The combination of a neprilysin inhibitor (sacubitril) and angiotensin-II receptor blocker (valsartan) attenuates glomerular and tubular injury in the Zucker Obese rat

Role of angiotensin receptor-neprilysin inhibitor in diabetic complications

Diabetes mellitus is a prevalent disorder with multi-system manifestations, causing a significant burden in terms of disability and deaths globally. Angio-tensin receptor-neprilysin inhibitor (ARNI) belongs to a class of medications for treating heart failure, with the benefits of reducing hospitalization rates and mortality. This review mainly focuses on the clinical and basic investigations related to ARNI and diabetic complications, discussing possible physiological and molecular mechanisms, with insights for future applications.

Sacubitril/valsartan ameliorates tubulointerstitial fibrosis by restoring mitochondrial homeostasis in diabetic kidney disease

BACKGROUND

Tubulointerstitial fibrosis plays an important role in the progression of diabetic kidney disease (DKD). Sacubitril/valsartan (Sac/Val) exerts a robust beneficial effect in DKD. However, the potential functional effect of Sac/Val on tubulointerstitial fibrosis in DKD is still largely unclear.

METHODS

Streptozotocin-induced diabetic mice were given Sac/Val or Val by intragastric administration once a day for 12 weeks. The renal function, the pathological changes of tubule injury and tubulointerstitial fibrosis, as well as mitochondrial morphology of renal tubules in mice, were evaluated. Genome-wide gene expression analysis was performed to identify the potential mechanisms. Meanwhile, human tubular epithelial cells (HK-2) were cultured in high glucose condition containing LBQ657/valsartan (LBQ/Val). Further, mitochondrial functions and Sirt1/PGC1α pathway of tubular epithelial cells were assessed by Western blot, Real-time-PCR, JC-1, MitoSOX or MitoTracker. Finally, the Sirt1 specific inhibitor, EX527, was used to explore the potential effects of Sirt1 signaling in vivo and in vitro.

RESULTS

We found that Sac/Val significantly ameliorated the decline of renal function and tubulointerstitial fibrosis in DKD mice. The enrichment analysis of gene expression indicated metabolism as an important modulator in DKD mice with Sac/Val administration, in which mitochondrial homeostasis plays a pivotal role. Then, the decreased expression of Tfam and Cox IV;, as well as changes of mitochondrial function and morphology, demonstrated the disruption of mitochondrial homeostasis under DKD conditions. Interestingly, Sac/Val administration was found to restore mitochondrial homeostasis in DKD mice and in vitro model of HK-2 cells. Further, we demonstrated that Sirt1/PGC1α, a crucial pathway in mitochondrial homeostasis, was activated by Sac/Val both in vivo and in vitro. Finally, the beneficial effects of Sac/Val on mitochondrial homeostasis and tubulointerstitial fibrosis was partially abolished in the presence of Sirt1 specific inhibitor.

CONCLUSIONS

Taken together, we demonstrate that Sac/Val ameliorates tubulointerstitial fibrosis by restoring Sirt1/PGC1α pathway-mediated mitochondrial homeostasis in DKD, providing a theoretical basis for delaying the progression of DKD in clinical practice.

Impact of sacubitril/valsartan on cardiac and systemic hypoxia in chronic heart failure

In heart failure patients with reduced ejection fraction, Sacubitril/valsartan (S/V) increased proBNP T71 glycosylation, which is regulated negatively by hypoxia via miR-30a in vitro. Using a cohort of 73 HFrEF patients who were transitioned from standard HF medication to S/V, we found that the increase in proBNP T71 glycosylation after S/V was associated with a decrease in cardiac hypoxia. We further found that plasma levels of K709-acteylated HIF1α, HIF-regulated and HIF-independent biomarkers also evolved consistently with a decrease in hypoxia. We further confirmed that biomarker changes were related to hypoxia, in a rat model subjected to isobaric hypoxia. We measured them in rats subjected to isobaric hypoxia. Overall, these data strongly suggest that optimally treated HFrEF patients exhibited subclinical hypoxia that is improved by S/V. The data also posit proBNP T71 glycosylation as a biomarker of cardiac hypoxia.

Obesity and heart failure with preserved ejection fraction

OBJECTIVE

Aim: To perform an overall assessment of heart failure with preserved ejection fraction (HFpEF) adults with central obesity.

PATIENTS AND METHODS

Materials and Methods: We enrolled HFpEF patients with central obesity (n =73, mean age 52.4 ± 6.3 years) and without obesity (n =70, mean age 51.9 ± 7.1 years) and compared with an age-matched healthy subjects who had not suffered from HF (n = 69, mean age 52.3 ± 7.5 years). Physical examination, routine laboratory tests such as fasting blood glucose, fasting insulin, insulin resistance (HOMA) index, serum lipids, haemoglobin, creatinine, ALT, AST, uric acide, hs CRP, TSH, N-terminal proB-type natriuretic peptide (NT-proBNP) and standard transthoracic echocardiogram (2D and Doppler) examinations were performed and assessed.

RESULTS

Results: The average values of diastolic blood pressure (DBP), glucose and lipid profiles, uric acide, hs CRP were found to be significantly higher among obese patients with HFpEF than non-obese. Despite more severe symptoms and signs of HF, obese patients with HFpEF had lower NT-proBNP values than non-obese patients with HFpEF (129±36.8 pg/ml, 134±32.5 pg/ml vs 131±30.4 pg/ml, 139±33.8 pg/ml respectively; p < 0.05). However, it was found that patients with high central (visceral) adiposity have more pronounced obesity-related LV diastolic dysfunction, lower E/e' ratio, lower mitral annular lateral e' velocity, an increased LV diastolic dimension and LV mass index. Compared with non-obese HFpEF and control subjects, obese patients displayed greater right ventricular dilatation (base, 35±3.13 mm, 36±4.7 mm vs 33±2.8 mm, 34±3.2 mm and 29±5.3 mm, 30±3.9 mm; length, 74±5 mm, 76±8 mm vs 67±4 mm, 69±6 mm and 60±3 mm, 61±5 mm respectively; p < 0.05), more right ventricular dysfunction (TAPSE 16±2 mm, 15±3 mm vs 17±2 mm, 17±1 mm and 19±2 mm, 20±3 mm respectively; p < 0.05).

CONCLUSION

Conclusions: Obese patients with HFpEF have higher diastolic BP, atherogenic dyslipidemia, insulin resistance index values and greater systemic inflammatory biomarkers, despite lower NT-proBNP values, which increase the risk of cardiovascular events in future. Echocardiography examination revealed not only significant LV diastolic dysfunction, but also displayed greater RV dilatation and dysfunction.

Benefits and risks of drug combination therapy for diabetes mellitus and its complications: a comprehensive review

Diabetes is a chronic metabolic disease, and its therapeutic goals focus on the effective management of blood glucose and various complications. Drug combination therapy has emerged as a comprehensive treatment approach for diabetes. An increasing number of studies have shown that, compared with monotherapy, combination therapy can bring significant clinical benefits while controlling blood glucose, weight, and blood pressure, as well as mitigating damage from certain complications and delaying their progression in diabetes, including both type 1 diabetes (T1D), type 2 diabetes (T2D) and related complications. This evidence provides strong support for the recommendation of combination therapy for diabetes and highlights the importance of combined treatment. In this review, we first provided a brief overview of the phenotype and pathogenesis of diabetes and discussed several conventional anti-diabetic medications currently used for the treatment of diabetes. We then reviewed several clinical trials and pre-clinical animal experiments on T1D, T2D, and their common complications to evaluate the efficacy and safety of different classes of drug combinations. In general, combination therapy plays a pivotal role in the management of diabetes. Integrating the effectiveness of multiple drugs enables more comprehensive and effective control of blood glucose without increasing the risk of hypoglycemia or other serious adverse events. However, specific treatment regimens should be tailored to individual patients and implemented under the guidance of healthcare professionals.

Optimizing diabetic kidney disease animal models: Insights from a meta-analytic approach

Diabetic kidney disease (DKD) is a prevalent complication of diabetes, often leading to end-stage renal disease. Animal models have been widely used to study the pathogenesis of DKD and evaluate potential therapies. However, current animal models often fail to fully capture the pathological characteristics of renal injury observed in clinical patients with DKD. Additionally, modeling DKD is often a time-consuming, costly, and labor-intensive process. The current review aims to summarize modeling strategies in the establishment of DKD animal models by utilizing meta-analysis related methods and to aid in the optimization of these models for future research. A total of 1215 articles were retrieved with the keywords of "diabetic kidney disease" and "animal experiment" in the past 10 years. Following screening, 84 articles were selected for inclusion in the meta-analysis. Review manager 5.4.1 was employed to analyze the changes in blood glucose, glycosylated hemoglobin, total cholesterol, triglyceride, serum creatinine, blood urea nitrogen, and urinary albumin excretion rate in each model. Renal lesions shown in different models that were not suitable to be included in the meta-analysis were also extensively discussed. The above analysis suggested that combining various stimuli or introducing additional renal injuries to current models would be a promising avenue to overcome existing challenges and limitations. In conclusion, our review article provides an in-depth analysis of the limitations in current DKD animal models and proposes strategies for improving the accuracy and reliability of these models that will inspire future research efforts in the DKD research field.

The angiotensin receptor neprilysin inhibitor LCZ696 attenuates renal fibrosis via ASK1/JNK/p38 MAPK-mediated apoptosis in unilateral ureteral obstruction

The angiotensin receptor neprilysin inhibitor LCZ696 affords superior cardioprotection and renoprotection compared with renin-angiotensin blockade monotherapy, but the underlying mechanisms remain elusive. Herein, we evaluated whether LCZ696 attenuates renal fibrosis by inhibiting ASK1/JNK/p38 mitogen-activated protein kinase (MAPK)-mediated apoptosis in a rat model of unilateral ureteral obstruction (UUO) and in vitro. Rats with UUO were treated daily for 7 days with LCZ696, valsartan, or the selective ATP competitive inhibitor of apoptosis signal-regulating kinase 1 (ASK1), GS-444217. The effects of LCZ696 on renal injury were examined by assessing the histopathology, oxidative stress, intracellular organelles, apoptotic cell death, and MAPK pathways. H2O2-exposed human kidney 2 (HK-2) cells were also examined. LCZ696 and valsartan treatment significantly attenuated renal fibrosis caused by UUO, and this was paralleled by downregulation of proinflammatory cytokines and decreased inflammatory cell influx. Intriguingly, LCZ696 had stronger effects on renal fibrosis and inflammation than valsartan. UUO-induced oxidative stress triggered mitochondrial destruction and endoplasmic reticulum stress, which resulted in apoptotic cell death; these effects were reversed by LCZ696. Both GS-444217 and LCZ696 hampered the expression of death-associated ASK1/JNK/p38 MAPKs. In H2O2-treated HK-2 cells, LCZ696 and GS-444217 increased cell viability but decreased the production of intracellular reactive oxygen species and MitoSOX and apoptotic cell death. Both agents also deactivated H2O2-stimulated activation of ASK1/JNK/p38 MAPKs. These findings suggest that LCZ696 protects against UUO-induced renal fibrosis by inhibiting ASK1/JNK/p38 MAPK-mediated apoptosis.

Nox4 as a novel therapeutic target for diabetic vascular complications

Diabetic vascular complications can affect both microvascular and macrovascular. Diabetic microvascular complications, such as diabetic nephropathy, diabetic retinopathy, diabetic neuropathy, and diabetic cardiomyopathy, are believed to be caused by oxidative stress. The Nox family of NADPH oxidases is a significant source of reactive oxygen species and plays a crucial role in regulating redox signaling, particularly in response to high glucose and diabetes mellitus. This review aims to provide an overview of the current knowledge about the role of Nox4 and its regulatory mechanisms in diabetic microangiopathies. Especially, the latest novel advances in the upregulation of Nox4 that aggravate various cell types within diabetic kidney disease will be highlighted. Interestingly, this review also presents the mechanisms by which Nox4 regulates diabetic microangiopathy from novel perspectives such as epigenetics. Besides, we emphasize Nox4 as a therapeutic target for treating microvascular complications of diabetes and summarize drugs, inhibitors, and dietary components targeting Nox4 as important therapeutic measures in preventing and treating diabetic microangiopathy. Additionally, this review also sums up the evidence related to Nox4 and diabetic macroangiopathy.

The history and mystery of sacubitril/valsartan: From clinical trial to the real world

Heart failure is a serious threat to human health, with morbidity and mortality rates increasing despite the existence of multiple treatment options. Therefore, it is necessary to identify new therapeutic targets for this disease. Sacubitril/valsartan is a supramolecular sodium salt complex of the enkephalinase inhibitor prodrug sacubitril and the angiotensin receptor blocker valsartan. Its combined action increases endogenous natriuretic peptides while inhibiting the renin-angiotensin-aldosterone system and exerting cardioprotective effects. Clinical evidence suggests that sacubitril/valsartan is superior to conventional renin-angiotensin-aldosterone inhibitor therapy for patients with reduced ejection fraction heart failure who can tolerate angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers. The therapy reduces the risk of heart failure hospitalization, cardiovascular mortality, and all-cause mortality and has a better safety and tolerability record. This review describes the potential pathophysiological mechanisms of cardiomyocyte injury amelioration by sacubitril/valsartan. We explore the protective effects of sacubitril/valsartan and outline the therapeutic value in patients with heart failure by summarizing the results of recent large clinical trials. Furthermore, a preliminary outlook shows that sacubitril/valsartan may be effective at treating other diseases, and provides some exploratory observations that lay the foundation for future studies on this drug.

Angiotensin receptor-neprilysin inhibitor improves coronary collateral perfusion

Background

We investigated the pleiotropic effects of an angiotensin receptor-neprilysin inhibitor (ARNi) on collateral-dependent myocardial perfusion in a rat model of coronary arteriogenesis, and performed comprehensive analyses to uncover the underlying molecular mechanisms.

Methods

A rat model of coronary arteriogenesis was established by implanting an inflatable occluder on the left anterior descending coronary artery followed by a 7-day repetitive occlusion procedure (ROP). Coronary collateral perfusion was measured by using a myocardial particle infusion technique. The putative ARNi-induced pro-arteriogenic effects were further investigated and compared with an angiotensin-converting enzyme inhibitor (ACEi). Expression of the membrane receptors and key enzymes in the natriuretic peptide system (NPS), renin-angiotensin-aldosterone system (RAAS) and kallikrein-kinin system (KKS) were analyzed by quantitative polymerase chain reaction (qPCR) and immunoblot assay, respectively. Protein levels of pro-arteriogenic cytokines were measured by enzyme-linked immunosorbent assay, and mitochondrial DNA copy number was assessed by qPCR due to their roles in arteriogenesis. Furthermore, murine heart endothelial cells (MHEC5-T) were treated with a neprilysin inhibitor (NEPi) alone, or in combination with bradykinin receptor antagonists. MHEC5-T proliferation was analyzed by colorimetric assay.

Results

The in vivo study showed that ARNis markedly improved coronary collateral perfusion, regulated the gene expression of KKS, and increased the concentrations of relevant pro-arteriogenic cytokines. The in vitro study demonstrated that NEPis significantly promoted MHEC5-T proliferation, which was diminished by bradykinin receptor antagonists.

Conclusion

ARNis improve coronary collateral perfusion and exert pro-arteriogenic effects via the bradykinin receptor signaling pathway.

Renal Safety of Sacubitril/Valsartan: A Meta-Analysis of Randomized Controlled Trials

ABSTRACT

As a first-line therapy, sacubitril/valsartan (S/V) plays a significant role in the treatment of heart failure. However, its effect on renal function is still uncertain. We searched PubMed, EMBASE, the Cochrane Library, and Clinical Trials for randomized controlled trials to evaluate the effect of S/V on renal function in patients. The results are reported as the mean difference, relative ratio, and 95% confidence intervals. A total of 13 randomized controlled trials were included (19,367 patients). Among them, 11 studies focused on patients with heart failure, 1 on patients with acute myocardial infarction, and 1 on patients with chronic kidney disease. We found that fewer worsening renal function events, elevated creatine level events, and severe hyperkalemia events (blood potassium >6.0 mmol/L) occurred in the S/V group than those in the renin-angiotensin-aldosterone system inhibitor (RASi) group. The estimated glomerular filtration rate decreased in both the S/V group and the RASi group, but the change was more obvious in the RASi group. There was no significant difference in hyperkalemia events (blood potassium >5.5 mmol/L) between the 2 groups. Subgroup analysis showed that with the extension of follow-up time (>6 months), worsening renal function events occurred less frequently in the S/V group than in the RASi group. Existing evidence has shown that S/V is superior to RASi in general renal safety. Perhaps with the prolongation of treatment time, the advantages of S/V are more obvious.

Protective effect of Eprosartan against ischemic acute renal injury: Acting on NF-κB, caspase 3, and Sirtuin 1

Kidney ischemia/reperfusion (I/R) injury is a leading cause of acute kidney injury (AKI) occurring frequently under major surgeries and sepsis. This study aimed to evaluate the effect of Eprosartan, an angiotensin II receptor type-1 (AT-1) antagonist, on the kidney I/R rat model. Male Wistar rats (n = 24) were allocated into (i) Sham, (ii) Eprosartan, (iii) I/R, and (iv) Eprosartan + I/R groups. Animals in the last group received a single dose of Eprosartan (60 mg/kg) 1 h before kidney I/R. Renal oxidant/antioxidant, inflammatory (NF-κB p65, COX-2, IL-6, TNF-α), and apoptotic (caspase-3, Bax, Bcl2) factors along with Sirtuin 1, Klotho, and mitochondrial biogenesis (PGC-1α, and Sirtuin 3) factors were evaluated by Western blotting. Significant recovery of kidney function and increased levels of antioxidant markers were observed in the Eprosartan + I/R group. The Eprosartan anti-inflammatory activity was demonstrated by significant downregulation of NF-κB and its downstream pro-inflammatory factors. Eprosartan pretreatment could also abolish I/R-induced alterations in the apoptotic parameters. Moreover, Eprosartan + I/R rats significantly presented higher levels of Sirtuin 1 content. In conclusion, Eprosartan exhibited nephroprotective effects against kidney damage induced by I/R in rats by decreasing oxidative stress, inflammatory, and apoptotic pathways along with increasing Sirtuin1 level.

Augmentation of Natriuretic Peptide Bioactivity via Combined Inhibition of Neprilysin and Phosphodiesterase-9 in Heart Failure

BACKGROUND

The natriuretic peptides (NPs) are potent natriuretic/diuretic and vasodilatory factors, and augmentation of their levels or signaling via inhibition of the enzymes neprilysin (NEP) and phosphodiesterase 9 (PDE9), respectively, has beneficial actions in heart failure (HF).

OBJECTIVES

The authors investigated dual enhancement of NP bioactivity by combining PDE9 inhibition and NEP inhibition in HF using an ovine model.

METHODS

Eight sheep with pacing-induced HF received on 4 separate days intravenous PDE9 inhibition (PF-04749982), NEP inhibition (SCH-32615), PDE9 inhibition + NEP inhibition (PI+NI), and vehicle control treatment.

RESULTS

Compared with the control treatment, NEP inhibition significantly increased plasma NP concentrations with a corresponding rise in second messenger cyclic guanosine monophosphate (cGMP), whereas PDE9 inhibition increased circulating cGMP with a negligible effect on NP levels. Combined PI+NI elevated plasma NPs to an extent comparable to that seen with NEP inhibition alone but further increased cGMP, resulting in a rise in the cGMP-to-NP ratio. All active treatments reduced mean arterial pressure, left atrial pressure, pulmonary arterial pressure, and peripheral resistance, with combined PI+NI further reducing mean arterial pressure and left atrial pressure relative to either inhibitor separately. Active treatments increased urine volume and sodium, potassium and creatinine excretion, and creatinine clearance, in association with rises in urine cGMP levels. PI+NI induced a significantly greater natriuresis and increase in urinary cGMP relative to either inhibitor singly.

CONCLUSIONS

The present study demonstrates for the first time that combined PI+NI has additional beneficial hemodynamic and renal effects when compared with either PDE9 inhibition or NEP inhibition alone. The superior efficacy of this 2-pronged augmentation of NP bioactivity supports PI+NI as a potential therapeutic strategy for HF.

Potential Impacts of Hydralazine as a Novel Antioxidant on Cardiovascular and Renal Disease-Beyond Vasodilation and Blood Pressure Lowering

Hydralazine is a traditional antihypertensive drug that was developed several decades ago. Its most well-known effect is blood pressure lowering by arterial vasodilation. While mainly used an adjunct treatment for clinical hypertension or chronic heart failure, this old drug has also shown potential as a repurposing drug for the atherosclerosis vascular disease and various kidney diseases. Recent experimental studies suggest that hydralazine exerts antioxidative, anti-apoptotic, and HIF-1α stabilization effects for angiogenesis and vascular protection. Hydralazine also exerts reno-protective effects via its antioxidation, DNA demethylation, and anti-inflammation abilities. The above evidence provides advanced rationales for new applications of this drug beyond blood pressure lowering and arterial vasodilation. Here, we summarized the recent experimental advances in the use of hydralazine for either a vascular disease or kidney diseases, or both. Given the wide populations of people with cardiovascular and/or kidney diseases, future studies are worth validating the potential impacts of hydralazine on the clinical outcomes in selected patients.

Efficacy and safety of sacubitril/valsartan on heart failure with preserved ejection fraction: A meta-analysis of randomized controlled trials

Aims

The efficacy and safety of sacubitril/valsartan for patients with heart failure with preserved ejection fraction (HFpEF) are controversial. Hence, the primary objective of the study was to evaluate the efficacy and safety of sacubitril/valsartan treatment for patients with HFpEF.

Methods and results

We used the PubMed, Embase, and Web of Science databases to search for randomized controlled trials of sacubitril–valsartan in patients with HFpEF. Three studies, involving a total of 7,663 patients, were eligible for inclusion. Sacubitril–valsartan reduced the risk of hospitalization for heart failure (HF) [odds ratio (OR): 0.78; 95% CI: 0.70–0.88; p &lt; 0.0001] and the incidence of worsening renal function [risk ratio (RR): 0.79, p = 0.002] among patients with HFpEF in the three trials, but there was no significant reduction in all-cause mortality (0.99, 95% CI: 0.84–1.15; p = 0.86) or cardiovascular mortality (0.95, 95% CI: 0.78–1.15; p = 0.16). Moreover, sacubitril/valsartan was associated with an increased risk of symptomatic hypotension (RR: 1.44; p &lt; 0.00001) and angioedema (RR: 2.66; p &lt; 0.04); there was no difference for decreasing the incidence of hyperkalemia (RR: 0.89; p = 0.11).

Conclusion

Compared with valsartan or individualized medical therapy (IMT), sacubitril/valsartan significantly decreased the risk of hospitalization for HF and reduced the incidence of renal dysfunction.

Neprilysin Inhibitors in Heart Failure: The Science, Mechanism of Action, Clinical Studies, and Unanswered Questions

This article provides a contemporary review and a new perspective on the role of neprilysin inhibition in heart failure (HF) in the context of recent clinical trials and addresses potential mechanisms and unanswered questions in certain HF patient populations. Neprilysin is an endopeptidase that cleaves a variety of peptides such as natriuretic peptides, bradykinin, adrenomedullin, substance P, angiotensin I and II, and endothelin. It has a broad role in cardiovascular, renal, pulmonary, gastrointestinal, endocrine, and neurologic functions. The combined angiotensin receptor and neprilysin inhibitor (ARNi) has been developed with an intent to increase vasodilatory natriuretic peptides and prevent counterregulatory activation of the angiotensin system. ARNi therapy is very effective in reducing the risks of death and hospitalization for HF in patients with HF and New York Heart Association functional class II to III symptoms, but studies failed to show any benefits with ARNi when compared with angiotensin-converting enzyme inhibitors or angiotensin receptor blocker in patients with advanced HF with reduced ejection fraction or in patients following myocardial infarction with left ventricular dysfunction but without HF. These raise the questions about whether the enzymatic breakdown of natriuretic peptides may not be a very effective solution in advanced HF patients when there is downstream blunting of the response to natriuretic peptides or among post-myocardial infarction patients in the absence of HF when there may not be a need for increased natriuretic peptide availability. Furthermore, there is a need for additional studies to determine the long-term effects of ARNi on albuminuria, obesity, glycemic control and lipid profile, blood pressure, and cognitive function in patients with HF.

Kidney Angiotensin in Cardiovascular Disease: Formation and Drug Targeting

The concept of local formation of angiotensin II in the kidney has changed over the last 10-15 years. Local synthesis of angiotensinogen in the proximal tubule has been proposed, combined with prorenin synthesis in the collecting duct. Binding of prorenin via the so-called (pro)renin receptor has been introduced, as well as megalin-mediated uptake of filtered plasma-derived renin-angiotensin system (RAS) components. Moreover, angiotensin metabolites other than angiotensin II [notably angiotensin-(1-7)] exist, and angiotensins exert their effects via three different receptors, of which angiotensin II type 2 and Mas receptors are considered renoprotective, possibly in a sex-specific manner, whereas angiotensin II type 1 (AT1) receptors are believed to be deleterious. Additionally, internalized angiotensin II may stimulate intracellular receptors. Angiotensin-converting enzyme 2 (ACE2) not only generates angiotensin-(1-7) but also acts as coronavirus receptor. Multiple, if not all, cardiovascular diseases involve the kidney RAS, with renal AT1 receptors often being claimed to exert a crucial role. Urinary RAS component levels, depending on filtration, reabsorption, and local release, are believed to reflect renal RAS activity. Finally, both existing drugs (RAS inhibitors, cyclooxygenase inhibitors) and novel drugs (angiotensin receptor/neprilysin inhibitors, sodium-glucose cotransporter-2 inhibitors, soluble ACE2) affect renal angiotensin formation, thereby displaying cardiovascular efficacy. Particular in the case of the latter three, an important question is to what degree they induce renoprotection (e.g., in a renal RAS-dependent manner). This review provides a unifying view, explaining not only how kidney angiotensin formation occurs and how it is affected by drugs but also why drugs are renoprotective when altering the renal RAS. SIGNIFICANCE STATEMENT: Angiotensin formation in the kidney is widely accepted but little understood, and multiple, often contrasting concepts have been put forward over the last two decades. This paper offers a unifying view, simultaneously explaining how existing and novel drugs exert renoprotection by interfering with kidney angiotensin formation.

Antioxidation and Nrf2-mediated heme oxygenase-1 activation contribute to renal protective effects of hydralazine in diabetic nephropathy

Reactive oxygen species (ROS) and oxidative stress are associated with the progression of diabetic nephropathy (DN). Hydralazine is an antihypertensive agent and may act as a xanthine oxidase (XO) inhibitor to reduce uric acid levels in a mouse renal injury model. This study aimed to investigate the potential mechanisms of hydralazine in experimental DN. Streptozotocin-induced diabetic mice were fed a high-fat diet to generate DN. Human renal proximal tubular epithelial cells were used in vitro. Nitrendipine and allopurinol which can reduce blood pressure or XO activity levels, were used as two positive controls. Hydralazine downregulated NF-κB/p38 signaling pathways and reduced TNF-α/IL-6 expressions in high glucose-stimulated renal proximal tubular epithelial cells. Hydralazine reduced in vitro ROS production via XO inhibition and nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated heme oxygenase (HO)-1 activation. Furthermore, hydralazine reduced high glucose-induced apoptosis by downregulating PARP/caspase-3 signaling. Hydralazine and allopurinol but not nitrendipine reduced serum uric acid levels and systemic inflammation. Hydralazine and allopurinol treatment improved renal function with decreased urinary albumin-to-creatinine ratios, glomerular hypertrophy, glomerulosclerosis, and fibrosis in the kidney of DN mice. While both hydralazine and allopurinol downregulated XO and NADPH oxidase expression, only hydralazine upregulated Nrf2/HO-1 renal expression, suggesting the additional effects of hydralazine independent of XO/ NADPH oxidase inhibition. In conclusion, hydralazine protected renal proximal tubular epithelial cells against the insults of high glucose and prevented renal damage via XO/NADPH oxidase inhibition and Nrf-2/HO-1 activation, suggesting the comprehensive antioxidation and anti-inflammation mechanisms for the management of DN.

The Effect of Sacubitril/Valsartan Treatment on Cardiac and Renal Functions of a Patient With Cardiorenal Syndrome Type 4 and Stage 5 CKD After More Than Three Years of Follow-Up

It is difficult to treat cardiorenal syndrome (CRS) in clinical practice, which is the common reason for the death of patients. This report aimed to describe the effects of sacubitril/valsartan treatment on cardiac and renal functions of a patient with cardiorenal syndrome type 4 (CRS4) after more than 3 years of follow-up. A 77-year-old Chinese woman was admitted to our hospital because of CRS4 and stage 5 chronic kidney disease (CKD), who had a history of long-term proteinuria and renal failure. The patient's cardiothoracic ratio (CTR) measured by chest X–ray was 0.6. Cardiac ultrasonography showed that the left ventricular ejection fraction (LVEF) was 0.40. The patient had been treated for heart failure (HF) for 5 months, but there was no improvement in clinical manifestations, and the renal function gradually deteriorated. In our hospital, she received sacubitril/valsartan treatment for at least 40 months. The symptoms of HF relieved, and the indices of cardiac function improved. In addition, the patient's renal function was stable. During the treatment, the dosage of sacubitril/valsartan needed to be adjusted to achieve the optimal therapeutic effect. Follow-up results showed that she achieved cardiac function of New York Heart Association (NYHA) class II with an ejection fraction of 0.60 and E/A &gt; 1 indicated by echocardiogram, and did not develop hyperkalemia. In summary, the improvement of cardiac and renal functions of the CRS4 patient was associated with the long-term sacubitril/valsartan treatment.

Mitochondrial Oxidative Stress and Cell Death in Podocytopathies

Podocytopathies are kidney diseases that are driven by podocyte injury with proteinuria and proteinuria-related symptoms as the main clinical presentations. Albeit podocytopathies are the major contributors to end-stage kidney disease, the underlying molecular mechanisms of podocyte injury remain to be elucidated. Mitochondrial oxidative stress is associated with kidney diseases, and increasing evidence suggests that oxidative stress plays a vital role in the pathogenesis of podocytopathies. Accumulating evidence has placed mitochondrial oxidative stress in the focus of cell death research. Excessive generated reactive oxygen species over antioxidant defense under pathological conditions lead to oxidative damage to cellular components and regulate cell death in the podocyte. Conversely, exogenous antioxidants can protect podocyte from cell death. This review provides an overview of the role of mitochondrial oxidative stress in podocytopathies and discusses its role in the cell death of the podocyte, aiming to identify the novel targets to improve the treatment of patients with podocytopathies.

Update on Pathogenesis of Glomerular Hyperfiltration in Early Diabetic Kidney Disease

In the existing stages of diabetic kidney disease (DKD), the first stage of DKD is called the preclinical stage, characterized by glomerular hyperfiltration, an abnormally elevated glomerular filtration rate. Glomerular hyperfiltration is an independent risk factor for accelerated deterioration of renal function and progression of nephropathy, which is associated with a high risk for metabolic and cardiovascular disease. It is imperative to understand hyperfiltration and identify potential treatments to delay DKD progress. This paper summarizes the current mechanisms of hyperfiltration in early DKD. We pay close attention to the effect of glucose reabsorption mediated by sodium-glucose cotransporters and renal growth on hyperfiltration in DKD patients, as well as the mechanisms of nitric oxide and adenosine actions on renal afferent arterioles via tubuloglomerular feedback. Furthermore, we also focus on the contribution of the atrial natriuretic peptide, cyclooxygenase, renin-angiotensin-aldosterone system, and endothelin on hyperfiltration. Proposing potential treatments based on these mechanisms may offer new therapeutic opportunities to reduce the renal burden in this population.

Sacubitril/Valsartan Improves Progression of Early Diabetic Nephropathy in Rats Through Inhibition of NLRP3 Inflammasome Pathway

PURPOSE

Diabetic nephropathy (DN), a global disease, is the leading cause of end-stage renal disease. There is a lack of specific treatment for this disease, and early intervention in disease progression is essential. In this paper, we used a rat model of early diabetic nephropathy to explore the therapeutic mechanism of sacubitril/valsartan in rats with early diabetic nephropathy.

MATERIALS AND METHODS

Rats were grouped into 1 normal group; 2. Model group (DN group): STZ (45 mg/kg/d) induced early diabetic nephropathy rats; 3. Sac group: DN rats + Sac group (orally, 60 mg/kg/d) for 6 weeks. After 6 weeks, the levels of serum albumin (ALB), glucose (GLU), creatinine (Cr), urea nitrogen (BUN) and 24-h urinary protein excretion were measured. In renal tissue homogenates, NLRP3 inflammasome, proinflammatory factors IL1-β and TNF-α, oxidative stress MDA and pro-fibrotic cytokine TGF-β1 were performed. Histological analysis of kidneys by hematoxylin and eosin (HE), PAS and Masson trichrome staining.

RESULTS

1. Sacubitril/valsartan (Sac) significantly improved renal hypertrophy, proteinuria and serum albumin levels in rats with early diabetic nephropathy (P < 0.001), and decreased GLU, Scr (P<0.001), and BUN levels (P < 0.01).2. Light microscopy of renal tissues showed glomerular hypertrophy and interstitial inflammatory cell infiltration, and mean glomerular area (MGA) and mean glomerular volume (MGV) were crucially increased in early diabetic nephropathy (P < 0.001), and the Sac group showed reduced renal pathology and improved MGA and MGV (P < 0.001).3. Kidney tissue homogenate levels of NLRP3, Caspase-1, IL1-β, TNF-α, MDA and TGF-β1 were critically, increased in DN rats (P < 0.001), and SOD was significantly decreased. All these indicators above were improved after treatment (P < 0.0001).

CONCLUSION

Nlrp3-inflammasome promote progression of diabetic nephropathy through inflammation, fibrosis and oxidative stress; sacubitril/valsartan ameliorated early diabetes-induced renal damage by inhibiting NLRP3 pathway activation.

Potential effects and application prospect of angiotensin receptor-neprilysin inhibitor in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the main causes of end-stage renal disease (ESRD) and all-cause mortality in diabetic patients, despite the extensive use of angiotensin-converting enzyme inhibitor (ACEI) and angiotensin II receptor blocker (ARB). Angiotensin receptor-neprilysin inhibitor (ARNI), combining ARB and neutral endopeptidase inhibitor (NEPI), is likely to have potential favorable effects in DKD. This review summarizes existing preclinical and clinical studies on mechanism of ARNI and its potential effects on DKD. In preclinical studies, ARNI manifested its renoprotective effects by improving natriuresis, ameliorating inflammation, oxidative stress and renal dysfunction, and slowing down glomerulosclerosis and tubulointerstitial injury of kidney, but its effect on proteinuria is still controversial. Beneficial effects of ARNI on blood glucose regulation and glycometabolism have also been reported. There are no clinical studies of ARNI that specifically focus on DKD patients so far. ARNI has application potential in DKD, but there still need clinical studies that focus on DKD patients to determine its effectiveness, safety and underlying mechanism.

Effect of sacubitril/valsartan on inflammation and oxidative stress in doxorubicin-induced heart failure model in rabbits

Our study evaluates the effects of sacubitril/valsartan (SAC/VAL) in the rabbit model of doxorubicin-induced heart failure. Twenty rabbits (5 per group) were administered with doxorubicin (DOX, 1.5 mg kg^-1, i.v.) to induce heart failure. Specific biomarkers such as BNP, CnT, CRP and ROMs were determined. The cardiac enzymatic anti-oxidant systems were recorded with their electrographic profiles. HR, SBP, DBP and MAP were restored at 5 or 10 mg kg^-1 (p.o.) of SAC/VAL compared to DOX, followed by reduced levels of creatinine and BNP (p < 0.001). Significant improvements (p < 0.05) compared to DOX were also noticed in CAT, SOD and LPO with the same doses of SAC/VAL. Specific biomarkers such as BNP, CnT, CRP and ROMs descended significantly (p < 0.001) with treatment when compared to their baseline values. Our findings implied that SAC/VAL treatment reduced the inflammation and oxidative stress to improve the cardiac function.

Effects of angiotensin receptor neprilysin inhibitor on renal function in patients with heart failure: a systematic review and meta-analysis

The angiotensin receptor neprilysin inhibitor (ARNI) has been recommended as a first-line treatment in patients with heart failure (HF). However, the effects of ARNI on renal function remain controversial.The PubMed, Embase, the Cochrane Library of Trials and Web of Science were searched in the period from inception to 31 January 2021. Randomised controlled trial, cohort studies and observational studies reporting at least one of renal function indicators were included.In patients with HF with reduced ejection fraction (HFrEF), ARNI did not lead to a significant decrease in estimated glomerular filtration rate (eGFR, p=0.87), and the risk of worsening renal function (WRF) dropped by 11% compared with control group. Though the level of serum creatinine (SCr) and serum potassium had a slight increase (p=0.01; p=0.02), in contrast to the baseline level, but without clinical significance. In patients with HF with preserved ejection fraction (HFpEF), the level of SCr and serum potassium did not have a significant change, and patients with HFpEF assigned to ARNI had a much lower rate of WRF (p=0.0007). In contrast to control group, both patients with HFrEF and HFpEF had a less decrease in eGFR and a lower rate of hyperkalaemia in ARNI group.ARNI did not lead to a significant decrease in eGFR in HFrEF. Compared with control group, ARNI could delay the progression of decrease in eGFR and result in less events of hyperkalaemia in patients with HF. Besides, patients with HFpEF had a lower rate in the events of WRF.

Sacubitril/valsartan inhibits obesity-associated diastolic dysfunction through suppression of ventricular-vascular stiffness

OBJECTIVE

Cardiac diastolic dysfunction (DD) and arterial stiffness are early manifestations of obesity-associated prediabetes, and both serve as risk factors for the development of heart failure with preserved ejection fraction (HFpEF). Since the incidence of DD and arterial stiffness are increasing worldwide due to exponential growth in obesity, an effective treatment is urgently needed to blunt their development and progression. Here we investigated whether the combination of an inhibitor of neprilysin (sacubitril), a natriuretic peptide-degrading enzyme, and an angiotensin II type 1 receptor blocker (valsartan), suppresses DD and arterial stiffness in an animal model of prediabetes more effectively than valsartan monotherapy.

METHODS

Sixteen-week-old male Zucker Obese rats (ZO; n = 64) were assigned randomly to 4 different groups: Group 1: saline control (ZOC); Group 2: sacubitril/valsartan (sac/val; 68 mg•kg-1•day-1; ZOSV); Group 3: valsartan (31 mg•kg-1•day-1; ZOV) and Group 4: hydralazine, an anti-hypertensive drug (30 mg•kg-1•day-1; ZOH). Six Zucker Lean (ZL) rats that received saline only (Group 5) served as lean controls (ZLC). Drugs were administered daily for 10 weeks by oral gavage.

RESULTS

Sac/val improved echocardiographic parameters of impaired left ventricular (LV) stiffness in untreated ZO rats, without altering the amount of food consumed or body weight gained. In addition to improving DD, sac/val decreased aortic stiffness and reversed impairment in nitric oxide-induced vascular relaxation in ZO rats. However, sac/val had no impact on LV hypertrophy. Notably, sac/val was more effective than val in ameliorating DD. Although, hydralazine was as effective as sac/val in improving these parameters, it adversely affected LV mass index. Further, cytokine array revealed distinct effects of sac/val, including marked suppression of Notch-1 by both valsartan and sac/val, suggesting that cardiovascular protection afforded by both share some common mechanisms; however, sac/val, but not val, increased IL-4, which is increasingly recognized for its cardiovascular protection, possibly contributing, in part, to more favorable effects of sac/val over val alone in improving obesity-associated DD.

CONCLUSIONS

These studies suggest that sac/val is superior to val in reversing obesity-associated DD. It is an effective drug combination to blunt progression of asymptomatic DD and vascular stiffness to HFpEF development in a preclinical model of obesity-associated prediabetes.

Update on the Mechanisms of Tubular Cell Injury in Diabetic Kidney Disease

Increasing evidence supports a role of proximal tubular (PT) injury in the progression of diabetic kidney disease (DKD), in patients with or without proteinuria. Research on the mechanisms of the PT injury in DKD could help us to identify potential new biomarkers and drug targets for DKD. A high glucose transport state and mismatched local hypoxia in the PT of diabetes patients may be the initiating factors causing PT injury. Other mechanism such as mitochondrial dysfunction, reactive oxygen species (ROS) overproduction, ER stress, and deficiency of autophagy interact with each other leading to more PT injury by forming a vicious circle. PT injury eventually leads to the development of tubulointerstitial inflammation and fibrosis in DKD. Many downstream signaling pathways have been demonstrated to mediate these diseased processes. This review focuses mostly on the novel mechanisms of proximal renal tubular injury in DKD and we believe such review could help us to better understand the pathogenesis of DKD and identify potential new therapies for this disease.

Angiotensin-neprilysin inhibition confers renoprotection in rats with diabetes and hypertension by limiting podocyte injury

OBJECTIVES

Combined angiotensin receptor--neprilysin inhibition (ARNI) reduces glomerulosclerosis better than single angiotensin receptor blockade (ARB) in diabetic, hypertensive rats. The renoprotective mechanism remains unknown, but may depend on superior blood pressure control, improved renal hemodynamics, suppressed renal inflammation or prevention of podocyte loss.

METHODS

To address this, TGR(mREN2)27 rats (a model of angiotensin II-dependent hypertension) were made diabetic for 12 weeks and treated with vehicle (n = 10), valsartan (ARB; n = 7) or sacubitril/valsartan (ARNI; n = 8) for the final 3 weeks. Arterial pressure was measured via radiotelemetry.

RESULTS

Sacubitril/valsartan lowered mean arterial pressure by -50 ± 4 mmHg and valsartan by -43 ± 4 mmHg (P = 0.3). Both treatments lowered albuminuria, but only sacubitril/valsartan maintained high urinary atrial natriuretic peptide, improved glycemic control and protected podocyte integrity, reflected by increased nephrin expression and suppression of transient receptor potential canonical 6 and regulator of calcineurin 1. This resulted in markedly reduced glomerulosclerosis (P < 0.05 vs. control and valsartan). Despite higher effective renal plasma flow and glomerular filtration rates, sacubitril/valsartan did neither improve filtration fraction nor renal immune cell infiltration.

CONCLUSION

Sacubitril/valsartan offers drug-class-specific renoprotection in a preclinical model of diabetes and hypertension. Renoprotection is unrelated to antihypertensive efficacy, renal hemodynamics or inflammation, but may be related to protective effects of natriuretic peptides on podocyte integrity.

The effect of neprilysin and renin inhibition on the renal dysfunction following ischemia-reperfusion injury in the rat

The natriuretic peptide (NP) system counter-regulates the renin-angiotensin system (RAS), so enhancing the activity of natriuretic peptides (NPs) may be beneficial in conditions when RAS is activated such as ischemia-reperfusion injury (IRI). Neprilysin is the key enzyme responsible for the degradation of NPs. The effects of neprilysin inhibition or the combination of neprilysin inhibition and RAS inhibition on renal IRI-induced renal dysfunction have not been investigated yet. To investigate this, rats underwent sham surgery or bilateral IRI for 20 min. G-Als, G-Scb, and G-Als+Scb underwent similar protocol but received aliskiren (renin inhibitor), sacubitril (neprilysin inhibitor) or a combination of both pre- and post-IRI, respectively. IRI caused significant alterations in all renal functional parameters, markers of acute renal injury, pro-inflammatory and pro-fibrotic cytokines, and histological features. All these alterations were significantly attenuated in G-Als, G-Scb, and G-Als+Scb. The attenuations in the alterations in serum creatinine, creatinine clearance, and histological features were larger in G-Als+Scb compared to either G-Als or G-Scb. We conclude that RAS blockade by a renin inhibitor (aliskiren) or neprilysin inhibition by sacubitril separately led to significant attenuation in the renal IRI-induced renal dysfunction. The combination of aliskiren and sacubitril was more effective than either one alone.

ACE2 and energy metabolism: the connection between COVID-19 and chronic metabolic disorders

The renin-angiotensin system (RAS) has currently attracted increasing attention due to its potential function in regulating energy homeostasis, other than the actions on cellular growth, blood pressure, fluid, and electrolyte balance. The existence of RAS is well established in metabolic organs, including pancreas, liver, skeletal muscle, and adipose tissue, where activation of angiotensin-converting enzyme (ACE) - angiotensin II pathway contributes to the impairment of insulin secretion, glucose transport, fat distribution, and adipokines production. However, the activation of angiotensin-converting enzyme 2 (ACE2) - angiotensin (1-7) pathway, a novel branch of the RAS, plays an opposite role in the ACE pathway, which could reverse these consequences by improving local microcirculation, inflammation, stress state, structure remolding, and insulin signaling pathway. In addition, new studies indicate the protective RAS arm possesses extraordinary ability to enhance brown adipose tissue (BAT) activity and induces browning of white adipose tissue, and consequently, it leads to increased energy expenditure in the form of heat instead of ATP synthesis. Interestingly, ACE2 is the receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is threating public health worldwide. The main complications of SARS-CoV-2 infected death patients include many energy metabolism-related chronic diseases, such as diabetes. The specific mechanism leading to this phenomenon is largely unknown. Here, we summarize the latest pharmacological and genetic tools on regulating ACE/ACE2 balance and highlight the beneficial effects of the ACE2 pathway axis hyperactivity on glycolipid metabolism, as well as the thermogenic modulation.

TaleNeprilysin and Neprilysin inhibition in chronic kidney disease

PURPOSE OF REVIEW

Chronic kidney disease (CKD) is associated with increased risk of progression to end-stage kidney disease and cardiovascular events. There is limited evidence that available treatments have beneficial effects on cardiorenal outcomes in all people with nondiabetic CKD. Neprilysin inhibition (NEPi) is a new therapeutic strategy with potential to improve outcomes for patients with CKD.

RECENT FINDINGS

NEPi enhances the activity of the natriuretic peptide system producing natriuresis, diuresis and inhibition of the renin-angiotensin system and sympathetic nervous system. Sacubitril/valsartan is the first Angiotensin receptor-neprilysin inhibitor (ARNI) to be produced and has been shown to substantially improve cardiovascular outcomes in heart failure and delay progression of kidney disease in this population. Although ARNIs have not shown similar effects on kidney function in the short-to-medium term in people with CKD, they are associated with substantial reductions in cardiac biomarkers and blood pressure in CKD.

SUMMARY

These data suggest that NEPi with an ARNI could benefit patients with CKD by reducing the risk of cardiovascular disease and have the possibility of retarding the progression of CKD (hence delaying the need for renal replacement therapy).

Diabetes and Covid-19 among hospitalized patients in Saudi Arabia: a single-centre retrospective study

BACKGROUND

Information on the clinical characteristics and outcomes of hospitalized Covid-19 patients with or without diabetes mellitus (DM) is limited in the Arab region. This study aims to fill this gap.

METHODS

In this single-center retrospective study, medical records of hospitalized adults with confirmed Covid-19 [RT-PCR positive for SARS-CoV2] at King Saud University Medical City (KSUMC)-King Khaled University Hospital (KKUH), Riyadh, Saudi Arabia from May to July 2020 were analyzed. Clinical, radiological and serological information, as well as outcomes were recorded and analyzed.

RESULTS

A total of 439 patients were included (median age 55 years; 68.3% men). The most prevalent comorbidities were vitamin D deficiency (74.7%), DM (68.3%), hypertension (42.6%) and obesity (42.2%). During hospitalization, 77 out of the 439 patients (17.5%) died. DM patients have a significantly higher death rate (20.5% versus 12.3%; p = 0.04) and lower survival time (p = 0.016) than non-DM. Multivariate cox proportional hazards regression model revealed that age [Hazards ratio, HR 3.0 (95% confidence interval, CI 1.7-5.3); p < 0.001], congestive heart failure [adjusted HR 3.5 (CI 1.4-8.3); p = 0.006], smoking [adjusted HR 5.8 (CI 2.0-17.2); p < 0.001], β-blocker use [adjusted HR 1.7 (CI 1.0-2.9); p = 0.04], bilateral lung infiltrates [adjusted HR 1.9 (CI 1.1-3.3); p = 0.02], creatinine > 90 µmol/l [adjusted HR 2.1 (CI 1.3-3.5); p = 0.004] and 25(OH)D < 12.5 nmol/l [adjusted HR 7.0 (CI 1.7-28.2); p = 0.007] were significant predictors of mortality among hospitalized Covid-19 patients. Random blood glucose ≥ 11.1 mmol/l was significantly associated with intensive care admission [adjusted HR 1.5 (CI 1.0-2.2); p = 0.04], as well as smoking, β-blocker use, neutrophil > 7.5, creatinine > 90 µmol/l and alanine aminotransferase > 65U/l.

CONCLUSION

The prevalence of DM is high among hospitalized Covid-19 patients in Riyadh, Saudi Arabia. While DM patients have a higher mortality rate than their non-DM counterparts, other factors such as old age, congestive heart failure, smoking, β-blocker use, presence of bilateral lung infiltrates, elevated creatinine and severe vitamin D deficiency, appear to be more significant predictors of fatal outcome. Patients with acute metabolic dysfunctions, including hyperglycemia on admission are more likely to receive intensive care.

Effect of sacubitril/valsartan on renal function: a systematic review and meta-analysis of randomized controlled trials

A worsening renal function is prevalent among patients with cardiovascular disease, especially heart failure (HF). Sacubitril/valsartan appears to prevent worsening of renal function and progression of chronic kidney disease (CKD) as compared with renin-angiotensin system (RAS) inhibitors alone in HF patients. It is unclear whether these advantages are present in HF patients only, or can be extended to other categories of patients, in which this drug was studied. We performed a systematic review and meta-analysis to assess the consistency of effect size regarding renal outcome across randomized controlled trials (RCTs) that compared sacubitril/valsartan with RAS inhibitors in patients with or without HF. We searched Medline (PubMed), Scopus, and Thomson Reuters Web of Science databases until June 2020. We took into account RCTs that compared sacubitril/valsartan with a RAS inhibitor and reported data regarding renal function. We used random-effects models to obtain summary odds ratio (OR) with 95% confidence interval (CI). We extracted hazard ratios for renal outcomes, glomerular filtration rate slopes or rates of renal adverse events. Sensitivity analyses were performed by moderator analysis and random-effects meta-regression. The search revealed 10 RCTs (published between 2012 and 2019) on 16 456 subjects. Sacubitril/valsartan resulted in a lower risk of renal dysfunction as compared with RAS inhibitors alone [k = 10; pooled OR = 0.70 (95% CI 0.57-0.85); P < 0.001], with a moderate inconsistency between studies [Q(9) = 15.18; P = 0.086; I2  = 40.73%]. A stronger association was found in studies including older patients (k = 10; β = -0.047730; P = 0.020) or HF patients with preserved ejection fraction [pooled OR = 0.53 (0.41-0.68) vs. 0.76 (0.57-1.01) for studies on HF patients with reduced ejection fraction; P for comparison = 0.065]. The effect size did not change with different comparators (angiotensin-converting enzyme inhibitors vs. angiotensin II type 1 receptor blockers, P = 0.279). No significant association was found when the analysis was restricted to studies on non-HF patients [k = 3; pooled OR = 0.86 (0.61-1.22); P = 0.403] and studies with high risk of bias [k = 3; pooled OR = 0.34 (0.08-1.44); P = 0.143]. Our findings support the role of sacubitril/valsartan on preservation of renal function, especially in older patients and HF patients with preserved ejection fraction. However, evidence is currently limited to HF patients, while the renal outcome of sacubitril/valsartan therapy outside the HF setting needs to be further investigated.

Silencing of CRT relieves Ang II-Induced injury of HUVECs with insulin resistance

In this study, we investigated the effects of Angiotensin II (Ang II) on insulin-resistant endothelial cells. High glucose and insulin at series of concentrations were used to induce IR in Human Umbilical Vein Endothelial Cells (HUVECs). Successful IR induction was confirmed according to glucose consumption and glycogen content levels. Cell morphology was observed under a microscope. Expression levels of Ang II and Calreticulin (CRT) were measured by ELISA, qRT-PCR and Western blot as appropriate. Cell viability and apoptosis were measured by CCK-8 assay and flow cytometry, respectively. HUVECs with IR were exposed to Ang II at series of concentrations, and then the cell viability, apoptosis and CRT were detected. Rescue assays were performed by transfection of siCRT or overexpression of CRT with or without Ang II stimulation into the HUVECs with IR. Expressions of cell apoptosis-related proteins Bcl-2 and Bax were measured by qRT-PCR and Western blot. Glucose (33.3 mmol/L) and insulin (4 µmol/L) induced significantly strong IR to the HUVECs, with a pathological appearance. Levels of Agn II and CRT were both up-regulated by IR. Cell viability of HUVECs was slightly reduced after IR induction for 2 h, and cell apoptosis rate was increased. In addition, Ang II (10^-7 mol/l) suppressed cell viability and glucose uptake, promoted cell apoptosis and increased CRT, and these effects could be weakened by silencing CRT. Thus, we preliminarily proved that Ang II up-regulates CRT, and CRT knockdown can relieve Ang II-induced injury of HUVECs with IR.

Differential effects of low-dose sacubitril and/or valsartan on renal disease in salt-sensitive hypertension

Diuretics and renin-angiotensin system blockers are often insufficient to control the blood pressure (BP) in salt-sensitive (SS) subjects. Abundant data support the proposal that the level of atrial natriuretic peptide may correlate with the pathogenesis of SS hypertension. We hypothesized here that increasing atrial natriuretic peptide levels with sacubitril, combined with renin-angiotensin system blockage by valsartan, can be beneficial for alleviation of renal damage in a model of SS hypertension, the Dahl SS rat. To induce a BP increase, rats were challenged with a high-salt 4% NaCl diet for 21 days, and chronic administration of vehicle or low-dose sacubitril and/or valsartan (75 μg/day each) was performed. Urine flow, Na+ excretion, and water consumption were increased on the high-salt diet compared with the starting point (0.4% NaCl) in all groups but remained similar among the groups at the end of the protocol. Upon salt challenge, we observed a mild decrease in systolic BP and urinary neutrophil gelatinase-associated lipocalin levels (indicative of alleviated tubular damage) in the valsartan-treated groups. Sacubitril, as well as sacubitril/valsartan, attenuated the glomerular filtration rate decline induced by salt. Alleviation of protein cast formation and lower renal medullary fibrosis were observed in the sacubitril/valsartan- and valsartan-treated groups, but not when sacubitril alone was administered. Interestingly, proteinuria was mildly mitigated only in rats that received sacubitril/valsartan. Further studies of the effects of sacubitril/valsartan in the setting of SS hypertension, perhaps involving a higher dose of the drug, are warranted to determine if it can interfere with the progression of the disease.

LCZ696 mitigates diabetic-induced nephropathy through inhibiting oxidative stress, NF-κB mediated inflammation and glomerulosclerosis in rats

Background

Diabetic nephropathy (DN) is among the most common microvascular complications of diabetes resulting in end-stage renal disease and therefore search for candidates which can ameliorate the kidney function is needed simultaneously with standard diabetic pharmacotherapy. The current study was aimed to investigate the effect of long term sacubitril/valsartan therapy (LCZ696) in diabetic rats to assess its ameliorative impact against various pathological parameters such as oxidative stress, inflammation and glomerulosclerosis associated with chronic DN.

Methods

A single dose (60 mg/kg/day) of STZ was used to induce type 1 diabetes in adult male wistar rats. 2 weeks after diabetes induction, these rats were treated orally with valsartan (31 mg/kg) or LCZ696 (68 mg/kg) for 6 weeks. At end of the treatment period, serum and kidney samples were collected and analyzed. The serum levels of glucose, insulin, urea, creatinine, TNF-α, IL-1β, IL-6 and IL-10 levels were estimated. In renal tissue homogenate, the levels of inflammatory markers such as TNF-α, IL-1β, IL-6, NF-kB along with oxidative stress biomarkers including thiobarbituric acid-reacting substances (TBARs), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST) were assessed. Histological changes were observed in kidney.

Results

Time course therapy withLCZ696 and valsartan in diabetic rats resulted in significant reduction of serum glucose, urea and creatinine levels (P < 0.05). Additionally, serum of treated diabetic rats showed a diminution in inflammatory (TNF-α, IL-1β, IL-6) and increment in anti-inflammatory (IL-10) cytokines levels (P < 0.05). Tissue homogenate of the kidney extracted from LCZ696 and valsartan treated diabetic rats revealed a substantial reduction in the levels of inflammatory markers such as TNF-α, IL-1β, IL-6, NF-kB and sufficient restoration of anti-oxidant enzyme levels (P < 0.05). Finally, in the histological sections of the kidney, prevention of renal injury was observed with limited necrosis and inflammatory cells infiltration.

Conclusion

Present data suggest that LCZ696 has sufficient therapeutic potential to restrict DN progression through inhibiting inflammation, oxidative stress and glomerulosclerosis.

Dual Angiotensin Receptor and Neprilysin Inhibitor Ameliorates Portal Hypertension in Portal Hypertensive Rats

BACKGROUND

Portal hypertension is characterized by exaggerated activation of the renin-angiotensin-aldosterone axis. Natriuretic peptide system plays a counter-regulatory role, which is modulated by neprilysin. LCZ696 (sacubitril/valsartan) is a dual angiotensin receptor and neprilysin inhibitor. This study evaluated the effect of LCZ696 on portal hypertensive rats.

METHODS

Portal hypertension was induced by partial portal vein ligation (PVL) in rats. LCZ696, valsartan (angiotensin receptor blocker), or normal saline (control) was administered in PVL rats for 10 days. Then, hemodynamic and biochemistry data were obtained. The hepatic histology and protein expressions were surveyed. On the parallel groups, the portal-systemic shunting degrees were determined.

RESULTS

LCZ696 and valsartan reduced mean arterial pressure and systemic vascular resistance. LCZ696, but not valsartan, reduced portal pressure in portal hypertensive rats (control vs. valsartan vs. LCZ696: 15.4 ± 1.6 vs. 14.0 ± 2.3 vs. 12.0 ± 2.0 mmHg, control vs. LCZ696: P < 0.05). LCZ696 and valsartan improved liver biochemistry data and reduced intrahepatic Cluster of Differentiation 68 (CD68)-stained macrophages infiltration. Hepatic endothelin-1 (ET-1) protein expression was downregulated by LCZ696. The portal-systemic shunting was not affected by LCZ696 and valsartan.

CONCLUSION

LCZ696 and valsartan reduced mean arterial pressure through peripheral vasodilation. Furthermore, LCZ696 significantly reduced portal pressure in PVL rats via hepatic ET-1 downregulation.

Angiotensin II receptor Neprilysin inhibitor (LCZ696) compared to Valsartan attenuates Hepatotoxicity in STZ-induced hyperglycemic rats

Background and objectives: Although diabetic-induced hepatotoxicity is less common, it can be included in the list of target organ pathologies associated with diabetes. This study aimed to investigate the potential therapeutic role of sacubitril/valsartan (LCZ696) in modulating oxidative and inflammatory injuries and liver fibrosis in STZ-induced hyperglycemic rats in comparison to valsartan alone. Materials and Methods: Following the induction of diabetes using a single dose of streptozotocin (STZ), STZ-induced hyperglycemic animals were administered LCZ696 or valsartan for 6 weeks. Glucose, transaminases, lipid profile, tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1β), and interleukin - 6 (IL-6), were estimated using the obtained serum. Oxidative stress biomarkers including thiobarbituric acid reactive substances (TBARS), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione S-transferase (GST) were measured in the liver homogenate. Additionally, the levels of TNF-α, IL-1β, IL-6, and nuclear factor - kappa β (NF-κB) levels were estimated in hepatic tissue. To assess the general histopathological changes, harvested liver tissue was treated with hematoxylin and eosin or Masson's trichrome staining to detect fibrosis. Results: STZ-induced hyperglycemic rats demonstrated high blood glucose, dyslipidemia, and significant elevation in hepatic transaminases, proinflammatory cytokines, NF-κB, lipid peroxidation, and hepatic fibrosis, with impairment in antioxidant enzymes. In STZ-induced hyperglycemic rats, the administration of LCZ696 ameliorated hyperglycemia, dyslipidemia, improved liver functions, and boosted antioxidants enzymes. Furthermore, LCZ696 therapy attenuated oxidation, inflammation, progression of liver injury, and hepatic fibrosis. LCZ696 was superior to valsartan in reducing AST, hepatic fibrosis, tissue IL-1β, TNF-α and NF-κB. In addition, compared with the valsartan group, LCZ696 significantly increased the antioxidant parameters such as GSH, SOD, CAT and GPx. Conclusion: Collectively, our data demonstrated that LCZ696 could suppress the progression of diabetes-induced hepatic fibrosis, correlating with reduced oxidative stress, hepatic inflammation and NF-κB compared with valsartan alone.

Potential of Renin-Angiotensin-Aldosterone System Modulations in Diabetic Kidney Disease: Old Players to New Hope!

Due to a tragic increase in the incidences of diabetes globally, diabetic kidney disease (DKD) has emerged as one of the leading causes of end-stage renal diseases (ESRD). Hyperglycaemia-mediated overactivation of the renin-angiotensin-aldosterone system (RAAS) is key to the development and progression of DKD. Consequently, RAAS inhibition by angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARBs) is the first-line therapy for the clinical management of DKD. However, numerous clinical and preclinical evidences suggested that RAAS inhibition can only halt the progression of the DKD to a certain extent, and they are inadequate to cure DKD completely. Recent studies have improved understanding of the complexity of the RAAS. It consists of two counter-regulatory arms, the deleterious pressor arm (ACE/angiotensin II/AT1 receptor axis) and the beneficial depressor arm (ACE2/angiotensin-(1-7)/Mas receptor axis). These advances have paved the way for the development of new therapies targeting the RAAS for better treatment of DKD. In this review, we aimed to summarise the involvement of the depressor arm of the RAAS in DKD. Moreover, in modern drug discovery and development, an advance approach is the bispecific therapeutics, targeting two independent signalling pathways. Here, we discuss available reports of these bispecific drugs involving the RAAS as well as propose potential treatments based on neurohormonal balance as credible therapeutic strategies for DKD.

Neprilysin, the kidney brush border neutral proteinase: a possible potential target for ischemic renal injury

Neprilysin (NEP) is an endogenously induced peptidase for modulating production and degradation of various peptides in humans. It is most abundantly present in kidney and regulates the intrinsic renal homeostatic mechanism. Recently, drugs inhibiting NEP have been approved for the use in heart failure. In the context of increased prevalence of ischemia associated renal failure, NEP could be an attractive target for treating kidney failure. In the kidney, targeting NEP may possess potential benefits as well as adverse consequences. The unfavorable outcomes of NEP are mainly attributed to the degradation of the natriuretic peptides (NPs). NPs are involved in the inhibition of the renin-angiotensin-aldosterone system (RAAS) and activation of the sympathetic system contributing to the tubular and glomerular injury. In contrary, NEP exerts the beneficial effect by converting angiotensin-1 (Ang I) to angiotensin-(1-7) (Ang-(1-7)), thus activating MAS-related G-protein coupled receptor. MAS receptor antagonizes angiotensin type I receptor (AT-1R), reduces reactive oxygen species (ROS) and inflammation, thus ameliorating renal injury. However, the association of NEP with complex cascades of renal ischemia remains vague. Therefore, there is a need to evaluate the putative mechanism of NEP and its overlap with other signaling cascades in conditions of renal ischemia.

ARNi: A Novel Approach to Counteract Cardiovascular Diseases

Cardiovascular diseases (CVDs) still represent the greatest burden on healthcare systems worldwide. Despite the enormous efforts over the last twenty years to limit the spread of cardiovascular risk factors, their prevalence is growing and control is still suboptimal. Therefore, the availability of new therapeutic tools that may interfere with different pathophysiological pathways to slow the establishment of clinical CVDs is important. Previously, the inhibition of neurohormonal systems, namely the renin–angiotensin–aldosterone system (RAAS) and the sympathetic nervous system, has proven to be useful in the treatment of many CVDs. Attempts have recently been made to target an additional hormonal system, that of the natriuretic peptides (NPs), which, when dysregulated, can also play a role in the development CVDs. Indeed, a new class of drug, the angiotensin receptor–neprilysin inhibitors (ARNi), has the ability to counteract the effects of angiotensin II as well as to increase the activity of NPs. ARNi have already been proven to be effective in the treatment of heart failure with reduced ejection fraction. New evidence has suggested that, in the next years, the field of ARNi application will widen to include other CVDs, such as heart failure, with preserved ejection fraction and hypertension.