Role and Mechanism of the Renin-Angiotensin-Aldosterone System in the Onset and Development of Cardiorenal Syndrome

The significance of the apelinergic system in doxorubicin-induced cardiotoxicity

Cancer is the leading cause of death worldwide, and the number of cancer-related deaths is expected to increase. Common types of cancer include skin, breast, lung, prostate, and colorectal cancers. While clinical research has improved cancer therapies, these treatments often come with significant side effects such as chronic fatigue, hair loss, and nausea. In addition, cancer treatments can cause long-term cardiovascular complications. Doxorubicin (DOX) therapy is one example, which can lead to decreased left ventricle (LV) echocardiography (ECHO) parameters, increased oxidative stress in cellular level, and even cardiac fibrosis. The apelinergic system, specifically apelin and its receptor, together, has shown properties that could potentially protect the heart and mitigate the damages caused by DOX anti-cancer treatment. Studies have suggested that stimulating the apelinergic system may have therapeutic benefits for heart damage induced by DOX. Further research in chronic preclinical models is needed to confirm this hypothesis and understand the mechanism of action for the apelinergic system. This review aims to collect and present data on the effects of the apelinergic system on doxorubicin-induced cardiotoxicity.

Angiotensin-Converting Enzyme and Renin-Inhibitory Activities of Protein Hydrolysates Produced by Alcalase Hydrolysis of Peanut Protein

Hypertension is a major controllable risk factor associated with cardiovascular disease (CVD) and overall mortality worldwide. Most people with hypertension must take medications that are effective in blood pressure management but cause many side effects. Thus, it is important to explore safer antihypertensive alternatives to regulate blood pressure. In this study, peanut protein concentrate (PPC) was hydrolyzed with 3-5% Alcalase for 3-10 h. The in vitro angiotensin-converting enzyme (ACE) and renin-inhibitory activities of the resulting peanut protein hydrolysate (PPH) samples and their fractions of different molecular weight ranges were determined as two measures of their antihypertensive potentials. The results show that the crude PPH produced at 4% Alcalase for 6 h of hydrolysis had the highest ACE-inhibitory activity with IC50 being 5.45 mg/mL. The PPH samples produced with 3-5% Alcalase hydrolysis for 6-8 h also displayed substantial renin-inhibitory activities, which is a great advantage over the animal protein-derived bioactive peptides or hydrolysate. Remarkably higher ACE- and renin-inhibitory activities were observed in fractions smaller than 5 kDa with IC50 being 0.85 and 1.78 mg/mL. Hence, the PPH and its small molecular fraction produced under proper Alcalase hydrolysis conditions have great potential to serve as a cost-effective anti-hypertensive ingredient for blood pressure management.

The effect of glycine on oxidative stress, inflammation and renin-angiotensin system in kidneys and aorta of cyclosporine-administered rats

Cyclosporine A (CsA) is an immunosuppressive drug, used in organ transplantations. Oxidative stress, inflammation and renin-angiotensin system (RAS) activation play an important role in CsA-toxicity. Glycine (Gly) has antioxidant and anti-inflammatory effects. In this study, Gly was investigated for its protective role against CsA-induced toxicity. CsA (20 mg/kg/day; subcutaneously) was administered to rats along with Gly injection (250 or 1000 mg/kg; intraperitoneally) for 21 days. Renal function markers [serum urea and creatinine and urinary protein and kidney injury molecule levels and creatinine clearance values] together with histopathological examinations were performed. Oxidative stress (reactive oxygen species, thiobarbutiric acid reactive substances, advanced oxidation products of protein, glutathione, ferric reducing anti-oxidant power and 4-hydroxynonenal levels), and inflammation (myeloperoxidase activity) were determined in kidney tissue. The RAS system [angiotensin II (Ang II) levels, and mRNA expressions of angiotensin converting enzyme (ACE), angiotensin II type-I receptor (AT1R)] and NADPH-oxidase 4 (NOX4) were measured in kidney and aorta. CsA caused significant disturbances in renal function markers, increases in oxidative stress and inflammation parameters and renal damage. Serum angiotensin II levels and mRNA expressions of ACE, AT1R and NOX4 elevated in the aorta and kidney of CsA-rats. Gly, especially its high-dose, alleviated renal function markers, oxidative stress, inflammation and renal damage in CsA-rats. Moreover, serum Ang II levels and mRNA expressions of ACE, AT1R and NOX4 decreased significantly in aorta and kidney in CsA-rats due to Gly treatment. Our results indicate that Gly may be useful for the prevention of CsA-induced renal and vascular toxicity.

Sacubitril/valsartan improves all-cause mortality in heart failure patients with reduced ejection fraction and chronic kidney disease

BACKGROUND

Impaired renal function is frequently observed in patients with heart failure and reduced ejection fraction (HFrEF). The differential effect of sacubitril/valsartan and angiotensin-converting enzyme inhibitors/angiotensin-receptor blockers (ACEIs/ARBs) on the clinical and renal outcomes in patients with HFrEF and chronic kidney disease (CKD) remains unknown.

AIMS

This study aimed to explore the differential effect of sacubitril/valsartan and ACEI/ARB on the clinical and renal outcomes as well as renal function over a 12-month follow-up period in HFrEF patients with and without CKD.

METHODS

Patients with HfrEF (LVEF ≤35%) and NYHA class ≥II were enrolled from the Chang Gung Research Database between 2017 and 2020. Baseline characteristics were compared between patients prescribed sacubitril/valsartan and ACEI/ARB. After propensity score matching, the following clinical and renal outcomes were compared between the two groups in patients with and without CKD over a 12-month follow-up period: acute kidney injury (AKI), emergent dialysis/renal death, HF hospitalization, cardiovascular mortality, and all-cause mortality.

RESULTS

This study enrolled 3735 HFrEF patients with a mean left ventricular EF of 27.56 ± 5.86%, who had been prescribed sacubitril/valsartan (N = 1708) or ACEI/ARB (N = 2027). After propensity score matching, the clinical and renal outcomes did not differ between the sacubitril/valsartan and ACEI/ARB groups in patients without CKD. In patients with CKD, the ACEI/ARB group had a significantly higher incidence of all-cause mortality than the sacubitril/valsartan group (14.89% vs. 10.50%; hazard ratio 1.46; 95% confidence interval 1.06-2.00; p = 0.02), and the incidence of AKI, HF hospitalization, and CV mortality did not differ between the two groups.

CONCLUSIONS

Sacubitril/valsartan had a lower all-cause mortality compared to ACEI/ARB in symptomatic HFrEF patients with CKD. Further prospective randomized studies are warranted to confirm our findings.

What to do with foundation therapies for heart failure for patients with end-stage kidney disease on haemodialysis

There is a significant burden of cardiovascular disease morbidity and mortality in the end-stage kidney disease population, driven by traditional and non-traditional risk factors. Despite its prevalence, heart failure is difficult to diagnose in the dialysis population due to overlapping clinical presentations, limitations of investigations, and the impact on the cardiorenal axis. 'Foundation therapies' are the key medications which improve patient outcomes in heart failure with reduced ejection fraction and include beta-blockers, renin-angiotensin-aldosterone system inhibitors and sodium-glucose cotransporter-2 inhibitors. They are underutilised in the dialysis population due to the exclusion of chronic kidney disease patients from major trials and legitimate clinical concerns e.g. hyperkalaemia, intradialytic hypotension and residual kidney function preservation. A coordinated cardiorenal multidisciplinary approach can guide appropriate diagnostic considerations (biomarkers interpretation, imaging, addressing unique complications of kidney disease), optimise dialysis management (prescription length, frequency and ultrafiltration targets) and when at euvolaemia facilitate the stepwise introduction of appropriate foundation therapies.

Unveiling Selected Influences on Chronic Kidney Disease Development and Progression

Currently, more and more people are suffering from chronic kidney disease (CKD). It is estimated that CKD affects over 10% of the population worldwide. This is a significant issue, as the kidneys largely contribute to maintaining homeostasis by, among other things, regulating blood pressure, the pH of blood, and the water-electrolyte balance and by eliminating unnecessary metabolic waste products from blood. What is more, this disease does not show any specific symptoms at the beginning. The development of CKD is predisposed by certain conditions, such as diabetes mellitus or hypertension. However, these disorders are not the only factors promoting the onset and progression of CKD. The primary purpose of this review is to examine renin-angiotensin-aldosterone system (RAAS) activity, transforming growth factor-β1 (TGF-β1), vascular calcification (VC), uremic toxins, and hypertension in the context of their impact on the occurrence and the course of CKD. We firmly believe that a deeper comprehension of the cellular and molecular mechanisms underlying CKD can lead to an enhanced understanding of the disease. In the future, this may result in the development of medications targeting specific mechanisms involved in the decline of kidney function. Our paper unveils the selected processes responsible for the deterioration of renal filtration abilities.

Validity of mental and physical stress models

Different stress models are employed to enhance our understanding of the underlying mechanisms and explore potential interventions. However, the utility of these models remains a critical concern, as their validities may be limited by the complexity of stress processes. Literature review revealed that both mental and physical stress models possess reasonable construct and criterion validities, respectively reflected in psychometrically assessed stress ratings and in activation of the sympathoadrenal system and the hypothalamic-pituitary-adrenal axis. The findings are less robust, though, in the pharmacological perturbations' domain, including such agents as adenosine or dobutamine. Likewise, stress models' convergent- and discriminant validity vary depending on the stressors' nature. Stress models share similarities, but also have important differences regarding their validities. Specific traits defined by the nature of the stressor stimulus should be taken into consideration when selecting stress models. Doing so can personalize prevention and treatment of stress-related antecedents, its acute processing, and chronic sequelae. Further work is warranted to refine stress models' validity and customize them so they commensurate diverse populations and circumstances.

Clinical Significance of Apela in Acute Cardiorenal Insuffiency of Chronic Heart Failure

INTRODUCTION

Apela has a wide range of biological effects on the cardiovascular system, but the changes and significance of endogenous Apela in patients with chronic heart failure (CHF) and acute deterioration of cardiac and renal function are unclear.

METHODS

A total of 69 patients with stable CHF combined with well-preserved renal function were enrolled and followed for 12 months. The effects of Apela on human renal glomerular endothelial cells (hRGEC), human glomerular mesangial cells (hMC), and human renal tubular epithelial cells (HK-2) were observed.

RESULTS

Serum Apela concentration was positively correlated with NYHA class (r = 0.711) and N-terminal pro-brain natriuretic peptide (NT-proBNP) concentration (r = 0.303) but negatively correlated with left ventricular ejection fraction (LVEF) (r = -0.374) and 6-min walk distance (r = -0.860) in patients with stable CHF. Twenty-one patients experiencing deterioration of renal and cardiac function were diagnosed with cardiorenal syndrome (CRS) during the follow-up period. In addition, the serum Apela, as well as the difference in Apela between stable and worsening phases (ΔApela), was correlated with the estimated glomerular filtration rate (eGFR) and ΔeGFR in patients with CRS. Apela significantly inhibited the upregulated expression of MCP-1 and TNF-α induced by angiotensin II (AngII) in hRGEC, hMC, and HK-2 cells. Apela inhibited the adhesion of THP-1 cells to hRGEC and promoted the tubular formation of hRGEC. Moreover, Apela enhanced the expression of MMP-9 in hMC but inhibited the upregulated expression of α-SMA and vimentin in HK-2 cells by AngII.

CONCLUSION

This study suggests that the level of Apela can be used to diagnose heart failure and assess the severity of cardiac dysfunction in patients with stable CHF, and its dynamic changes can be used to evaluate the damage to renal function in patients with CRS. Apela plays multiple protective effects on renal cells, highlighting its clinical application prospect in the prevention and treatment of CRS.

Genetic variants in the renin-angiotensin-aldosterone system: Impact on cancer risk, prognosis, and therapeutic directions

Although renin-angiotensin-aldosterone system (RAAS) is known to maintain blood pressure and electrolyte balance, it has recently been linked to a number of biological processes such as angiogenesis, tumorigenesis, metastasis, and cellular proliferation, increasing the risk of cancer development and progression. Multiple genetic variants have been found to affect the genes encoding RAAS components, altering gene transcription and protein expression. This review provides an up-to-date insight into the role of RAAS in carcinogenesis, as well as the impact of RAAS genetic variants on the risk of cancer development, progression, and patient survival and outcomes, as well as response to treatment. This paves the way for the application of precision medicine in cancer risk assessment and management by implementing preventative programs in individuals at risk and guiding the therapeutic direction in cancer patients.

Differential expression of the angiotensin receptors (AT1, AT2, and AT4) in the placental bed of HIV-infected preeclamptic women of African ancestry

The Renin-Angiotensin-Aldosterone System (RAAS) is implicated in the pathophysiology of preeclampsia (PE). There is a paucity of data on uteroplacental angiotensin receptors AT1-2 and 4. We evaluated the immunoexpression of AT1R, AT2R, and AT4R within the placental bed of PE vs. normotensive (N) pregnancies stratified by HIV status. Placental bed (PB) biopsies (n = 180) were obtained from N and PE women. Both groups were stratified by HIV status and gestational age into early-and late onset-PE. Immuno-labeling of AT1R, AT2R, and AT4R was quantified using morphometric image analysis. Immunostaining of PB endothelial cells (EC) and smooth muscle cells of spiral arteries (VSMC) displayed an upregulation of AT1R expression compared to the N group (p < 0.0001). Downregulation of AT2R and AT4R expression was observed in PE vs. N group (p = 0.0042 and p < 0.0001), respectively. AT2R immunoexpression declined between HIV+ve and HIV-ve groups, while AT1R and AT4R displayed an increase. An increase in AT1R expression was noted in the EOPE-ve/+ve and LOPE-ve/+ve compared to N-ve/N+ve. In contrast, AT2R and AT4R expression decreased in EOPE-ve/+ve and LOPE-ve/+ve compared to N-ve/N+ve. We demonstrate a significant downregulation of AT2R and AT4R with a concomitant elevated AT1R immunoexpression within PB of HIV-infected PE women. In addition, a decline in AT2R and AT4R with an increase in AT1R immunoexpression in PE, EOPE, and LOPE vs. normotensive pregnancies, irrespective of HIV status. Thus highlighting differential immunoexpression of uteroplacental RAAS receptors based on pregnancy type, HIV status, and gestational age.

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.

Mineralocorticoid Receptor Antagonism Attenuates Multiple Organ Failure after Renal Ischemia and Reperfusion in Mice

Renal ischemia reperfusion (IR) injury is a major cause of acute kidney injury (AKI) that is often complicated by multiple organ failure of the liver and intestine. The mineralocorticoid receptor (MR) is activated in patients with renal failure associated with glomerular and tubular damage. We thus investigated whether canrenoic acid (CA), a mineralocorticoid receptor (MR) antagonist, protects against AKI-induced hepatic and intestinal injury, suggesting the underlying mechanisms. Mice were divided into five groups: sham mice, mice subjected to renal IR, and mice pretreated with canrenoic acid (CA; 1 or 10 mg/kg) 30 min prior to renal IR. At 24 h after renal IR, the levels of plasma creatinine, alanine aminotransferase and aldosterone were measured, and structural changes and inflammatory responses of the kidney, liver, and intestine were analyzed. We found that CA treatment reduced plasma creatinine levels, tubular cell death and oxidative stress induced by renal IR. CA treatment also decreased renal neutrophil infiltration and inflammatory cytokine expression and inhibited the release of high-mobility group box 1 induced by renal IR. Consistently, CA treatment reduced renal IR-induced plasma alanine transaminase, hepatocellular injury and neutrophil infiltration, and inflammatory cytokine expression. CA treatment also decreased small intestinal cell death, neutrophil infiltration and inflammatory cytokine expression induced by renal IR. Taken together, we conclude that MR antagonism by CA treatment protects against multiple organ failure in the liver and intestine after renal IR.

Organ Crosstalk in Acute Kidney Injury: Evidence and Mechanisms

Acute kidney injury (AKI) is becoming a public health problem worldwide. AKI is usually considered a complication of lung, heart, liver, gut, and brain disease, but recent findings have supported that injured kidney can also cause dysfunction of other organs, suggesting organ crosstalk existence in AKI. However, the organ crosstalk in AKI and the underlying mechanisms have not been broadly reviewed or fully investigated. In this review, we summarize recent clinical and laboratory findings of organ crosstalk in AKI and highlight the related molecular mechanisms. Moreover, their crosstalk involves inflammatory and immune responses, hemodynamic change, fluid homeostasis, hormone secretion, nerve reflex regulation, uremic toxin, and oxidative stress. Our review provides important clues for the intervention for AKI and investigates important therapeutic potential from a new perspective.