Combination therapy with ACE inhibitors and angiotensin II receptor blockers to halt progression of chronic renal disease: Pathophysiology and indications

Pharmacogenetic study of CES1 gene and enalapril efficacy

Enalapril is an orally administered angiotensin-converting enzyme inhibitor which is widely prescribed to treat hypertension, chronic kidney disease, and heart failure. It is an ester prodrug that needs to be activated by carboxylesterase 1 (CES1). CES1 is a hepatic hydrolase that in vivo biotransforms enalapril to its active form enalaprilat in order to produce its desired pharmacological impact. Several single nucleotide polymorphisms in CES1 gene are reported to alter the catalytic activity of CES1 enzyme and influence enalapril metabolism. G143E, L40T, G142E, G147C, Y170D, and R171C can completely block the enalapril metabolism. Some polymorphisms like Q169P, E220G, and D269fs do not completely block the CES1 function; however, they reduce the catalytic activity of CES1 enzyme. The prevalence of these polymorphisms is not the same among all populations which necessitate to consider the genetic panel of respective population before prescribing enalapril. These genetic variations are also responsible for interindividual variability of CES1 enzyme activity which ultimately affects the pharmacokinetics and pharmacodynamics of enalapril. The current review summarizes the CES1 polymorphisms which influence the enalapril metabolism and efficacy. The structure of CES1 catalytic domain and important amino acids impacting the catalytic activity of CES1 enzyme are also discussed. This review also highlights the importance of pharmacogenomics in personalized medicine.

Transformative Deep Neural Network Approaches in Kidney Ultrasound Segmentation: Empirical Validation with an Annotated Dataset

Kidney ultrasound (US) images are primarily employed for diagnosing different renal diseases. Among them, one is renal localization and detection, which can be carried out by segmenting the kidney US images. However, kidney segmentation from US images is challenging due to low contrast, speckle noise, fluid, variations in kidney shape, and modality artifacts. Moreover, well-annotated US datasets for renal segmentation and detection are scarce. This study aims to build a novel, well-annotated dataset containing 44,880 US images. In addition, we propose a novel training scheme that utilizes the encoder and decoder parts of a state-of-the-art segmentation algorithm. In the pre-processing step, pixel intensity normalization improves contrast and facilitates model convergence. The modified encoder-decoder architecture improves pyramid-shaped hole pooling, cascaded multiple-hole convolutions, and batch normalization. The pre-processing step gradually reconstructs spatial information, including the capture of complete object boundaries, and the post-processing module with a concave curvature reduces the false positive rate of the results. We present benchmark findings to validate the quality of the proposed training scheme and dataset. We applied six evaluation metrics and several baseline segmentation approaches to our novel kidney US dataset. Among the evaluated models, DeepLabv3+ performed well and achieved the highest dice, Hausdorff distance 95, accuracy, specificity, average symmetric surface distance, and recall scores of 89.76%, 9.91, 98.14%, 98.83%, 3.03, and 90.68%, respectively. The proposed training strategy aids state-of-the-art segmentation models, resulting in better-segmented predictions. Furthermore, the large, well-annotated kidney US public dataset will serve as a valuable baseline source for future medical image analysis research.

Obesity and chronic kidney disease

The prevalence of obesity has increased dramatically during the past decades, which has been a major health problem. Since 1975, the number of people with obesity worldwide has nearly tripled. An increasing number of studies find obesity as a driver of chronic kidney disease (CKD) progression, and the mechanisms are complex and include hemodynamic changes, inflammation, oxidative stress, and activation of the renin-angiotensin-aldosterone system (RAAS). Obesity-related kidney disease is characterized by glomerulomegaly, which is often accompanied by localized and segmental glomerulosclerosis lesions. In these patients, the early symptoms are atypical, with microproteinuria being the main clinical manifestation and nephrotic syndrome being rare. Weight loss and RAAS blockers have a protective effect on obesity-related CKD, but even so, a significant proportion of patients eventually progress to end-stage renal disease despite treatment. Thus, it is critical to comprehend the mechanisms underlying obesity-related CKD to create new tactics for slowing or stopping disease progression. In this review, we summarize current knowledge on the mechanisms of obesity-related kidney disease, its pathological changes, and future perspectives on its treatment.

Can SGLT2 inhibitors answer unmet therapeutic needs in chronic kidney disease?

Chronic kidney disease (CKD) is a global health problem, affecting more than 850 million people worldwide. The number of patients receiving renal replacement therapy (dialysis or renal transplantation) has increased over the years, and it has been estimated that the number of people receiving renal replacement therapy will more than double from 2.618 million in 2010 to 5.439 million in 2030, with wide differences among countries. The main focus of CKD treatment has now become preserving renal function rather than replacing it. This is possible, at least to some extent, through the optimal use of multifactorial therapy aimed at preventing end-stage kidney disease and cardiovascular events. Sodium/glucose cotransporter 2 inhibitors (SGLT2i) reduce glomerular hypertension and albuminuria with beneficial effects on progression of renal damage in both diabetic and non-diabetic CKD. SGLT2 inhibitors also show great benefits in cardiovascular protection, irrespective of diabetes. Therefore, the use of these drugs will likely be extended to the whole CKD population as a new standard of care.

Local Renin-Angiotensin System Signaling Mediates Cellular Function of Aortic Valves

The renin-angiotensin system (RAS) is activated in aortic valve disease, yet little is understood about how it affects the acute functional response of valve interstitial cells (VICs). Herein, we developed a gelatin-based valve thin film (vTF) platform to investigate whether the contractile response of VICs can be regulated via RAS mediators and inhibitors. First, the impact of culture medium (quiescent, activated, and osteogenic medium) on VIC phenotype and function was assessed. Contractility of VICs was measured upon treatment with angiotensin I (Ang I), angiotensin II (Ang II), angiotensin-converting enzyme (ACE) inhibitor, and Angiotensin II type 1 receptor (AT1R) inhibitor. Anisotropic cell alignment on gelatin vTF was achieved independent of culture conditions. Cells cultured in activated and osteogenic conditions were found to be more elongated than in quiescent medium. Increased α-SMA expression was observed in activated medium and no RUNX2 expression were observed in cells. VIC contractile stress increased with increasing concentrations (from 10-10 to 10-6 M) of Ang I and Ang II. Moreover, cell contraction was significantly reduced in all ACE and AT1R inhibitor-treated groups. Together, these findings suggest that local RAS is active in VICs, and our vTF may provide a powerful platform for valve drug screening and development.

MHC class II in renal tubules plays an essential role in renal fibrosis

Immunomodulation is considered a potential therapeutic approach for chronic kidney disease (CKD). Although it has been previously reported that CD4⁺ T cells contribute to the development of renal fibrosis, the role of MHC class II (MHCII) in the development of renal fibrosis remains largely unknown. The present study reports that the expression of MHCII molecules in renal cortical tubules is upregulated in mouse renal fibrosis models generated by unilateral ureter obstruction (UUO) and folic acid (FA). Proximal tubule epithelial cells (PTECs) are functional antigen-presenting cells that promote the proliferation of CD4⁺ T cells in an MHCII-dependent manner. PTECs from mice with renal fibrosis had a stronger ability to induce T cell proliferation and cytokine production than control cells. Global or renal tubule-specific ablation of H2-Ab1 significantly alleviated renal fibrosis following UUO or FA treatment. Renal expression of profibrotic genes showed a consistent reduction in H2-Ab1 gene-deficient mouse lines. Moreover, there was a marked increase in renal tissue CD4⁺ T cells after UUO or FA treatment and a significant decrease following renal tubule-specific ablation of H2-Ab1. Furthermore, renal tubule-specific H2-Ab1 gene knockout mice exhibited higher proportions of regulatory T cells (Tregs) and lower proportions of Th2 cells in the UUO- or FA-treated kidneys. Finally, Immunohistochemistry (IHC) studies showed increased renal expression of MHCII and the profibrotic gene α smooth muscle actin (α-SMA) in CKD patients. Together, our human and mouse data demonstrate that renal tubular MHCII plays an important role in the pathogenesis of renal fibrosis.

Comparative beneficial effects of nebivolol and nebivolol/valsartan combination against mitochondrial dysfunction in angiotensin II-induced pathology in H9c2 cardiomyoblasts

OBJECTIVES

Considering the complementary nature of signalling mechanisms and the therapeutic effects of nebivolol, a β1-adrenoreceptor antagonist, and valsartan, an angiotensin receptor blocker (ARB), here we aimed to investigate whether nebivolol/valsartan combination would complement the cardioprotective effects of nebivolol on angiotensin II (ANG II)-induced pathology in H9c2 cardiomyoblasts.

METHODS

H9c2 cardiomyoblasts were used to investigate the protective effects of nebivolol and nebivolol and valsartan combination against ANG II-induced pathology. Reactive oxygen species (ROS) generation was determined by 2',7'-dichlorofluorescein diacetate (DCFDA) and MitoSOX Red staining. Real-time PCR and immunoblotting were employed to quantify the changes in mRNA and protein expression levels, respectively.

KEY FINDINGS

Our data revealed that pretreatment with nebivolol and nebivolol/valsartan combination significantly reduced ANG II-induced oxidative stress and mTORC1 signalling. Concurrently, ANG II-induced activation of inflammatory cytokines and fetal gene expressions were significantly suppressed by nebivolol and nebivolol/valsartan combination. Pretreatment with nebivolol and nebivolol/valsartan combination alleviated ANG II-induced impairment of mitochondrial biogenesis by restoring the gene expression levels of PGC-1α, TFAM, NRF-1 and SIRT3. Our data further show that nebivolol and nebivolol/valsartan combination mediated up-regulation in mitochondrial biogenesis is accompanied by decrease in ANG II-stimulated mitochondrial ROS generation as well as increase in expression of mitochondrial fusion genes MFN2 and OPA1, indicative of improved mitochondrial dynamics.

SUMMARY

These findings suggest that both nebivolol and nebivolol/valsartan combination exert protective effects on ANG II-induced mitochondrial dysfunction by alleviating its biogenesis and dynamics. Moreover, addition of valsartan to nebivolol do not produce any additive effects compared with nebivolol alone on ANG II-induced cardiac pathology.

Discoidin Domain Receptor 2 Regulates AT1R Expression in Angiotensin II-Stimulated Cardiac Fibroblasts via Fibronectin-Dependent Integrin-β1 Signaling

This study probed the largely unexplored regulation and role of fibronectin in Angiotensin II-stimulated cardiac fibroblasts. Using gene knockdown and overexpression approaches, Western blotting, and promoter pull-down assay, we show that collagen type I-activated Discoidin Domain Receptor 2 (DDR2) mediates Angiotensin II-dependent transcriptional upregulation of fibronectin by Yes-activated Protein in cardiac fibroblasts. Furthermore, siRNA-mediated fibronectin knockdown attenuated Angiotensin II-stimulated expression of collagen type I and anti-apoptotic cIAP2, and enhanced cardiac fibroblast susceptibility to apoptosis. Importantly, an obligate role for fibronectin was observed in Angiotensin II-stimulated expression of AT1R, the Angiotensin II receptor, which would link extracellular matrix (ECM) signaling and Angiotensin II signaling in cardiac fibroblasts. The role of fibronectin in Angiotensin II-stimulated cIAP2, collagen type I, and AT1R expression was mediated by Integrin-β1-integrin-linked kinase signaling. In vivo, we observed modestly reduced basal levels of AT1R in DDR2-null mouse myocardium, which were associated with the previously reported reduction in myocardial Integrin-β1 levels. The role of fibronectin, downstream of DDR2, could be a critical determinant of cardiac fibroblast-mediated wound healing following myocardial injury. In summary, our findings suggest a complex mechanism of regulation of cardiac fibroblast function involving two major ECM proteins, collagen type I and fibronectin, and their receptors, DDR2 and Integrin-β1.

ACE2 Down-Regulation May Act as a Transient Molecular Disease Causing RAAS Dysregulation and Tissue Damage in the Microcirculatory Environment Among COVID-19 Patients

Severe acute respiratory syndrome coronavirus 2, the etiologic agent of coronavirus disease 2019 (COVID-19) and the cause of the current pandemic, produces multiform manifestations throughout the body, causing indiscriminate damage to multiple organ systems, particularly the lungs, heart, brain, kidney, and vasculature. The aim of this review is to provide a new assessment of the data already available for COVID-19, exploring it as a transient molecular disease that causes negative regulation of angiotensin-converting enzyme 2, and consequently, deregulates the renin-angiotensin-aldosterone system, promoting important changes in the microcirculatory environment. Another goal of the article is to show how these microcirculatory changes may be responsible for the wide variety of injury mechanisms observed in different organs in this disease. The new concept of COVID-19 provides a unifying pathophysiological picture of this infection and offers fresh insights for a rational treatment strategy to combat this ongoing pandemic.

Severity of arterial and/or arteriolar sclerosis in IgA nephropathy and the effects of renin-angiotensin system inhibitors on its prognosis

IgA nephropathy (IgAN) patients often suffer from arterial and/or arteriolar sclerosis (AAS); however, it is unclear whether these features are associated with a poor prognosis. This retrospective cohort study aimed to analyse the prognosis of IgAN patients with AAS and assess whether treatment with renin–angiotensin system inhibitors (RASI) improved their survival. The study included 678 IgAN patients, who were grouped into AAS0 (n = 340; AAS absent) and AAS1 (n = 338; AAS present) groups. Each patient's clinical, laboratory, and histological backgrounds and 20‐year renal prognosis were analysed. In the AAS1 group, the impact of RASI initiated during the follow‐up period on the renal prognosis was also evaluated after adjustments for background characteristics. IgAN patients with AAS had significantly higher age, blood pressure, body mass index, total cholesterol, uric acid levels, and proteinuria than patients without AAS; they also had more severe histological findings, decreased renal function, and lower survival rates than those without AAS (64.0 versus 84.7%, p < 0.001). Multivariate Cox regression analysis incorporating clinical and histological findings and treatments revealed AAS as an independent factor for disease progression (hazard ratio: 2.23, p = 0.010). Participants in the AAS1 group treated with RASI during follow‐up had a significantly higher renal survival rate than those who were not (75.5 versus 44.3%, p = 0.013). In conclusion, AAS was found to be associated with serious clinical, laboratory, and histological findings and poor prognosis. RASI initiated during the follow‐up period was found to improve renal prognosis.

Treatment of proteinuria in dogs with telmisartan: A retrospective study

Background

Use of telmisartan for the treatment of proteinuria in dogs has not been thoroughly investigated.

Hypothesis/Objectives

Telmisartan can be effective for the treatment of proteinuria in dogs.

Animals

Forty‐four client‐owned dogs with proteinuria.

Methods

Retrospective study. Dogs diagnosed with clinically relevant proteinuria (nonazotemic dogs with a urine protein‐to‐creatinine ratio [UPC] ≥2 and azotemic dogs with UPC ≥0.5) were separated into 3 groups: telmisartan alone, with benazepril, or with mycophenolate. The UPC was recorded before treatment and at subsequent follow‐ups (1, 3, 6, and 12 months, as available). Response to treatment was categorized as complete (UPC ˂0.5), partial (UPC decreased by ≥50% but still ≥0.5), or no response (UPC decreased by <50%). Serum creatinine and potassium concentrations and arterial pressure also were recorded.

Results

In the telmisartan group, treatment response (UPC ˂0.5 or decreased by ≥50%) was observed in 70%, 68%, 80%, and 60% of dogs at 1, 3, 6, and 12 months follow‐up, respectively. No significant changes were noted in serum creatinine or potassium concentrations, or in arterial blood pressure at all follow‐up times. Adverse effects consisted of mild self‐limiting gastrointestinal signs in 5 dogs. Two dogs developed clinically relevant azotemia that required discontinuation of the treatment before the first follow‐up.

Conclusions and Clinical Importance

Telmisartan can be considered for treatment of proteinuria in dogs, alone or in combination with other treatments for proteinuria.

A Review of the Current Practice of Diagnosis and Treatment of Idiopathic Membranous Nephropathy in China

Idiopathic membranous nephropathy (IMN), a common pathological type of nephrotic syndrome, is one of the main causes of kidney failure. With an increasing prevalence, IMN has received considerable attention in China. Based on recent studies, we discuss advances in the diagnosis of IMN and the understanding of its genetic background. Although the pathogenesis of IMN remains unclear, our understanding has been substantially enhanced by the discovery of new antigens such as phospholipase A₂ receptor, thrombospondin type-1 domain-containing 7A, exostosin1/exostosin2, neural epidermal growth factor-like 1 protein, neural cell adhesion molecule 1, semaphorin 3B, and factor H autoantibody. However, due to ethnic, environmental, economic, and lifestyle differences and other factors, a consensus has not yet been reached regarding IMN treatment. In view of the differences between Eastern and Western populations, in-depth clinical evaluations of biomarkers for IMN diagnosis are necessary. This review details the current treatment strategies for IMN in China, including renin-angiotensin system inhibitors, corticosteroid monotherapy, cyclophosphamide, calcineurin inhibitors, mycophenolate mofetil, adrenocorticotropic hormone, and traditional Chinese medicine, as well as biological preparations such as rituximab. In terms of management, the 2012 Kidney Disease Improving Global Outcomes (KDIGO) clinical practice guidelines do not fully consider the characteristics of the Chinese population. Therefore, this review aims to present the current status of IMN diagnosis and treatment in Chinese patients, and includes a discussion of new approaches and remaining clinical challenges.

Efficacy of telmisartan for the treatment of persistent renal proteinuria in dogs: A double-masked, randomized clinical trial

BACKGROUND

Information regarding efficacy of the angiotensin II receptor blocker, telmisartan, for treatment of proteinuria in dogs is limited.

OBJECTIVE

To evaluate the antiproteinuric efficacy of telmisartan, as compared to enalapril, in dogs with chronic kidney disease and persistent, renal proteinuria.

ANIMALS

Thirty-nine client-owned dogs with chronic kidney disease and urinary protein-to-creatinine ratio (UPC) > 0.5 (if azotemic) or ≥ 1.0 (if nonazotemic).

METHODS

In this prospective, randomized, double-masked clinical trial, dogs were block randomized, according to presence or absence of azotemia and systemic arterial hypertension, to receive telmisartan (1.0 mg/kg PO q24h), or enalapril (0.5 mg/kg PO q12h), and followed for 120 days. Up-titration of study drug dosage on days 30 and 60, and addition of the other study drug at day 90, were performed if UPC > 0.5 was noted at these visits. Percentage change in UPC relative to baseline was calculated for all time points. Data are presented as median (range).

RESULTS

Thirty-nine (20 telmisartan-treated, 19 enalapril-treated) dogs were included. At day 30, percentage change in UPC was greater for telmisartan-treated (-65% [-95% to 104%]) vs enalapril-treated (-35% [-74% to 87%]) dogs (P = .002). Among dogs persistently proteinuric at earlier visits, telmisartan remained superior to enalapril at days 60 (P = .02) and 90 (P = .02). No difference in percentage change in UPC between study groups was observed at day 120, when combination therapy was allowed. Combination therapy resulted in relevant azotemia in 4/13 (31%) dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

Telmisartan might be a suitable first-line therapy for dogs with renal proteinuria.

Sympathetic Hyperactivity—A Hidden Enemy in Chronic Kidney Disease Patients

Chronic kidney disease is often characterized by the presence of sympathetic hyperactivity. The aim of this brief review is to summarize available knowledge on the pathogenesis of sympathetic hyperactivity and to discuss its clinical relevance, the consequences of this knowledge for the choice of treatment, and the yet unresolved issues.

Metabolic reprogramming by N-acetyl-seryl-aspartyl-lysyl-proline protects against diabetic kidney disease

BACKGROUND AND PURPOSE

ACE inhibitors (ACEIs) and AT₁ receptor antagonists (ARBs) are first-line drugs that are believed to reduce the progression of end-stage renal disease in diabetic patients. Differences in the effects of ACEIs and ARBs are not well studied and the mechanisms responsible are not well understood.

EXPERIMENTAL APPROACH

Male diabetic CD-1 mice were treated with ACEI, ARB, N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP), ACEI + AcSDKP, ARB + AcSDKP, glycolysis inhibitors or non-treatment. Moreover, prolyl oligopeptidase inhibitor (POPi)-injected male diabetic C57Bl6 mice were treated with ACEI, AcSDKP and ARB or non-treatment. Western blot and immunofluorescent staining were used to examine key enzymes and regulators of central metabolism.

KEY RESULTS

The antifibrotic action of ACEI imidapril is due to an AcSDKP-mediated antifibrotic mechanism, which reprograms the central metabolism including restoring SIRT3 protein and mitochondrial fatty acid oxidation and suppression of abnormal glucose metabolism in the diabetic kidney. Moreover, the POPi S17092 significantly blocked the AcSDKP synthesis, accelerated kidney fibrosis and disrupted the central metabolism. ACEI partly restored the kidney fibrosis and elevated the AcSDKP level, whereas the ARB (TA-606) did not show such effects in the POPi-injected mice. ACE inhibition and AcSDKP suppressed defective metabolism-linked mesenchymal transformations and reduced collagen-I and fibronectin accumulation in the diabetic kidneys.

CONCLUSION AND IMPLICATIONS

The study envisages that AcSDKP is the endogenous antifibrotic mediator that controls the metabolic switch between glucose and fatty acid metabolism and that suppression of AcSDKP leads to disruption of kidney cell metabolism and activates mesenchymal transformations leading to severe fibrosis in the diabetic kidney.

Heart failure management in dialysis patients: Many treatment options with no clear evidence

Heart failure with reduced ejection fraction (HFrEF) impacts approximately 20% of dialysis patients and is associated with high mortality rates. Key issues discussed in this review of HFrEF management in dialysis include dialysis modality choice, vascular access, dialysate composition, pharmacological therapies, and strategies to reduce sudden cardiac death, including the use of cardiac devices. Peritoneal dialysis and more frequent or longer duration of hemodialysis may be better tolerated due to slower ultrafiltration rates, leading to less intradialytic hypotension and better volume control; dialysate cooling and higher dialysate calcium may also have benefits. While high-quality evidence exists for many drug classes in the non-dialysis population, dialysis patients were excluded from major trials, and only limited data exist for many medications in kidney failure patients. Despite limited evidence, beta blocker and angiotensin-converting enzyme inhibitor or angiotensin receptor blocker use is common in dialysis. Similarly, devices such as implantable cardiac defibrillators (ICDs) and cardiac resynchronization therapy that have proven benefits in non-dialysis HFrEF patients have not consistently been beneficial in the limited dialysis studies. The use of leadless pacemakers and subcutaneous ICDs can mitigate future hemodialysis access limitations. Additional research is critical to address knowledge gaps in treating maintenance dialysis patients with HFrEF.

Angiotensin II triggers RIPK3-MLKL-mediated necroptosis by activating the Fas/FasL signaling pathway in renal tubular cells

Our earlier studies proved that RIPK3-mediated necroptosis might be an important mode of renal tubular cell death in rats with chronic renal injury and the necroptotic cell death can be triggered by tumor necrosis factor-α (TNF-α) in vitro, but the triggering role of angiotensin II (AngII), which exerts notable effects on renal cells for the initiation and progression of renal tubulointerstitial fibrosis, is largely unknown. Here, we identified the presence of necroptotic cell death in the tubular cells of AngII-induced chronic renal injury and fibrosis mice and assessed the percentage of necroptotic renal tubular cell death with the disruption of this necroptosis by the addition of necrostatin-1 (Nec-1). Furthermore, the observation was further confirmed in HK-2 cells treated with AngII and RIPK1/3 or MLKL inhibitors. The detection of Fas and FasL proteins led us to investigate the contribution of the Fas/FasL signaling pathway to AngII-induced necroptosis. Disruption of FasL decreased the percentage of necroptotic cells, suggesting that Fas and FasL are likely key signal molecules in the necroptosis of HK-2 cells induced by AngII. Our data suggest that AngII exposure might trigger RIPK3-MLKL-mediated necroptosis in renal tubular epithelial cells by activating the Fas/FasL signaling pathway in vivo and in vitro.

Inhibition of Angiotensin-Converting Enzyme Ameliorates Renal Fibrosis by Mitigating DPP-4 Level and Restoring Antifibrotic MicroRNAs

Two class of drugs 1) angiotensin-converting enzyme inhibitors (ACEis) and 2) angiotensin II receptor blockers (ARBs) are well-known conventional drugs that can retard the progression of chronic nephropathies to end-stage renal disease. However, there is a lack of comparative studies on the effects of ACEi versus ARB on renal fibrosis. Here, we observed that ACEi ameliorated renal fibrosis by mitigating DPP-4 and TGFβ signaling, whereas, ARB did not show. Moreover, the combination of N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP), one of the substrates of ACE, with ACEi slightly enhanced the inhibitory effects of ACEi on DPP-4 and associated-TGFβ signaling. Further, the comprehensive miRome analysis in kidneys of ACEi+AcSDKP (combination) treatment revealed the emergence of miR-29s and miR-let-7s as key antifibrotic players. Treatment of cultured cells with ACEi alone or in combination with AcSDKP prevented the downregulated expression of miR-29s and miR-let-7s induced by TGFβ stimulation. Interestingly, ACEi also restored miR-29 and miR-let-7 family cross-talk in endothelial cells, an effect that is shared by AcSDKP suggesting that AcSDKP may be partially involved in the anti-mesenchymal action of ACEi. The results of the present study promise to advance our understanding of how ACEi regulates antifibrotic microRNAs crosstalk and DPP-4 associated-fibrogenic processes which is a critical event in the development of diabetic kidney disease.

Thrombospondin-1: A Key Protein That Induces Fibrosis in Diabetic Complications

Fibrosis accompanies most common pathophysiological features of diabetes complications in different organs. It is characterized by an excessive accumulation of extracellular matrix (ECM) components, the response to which contributes to inevitable organ injury. The extracellular protein thrombospondin-1 (TSP-1), a kind of extracellular glycoprotein, is upregulated by the increased activity of some transcription factors and results in fibrosis by activating multiple pathways in diabetes. The results of studies from our team and other colleagues indicate that TSP-1 is associated with the pathological process leading to diabetic complications and is considered to be the most important factor in fibrosis. This review summarizes the molecular mechanism of increased TSP-1 induced by hyperglycemia and the role of TSP-1 in fibrosis during the development of diabetes complications.

AT1 and AT2 receptors modulate renal tubular cell necroptosis in angiotensin II-infused renal injury mice

Abnormal renin-angiotensin system (RAS) activation plays a critical role in the initiation and progression of chronic kidney disease (CKD) by directly mediating renal tubular cell apoptosis. Our previous study showed that necroptosis may play a more important role than apoptosis in mediating renal tubular cell loss in chronic renal injury rats, but the mechanism involved remains unknown. Here, we investigate whether blocking the angiotensin II type 1 receptor (AT1R) and/or angiotensin II type 2 receptor (AT2R) beneficially alleviates renal tubular cell necroptosis and chronic kidney injury. In an angiotensin II (Ang II)-induced renal injury mouse model, we found that blocking AT1R and AT2R effectively mitigates Ang II-induced increases in necroptotic tubular epithelial cell percentages, necroptosis-related RIP3 and MLKL protein expression, serum creatinine and blood urea nitrogen levels, and tubular damage scores. Furthermore, inhibition of AT1R and AT2R diminishes Ang II-induced necroptosis in HK-2 cells and the AT2 agonist CGP42112A increases the percentage of necroptotic HK-2 cells. In addition, the current study also demonstrates that Losartan and PD123319 effectively mitigated the Ang II-induced increases in Fas and FasL signaling molecule expression. Importantly, disruption of FasL significantly suppressed Ang II-induced increases in necroptotic HK-2 cell percentages, and necroptosis-related proteins. These results suggest that Fas and FasL, as subsequent signaling molecules of AT1R and AT2R, might involve in Ang II-induced necroptosis. Taken together, our results suggest that Ang II-induced necroptosis of renal tubular cell might be involved both AT1R and AT2R and the subsequent expression of Fas, FasL signaling. Thus, AT1R and AT2R might function as critical mediators.

Ursolic acid inhibits epithelial-mesenchymal transition in vitro and in vivo

CONTEXT

Ursolic acid (UA; 3β-hydroxy-urs-12-en-28-oic acid), one of the pentacyclic triterpenoids found in various plants and herbs, possesses some beneficial effects under pathological conditions, including combating hepatic fibrosis.

OBJECTIVE

This study investigates the effects of UA on renal tubulointerstitial fibrosis in vivo and in vitro.

MATERIALS AND METHODS

In vivo, 24 male C57BL6 mice were divided into four groups. Eighteen mice were subjected to unilateral ureteral obstruction (UUO) and the remaining six sham-operated mice served as control. UUO mice received either vehicle or UA (50 or 100 mg/kg) by gastric gavage for 6 days. In vitro, HK-2 cells were treated with 10 or 50 μM UA and 10 ng/mL recombinant human transforming growth factor-β1 (TGF-β1). The molecular mechanisms of fibrosis were investigated.

RESULTS

UUO induced marked interstitial collagen I and fibronectin deposition and epithelial-mesenchymal transition (EMT), as evidenced by increased α-smooth muscle actin (α-SMA) and decreased E-cadherin. However, UA treatment significantly reduced collagen I and fibronectin accumulation in the fibrotic kidney. UA treatment also decreased α-SMA and preserved E-cadherin in vivo. In vitro, TGF-β1-treated HK-2 cells demonstrated elevated α-SMA, snail1, slug, TGF-β1, and p-smad3, as well as diminished E-cadherin. UA pretreatment prevented E-cadherin loss and diminished α-SMA expression in HK-2 cells. UA downregulated mRNA expression of snail1 and slug. UA also lowered TGF-β1 protein expression and p-Smad3 in HK-2 cells.

CONCLUSIONS

UA attenuated renal tubulointerstitial fibrosis by inhibiting EMT, and such inhibition may be achieved by decreasing profibrotic factors. UA may be a novel therapeutic agent for renal fibrosis.

Changes in Serum and Urinary Potassium Handling Associated with Renin-Angiotensin-Aldosterone System Inhibitors in Advanced Chronic Kidney Disease Patients

Objective This study aimed to (i) compare the extent of urinary potassium (K+) excretion in addition to the changes in serum K+ concentration: and (ii) clarify the association between changes in serum K+ concentration, urinary K+ excretion, and acid-base status with or without renin-angiotensin-aldosterone system (RAAS) inhibitors in patients with advanced chronic kidney disease (CKD) stages. Methods Six hundred and ninety-one patients with advanced CKD (CKD G3b, 161; G4, 271; G5, 259) were retrospectively evaluated. Differences in serum K+ concentration, urinary K+ excretion, and serum sodium and chloride differences (Na+-Cl-) were compared among patients with RAAS inhibitors, RAAS inhibitors and diuretic agents, and without either medication in each CKD stage. Results Serum K+ concentrations in patients with RAAS inhibitors were significantly higher than in those with RAAS inhibitors and diuretics in CKD stage G3b and the other two treatment groups in CKD stage G4. Urinary K+ excretion among the three groups did not differ significantly in each CKD stage. Serum Na+-Cl- differences in patients with RAAS inhibitors were significantly smaller than in those with RAAS inhibitors and diuretics in CKD stages G3b (p = 0.006) and the other two groups in CKD stage G4 (vs. RAAS inhibitors and diuretics, p <0.001; vs. without either medication, p = 0.008). Conclusion Our study demonstrated that RAAS inhibitor use might be associated with hyperkalemia via not decreased urinary K+ excretion but rather K+ redistribution from intracellular to extracellular fluid induced by the progression of metabolic acidosis in patients with advanced CKD, particularly stages G3b and G4.

Oxidative Stress and TGF-β1/Smads Signaling Are Involved in Rosa roxburghii Fruit Extract Alleviating Renal Fibrosis

Fibrosis is involved in the pathogenesis of kidney diseases. We previously discovered that Rosa roxburghii fruit (Cili) possesses antifibrosis property in chronic renal disease, but the mechanisms are unknown. We hypothesized that Cili might prevent fibrosis development through mediating TGF-β/Smads signaling, which is known to be involved in renal fibrosis. This study aimed to confirm the effects of freeze-dried Cili powder in a rat model of unilateral ureteral obstruction (UUO) and examine TGF-β/Smads signaling. Rats were randomized to (n=12/group): sham operation, UUO, UUO with losartan, UUO with moderate Cili dose (3 g/kg/d), and UUO with high Cili dose (6 g/kg/d). The rats were sacrificed after 14 days of treatment. Collagen deposition was tested using Masson's staining. TGF-β/Smads signaling was examined by qRT-PCR, western blot, and immunohistochemistry. Rats in the UUO group showed excessive deposition of collagen in kidney interstitium, accompanied with high levels of renal 8-hydroxy-2′-deoxyguanosine, renal malondialdehyde, blood urea nitrogen (BUN), serum creatinine (Scr), and proteinuria (all P<0.05). Cili powder efficiently alleviated the pathological changes and oxidative stress in the kidneys of UUO rats, and decreased BUN, Scr and proteinuria (all P<0.05). Cili powder also inhibited the upregulation of TGFB1, TGFBR1, TGFBR2, SMAD2, and SMAD3 and reversed the downregulation of SMAD7 in obstructed kidneys (mRNA and protein) (all P<0.05). In summary, the results suggest that Cili freeze-dried powder effectively prevents renal fibrosis and impairment in UUO rats, which is associated with the inhibition of oxidative stress and TGF-β1/Smads signaling.

Protective Effects of Combination of Radix Astragali and Radix Salviae Miltiorrhizae on Kidney of Spontaneously Hypertensive Rats and Renal Intrinsic Cells

OBJECTIVE

To evaluate the effects of combination of Radix Astragali (RA) and Radix Salviae Miltiorrhizae (RS) on kidney of spontaneously hypertensive rats (SHRs) and renal intrinsic cells.

METHODS

SHRs were intragastrically administrated with RA (5.09 g/kg) and RS (2.55 g/kg) either alone or with combination for 4 weeks; valsartan (13.35 mg/kg) was used as a positive control. Blood pressure and renal ultrasonography were monitored periodically. The biomarkers [microalbumin (mALB), cystatin ^C, angiotensin II (Ang II), interleukin-1 beta (IL-1β), and β2-microglobulin (β2-Mg), etc.] in serum and urine were measured by enzyme-linked immunosorbent assay (ELISA). The protein expressions [phosphorylated adenosine 5'-monophosphate-activated protein kinase-α1 (p-AMPKα1), sestrin-β, calcium/calmodulin-dependent protein kinase kinase-β (CaMKK-β), phosphoinositide 3-kinases (PI3K), serine-threonine protein kinase 1 (AKT1), and vascular endothelial growth factor receptor 2 (VEGFR2)] in renal cortex were determined by Western blot. In vitro, the hypertensive cellular model was established by applying 2×10^-6 mol/L Ang ^II. The primary human podocytes, human glomerular endothelial cells (HRGECs), and human proximal tubular epithelial cells (HK-2s) were pre-incubated with sulfotanshinone sodium (Tan, 10 μg/mL) and/or calycosin-7-O-β-D-glucoside (Cal, 5 μg/mL). The cellular viability and apoptosis were assayed by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and Annexin V/PI staining, respectively. The level of endothelial nitric oxide synthase (eNOS) in culture supernatant was determined by ELISA.

RESULTS

RA+RS signifificantly decreased the diastolic blood pressure, renal vascular resistance index, and parenchymal thickness, increased 24 h urinary volume as well as lowered the levels of urine mALB and serum cystatin ^C, IL-1β and β2-Mg of SHRs (P <0.05 vs. SHRs). The decreased protein levels of p-AMPKα1, sestrinβ and CaMKK-β and the increased protein levels of PI3K, AKT1 and VEGFR2 in renal cortex of SHRs were normalized after RA+RS treatment (P <0.05). In vitro, Tan and Cal attenuated the Ang II-induced abnormal proliferation and increased the apoptosis of HRGECs and HK-2s and improved the level of eNOS in culture supernatant. Whereas, neither of them showed powerful effect on podocyte.

CONCLUSION

The combination of RA and RS had potential effects on alleviating the renal damages of SHRs and the renoprotection was independent of blood pressure level.

Effects of valsartan, benazepril and their combination in overt nephropathy of type 2 diabetes: A prospective, randomized, controlled trial

AIMS

To evaluate whether angiotensin-converting enzyme (ACE) inhibitor and angiotensin II receptor blocker (ARB) combination therapy is more nephroprotective than ACE inhibitor or ARB monotherapy in people with type 2 diabetes and overt nephropathy.

MATERIALS AND METHODS

In this prospective, randomized, open, blind-endpoint phase III trial sponsored by the Italian Drug Agency, 103 consenting patients with type 2 diabetes, aged >40 years, with serum creatinine levels 159 to 309 μmol/L, spot morning urinary albumin-creatinine ratio > 1000 mg/g (or > 500 mg/g in those on ACE inhibitor or ARB therapy at inclusion) were stratified by centre and randomized to 4.5-year treatment with valsartan 320 mg/d (n = 36), benazepril 20 mg/d (n = 34) or halved doses of both medications (n = 33). The primary endpoint was end-stage renal disease (ESRD). Modified intention-to-treat analyses were performed.

RESULTS

Recruitment took place between June 2007 and February 2013 at 10 centres in Italy and one in Slovenia. A total of 77 participants completed the study and 26 were prematurely withdrawn. During a median (interquartile range) of 41 (18-54) months, 12 participants on benazepril (35.3%) and nine on combination therapy (27.3%) progressed to ESRD, versus five on valsartan (13.9%). Differences between benazepril (hazard ratio [HR] 3.59, 95% confidence interval [CI] 1.25-10.30; P = 0.018) or combination therapy (HR 3.28, 95% CI 1.07-10.0; P = 0.038) and valsartan were significant, even after adjustment for age, gender and baseline serum creatinine, systolic blood pressure and 24-hour proteinuria (HR 5.16, 95% CI 1.50-17.75, P = 0.009 and HR 4.75, 95% CI 1.01-22.39, P = 0.049, respectively). Adverse events were distributed similarly among the groups.

CONCLUSIONS

In people with type 2 diabetes with nephropathy, valsartan (320 mg/d) safely postponed ESRD more effectively than benazepril (20 mg/d) or than halved doses of both medications.

Angiotensin-converting enzyme inhibitors or angiotensin receptor blocker monotherapy retard deterioration of renal function in Taiwanese chronic kidney disease population

It remains unclear how different uses of angiotensin-converting inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) influence the progression of chronic kidney disease (CKD). This study explored CKD progression in a multicentre, longitudinal cohort study that included 2639 patients with CKD stage 1–5 and hypertension. Patients treated with ACEI or ARB for ≥90 days during a 6-mo period comprised the study group, or no treatment, comprised the control group. The study group was subdivided on the basis of treatment: ACEI monotherapy or ARB monotherapy. Progression of renal deterioration was defined by an average eGFR decline of more than 5 mL/min/1.73 m²/yr or the commencement of dialysis. With at least 1-year follow up, a progression of renal deterioration was demonstrated in 29.70% of the control group and 25.09% of the study group. Patients in the study group had significantly reduced progression of CKD with adjusted odds ratio 0.79 (95% confidence interval: 0.63–0.99). However, when ACEI monotherapy and ARB monotherapy were analyzed separately, none of their associations with CKD progression was statistically significant. In conclusion, ACEI or ARB monotherapy may retard the deterioration of renal function among patients with CKD and hypertension.

Chronic Hyperkalemia in Cardiorenal Patients: Risk Factors, Diagnosis, and New Treatment Options

Chronic hyperkalemia (HK) is a serious medical condition that often manifests in patients with chronic kidney disease (CKD) and heart failure (HF) leading to poor outcomes and necessitating careful management by cardionephrologists. CKD, HF, diabetes, and renin-angiotensin-aldosterone system inhibitors use is known to induce HK. Current therapeutic options are not optimal, as pointed out by a large number of CKD and HF patients with HK. The following review will focus on the main risk factors for developing HK and also aims to provide a guide for a correct diagnosis and present new approaches to therapy.

Chronic hyperkalemia in non-dialysis CKD: controversial issues in nephrology practice

Chronic hyperkalemia is a major complication of chronic kidney disease (CKD) that occurs frequently, heralds poor prognosis, and necessitates careful management by the nephrologist. Current strategies aimed at prevention and treatment of hyperkalemia are still suboptimal, as evidenced by the relatively high prevalence of hyperkalemia in patients under stable nephrology care, and even in the ideal setting of randomized trials where best treatment and monitoring are mandatory. The aim of this review was to identify and discuss a range of unresolved issues related to the management of chronic hyperkalemia in non-dialysis CKD. The following topics of clinical interest were addressed: diagnosis, relationship with main comorbidities of CKD, therapy with inhibitors of the renin-angiotensin-aldosterone system, efficacy of current dietary and pharmacological treatment, and the potential role of the new generation of potassium binders. Opinion-based answers are provided for each of these controversial issues.

Lipocalin-2 derived from adipose tissue mediates aldosterone-induced renal injury

Lipocalin-2 is not only a sensitive biomarker, but it also contributes to the pathogenesis of renal injuries. The present study demonstrates that adipose tissue-derived lipocalin-2 plays a critical role in causing both chronic and acute renal injuries. Four-week treatment with aldosterone and high salt after uninephrectomy (ANS) significantly increased both circulating and urinary lipocalin-2, and it induced glomerular and tubular injuries in kidneys of WT mice. Despite increased renal expression of lcn2 and urinary excretion of lipocalin-2, mice with selective deletion of lcn2 alleles in adipose tissue (Adipo-LKO) are protected from ANS- or aldosterone-induced renal injuries. By contrast, selective deletion of lcn2 alleles in kidney did not prevent aldosterone- or ANS-induced renal injuries. Transplantation of fat pads from WT donors increased the sensitivity of mice with complete deletion of Lcn2 alleles (LKO) to aldosterone-induced renal injuries. Aldosterone promoted the urinary excretion of a human lipocalin-2 variant, R81E, in turn causing renal injuries in LKO mice. Chronic treatment with R81E triggered significant renal injuries in LKO, resembling those observed in WT mice following ANS challenge. Taken in conjunction, the present results demonstrate that lipocalin-2 derived from adipose tissue causes acute and chronic renal injuries, largely independent of local lcn2 expression in kidney.

Induction of cytochrome P450 4A14 contributes to angiotensin II-induced renal fibrosis in mice

Angiotensin II (AngII) plays an important role in the pathogenesis of hypertension and associated renal injuries. To elucidate the molecular mechanism by which AngII induces renal damage, we found that AngII infusion significantly induced CYP4A14 expression in renal proximal tubule cells (RPTCs) with marked increases in blood pressure and proteinuria. Renal production of the major CYP4A metabolite, 20-HETE, was also significantly increased in the AngII-treated mice. Compared to wild-type (WT) mice, CYP4A14 knockout (CYP4A14^-/-) mice exhibited significantly lower levels of blood pressure, renal 20-HETE production, proteinuria and renal fibrosis following AngII infusion. Furthermore, AngII-induced renal expression of profibrotic genes and proinflammatory genes was significantly attenuated in CYP4A14^-/- mice. In vitro studies using cultured RPTCs demonstrated that AngII significantly induced CYP4A14 expression and 20-HETE production via the MAPK signaling pathway. AngII treatment increased TGF-β and collagen expression, which was attenuated by the CYP4A inhibitor, TS-011. Moreover, 20-HETE treatment potently induced CYP4A14 expression and TGF-β and collagen levels. Collectively, these findings suggest that attenuated renal fibrosis in AngII-treated CYP4A14^-/- mice may result from both reduced systemic blood pressure and renal 20-HETE production. Therefore, CYP4A14 may represent a useful target for the treatment of AngII-associated renal damage.

Effects of IQP, VEP and Spirulina platensis hydrolysates on the local kidney renin angiotensin system in spontaneously hypertensive rats

The aim of the present study was to investigate the antihypertensive effects of the bioactive Spirulina platensis peptides Ile‑Gln‑Pro (IQP), Val‑Glu‑Pro (VEP), as well as Spirulina platensis hydrolysates (SH), and assessed whether the synthesis of components of the myocardial and renal local renin angiotensin system (RAS) are regulated differentially in spontaneously hypertensive rats (SHR). The SHR were administrated with IQP, VEP and SH respectively (10 mg/kg/day) for 6 weeks and received continuous monitoring of blood pressure (BP) for two more weeks. During the trial, the rats' kidney tissues were removed from these rats and collected at weeks 3, 6 and 8. The expression of the main components of local kidney RAS was measured at the mRNA levels by reverse transcription‑quantitative polymerase chain reaction, and at the protein levels by ELISA or western blotting. Oral administration of IQP, VEP and SH into SHR resulted in marked antihypertensive effects. IQP, VEP and SH decreased rats' BP by affecting the expression of local kidney RAS components via downregulating the angiotensin‑converting enzyme (ACE), Ang II and angiotensin II (Ang II) and angiotensin type‑1 receptor (AT 1), while upregulating ACE2, Ang (1‑7), Mas and AT 2. The comparisons of SH effects on local tissue RAS demonstrated that local kidney RAS regulated BP via the ACE‑Ang II‑AT 1/AT 2 axis and the ACE2‑Ang (1‑7)‑Mas axis primarily at the mRNA level, while the local myocardium RAS mainly at the protein level. This preliminary study suggests that the main components of local RAS presented different expression levels in myocardium and kidney, which is important to the development of bioactive peptides targeting for lowering BP by changing the levels of some components in local RAS in specific tissues.

Review of Top 10 Prescribed Drugs and Their Interaction with Dental Treatment

The proportion of people over age 60 is growing faster than any other group. Many patients take several medications to manage multiple chronic medical conditions. Poor oral health is common and dental visits by patients over the age of 65 are increasing. The dentist must recognize that these medications may interact with dental treatment. This article reviews the top 10 prescribed drugs as listed in the IMS Institute national prescription audit in January 2015 and reviews the interactions between these medications and dental treatment. The medications reviewed include levothyroxine, acetaminophen/hydrocodone, lisinopril, metoprolol, atorvastatin, amlodipine, metformin, omeprazole, simvastatin, and albuterol.

The NLPR3 inflammasome and obesity-related kidney disease

Over the past decade, the prevalence of obesity has increased, accompanied by a parallel increase in the prevalence of chronic kidney disease (CKD). Mounting evidence suggests that high body mass index (BMI) and obesity are important risk factors for CKD, but little is known about the mechanisms of obesity‐related kidney disease (ORKD). The NLRP3 inflammasome is a polyprotein complex that plays a crucial role in the inflammatory process, and numerous recent studies suggest that the NLRP3 inflammasome is involved in ORKD development and may serve as a key modulator of ORKD. Moreover, inhibiting activation of the NLRP3 inflammasome has been shown to attenuate ORKD. In this review, we summarize recent progress in understanding the link between the NLRP3 inflammasome and ORKD and discuss targeting the NLRP3 inflammasome as a novel therapeutic approach for ORKD.

Recent Research in Antihypertensive Activity of Food Protein-derived Hydrolyzates and Peptides

Year to year obesity prevalence, reduced physical activities, bad habits/or stressful lifestyle, and other environmental and physiological impacts lead to increase in diseases such as coronary heart disease, stroke, cancer, diabetes, and hypertension worldwide. Hypertension is considered as one of the most common serious chronic diseases; however, discovery of medications with high efficacy and without side effects for treatment of patients remains a challenge for scientists. Recent trends in functional foods have evidenced that food bioactive proteins play a major role in the concepts of illness and curing; therefore, nutritionists, biomedical scientists, and food scientists are working together to develop improved systems for the discovery of peptides with increased potency and therapeutic benefits. This review presents a recent research carried out to date for the purpose of isolation and identification of bioactive hydrolyzates and peptides with angiotensin I converting enzyme inhibitory activity and antihypertensive effect from animal, marine, microbial, and plant food proteins. Effects of food processing and hydrolyzation conditions as well as some other impacts on formation, activity, and stability of these hydrolyzates and peptides are also presented.

Homocysteine and hydrogen sulfide in epigenetic, metabolic and microbiota related renovascular hypertension

Over the past several years, hydrogen sulfide (H₂S) has been shown to be an important player in a variety of physiological functions, including neuromodulation, vasodilation, oxidant regulation, inflammation, and angiogenesis. H₂S is synthesized primarily through metabolic processes from the amino acid cysteine and homocysteine in various organ systems including neuronal, cardiovascular, gastrointestinal, and kidney. Derangement of cysteine and homocysteine metabolism and clearance, particularly in the renal vasculature, leads to H₂S biosynthesis deregulation causing or contributing to existing high blood pressure. While a variety of environmental influences, such as diet can have an effect on H₂S regulation and function, genetic factors, and more recently epigenetics, also have a vital role in H₂S regulation and function, and therefore disease initiation and progression. In addition, new research into the role of gut microbiota in the development of hypertension has highlighted the need to further explore these microorganisms and how they influence the levels of H₂S throughout the body and possibly exploiting microbiota for use of hypertension treatment. In this review, we summarize recent advances in the field of hypertension research emphasizing renal contribution and how H₂S physiology can be exploited as a possible therapeutic strategy to ameliorate kidney dysfunction as well as to control blood pressure.

Combined Treatment With Angiotensin-Converting Enzyme Inhibitors and Angiotensin II Receptor Blockers: A Review of the Current Evidence

Several studies have shown that angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers are useful in the treatment of hypertension, cardiovascular disease, chronic heart failure, and some types of nephropathy. In this context, dual renin-angiotensin system blockade with both angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers may be more effective than treatment with each agent alone. Many clinical trials have demonstrated the beneficial effect of this combined treatment on proteinuria, hypertension, heart failure, and cardiovascular events. Moreover, these studies demonstrated that dual renin-angiotensin system blockade is generally safe and well tolerated. Long-term studies are under way to confirm these effects and also investigate the effectiveness of dual reninangiotensin system blockade on cerebrovascular disease and prevention of type 2 diabetes mellitus. These studies are expected to define the optimal use of combination treatment in everyday clinical practice. This review considers the most important clinical trials that evaluated the effect of dual renin-angiotensin system blockade on blood pressure, heart failure, and renal function.

Long-Term and Interactive Effects of Pay-For-Performance Interventions among Diabetic Nephropathy Patients at the Early Chronic Kidney Disease Stage

Chronic kidney disease (CKD) is a major health problem worldwide because of the aging population and lifestyle changes. One of the important etiologies of CKD is diabetes mellitus (DM). The long-term effects of pay-for-performance (P4P) on disease progression have not been thoroughly examined.This study is a retrospective population-based patient cohort design to examine the continuous effects of diabetes and CKD P4P interventions. This study used the health insurance claims database to conduct a longitudinal analysis. A total of 32,084 early CKD patients with diabetes were extracted from the outpatient claims database from January 2011 to December 2012, and the follow-up period was extended to August 2014. A 4-group matching design, including both diabetes and early CKD P4P interventions, with only diabetes P4P intervention, with only early CKD P4P intervention, and without any P4P interventions, was performed according to their descending intensity. The primary outcome of this study was all-cause mortality and the causes of death. The statistical methods included a Chi-squared test, ANOVA, and multi-variable Cox regression models.A dose-response relationship between the intervention groups and all-cause mortality was observed as follows: comparing to both diabetes and early CKD P4P interventions (reference), hazard ratio (HR) was 1.22 (95% confidence interval [CI], 1.00-1.50) for patients with only a diabetes P4P intervention; HR was 2.00 (95% CI, 1.66-2.42) for patients with only an early CKD P4P intervention; and HR was 2.42 (95% CI, 2.02-2.91) for patients without any P4P interventions. The leading cause of death of the total diabetic nephropathy patient cohort was infectious diseases (34.32%) followed by cardiovascular diseases (17.12%), acute renal failure (1.50%), and malignant neoplasm of liver (1.40%).Because the earlier interventions have lasting long-term effects on the patient's prognosis regardless of disease course, an integrated early intervention plan is suggested in future care plan designs. The mechanisms regarding the effects of P4P intervention, such as health education on diet control, continuity of care, and practice guidelines and adherence, are the primary components of disease management programs.

Oral Administration of N-Acetyl-seryl-aspartyl-lysyl-proline Ameliorates Kidney Disease in Both Type 1 and Type 2 Diabetic Mice via a Therapeutic Regimen

Kidney fibrosis is the final common pathway of progressive kidney diseases including diabetic nephropathy. Here, we report that the endogenous antifibrotic peptide N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP), the substrate of angiotensin-converting enzyme (ACE), is an orally available peptide drug used to cure kidney fibrosis in diabetic mice. We utilized two mouse models of diabetic nephropathy, streptozotocin- (STZ-) induced type 1 diabetic CD-1 mice and type 2 diabetic nephropathy model db/db mice. Intervention with the ACE inhibitor imidapril, oral AcSDKP, or imidapril + oral AcSDKP combination therapy increased urine AcSDKP levels. AcSDKP levels were significantly higher in the combination group compared to those of the other groups. AcSDKP oral administration, either AcSDKP alone or in addition to imidapril, ameliorated glomerulosclerosis and tubulointerstitial fibrosis. Plasma cystatin C levels were higher in both models, at euthanasia, and were restored by all the treatment groups. The levels of antifibrotic miRs, such as miR-29 or let-7, were suppressed in the kidneys of both models; all treatments, especially the combination of imidapril + oral AcSDKP, restored the antifibrotic miR levels to a normal value or even higher. AcSDKP may be an oral antifibrotic peptide drug that would be relevant to combating fibroproliferative kidney diseases such as diabetic nephropathy.

May the fibrosis be with you: Is discoidin domain receptor 2 the receptor we have been looking for?

In a recent issue of Journal of Molecular and Cellular Cardiology, George et al. [1] identified discoidin domain receptor 2 (DDR2) as a positive modulator of collagen production in cardiac fibroblasts stimulated with angiotensin II (Ang II). DDR2 is a tyrosine kinase collagen receptor and is associated with pathological scarring of multiple organs; nevertheless, the functional role of DDR2 in the myocardium remains unclear. George et al. present evidence for the first time that Ang II induces cardiac fibrosis by enhancing DDR2 expression in cardiac fibroblasts via p38 mitogen activated protein kinase (p38 MAPK)-mediated activation of nuclear factor-κB (NF-κB).

Effects of combination of aliskiren and pentoxyfylline on renal function in the rat remnant kidney model of chronic renal failure

Objectives:

The aim was to investigate the nephroprotective effect of combination of aliskiren (ASK), a direct renin inhibitor and pentoxifylline (PTX), inhibitor of tumor necrotic factor-alpha (TNF-alpha), in rat remnant kidney model of chronic kidney disease (CKD).

Materials and Methods:

Nephrectomized (NPX) rats were treated with ASK (10 mg/kg, p.o.), PTX (100 mg/kg, p.o.), and combination of PTX + ASK once daily for 28 days. We have performed analysis of various renal injury parameters after 4 weeks of treatment.

Results:

Treatment with PTX, ASK and combination showed significant improvement in urea, creatinine and total protein in plasma when compared with vehicle treated group in NPX rats. ASK and combination of PTX + ASK elicited significant reduction in blood pressure but PTX alone did not produce blood pressure reduction. ASK treatment showed significant elevation in TNF-alpha, whereas PTX and ASK + PTX showed significant reduction in TNF-alpha in plasma. Histopathologically, the extent of the kidney injury was similar in NPX + vehicle and NPX + ASK-treated rats. PTX and ASK + PTX-treated group showed lesser extent of kidney injury. There was good correlation of mRNA expression levels of kidney injury molecule-1 and bradykinin B1 receptor data with histopathological findings in kidney samples and elevated TNF-alpha levels in plasma.

Conclusions:

We conclude that combination of PTX + ASK may be better therapeutic intervention for nephroprotection in CKD patients.

Renin Angiotensin System Blocker Fetopathy: A Midwest Pediatric Nephrology Consortium Report

OBJECTIVES

Fetuses continue to be exposed to renin angiotensin system (RAS) blockers despite their known teratogenicity and a black box warning. We hypothesized that fetopathy from in utero exposure to RAS blockers has a broader spectrum of clinical manifestations than described previously and that there are a variety of clinical scenarios leading to such exposures.

STUDY DESIGN

This was a retrospective study performed through the Midwest Pediatric Nephrology Consortium. Cases of RAS blocker fetopathy were identified, with determination of renal and extrarenal manifestations, timing of exposure, and the explanation for the fetal exposure.

RESULTS

Twenty-four cases were identified. RAS blocker exposure after the first trimester was associated with more severe renal manifestations. Chronic dialysis or kidney transplantation was required in 8 of 17 (47%) patients with RAS blocker exposure after the first trimester and 0 of 7 patients with exposure restricted to the first trimester (P = .05). Extrarenal manifestations, some not previously noted in the literature, included central nervous system anomalies (cystic encephalomalacia, cortical blindness, sensorineural hearing loss, arachnoid cysts) and pulmonary complications (pneumothorax, pneumomediastinum). RAS blocker exposure usually was secondary to absent or poor prenatal care or undiagnosed pregnancy.

CONCLUSION

RAS blocker fetopathy continues to be a cause of considerable morbidity, with more severe renal manifestations associated with exposure after the first trimester. A variety of significant extrarenal manifestations occur in these patients. Clinicians should emphasize the risk of fetopathy when prescribing RAS blockers to women of childbearing age.

Angiotensin-(1-7) administration benefits cardiac, renal and progenitor cell function in db/db mice

BACKGROUND AND PURPOSE

Diabetic patients are at an increased risk of cardiovascular disease, in part due to inflammation and oxidative stress. These two pathological mechanisms also affect other organs and cells including the kidneys and progenitor cells. Angiotensin-(1-7) [Ang-(1-7)] has previously been shown to counterbalance pathological effects of angiotensin II, including inflammation and oxidative stress. The aim of this study was to investigate the effects of short-term (2 weeks) Ang-(1-7) treatment on cardiovascular and renal function in a mouse model of type 2 diabetes (db/db).

EXPERIMENTAL APPROACH

Eight- to nine-week-old db/db mice were administered either vehicle, Ang-(1-7) alone, or Ang-(1-7) combined with an inhibitor (losartan, PD123319, A-779, L-NAME or icatibant) daily for 14 days.

KEY RESULTS

An improvement in physiological heart function was observed in Ang-(1-7)-treated mice. Ang-(1-7) also reduced cardiomyocyte hypertrophy, fibrosis and inflammatory cell infiltration of the heart tissue and increased blood vessel number. These changes were blocked by antagonists of the MAS1, AT2 and bradykinin receptors and inhibition of NO formation. Treatment with Ang-(1-7) reduced glomerular damage and oxidative stress in kidney tissue. Bone marrow and circulating endothelial progenitors, as well as bone marrow mesenchymal stem cells, were increased in mice treated with Ang-(1-7).

CONCLUSIONS AND IMPLICATIONS

Short-term Ang-(1-7) treatment of young db/db mice improved heart function and reduced kidney damage. Treatment also improved bone marrow and circulating levels of endothelial and mesenchymal stem cells. All of this may contribute to improved cardiovascular and renal function.

Hydrogen Sulfide: A Therapeutic Candidate for Fibrotic Disease?

Fibrotic diseases including chronic kidney disease, liver cirrhosis, idiopathic pulmonary fibrosis, and chronic disease account for 45% mortality in the developed countries and pose a great threat to the global health. Many great targets and molecules have been reported to be involved in the initiation and/or progression of fibrosis, among which inflammation and oxidative stress are well-recognized modulation targets. Hydrogen sulfide (H₂S) is the third gasotransmitter with potent properties in inhibiting inflammation and oxidative stress in various organs. Recent evidence suggests that plasma H₂S level is decreased in various animal models of fibrotic diseases and supplement of exogenous H₂S is able to ameliorate fibrosis in the kidney, lung, liver, and heart. This leads us to propose that modulation of H₂S production may represent a promising therapeutic venue for the treatment of a variety of fibrotic diseases. Here, we summarize and discuss the current data on the role and underlying mechanisms of H₂S in fibrosis diseases related to heart, liver, kidney, and other organs.

Interplay of vitamin D, erythropoiesis, and the renin-angiotensin system

For many years deficiency of vitamin D was merely identified and assimilated to the presence of bone rickets. It is now clear that suboptimal vitamin D status may be correlated with several disorders and that the expression of 1-α-hydroxylase in tissues other than the kidney is widespread and of clinical relevance. Recently, evidence has been collected to suggest that, beyond the traditional involvement in mineral metabolism, vitamin D may interact with other kidney hormones such as renin and erythropoietin. This interaction would be responsible for some of the systemic and renal effects evoked for the therapy with vitamin D. The administration of analogues of vitamin D has been associated with an improvement of anaemia and reduction in ESA requirements. Moreover, vitamin D deficiency could contribute to an inappropriately activated or unsuppressed RAS, as a mechanism for progression of CKD and/or cardiovascular disease. Experimental data on the anti-RAS and anti-inflammatory effects treatment with active vitamin D analogues suggest a therapeutic option particularly in proteinuric CKD patients. This option should be considered for those subjects that are intolerant to anti-RAS agents or, as add-on therapy, in those already treated with anti-RAS but not reaching the safe threshold level of proteinuria.

Combination therapy in chronic kidney disease?

The renin-angiotensin system (RAS) plays a fundamental role in preserving the circulation and yet, it may be injurious to heart and blood vessels and may also allow, and sometimes hasten, kidney disease progression. Thus, effective RAS inhibition may be a major pharmacologic necessity to control hypertension, to decrease cardiovascular complication, and to inhibit kidney disease progression. Unfortunately, the beneficial effects attained in the management of renal disease sometimes are incomplete. The reasons for these inadequate outcomes may include angiotensin escape or excessive local angiotensin production. Two pharmacologic strategies have been proposed to overcome this drawback including higher than recommended doses of RAS inhibitors and the combination of two different RAS inhibitors. However, three large studies have shown that these more intensive pharmacologic approaches should be treated with caution when applied to high-risk patients, as organ perfusion may fall to critical levels that may cause severe complications. Nevertheless, intensive RAS inhibition (including combination therapy) may be the sole alternative in patients with chronic kidney disease (CKD) in whom other therapeutics options have failed. In these cases, adequate precautions including close clinical and laboratory follow up should prevent major complications.

Effects of losartan on expression of monocyte chemoattractant protein-1 (MCP-1) in hyperuricemic nephropathy rats

The monocyte chemoattractant protein-1 (MCP-1) plays an important role in the pathogenesis of progression of renal failure. This is based on the observations done both in various animal models of renal damage and in different types of human renal disease. During the development of non-infectious kidney stones, crystals are formed and deposited on the kidneys and the kidneys are surrounded by monocytes/macrophages. We have proposed that in response to crystal exposure, renal epithelial cells produce chemokines, which attract the monocytes/macrophages to the sites of crystal deposition. In this study, we investigated the expression of MCP-1 protein by SD rats exposed to oxonic acid (OA). Our study showed that hyperuricemia accelerates renal progression via a mechanism linked to high MCP-1 which may mediate the inflammation reaction of renal diseases induced by hyperuricemia. Losartan may retard the progression of advanced renal dysfunction, and the mechanism was partly due to blocking of renal inflammation induced by the uric acid. Because the number of experiments performed here is very few, results must be confirmed by more extensive studies with a larger sample size.