Endothelial factors in the pathogenesis and treatment of chronic kidney disease Part I: General mechanisms: a joint consensus statement from the European Society of Hypertension Working Group on Endothelin and Endothelial Factors and The Japanese Society of Hypertension

Endothelin System in Hypertension and Chronic Kidney Disease

ET (endothelin) is a powerful vasoconstrictor 21-amino acid peptide present in many tissues, which exerts many physiological functions across the body and participates as a mediator in many pathological conditions. ETs exert their effects through ETA and ETB receptors, which can be blocked by selective receptor antagonists. ETs were shown to play important roles among others, in systemic hypertension, particularly when resistant or difficult to control, and in pulmonary hypertension, atherosclerosis, cardiac hypertrophy, subarachnoid hemorrhage, chronic kidney disease, diabetic cardiovascular disease, scleroderma, some cancers, etc. To date, ET antagonists are only approved for the treatment of primary pulmonary hypertension and recently for IgA nephropathy and used in the treatment of digital ulcers in scleroderma. However, they may soon be approved for the treatment of patients with resistant hypertension and different types of nephropathy. Here, the role of ETs is reviewed with a special emphasis on participation in and treatment of hypertension and chronic kidney disease.

Challenges in the evaluation of endothelial cell dysfunction: a statement from the European Society of Hypertension Working Group on Endothelin and Endothelial Factors

Endothelial cell function is mediated by different mechanisms in different vascular beds. Moreover, in humans, endothelial cell dysfunction triggers and accelerates the progression of cardiovascular and chronic kidney diseases. Progression of such diseases can be in part mitigated by the control of cardiovascular risk factors and drugs targeting different systems, including endothelin receptor antagonists (ERAs), renin-angiotensin aldosterone antagonists and agents affecting glucose metabolism, all of which were shown to improve endothelial cell function. In recent years, the microRNAs, which are endogenous regulators of gene expression, have been identified as transmitters of information from endothelial cells to vascular smooth muscle cells, suggesting that they can entail tools to assess the endothelial cell dysfunction in arterial hypertension and target for pharmacologic intervention. This article critically reviews current challenges and limitations of available techniques for the invasive and noninvasive assessment of endothelial cell function, and also discusses therapeutic aspects as well as directions for future research in the areas of endothelial cell biology and pathophysiology in humans.

Peptide 17 alleviates early hypertensive renal injury by regulating the Hippo/YAP signaling pathway

Aim

Hypertensive nephropathy is embodied by kidney tissue fibrosis and glomerular sclerosis, as well as renal inflammation. The Hippo/YAP (yes‐associated protein, YAP) axis has been reported to promote inflammation and fibrosis and may participate in the pathogenesis of heart, vascular and renal injuries. However, the role of the Hippo/YAP pathway in hypertensive renal injury has not been reported so far. We explored the role of the Hippo/YAP signalling pathway in hypertensive renal injury and the effect of peptide 17 on its effects.

Methods

Histopathological analyses were performed based on the Masson and Haematoxylin/eosin (HE) staining approaches. Biochemical indexes were determined and immunofluorescence and western blotting were used to detect protein expression levels. The mRNA expression levels were determined by qRT‐PCR.

Results

Our results showed that peptide 17 reduced the systolic blood pressure (SBP) and urine protein/creatinine ratio in hypertensive rats. In addition, peptide 17 reduced the histopathological damage of kidneys in spontaneously hypertensive rats (SHRs). Moreover, peptide 17 downregulated genes in the Hippo/Yap pathway in kidney tissue of SHRs and Ang II‐treated kidney cells. The expression levels of inflammatory factors TNF‐α, IL‐1β and MCP‐1 and the pro‐fibrotic factors TGF‐β1, fibronectin, and CTGF were increased in the kidney of hypertensive rats, but reversed by peptide 17 treatment. Silencing of YAP had effect similar to that of peptide 17 in vivo and in vitro.

Conclusion

Peptide 17 alleviates early renal injury in hypertension by regulating the Hippo/YAP signalling pathway. These findings may be useful in the treatment of hypertensive renal injury.

Herein, we explored the effect of peptide 17 on hypertensive renal injury and its mechanism of action. The results hinted that peptide 17 attenuated the deleterious inflammatory and fibrotic effects of hypertensive renal injury via downregulating the Hippo/YAP axis. These findings may be relevant for treating hypertensive nephropathy.

The Difference between Sacubitril Valsartan and Valsartan on Vascular Endothelial Function, APN, MMP-9, and BNP Levels in Patients with Hypertension and Chronic Heart Failure

Background

Sacubitril valsartan and valsartan are the first new drugs approved for angiotensin receptor neprilysin lysine inhibitors (ARNIs) in outpatients with chronic heart failure (CHF) and hypertension. Compared with enalapril, sacubitril valsartan and valsartan have been shown to reduce the mortality and morbidity of cardiovascular diseases. However, there is little actual evidence regarding the efficacy of ARNIs in hypertensive patients with CHF.

Methods

From January 2019 to January 2021, 60 patients with hypertension and chronic heart failure were diagnosed and treated in our hospital. The patients were randomly divided into an observation group and a control group, with 30 cases in each group. The control group was given valsartan, the observation group was given sacubitril valsartan, and both groups were treated for six months. The endothelium-dependent vasodilation (EDD) function of the brachial artery and serum nitric oxide (NO), endothelin-1 (ET-1), carotid artery intima-media thickness, and glomerular filtration, excess rate (eGFR), and left ventricular ejection fraction (LVEF) were compared between the two groups of patients before and after treatment. The serum adiponectin (APN), matrix metalloproteinase-9 (MMP-9), and brain natriuretic peptide (BNP) levels were compared before and after treatment.

Results

The total effective rate of treatment in the research group was higher than that in the control group (P < 0.05). After treatment, the cardiac function indexes LVESD and LVEDD of the two groups of patients were lower than before treatment, and LVEF was higher than before treatment, and the improvement rate of the treatment group was better than that of the control group (P < 0.05). After treatment, the serum APN of the two groups was higher than before treatment, the levels of MMP-9 and BNP were lower than before treatment, and the improvement rate of patients in the treatment group was better than that of patients in the control group (P < 0.05). There was no statistically significant in the levels of EDD, NO, and ET-1 of the two groups of patients before treatment (P < 0.05). After treatment, compared with the control group, the EDD function and NO level of the research group were significantly increased (P < 0.05), and the level of ET-1 was significantly reduced (P < 0.05). There was no statistically significant difference in carotid artery intima-media thickness, glomerular filtration rate, and left ventricular ejection fraction before and after treatment in the two groups (P < 0.05).

Conclusion

In the treatment of hypertension and chronic heart failure, sacubitril valsartan can improve the clinical symptoms of patients to the greatest extent and can significantly improve the levels of LVEF, LVEDD, NT-proBNP, heart function, and other indicators. Sacubitril valsartan can increase serum APN levels, reduce MMP-9 and BNP levels, and have good clinical effects. Sacubitril valsartan has a protective effect on the vascular endothelial function of patients with hypertension and CHF. However, these results need to be confirmed in studies involving more subjects and require longer follow-up times.

Significance of modern diagnostic methods in the early diagnosis of hypertensive nephropathy

The review analyzes modern criteria for early diagnosis of renal damage in hypertensive patients. Based on numerous studies, the role of impaired renal function markers and renal artery Doppler ultrasound in the diagnosis of hypertensive nephropathy is indicated. A search was made for the relationship between laboratory criteria for kidney damage and renal Doppler ultrasound characteristics in hypertensive patients. In addition, the importance of revealing intrarenal hemodynamic disorders in the early diagnosis of hypertensive nephropathy was established.

Modern Management of Hypertensive Emergencies

Acute increases of blood pressure values are common causes of patients' presentation to emergency departments, and their management represents a clinical challenge. They are usually described as 'hypertensive crises', 'hypertensive urgencies', terms that should be abandoned because they are misleading and inappropriate according to a recent task force of the European Society of Cardiology, which recommended to focus only on 'hypertensive emergencies'. The latter can be esasily identified by using the Brain, Arteries, Retina, Kidney, and/or Heart (BARKH) strategy as herein described. Although current guidelines recommendations/suggestions for treatment of these patients are not evidence-based, owing to the lack of randomized clinical trials, improved understanding of the underlying pathophysiology has changed the approach to management of the patients presenting with hypertensive emergencies in recent years. Starting from these premises and a systematic review of the available studies graded by their quality, using the AHA class of recommendation/level of evidence grading, whenever possible, we herein present a novel a streamlined symptoms- and evidence-based algorithm for the assessment and management of patients with hypertensive emergencies.

Management of hypertensive emergencies: a practical approach

Background: Acute increases of high blood pressure values, usually described as 'hypertensive crises', 'hypertensive urgencies' or 'hypertensive emergencies', are common causes of patients' presentation to emergency departments. Owing to the lack of ad hoc randomized clinical trials, current recommendations/suggestions for treatment of these patients are not evidenced-based and, therefore, the management of acute increases of blood pressure values represent a clinical challenge. However, an improved understanding of the underlying pathophysiology has changed radically the approach to management of the patients presenting with these conditions in recent years. Accordingly, it has been proposed to abandon the terms 'hypertensive crises' and 'hypertensive urgencies', and restrict the focus to 'hypertensive emergencies'. Aims and Methods: Starting from these premises, we aimed at systematically review all available studies (years 2010-2020) to garner information on the current management of hypertensive emergencies, in order to develop a novel symptoms- and evidence-based streamlined algorithm for the assessment and treatment of these patients.Results and Conclusions: In this educational review we proposed the BARKH-based algorithm for a quick identification of hypertensive emergencies and associated acute organ damage, to allow the patients with hypertensive emergencies to receive immediate treatment in a proper setting.

Endothelial Glycocalyx as a Regulator of Fibrotic Processes

The endothelial glycocalyx, the gel layer covering the endothelium, is composed of glycosaminoglycans, proteoglycans, and adsorbed plasma proteins. This structure modulates vessels’ mechanotransduction, vascular permeability, and leukocyte adhesion. Thus, it regulates several physiological and pathological events. In the present review, we described the mechanisms that disturb glycocalyx stability such as reactive oxygen species, matrix metalloproteinases, and heparanase. We then focused our attention on the role of glycocalyx degradation in the induction of profibrotic events and on the possible pharmacological strategies to preserve this delicate structure.

Mechanism of herbal medicine on hypertensive nephropathy (Review)

Hypertensive nephropathy is the most common complication of hypertension, and is one of the main causes of end-stage renal disease (ESRD) in numerous countries. The basic pathological feature of hypertensive nephropathy is arteriolosclerosis followed by renal parenchymal damage. The etiology of this disease is complex, and its pathogenesis is mainly associated with renal hemodynamic changes and vascular remodeling. Despite the increased knowledge on the pathogenesis of hypertensive nephropathy, the current clinical treatment methods are still not effective in preventing the development of the disease to ESRD. Herbal medicine, which is used to relieve symptoms, can improve hypertensive nephropathy through multiple targets. Since there are few clinical studies on the treatment of hypertensive nephropathy with herbal medicine, this article aims to review the progress on the basic research on the treatment of hypertensive nephropathy with herbal medicine, including regulation of the renin angiotensin system, inhibition of sympathetic excitation, antioxidant stress and anti-inflammatory protection of endothelial cells, and improvement of obesity-associated factors. Herbal medicine with different components plays a synergistic and multi-target role in the treatment of hypertensive nephropathy. The description of the mechanism of herbal medicine in the treatment of hypertensive nephropathy will contribute towards the progress of modern medicine.

Complications of metabolic acidosis and alkalinizing therapy in chronic kidney disease patients: a clinician-directed organ-specific primer

Chronic kidney disease is prevalent, affecting more than one in ten adults. In this population, metabolic acidosis is considered a key underlying pathophysiological feature, tying together bone mineral disorders, sarcopenia, insulin resistance, vascular calcification, pro-inflammatory and pro-thrombotic states. This review aims to address the paucity of literature on alkalinizing agents, a promising treatment option that has known adverse effects.

Endothelium structure and function in kidney health and disease

The kidney harbours different types of endothelia, each with specific structural and functional characteristics. The glomerular endothelium, which is highly fenestrated and covered by a rich glycocalyx, participates in the sieving properties of the glomerular filtration barrier and in the maintenance of podocyte structure. The microvascular endothelium in peritubular capillaries, which is also fenestrated, transports reabsorbed components and participates in epithelial cell function. The endothelium of large and small vessels supports the renal vasculature. These renal endothelia are protected by regulators of thrombosis, inflammation and complement, but endothelial injury (for example, induced by toxins, antibodies, immune cells or inflammatory cytokines) or defects in factors that provide endothelial protection (for example, regulators of complement or angiogenesis) can lead to acute or chronic renal injury. Moreover, renal endothelial cells can transition towards a mesenchymal phenotype, favouring renal fibrosis and the development of chronic kidney disease. Thus, the renal endothelium is both a target and a driver of kidney and systemic cardiovascular complications. Emerging therapeutic strategies that target the renal endothelium may lead to improved outcomes for both rare and common renal diseases.

Endothelin: 30 Years From Discovery to Therapy

Discovered in 1987 as a potent endothelial cell-derived vasoconstrictor peptide, endothelin-1 (ET-1), the predominant member of the endothelin peptide family, is now recognized as a multifunctional peptide with cytokine-like activity contributing to almost all aspects of physiology and cell function. More than 30 000 scientific articles on endothelin were published over the past 3 decades, leading to the development and subsequent regulatory approval of a new class of therapeutics-the endothelin receptor antagonists (ERAs). This article reviews the history of the discovery of endothelin and its role in genetics, physiology, and disease. Here, we summarize the main clinical trials using ERAs and discuss the role of endothelin in cardiovascular diseases such as arterial hypertension, preecclampsia, coronary atherosclerosis, myocardial infarction in the absence of obstructive coronary artery disease (MINOCA) caused by spontaneous coronary artery dissection (SCAD), Takotsubo syndrome, and heart failure. We also discuss how endothelins contributes to diabetic kidney disease and focal segmental glomerulosclerosis, pulmonary arterial hypertension, as well as cancer, immune disorders, and allograft rejection (which all involve ET_A autoantibodies), and neurological diseases. The application of ERAs, dual endothelin receptor/angiotensin receptor antagonists (DARAs), selective ET_B agonists, novel biologics such as receptor-targeting antibodies, or immunization against ET_A receptors holds the potential to slow the progression or even reverse chronic noncommunicable diseases. Future clinical studies will show whether targeting endothelin receptors can prevent or reduce disability from disease and improve clinical outcome, quality of life, and survival in patients.

Acute renal impairment characterization using diffusion magnetic resonance imaging: Validation by histology

Diffusion magnetic resonance imaging has been demonstrated to be a simple, noninvasive and accurate method for the detection of renal microstructure and microcirculation, which are closely linked to renal function. Moreover, serum endothelin-1 (ET-1) was also reported as a good indicator of early renal injury. The aim of this study was to evaluate the feasibility and capability of diffusion MRI and ET-1 to detect acute kidney injury by an operation simulating high-pressure renal pelvic perfusion, which is commonly used during ureteroscopic lithotripsy. Histological findings were used as a reference. Fourteen New Zealand rabbits in an experimental group and 14 in a control group were used in this study. Diffusion tensor imaging and intravoxel incoherent motion diffusion-weighted imaging were acquired by a 3.0 T MRI scanner. Significant corticomedullary differences were found in the values of the apparent diffusion coefficient (ADC), pure tissue diffusion, volume fraction of pseudo-diffusion (fp) and fractional anisotropy (FA) (P < 0.05 for all) in both preoperation and postoperation experimental groups. Compared with the control group, the values of cortical fp_mean , medullary ADC_mean and FA_mean decreased significantly (P < 0.05) after the operation in the experimental group. Also, the change rate of medullary ADC_mean in the experimental group was more pronounced than that in the control group (P = 0.018). No significant change was found in serum ET-1 concentration after surgery in either the experimental (P = 0.80) or control (P = 0.17) groups. In the experimental group, histological changes were observed in the medulla, while no visible change was found in the cortex. This study demonstrated the feasibility of diffusion MRI to detect the changes of renal microstructure and microcirculation in acute kidney injury, with the potential to evaluate renal function. Moreover, the sensitivity of diffusion MRI to acute kidney injury appears to be superior to that of serum ET-1.

Renal Parenchymal Thickness in Patients with Systemic Sclerosis Is Related to Intrarenal Hemodynamic Variables and Raynaud Renal Phenomenon

Objective.

Renal involvement in systemic sclerosis (SSc) ranges from urinary abnormalities, reduction of glomerular filtration rate, and high renal resistive index, to scleroderma renal crisis. Intrarenal resistance indices are considered markers of renal SSc-associated vasculopathy. The aim of this study is to evaluate renal morphological variables, such as renal length, parenchymal thickness, atrophy index, and renal sinus in patients with SSc and to correlate it with renal function and hemodynamic variables.

Methods.

There were 92 patients with SSc and 40 healthy controls (HC) enrolled in this study. Doppler and renal ultrasound (US) including renal length, parenchymal thickness, atrophy index, renal sinus, and intrarenal resistive index were measured in patients with SSc and HC.

Results.

Renal US showed significant differences between HC and patients with SSc. The renal length (mm; 106.7 ± 5.1 vs 102.3 ± 8.4) and renal sinus (70.7 ± 7.9 vs 65.3 ± 7.7 mm) were significantly (p = 0.001) higher in HC than patients with SSc. The parenchymal thickness was significantly (p = 0.004) higher in HC than patients with SSc (18 ± 3.1 vs 16.3 ± 2.5 mm). Pulsatility index, resistive index, and systolic/diastolic ratio were significantly (p < 0.0001) lower in HC than patients with SSc. The renal length was significantly (p = 0.004) higher in diffuse cutaneous SSc (105 ± 8.4) than in limited cutaneous SSc (99.5 ± 7.5).

Conclusion.

In SSc, kidney involvement is subclinical and is related to vascular injury, Raynaud phenomenon, and chronic hypoxia that can modify renal morphology. Serum creatinine is a poor marker of renal damage, and renal US could be a useful tool — together with Doppler — to evaluate renal involvement in a systemic and chronic disease such as SSc.

Evaluation of Allostatic Load as a Mediator of Sleep and Kidney Outcomes in Black Americans

Introduction

Poor sleep associates with adverse chronic kidney disease (CKD) outcomes yet the biological mechanisms underlying this relation remain unclear. One proposed mechanism is via allostatic load, a cumulative biologic measure of stress.

Methods

Using data from 5177 Jackson Heart Study participants with sleep measures available, we examined the association of self-reported sleep duration: very short, short, recommended, and long (≤5, 6, 7–8, or ≥9 hours per 24 hours, respectively) and sleep quality (high, moderate, low) with prevalent baseline CKD, and estimated glomerular filtration rate (eGFR) decline and incident CKD at follow-up. CKD was defined as eGFR <60 ml/min per 1.73 m² or urine albumin-to-creatinine ratio ≥30 mg/g. Models were adjusted for demographics, comorbidities, and kidney function. We further evaluated allostatic load (quantified at baseline using 11 biomarkers from neuroendocrine, metabolic, autonomic, and immune domains) as a mediator of these relations using a process analysis approach.

Results

Participants with very short sleep duration (vs. 7–8 hours) had greater odds of prevalent CKD (odds ratio [OR] 1.31, 95% confidence interval [CI] 1.03–1.66). Very short, short, or long sleep duration (vs. 7–8 hours) was not associated with kidney outcomes over a median follow-up of 8 years. Low sleep quality (vs. high) associated with greater odds of prevalent CKD (OR 1.26, 95% CI 1.00–1.60) and 0.18 ml/min per 1.73 m² (95% CI 0.00–0.36) faster eGFR decline per year. Allostatic load did not mediate the associations of sleep duration or sleep quality with kidney outcomes.

Conclusions

Very short sleep duration and low sleep quality were associated with adverse kidney outcomes in this all-black cohort, but allostatic load did not appear to mediate these associations.

Inhibition of Soluble Epoxide Hydrolase for Renal Health

A soluble epoxide hydrolase (sEH) mediates the metabolism of epoxy fatty acids to form the corresponding vicinal diols, which are usually inactive or less active than the epoxide substrates. The sEH enzyme presents in many organs, including but not limited to the liver, heart, spleen, lung, and kidney. Here we summarized the changes in the expression and activity of sEH in multiple renal diseases, such as acute kidney injury (AKI), diabetic nephrology (DN), chronic kidney diseases (CKD), hypertension-mediated renal damage, and other renal dysfunctions. We also discussed the pharmacologic effects and the underlying mechanisms of sEH inhibition by using an inhibitor of sEH and/or the generic deletion of sEH on multiple renal diseases. We believe that sEH is a potential therapeutic target for renal dysfunction although the target disease needs further investigation.