmacological and non-pharmacological therapies. In such a context, sodium-glucose cotransporter 2 (SGLT2) inhibitors, recommended as the first-line choice in the management of heart failure, might represent a promising strategy in the management of cardiorenal syndrome due to their efficacy in reducing both cardiac and renal outcomes. In this review, we will discuss the current knowledge on the pathophysiology of cardiorenal syndrome in adults, as well as the utility of biomarkers in cardiac and kidney dysfunction and potential insights into novel therapeutics.

Beyond the Cardiorenal Syndrome: Pathophysiological Approaches and Biomarkers for Renal and Cardiac Crosstalk

Cardiorenal syndrome encompasses complex multifactorial facets and carries significant morbidity and mortality worldwide. The bi-directional relationship between the heart and kidneys, where dysfunction in one organ worsens the function of the other, has been the leading motor for research in the last few years. In the pathophysiological process, small noncoding RNAs, epigenetics, vascular growth factors, oxidative stress, hemodynamic factors, and biomarkers play a pivotal role in the development of cardiorenal syndrome. It is therefore important to elucidate all the mechanisms in order to provide diagnostic and treatments tools. This review summarizes the hemodynamic and non-hemodynamic pathways along with biomarkers that could be the next target for diagnosis, treatment, and prognosis in cardiorenal syndrome.

Cardiorenal syndrome: long road between kidney and heart

Almost 200 years ago, the first evidence described by Robert Bright (1836) showed the strong interaction between the kidneys and heart and, since then, the scientific community has dedicated itself to better understanding the mechanisms involved in the kidney-heart relationship, known in recent decades as cardiorenal syndrome (CRS). This syndrome includes a wide clinical variety that affects the kidneys and heart, in an acute or chronic manner. Moreover, it is well established in the literature that the immune system, the sympathetic nervous system, the renin-angiotensin-aldosterone, and the oxidative stress actively play a strong role in the cellular and molecular processes present in CRS. More recently, uremic molecules and epigenetic factors have been also shown to be key mediators in the development of syndrome. The present review intends to present the state of the art regarding CRS and to show the paths known, until now, in the long road between the kidneys and heart.

Endothelial Dysfunction and SARS-CoV-2 Infection: Association and Therapeutic Strategies

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), has been recently considered a systemic disorder leading to the procoagulant state. Preliminary studies have shown that SARS-CoV-2 can infect endothelial cells, and extensive evidence of inflammation and endothelial dysfunction has been found in advanced COVID-19. Endothelial cells play a critical role in many physiological processes, such as controlling blood fluidity, leukocyte activation, adhesion, platelet adhesion and aggregation, and transmigration. Therefore, it is reasonable to think that endothelial dysfunction leads to vascular dysfunction, immune thrombosis, and inflammation associated with COVID-19. This article summarizes the association of endothelial dysfunction and SARS-CoV-2 infection and its therapeutic strategies.

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.

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.

Cardiorenal Syndrome: Classification, Pathophysiology, Diagnosis, and Treatment Strategies: A Scientific Statement From the American Heart Association

Cardiorenal syndrome encompasses a spectrum of disorders involving both the heart and kidneys in which acute or chronic dysfunction in 1 organ may induce acute or chronic dysfunction in the other organ. It represents the confluence of heart-kidney interactions across several interfaces. These include the hemodynamic cross-talk between the failing heart and the response of the kidneys and vice versa, as well as alterations in neurohormonal markers and inflammatory molecular signatures characteristic of its clinical phenotypes. The mission of this scientific statement is to describe the epidemiology and pathogenesis of cardiorenal syndrome in the context of the continuously evolving nature of its clinicopathological description over the past decade. It also describes diagnostic and therapeutic strategies applicable to cardiorenal syndrome, summarizes cardiac-kidney interactions in special populations such as patients with diabetes mellitus and kidney transplant recipients, and emphasizes the role of palliative care in patients with cardiorenal syndrome. Finally, it outlines the need for a cardiorenal education track that will guide future cardiorenal trials and integrate the clinical and research needs of this important field in the future.

Inflammation research sails through the sea of immunology to reach immunometabolism

Inflammation occurs as a result of acute trauma, invasion of the host by different pathogens, pathogen-associated molecular patterns (PAMPs) or chronic cellular stress generating damage-associated molecular patterns (DAMPs). Thus inflammation may occur under both sterile inflammatory conditions including certain cancers, autoimmune or autoinflammatory diseases (Rheumatic arthritis (RA)) and infectious diseases including sepsis, pneumonia-associated acute lung inflammation (ALI) or acute respiratory distress syndrome (ARDS). The pathogenesis of inflammation involves dysregulation of an otherwise protective immune response comprising of various innate and adaptive immune cells and humoral (cytokines and chemokines) mediators secreted by these immune cells upon the activation of signaling mechanisms regulated by the activation of different pattern recognition receptors (PRRs). However, the pro-inflammatory and anti-inflammatory action of these immune cells is determined by the metabolic stage of the immune cells. The metabolic process of immune cells is called immunometabolism and its shift determined by inflammatory stimuli is called immunometabolic reprogramming. The article focuses on the involvement of various immune cells generating the inflammation, their interaction, immunometabolic reprogramming, and the therapeutic targeting of the immunometabolism to manage inflammation.

Diet-Induced Obesity Promotes Kidney Endothelial Stiffening and Fibrosis Dependent on the Endothelial Mineralocorticoid Receptor

Obesity is characterized by enhanced MR (mineralocorticoid receptor) activation, vascular stiffness, and associated cardiovascular and kidney disease. Consumption of a Western-style diet (WD), high in saturated fat and refined carbohydrates, by female mice, leads to obesity and vascular stiffening. Use of ECMR (endothelial cell-specific MR) knockout mice supports that ECMR activation is critical for development of vascular and cardiac fibrosis and stiffening. However, the role of ECMR activation in kidney inflammation and fibrosis remains unknown. We hypothesized that cell-specific deletion of ECMR would prevent WD-induced central aortic stiffness and protect the kidney from endothelial dysfunction and vascular stiffening. Four-week-old female ECMR KO and wild-type mice were fed either mouse chow or WD for 16 weeks. WD feeding increased body weight and fat mass, proteinuria, as well as vascular stiffness indices (pulse wave velocity and kidney artery stiffening) and impaired endothelial-dependent vasodilatation without blood pressure changes. The WD-induced kidney arterial stiffening was associated with attenuated eNOS (endothelial NO synthase) activation, increased oxidative stress, proinflammatory immune responses, alterations in extracellular matrix degradation pathways, and fibrosis. ECMR deletion prevented these abnormalities by improving eNOS activation and reducing macrophage proinflammatory M1 polarization, expression of TG2 (transglutaminase 2), and MMP (matrix metalloproteinase)-9. Our data support the concept that ECMR activation contributes to endothelial dysfunction, increased kidney artery fibrosis/stiffening, and impaired NOS (NO synthase) activation, processes associated with macrophage infiltration and polarization, inflammation, and oxidative stress, collectively resulting in tubulointerstitial fibrosis in females consuming a WD.

Hepatorenal Syndrome or Hepatocardiorenal Syndrome: Revisiting Basic Concepts in View of Emerging Data

BACKGROUND

Accumulating evidence on the pathophysiology of hepatorenal syndrome has challenged the conventional model of liver-kidney connection. While liver cirrhosis is traditionally considered the origin of a cascade of pathophysiologic mechanisms directly affecting other organs such as the kidney, emerging data point to the heart as the potential mediator of the untoward renal effects.

SUMMARY

Herein, we briefly review the often-overlooked contribution of the heart to circulatory dysfunction in hepatorenal syndrome and put forward evidence arguing for the involvement of systemic inflammation and endothelial dysfunction in this setting. The temporality of cardiorenal interactions in hepatorenal syndrome and the observed beneficial effects of portosystemic shunting on these pathways lend further support to the notion that cardiac involvement plays a key role in the development of renal dysfunction in severe cirrhosis. Key Messages: The disturbances traditionally bundled within hepatorenal syndrome could represent a hepatic form of cardiorenal syndrome whereby the liver affects the kidney in part through cardiorenal pathways. This new model has practical implications and calls for a shift in the focus of diagnostic and therapeutic approaches to renal dysfunction in advanced cirrhosis.

Pathophysiological Mechanisms in Cardiorenal Syndrome

Cardiorenal syndrome represents the confluence of intricate hemodynamic, neurohormonal, and inflammatory pathways that initiate and propagate the maladaptive cross talk between the heart and kidneys. Several of these pathophysiological principles were described in older historical experiments. The last decade has witnessed major efforts in streamlining its definition, clinical phenotypes, and classification to improve diagnostic accuracy and deliver optimal goal-directed medical therapies. The ability to characterize the various facets of cardiorenal syndrome based on its pathophysiology is poised in an exciting vantage point, in the backdrop of several advanced diagnostic strategies, notably cardiorenal biomarkers that may help with accurate delineation of clinical phenotype, prognosis, and delivery of optimal medical therapies in future studies. This promises to help integrate precision medicine into the clinical diagnosis and treatment strategies for cardiorenal syndrome and, through a heightened understanding of its pathophysiology, to deliver appropriate therapies that will reduce its associated morbidity and mortality.