Renal injury due to renin-angiotensin-aldosterone system activation of the transforming growth factor-beta pathway

Impact of Angiotensin Blockade on Development of Chronic Lung Allograft Dysfunction

Background: The renin-angiotensin-aldosterone system (RAAS) is responsible for a multitude of physiological functions, including immunological effects such as promotion of TGF-β and upregulation of IL-6 and IL-8 which are also implicated in the development of chronic lung allograft dysfunction (CLAD). Blockade of the RAAS pathway in pre-clinical models has demonstrated a decrease in these cytokines and pulmonary neutrophil recruitment. Objective: This study sought to evaluate whether use of RAAS inhibitor (RAASi) in lung transplant recipients impacted CLAD-free survival. Methods: In this retrospective, single-center study, 35 lung transplant recipients who received a RAASi post-transplant were compared to 70 lung transplant recipients not exposed to a RAASi and were followed for up to 5 years post-transplant. Results: The incidence of CLAD did not differ based on RAASi treatment (34.3% in RAASi vs 38.6%, P-value .668). This was confirmed with a multivariable Cox proportional hazards model with RAASi initiation as a time-varying covariate (RAASi hazard ratio of 1.01, P-value .986). Incidence of hyperkalemia and acute kidney injury were low in the RAASi group. Conclusions: This study demonstrated no association between post-transplant RAASi use and decreased risk of CLAD development. RAASi were also well tolerated in this patient population.

Therapeutic approaches and novel antifibrotic agents in renal fibrosis: A comprehensive review

Renal fibrosis (RF) is one of the underlying pathological conditions leading to progressive loss of renal function and end-stage renal disease (ESRD). Over the years, various therapeutic approaches have been explored to combat RF and prevent ESRD. Despite significant advances in understanding the underlying molecular mechanism(s), effective therapeutic interventions for RF are limited. Current therapeutic strategies primarily target these underlying mechanisms to halt or reverse fibrotic progression. Inhibition of transforming growth factor-β (TGF-β) signaling, a pivotal mediator of RF has emerged as a central strategy to manage RF. Small molecules, peptides, and monoclonal antibodies that target TGF-β receptors or downstream effectors have demonstrated potential in preclinical models. Modulating the renin-angiotensin system and targeting the endothelin system also provide established approaches for controlling fibrosis-related hemodynamic changes. Complementary to pharmacological strategies, lifestyle modifications, and dietary interventions contribute to holistic management. This comprehensive review aims to summarize the underlying mechanisms of RF and provide an overview of the therapeutic strategies and novel antifibrotic agents that hold promise in its treatment.

Role of platelet factor 4 in arteriovenous fistula maturation failure: What do we know so far?

The rate of arteriovenous fistula (AVF) maturation failure remains unacceptably high despite continuous efforts on technique improvement and careful pre-surgery planning. In fact, half of all newly created AVFs are unable to be used for hemodialysis (HD) without a salvage procedure. While vascular stenosis in the venous limb of the access is the culprit, the underlying factors leading to vascular narrowing and AVF maturation failure are yet to be determined. We have recently demonstrated that AVF non-maturation is associated with post-operative medial fibrosis and fibrotic stenosis, and post-operative intimal hyperplasia (IH) exacerbates the situation. Multiple pathological processes and signaling pathways are underlying the stenotic remodeling of the AVF. Our group has recently indicated that a pro-inflammatory cytokine platelet factor 4 (PF4/CXCL4) is upregulated in veins that fail to mature after AVF creation. Platelet factor 4 is a fibrosis marker and can be detected in vascular stenosis tissue, suggesting that it may contribute to AVF maturation failure through stimulation of fibrosis and development of fibrotic stenosis. Here, we present an overview of the how PF4-mediated fibrosis determines AVF maturation failure.

Metabolic implications of amino acid metabolites in chronic kidney disease progression: a metabolomics analysis using OPLS-DA and MBRole2.0 database

BACKGROUND

As chronic kidney disease (CKD) progresses, metabolites undergo diverse transformations. Nevertheless, the impact of these metabolic changes on the etiology, progression, and prognosis of CKD remains uncertain. Our objective is to conduct a metabolomics analysis to scrutinize metabolites and identify significant metabolic pathways implicated in CKD progression, thereby pinpointing potential therapeutic targets for CKD management.

METHODS

We recruited 145 patients with CKD and determined their mGFR by measuring the plasma iohexol clearance, whereupon we partitioned them into four groups based on their mGFR values. Non-targeted metabolomics analysis was conducted using UPLC-MS/MS assays. Differential metabolites were identified via one-way ANOVA, PCA, PLS-DA, and OPLS-DA analyses employing the MetaboAnalyst 5.0 platform. Ultimately, we performed differential metabolite pathway enrichment analysis, using both the MetaboAnalyst 5.0 platform and the MBRole2.0 database.

RESULTS

According to the findings of the MBRole2.0 and MetaboAnalyst 5.0 enrichment analysis, six amino acid metabolism pathways were discovered to have significant roles in the progression of CKD, with the glycine, serine, and threonine metabolism pathway being the most prominent. The latter enriched 14 differential metabolites, of which six decreased while two increased concomitantly with renal function deterioration.

CONCLUSIONS

The metabolic analysis unveiled that glycine, serine, and threonine metabolism plays a pivotal role in the progression of CKD. Specifically, glycine was found to increase while serine decreased with the deterioration of CKD.

Unraveling the relationship between the renin-angiotensin system and endometrial cancer: a comprehensive review

Endometrial cancer (EC), the most common adenocarcinoma, represents 90% of uterine cancer in women with an increased incidence of occurrence attributed to age, obesity, hypertension, and hypoestrogenism. Being the most common gynecological malignancy in women, it shows a relation with the activation of different components of the renin-angiotensin system (RAS), which is predominantly involved in maintaining blood pressure, salt, water, and aldosterone secretion, thereby playing a significant role in the etiology of hypertension. The components of the RAS, i.e., ACE-I, ACE-II, AT1R, AT2R, and Pro(renin) receptor, are widely expressed in both glandular and stromal cells of the endometrium, with varying levels throughout the different phases of the menstrual cycle. This causes the endometrial RAS to implicate angiogenesis, neovascularization, and cell proliferation. Thus, dysfunctioning of the endometrial RAS could predispose the growth and spread of EC. Interestingly, the increased expression of AngII, AGTR1, and AGTR2 showed advancement in the stages and progression of EC via the prorenin/ATP6AP2 and AngII/AGTR1 pathway. Therefore, this review corresponds to unraveling the relationship between the progression and development of endometrial cancer with the dysfunction in the expression of various components associated with RAS in maintaining blood pressure.

Diagnostic accuracy of using multiple cytokines to predict aldosterone-producing adenoma

Here, we aimed to study the important cytokines in plasma to identify the aldosterone-producing adenoma (APA). 19 unilateral primary aldosteronism (UPA) patients and 19 healthy people were divided into UPA group and Control group, and the serum of bilateral adrenal veins and inferior vena cava collected by adrenal blood sampling (AVS) in UPA patients and the serum from the healthy subjects were all used to detect multiple cytokines by Luminex immunoassays. Additionally, The UPA patients subjected to laparoscopic adrenalectomy were divided into different groups by pathological results for further study. According our results, IP-10, CXCL9 and RANTES were significantly higher in UPA group compared with control group, and the combination of the three cytokines have significant predictive power for predicting UPA, while the correlational analyses demonstrated that IP-10 and CXCL9 were positively correlated with BP and HR, while EGF was positively correlated with HDL. Additionally, IL-1b was suggested to be the most potential diagnostic biomarker to discriminate the APA and unilateral adrenal hyperplasia (UAH). The present findings might suggest a possibility of IP-10, CXCL9 and RANTES served as a sign to help UPA diagnosis and finally used to assist the diagnosis of APA, while IL-1b was suggested to be the most potential diagnostic biomarker to identify the APA from the UAH patients.

Retrieval of Renal Function After Renal Artery Stenting Improves Event-Free Survival in a Sub-group Analysis of the Cardiovascular Outcomes in Renal Atherosclerotic Lesions Trial

OBJECTIVE

The Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) Trial, a multicenter randomized controlled trial with 947 patients, concluded that there was no benefit of renal artery stenting (RAS) over medical therapy. However, patients with chronic kidney disease (CKD) were not analyzed separately in the CORAL trial. CKD is a risk factor for cardiovascular and renal morbidity. We hypothesized that improved renal function after RAS would be associated with increased long-term survival and a lower risk of cardiovascular and renal events in patients with CKD.

METHODS

This post hoc analysis of the CORAL Trial included 842 patients with CKD stages 2-4 at baseline who were randomized to optimal medical therapy alone (OMT; n= 432) or RAS plus OMT (RAS+OMT; n = 410). Patients were categorized as "responders" or "non-responders" based on change in estimated glomerular filtration rate (eGFR) from baseline to last follow-up (median 3.6 years, interquartile range 2.6-4.6 years). Responders were defined by a 20% or greater increase in eGFR from baseline; all others were non-responders. Event-free survival was defined as freedom from death and multiple cardiovascular and renal complications. Event-free survival was analyzed using the Kaplan-Meier method and log-rank test. Multivariable Cox proportional hazards regression analysis was used to identify independent predictors of event-free survival.

RESULTS

The RAS+OMT group had a higher proportion of patients with improved renal function (≥20% increase in eGFR over baseline), compared to the OMT group (25.6% vs. 17.1%; P = .003). However, event-free survival was no different for the two cohorts (P = .18 by log-rank test). Multivariable Cox proportional hazards regression analysis identified four variables that independently correlated with event-free survival for the stented cohort. Higher preoperative eGFR (Hazard Ratio [HR] = 0.98, 95% Confidence Interval [CI] 0.96-0.99; P = .002) and being a responder to stenting (HR = 0.49, 95% CI 0.26-0.95; P = .033) increased event-free survival, while history of congestive heart failure (HR 2.52, 95% CI 1.46-4.35; P < .001) and higher preoperative systolic BP (HR 1.02, 95% CI 1.01-1.03; P = .002) decreased event-free survival. Within the stented group, 105 of 410 patients (25.6%) were responders. Event-free survival was superior for responders, compared to non-responders (P=0.009 by log-rank test). The only independent preoperative negative predictor of improved renal function after stenting was diabetes (Odds Ratio 0.37, 95% CI 0.16-0.84; P = 0.017), which decreased the probability of improved renal function after RAS+OMT. A subset of patients (23.4%) after RAS had worsened renal function, but OMT alone produced an equivalent incidence of worsened renal function. Increased urine albumin/creatinine ratio was an independent predictor of worsened renal function after RAS.

CONCLUSIONS

CORAL participants who demonstrated improved kidney function after RAS+OMT demonstrated improved event-free survival. This finding reinforces the need for predictors of outcome to guide patient selection for RAS.

Eplerenone inhibits the macrophage-to-myofibroblast transition in rats with UUO-induced type 4 cardiorenal syndrome through the MR/CTGF pathway

Cardiovascular complications are the leading causes of death in patients with chronic kidney disease (CKD), accounting for approximately 50% of deaths. Despite significant advances in the understanding of cardiac disease due to CKD, the underlying mechanisms involved in many pathological changes have not been fully elucidated. In our previous study, we observed severe fibrosis in the contralateral kidney of a 6-month-old rat UUO model. In the present experiment, we also observed severe fibrosis in the hearts of rats subjected to UUO and the macrophage-to-myofibroblast transition (MMT). These effects were inhibited by the mineralocorticoid receptor (MR) blocker eplerenone. Notably, in vitro, aldosterone-activated MR induced the MMT and subsequently promoted the secretion of CTGF, the target of MR, from macrophages; these changes were inhibited by eplerenone. The CTGF also induced the MMT and both the aldosterone and CTGF-induced MMT could be alleviated by the CTGF blocker. In conclusion, our results suggest that targeting the MR/CTGF pathway to inhibit the MMT may be an effective therapeutic strategy for the treatment of cardiac fibrosis.

Diabetic Nephropathy: Pathogenesis to Cure

Diabetic nephropathy (DN) is a leading cause of end-stage renal disorder (ESRD). It is defined as the increase in urinary albumin excretion (UAE) when no other renal disease is present. DN is categorized into microalbuminuria and macroalbuminuria. Factors like high blood pressure, high blood sugar levels, genetics, oxidative stress, hemodynamic and metabolic changes affect DN. Hyperglycemia causes renal damage through activating protein kinase C (PKC), producing advanced end glycation products (AGEs) and reactive oxygen species (ROS). Growth factors, chemokines, cell adhesion molecules, inflammatory cytokines are found to be elevated in the renal tissues of the diabetic patient. Many different and new diagnostic methods and treatment options are available due to the increase in research efforts and progression in medical science. However, until now, no permanent cure is available. This article aims to explore the mechanism, diagnosis, and therapeutic strategies in current use for increasing the understanding of DN.

Efficacy and Safety of Rituximab in the Treatment of Idiopathic Membranous Nephropathy: A Meta-Analysis

Background

Primary membranous nephropathy (MN), sometimes referred to as idiopathic membranous nephropathy (IMN), is a kind of MN whose pathogenesis is yet unclear. According to research reports, the incidence of IMN is about 9.8-26.8%, and it is on the rise.

Methods

The computer retrieves eight databases to obtain controlled trials at home and abroad on the rituximab (RTX) actions in IMN management. After a rigorous literature quality evaluation, software called RevMan 5.3 was used for data analysis.

Results

This meta-analysis finally contained 8 papers. They were all regarded as controlled trials. Six studies reported serum creatinine (standardized mean difference [SMD]: -6.87; 95% CI: -14.09, 0.35; P = 0.062), ALB (SMD: 1.91; 95% CI: -0.31, 4.14; P = 0.092), and adverse reactions (OR: 0.56; 95% CI: 0.36, 0.90; P < 0.01), all of which were significantly higher in the test group than in the control group (OR: 1.37; 95% CI: 1.07, 1.76; P < 0.01).

Conclusion

The overall effective rate, serum creatinine, adverse effects, and ALB of this trial indicate that RTX may be beneficial for individuals with IMN, but further high-quality research is required to confirm these findings.

Angiotensin-converting Enzyme-2 (ACE2) Expression in Pediatric Liver Disease

The membrane protein angiotensin-converting enzyme-2 (ACE2) has gained notoriety as the receptor for severe acute respiratory syndrome coronavirus 2. Prior evidence has shown ACE2 is expressed within the liver but its function has not been fully discerned. Here, we utilized novel methodology to assess ACE2 expression in pediatric immune-mediated liver disease to better understand its presence in liver diseases and its role during infections such as COVID-19. We stained liver tissue with ACE2-specific immunofluorescent antibodies, analyzed via confocal microscopy. Computational deep learning-based segmentation models identified nuclei and cells, allowing the quantification of mean cellular and cytosolic immunofluorescent. Spatial transcriptomics provided high-throughput gene expression analysis in tissue to determine cellular composition for ACE2 expression. ACE2 plasma expression was quantified via enzyme-linked immunosorbent assay. High ACE2 expression was seen at the apical surface of cholangiocytes, with lower expression within hepatocyte cytosol and nonparenchymal cells (P<0.001). Children with liver disease had higher ACE2 hepatic expression than pediatric control tissue (P<0.001). Adult control tissue had higher expression than pediatric control (P<0.001). Plasma ACE2 was not found to be statistically different between samples. Spatial transcriptomics identified cell composition of ACE2-expressing spots containing antibody-secreting cells. Our results show ACE2 expression throughout the liver, with strongest localization to cholangiocyte membranes. Machine learning can be used to rapidly identify hepatic cellular components for histologic analysis. ACE2 expression in the liver may be increased in pediatric liver disease. Future work is needed to better understand the role of ACE2 in chronic disease and acute infections.

NK-cell dysfunction of acute myeloid leukemia in relation to the renin–angiotensin system and neurotransmitter genes

Acute myeloid leukemia (AML) is the most heterogeneous hematological disorder and blast cells need to fight against immune system. Natural killer (NK) cells can elicit fast anti-tumor responses in response to surface receptors of tumor cells. NK-cell activity is often impaired in the disease, and there is a risk of insufficient tumor suppression and progression. The aim of this study is to assess the dysfunction of NK cells in AML patients via focusing on two important pathways. We obtained single-cell RNA-sequencing data from NK cells obtained from healthy donors and AML patients. The data were used to perform a wide variety of approaches, including DESeq2 (version 3.9), limma (version 3.26.8) power differential expression analyses, hierarchical clustering, gene set enrichment, and pathway analysis. ATP6AP2, LNPEP, PREP, IGF2R, CTSA, and THOP1 genes were found to be related to the renin–angiotensin system (RAS) family, while DPP3, GLRA3, CRCP, CHRNA5, CHRNE, and CHRNB1 genes were associated with the neurotransmitter pathways. The determined genes are expressed within different patterns in the AML and healthy groups. The relevant molecular pathways and clusters of genes were identified, as well. The cross-talks of NK-cell dysfunction in relation to the RAS and neurotransmitters seem to be important in the genesis of AML.

Development of pharmacotherapies for abdominal aortic aneurysms

The cardiovascular field is still searching for a treatment for abdominal aortic aneurysms (AAA). This inflammatory disease often goes undiagnosed until a late stage and associated rupture has a high mortality rate. No pharmacological treatment options are available. Three hallmark factors of AAA pathology include inflammation, extracellular matrix remodeling, and vascular smooth muscle dysfunction. Here we discuss drugs for AAA treatment that have been studied in clinical trials by examining the drug targets and data present for each drug's ability to regulate the aforementioned three hallmark pathways in AAA progression. Historically, drugs that were examined in interventional clinical trials for treatment of AAA were repurposed therapeutics. Novel treatments (biologics, small-molecule compounds etc.) have not been able to reach the clinic, stalling out in pre-clinical studies. Here we discuss the backgrounds of previous investigational drugs in hopes of better informing future development of potential therapeutics. Overall, the highlighted themes discussed here stress the importance of both centralized anti-inflammatory drug targets and rigor of translatability. Exceedingly few murine studies have examined an intervention-based drug treatment in halting further growth of an established AAA despite interventional treatment being the therapeutic approach taken to treat AAA in a clinical setting. Additionally, data suggest that a potentially successful drug target may be a central inflammatory biomarker. Specifically, one that can effectively modulate all three hallmark factors of AAA formation, not just inflammation. It is suggested that inhibiting PGE2 formation with an mPGES-1 inhibitor is a leading drug target for AAA treatment to this end.

2-Methoxyestradiol TPGS Micelles Attenuate Cyclosporine A-Induced Nephrotoxicity in Rats through Inhibition of TGF-β1 and p-ERK1/2 Axis

The immunosuppressant cyclosporine A (CSA) has been linked to serious renal toxic effects. Although 2-methoxyestradiol (2ME) possesses a wide range of pharmacological abilities, it suffers poor bioavailability after oral administration. The purpose of this study was to evaluate the potential of 2ME loaded D-ɑ-tocopheryl polyethylene glycol succinate (TPGS) micelles to prevent CSA-induced nephrotoxicity in rats. A 2ME-TPGS was prepared and showed particle size of 44.3 ± 3.5 nm with good entrapment efficiency and spherical structures. Male Wistar rats were divided into 5 groups, namely: Control, Vehicle, CSA, CSA + 2ME-Raw, and CSA + 2ME-Nano. CSA was injected daily at a SC dose of 20 mg/kg. Both 2ME-Raw and 2ME-Nano were given daily at oral doses of 5 mg/kg. Treatments continued for three successive weeks. 2ME-TPGS exerted significant protective effects against CSA nephrotoxicity. This was evidenced in ameliorating deterioration of renal functions, attenuation of pathological changes in kidney tissues, exerting significant anti-fibrotic, antioxidant, and anti-inflammatory effects together with significant anti-apoptotic effects. Western blot analyses showed both 2ME-Raw and 2ME-Nano significantly inhibited protein expression of TGF-β1 and phospho-ERK (p-ERK). It was observed that 2ME-TPGS, in almost all experiments, exerted superior protective effects as compared with 2ME-Raw. In conclusion, 2ME loaded in a TPGS nanocarrier possesses significant protective activities against CSA-induced kidney injury in rats. This is attributable to 2ME anti-fibrotic, antioxidant, anti-inflammatory, and anti-apoptotic activities which are mediated at least partly by inhibition of TGF-β1/p-ERK axis.

The Diabetic Cardiorenal Nexus

The end-stage of the clinical combination of heart failure and kidney disease has become known as cardiorenal syndrome. Adverse consequences related to diabetes, hyperlipidemia, obesity, hypertension and renal impairment on cardiovascular function, morbidity and mortality are well known. Guidelines for the treatment of these risk factors have led to the improved prognosis of patients with coronary artery disease and reduced ejection fraction. Heart failure hospital admissions and readmission often occur, however, in the presence of metabolic, renal dysfunction and relatively preserved systolic function. In this domain, few advances have been described. Diabetes, kidney and cardiac dysfunction act synergistically to magnify healthcare costs. Current therapy relies on improving hemodynamic factors destructive to both the heart and kidney. We consider that additional hemodynamic solutions may be limited without the use of animal models focusing on the cardiomyocyte, nephron and extracellular matrices. We review herein potential common pathophysiologic targets for treatment to prevent and ameliorate this syndrome.

NMR-Based Metabolomics in Differential Diagnosis of Chronic Kidney Disease (CKD) Subtypes

Chronic Kidney Disease (CKD) is considered as a major public health problem as it can lead to end-stage kidney failure, which requires replacement therapy. A prompt and accurate diagnosis, along with the appropriate treatment, can delay CKD's progression, significantly. Herein, we sought to determine whether CKD etiology can be reflected in urine metabolomics during its early stage. This is achieved through the analysis of the urine metabolic fingerprint from 108 CKD patients by means of Nuclear Magnetic Resonance (NMR) spectroscopy metabolomic analysis. We report the first NMR-metabolomics data regarding the three most common etiologies of CKD: Chronic Glomerulonephritis (IgA and Membranous Nephropathy), Diabetic Nephropathy (DN) and Hypertensive Nephrosclerosis (HN). Analysis aided a moderate glomerulonephritis clustering, providing characterization of the metabolic fluctuations between the CKD subtypes and control disease. The urine metabolome of IgA Nephropathy reveals a specific metabolism, reflecting its different etiology or origin and is useful for determining the origin of the disease. In contrast, urine metabolomes from DN and HN patients did not reveal any indicative metabolic pattern, which is consistent with their fused clinical phenotype. These findings may contribute to improving diagnostics and prognostic approaches for CKD, as well as improving our understanding of its pathology.

Metabolomics as a tool for the early diagnosis and prognosis of diabetic kidney disease

Diabetic kidney disease (DKD) is one of the most prevalent comorbidities of diabetes mellitus and the leading cause of the end-stage renal disease (ESRD). DKD results from chronic exposure to hyperglycemia, leading to progressive alterations in kidney structure and function. The early development of DKD is clinically silent and when albuminuria is detected the lesions are often at advanced stages, leading to rapid kidney function decline towards ESRD. DKD progression can be arrested or substantially delayed if detected and addressed at early stages. A major limitation of current methods is the absence of albuminuria in non-albuminuric phenotypes of diabetic nephropathy, which becomes increasingly prevalent and lacks focused therapy. Metabolomics is an ever-evolving omics technology that enables the study of metabolites, downstream products of every biochemical event that occurs in an organism. Metabolomics disclosures complex metabolic networks and provide knowledge of the very foundation of several physiological or pathophysiological processes, ultimately leading to the identification of diseases' unique metabolic signatures. In this sense, metabolomics is a promising tool not only for the diagnosis but also for the identification of pre-disease states which would confer a rapid and personalized clinical practice. Herein, the use of metabolomics as a tool to identify the DKD metabolic signature of tubule interstitial lesions to diagnose or predict the time-course of DKD will be discussed. In addition, the proficiency and limitations of the currently available high-throughput metabolomic techniques will be discussed.

Renal biomarkers in cats: A review of the current status in chronic kidney disease

Serum creatinine concentration, the classical biomarker of chronic kidney disease (CKD) in cats, has important limitations that decrease its value as a biomarker of early CKD. Recently, serum symmetric dimethylarginine concentration was introduced as a novel glomerular filtration rate biomarker for the early detection of CKD in cats. However, data on its specificity are still limited. The limitations of conventional biomarkers and the desire for early therapeutic intervention in cats with CKD to improve outcomes have prompted the discovery and validation of novel renal biomarkers to detect glomerular or tubular dysfunction. Changes in the serum or urinary concentrations of these biomarkers may indicate early kidney damage or predict the progression of kidney before changes in conventional biomarkers are detectable. This review summarizes current knowledge on renal biomarkers in CKD in cats, a field that has progressed substantially over the last 5 years.

The Influence of ACE Insertion/Deletion Gene Polymorphism on the Risk of IgA Nephropathy: A Debatable Topic

Background

The connection between angiotensin-converting enzyme insertion/deletion (ACE I/D) gene polymorphisms and IgA nephropathy (IgAN) was conflicting. This pooled analysis was performed to explore this issue.

Methods

All eligible investigations were identified from various electronic databases, and the pooled analysis was evaluated using Stata software.

Results

27 studies with 2538 IgAN cases and 3592 controls were included. In overall subjects, ACE D allele, DD, and II genotype were associated with IgAN susceptibility (D vs. I: OR = 1.21, 95% CI: 1.10–1.32, P < 0.001; DD vs. ID + II: OR = 1.38, 95% CI: 1.20–1.60, P < 0.001; and II vs. DD + ID: OR = 0.83, 95% CI: 0.73–0.95, P=0.007). In Asian and Chinese patients, ACE I/D gene polymorphism was also correlated with IgAN vulnerability. Moreover, ACE D allele, DD, and II genotype were correlated with the progression of IgAN (D vs. I: OR = 1.37, 95% CI: 1.09–1.73, P=0.008; DD vs. ID + II: OR = 1.57, 95% CI: 1.06–2.31, P=0.024; and II vs. DD + ID: OR = 0.69, 95% CI: 0.49–0.99, P=0.045). Conversely, in Caucasian subjects, there was no link between ACE I/D gene polymorphism and the risk of IgAN.

Conclusion

ACE I/D gene polymorphism was correlated with the vulnerability and progression of IgAN in Asian and Chinese patients, and ACE D allele and DD homozygote genotype could be adverse factors for IgAN, while the II homozygote genotype could be an advantage factor. But, no significant association was found between ACE I/D gene polymorphism and IgAN in Caucasians.

Morphology and cyclooxygenase-2 and renin expression in the kidney of young spontaneously hypertensive rats

The kidneys play an important role in blood pressure regulation under normal and pathological conditions. We examined the histological changes and expression patterns of cyclooxygenase-2, renin, and (pro)renin receptor (PRR) in the renal cortex of prehypertensive spontaneously hypertensive rats (SHRs) and Wistar Kyoto rats (WKYs). Moreover, blood pressure and plasma urea, creatinine, angiotensin II, and angiotensin (1-7) levels were measured. The results showed that both strains had similar blood pressure and plasma urea and creatinine levels. The glomerular area, basement membrane thickness, collagen fiber content, and arterial wall thickness were greater in SHRs than in WKYs. By immunohistochemistry, cyclooxygenase-2 was localized in the macula densa and renal tubules of both strains. In SHRs, cyclooxygenase-2 was detected in a larger number of tubules, and the cortical expression of cyclooxygenase-2 was also increased. In both strains, PRR and renin were localized in the tubular epithelium and juxtaglomerular cells, respectively. In SHRs, PRR immunolocalization was increased in the glomerulus. The cortical expression of immature renin was markedly increased in SHRs compared to that in WKYs, while renin was significantly decreased. These changes were associated with higher plasma angiotensin II levels and lower plasma angiotensin (1-7) levels in SHRs. The results indicate that the kidneys of SHRs showed morphological changes and variations in cortical expression patterns of PRR, cyclooxygenase-2, and renin before the development of hypertension.

The mTOR inhibitor everolimus attenuates tacrolimus-induced renal interstitial fibrosis in rats

AIMS

Tacrolimus-a widely used immunosuppressant to prevent allograft rejection after organ transplantation-is nephrotoxic, increasing the risk of kidney injury accompanied by kidney fibrosis. The mammalian target of rapamycin (mTOR) inhibitor, everolimus, is an immunosuppressant used together with tacrolimus. Although mTOR signaling inhibition has been demonstrated to exhibit antifibrotic effects, the efficacy of everolimus against tacrolimus-induced kidney fibrosis has not been explored. Therefore, we evaluated the protective effects of everolimus against tacrolimus-induced kidney fibrosis.

MAIN METHODS

To assess antifibrotic effect of everolimus against tacrolimus-induced kidney fibrosis, male Wistar rats were subcutaneously administered vehicle or tacrolimus (5 mg/kg per day) and/or everolimus (0.2 mg/kg per day) for 2 weeks after bilateral renal ischemia for 45 min. The antifibrotic effect of everolimus was also assessed using rat kidney fibroblast cell line (NRK-49F).

KEY FINDINGS

Tacrolimus administration increased predominant profibrotic cytokine transforming growth factor-β (TGF-β) and fibroblast activation marker α-smooth muscle actin (α-SMA) expression and promoted the infiltration of macrophages in the kidney cortex, resulting in renal interstitial fibrosis in rats. Tacrolimus increased serum creatinine, blood urea nitrogen, kidney injury molecule-1 (KIM-1), and kidney injuries, such as tubular dilation, vacuolization, and glomerular atrophy. Everolimus administration attenuated tacrolimus-induced kidney fibrosis and the associated abnormalities. Everolimus strongly suppressed TGF-β-induced kidney fibroblast activation and extracellular matrix protein expression by the mTOR signaling inhibition.

SIGNIFICANCE

We demonstrated that everolimus attenuates tacrolimus-induced renal interstitial fibrosis in rats. Owing to its protective effect against tacrolimus-induced kidney fibrosis, everolimus may be useful when used concomitantly with tacrolimus.

Protective effect of dapagliflozin against cyclosporine A-induced nephrotoxicity

This study aimed to reveal the possible protective effect of dapagliflozin (DAPA) against acute kidney damage due to cyclosporine A (CsA). Thirty-two mice with an eight-week-old Balb\c albino strain were divided into four groups: control group, CsA group, DAPA group, and CsA + DAPA group. On day 9 of treatment, the animals were decapitated, and bilateral nephrectomy was performed. Oxidative stress and apoptosis were evaluated with caspase-3 activity, total oxidant status (TOS), total antioxidant status (TAS), malondialdehyde (MDA), myeloperoxidase (MPO), B-cell lymphoma-2 (Bcl-2), and Bcl-2-associated X protein (Bax) in the right kidney resection material. The left kidney resection material was evaluated histopathologically. CsA increased caspase-3 activity, Bax, TOS, MDA, TAS, and MPO levels, and the administration of DAPA with CsA significantly reduced this increase in levels (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, and p < 0.001, respectively). CsA decreased Bcl-2 levels, and administration of CsA + DAPA significantly increased Bcl-2 levels compared with only CsA administration (p < 0.001). Additionally, administration of DAPA significantly reduced the histopathological findings (parenchymal inflammation, hyaline cast formation, vacuolization, and lysis of renal tubular cells) caused by CsA. DAPA reduces oxidative stress, apoptosis, and histopathological damage caused by CsA in renal tissue.

Early Prediction of Tacrolimus-Induced Tubular Toxicity in Pediatric Refractory Nephrotic Syndrome Using Machine Learning

Background and Aims: Tacrolimus(TAC)-induced nephrotoxicity, which has a large individual variation, may lead to treatment failure or even the end-stage renal disease. However, there is still a lack of effective models for the early prediction of TAC-induced nephrotoxicity, especially in nephrotic syndrome(NS). We aimed to develop and validate a predictive model of TAC-induced tubular toxicity in children with NS using machine learning based on comprehensive clinical and genetic variables. Materials and Methods: A retrospective cohort of 218 children with NS admitted between June 2013 and December 2018 was used to establish the models, and 11 children were prospectively enrolled for external validation. We screened 47 clinical features and 244 genetic variables. The changes in urine N- acetyl- β-D- glucosaminidase(NAG) levels before and after administration was used as an indicator of renal tubular toxicity. Results: Five machine learning algorithms, including extreme gradient boosting (XGBoost), gradient boosting decision tree (GBDT), extremely random trees (ET), random forest (RF), and logistic regression (LR) were used for model generation and validation. Four genetic variables, including TRPC6 rs3824934_GG, HSD11B1 rs846910_AG, MAP2K6 rs17823202_GG, and SCARB2 rs6823680_CC were incorporated into the final model. The XGBoost model has the best performance: sensitivity 75%, specificity 77.8%, accuracy 77.3%, and AUC 78.9%. Conclusion: A pre-administration model with good performance for predicting TAC-induced nephrotoxicity in NS was developed and validated using machine learning based on genetic factors. Physicians can estimate the possibility of nephrotoxicity in NS patients using this simple and accurate model to optimize treatment regimen before administration or to intervene in time after administration to avoid kidney damage.

Negative regulators of TGF-β1 signaling in renal fibrosis; pathological mechanisms and novel therapeutic opportunities

Elevated expression of the multifunctional cytokine transforming growth factor β1 (TGF-β1) is causatively linked to kidney fibrosis progression initiated by diabetic, hypertensive, obstructive, ischemic and toxin-induced injury. Therapeutically relevant approaches to directly target the TGF-β1 pathway (e.g., neutralizing antibodies against TGF-β1), however, remain elusive in humans. TGF-β1 signaling is subjected to extensive negative control at the level of TGF-β1 receptor, SMAD2/3 activation, complex assembly and promoter engagement due to its critical role in tissue homeostasis and numerous pathologies. Progressive kidney injury is accompanied by the deregulation (loss or gain of expression) of several negative regulators of the TGF-β1 signaling cascade by mechanisms involving protein and mRNA stability or epigenetic silencing, further amplifying TGF-β1/SMAD3 signaling and fibrosis. Expression of bone morphogenetic proteins 6 and 7 (BMP6/7), SMAD7, Sloan-Kettering Institute proto-oncogene (Ski) and Ski-related novel gene (SnoN), phosphate tensin homolog on chromosome 10 (PTEN), protein phosphatase magnesium/manganese dependent 1A (PPM1A) and Klotho are dramatically decreased in various nephropathies in animals and humans albeit with different kinetics while the expression of Smurf1/2 E3 ligases are increased. Such deregulations frequently initiate maladaptive renal repair including renal epithelial cell dedifferentiation and growth arrest, fibrotic factor (connective tissue growth factor (CTGF/CCN2), plasminogen activator inhibitor type-1 (PAI-1), TGF-β1) synthesis/secretion, fibroproliferative responses and inflammation. This review addresses how loss of these negative regulators of TGF-β1 pathway exacerbates renal lesion formation and discusses the therapeutic value in restoring the expression of these molecules in ameliorating fibrosis, thus, presenting novel approaches to suppress TGF-β1 hyperactivation during chronic kidney disease (CKD) progression.

Signaling Pathways Involved in Diabetic Renal Fibrosis

Diabetic kidney disease (DKD), as the most common complication of diabetes mellitus (DM), is the major cause of end-stage renal disease (ESRD). Renal interstitial fibrosis is a crucial metabolic change in the late stage of DKD, which is always considered to be complex and irreversible. In this review, we discuss the pathological mechanisms of diabetic renal fibrosis and discussed some signaling pathways that are closely related to it, such as the TGF-β, MAPK, Wnt/β-catenin, PI3K/Akt, JAK/STAT, and Notch pathways. The cross-talks among these pathways were then discussed to elucidate the complicated cascade behind the tubulointerstitial fibrosis. Finally, we summarized the new drugs with potential therapeutic effects on renal fibrosis and listed related clinical trials. The purpose of this review is to elucidate the mechanisms and related pathways of renal fibrosis in DKD and to provide novel therapeutic intervention insights for clinical research to delay the progression of renal fibrosis.

The Genomic Response to TGF-β1 Dictates Failed Repair and Progression of Fibrotic Disease in the Obstructed Kidney

Tubulointerstitial fibrosis is a common and diagnostic hallmark of a spectrum of chronic renal disorders. While the etiology varies as to the causative nature of the underlying pathology, persistent TGF-β1 signaling drives the relentless progression of renal fibrotic disease. TGF-β1 orchestrates the multifaceted program of kidney fibrogenesis involving proximal tubular dysfunction, failed epithelial recovery or re-differentiation, capillary collapse and subsequent interstitial fibrosis eventually leading to chronic and ultimately end-stage disease. An increasing complement of non-canonical elements function as co-factors in TGF-β1 signaling. p53 is a particularly prominent transcriptional co-regulator of several TGF-β1 fibrotic-response genes by complexing with TGF-β1 receptor-activated SMADs. This cooperative p53/TGF-β1 genomic cluster includes genes involved in cellular proliferative control, survival, apoptosis, senescence, and ECM remodeling. While the molecular basis for this co-dependency remains to be determined, a subset of TGF-β1-regulated genes possess both p53- and SMAD-binding motifs. Increases in p53 expression and phosphorylation, moreover, are evident in various forms of renal injury as well as kidney allograft rejection. Targeted reduction of p53 levels by pharmacologic and genetic approaches attenuates expression of the involved genes and mitigates the fibrotic response confirming a key role for p53 in renal disorders. This review focuses on mechanisms underlying TGF-β1-induced renal fibrosis largely in the context of ureteral obstruction, which mimics the pathophysiology of pediatric unilateral ureteropelvic junction obstruction, and the role of p53 as a transcriptional regulator within the TGF-β1 repertoire of fibrosis-promoting genes.

Prevention of hemorrhage-induced renal vasoconstriction and hypoxia by angiotensin II type 1 receptor antagonism in pigs

Angiotensin II (ANG II) is a potent vasoconstrictor and may reduce renal blood flow (RBF), causing renal hypoxia. Hypotensive hemorrhage elevates plasma ANG II levels and is associated with increased risk of acute kidney injury. We hypothesized that ANG II antagonism prevents renal vasoconstriction and hypoxia caused by hemorrhage. Pigs were anaesthetized, surgically prepared, and randomized to intravenous losartan (1.5 mg·kg^-1·h^-1, n = 8) or an equal volume of intravenous Ringer acetate (vehicle-treated, n = 8). Hemorrhage was induced by continuous aspiration of blood to reach and sustain mean arterial pressure of <50 mmHg for 30 min. Plasma ANG II levels, hemodynamics and oxygenation were assessed 60 min prehemorrhage, 30-min after the start of hemorrhage, and 60 min posthemorrhage. Erythropoietin mRNA was analyzed in cortical and medullary tissue sampled at the end of the experiment. Hypotensive hemorrhage increased plasma ANG II levels and decreased RBF and oxygen delivery in both groups. Losartan-treated animals recovered in RBF and oxygen delivery, whereas vehicle-treated animals had persistently reduced RBF and oxygen delivery. In accordance, renal vascular resistance increased over time post hemorrhage in vehicle-treated animals but was unchanged in losartan-treated animals. Renal oxygen extraction rate and cortical erythropoietin mRNA levels increased in the vehicle group but not in the losartan group. In conclusion, ANG II antagonism alleviates prolonged renal vasoconstriction and renal hypoxia in a large animal model of hypotensive hemorrhage.

Prevalence of Low Level of Vitamin D Among COVID-19 Patients and Associated Risk Factors in India - A Hospital-Based Study

Background

The world is facing the most challenging pandemic in the 21st century. The developed and developing countries are facing the burden equally and no proven treatment options available. Recent studies suggest the plausibility of vitamin D therapy and prophylaxis for COVID-19, in the setting where the deficiency is more prevalent. Though evaluation of vitamin D status is not a routine in India, the present study focuses on the level of Vitamin d among COVID-19 patients.

Methods

The study was a hospital-based cross-sectional to find the status of vitamin D among COVID-19 patients in a tertiary care hospital, Patna, Bihar, India. The demographic, comorbidity data were taken, and the level of vitamin D was measured by a chemiluminescence-based immunoassay analyzer. The analysis compared the level of deficiency and insufficiency among different groups of COVID-19 patients. The role of DM and HTN as risk factors for mortality was compared.

Results

Among the total study participants (156), 42.31% were obese and 17.31% were severe as per clinical severity. The total prevalence of vitamin D deficiency was 58.97% and insufficiency was 89.1%. The prevalence was found high among male (61.02%), overweight (65.52%), and severe (62.96%) patients. The severity increases with advanced age (p<0.05) and important risk factors for mortality are DM, HTN, and advanced age.

Conclusion

The level of vitamin D can be assessed for the prognosis of COIVD-19 patients and help to modify the treatment protocol. Appropriate therapeutic/preventive intervention of vitamin D can alter the course and severity of COVID-19.

Antiproteinuric and Hyperkalemic Mechanisms Activated by Dual Versus Single Blockade of the RAS in Renovascular Hypertensive Rats

This study aimed to investigate the antiproteinuric and hyperkalemic mechanisms activated by dual renin-angiotensin system (RAS) blockade in renovascular hypertensive rats (2-kidney 1-clip model [2K-1C]). Six weeks after clipping the left renal artery or sham operation (2K), rats were treated with losartan, enalapril, or both drugs for two weeks. We found that 2K-1C rats displayed higher tail-cuff blood pressure (BP), increased non-clipped kidney Ang II concentration, and more pronounced urinary albumin excretion than 2K. BP was decreased by the treatment with either enalapril or losartan, and the combination of both drugs promoted an additional antihypertensive effect in 2K-1C rats. Renal Ang II content and albuminuria were reduced by either enalapril or losartan in monotherapy and restored to control levels by dual RAS blockade. Albuminuria in 2K-1C rats was accompanied by downregulation of the glomerular slit protein podocin, reduction of the endocytic receptors megalin and cubilin, and a marked decrease in the expression of the ClC-5 chloride channel, compared to 2K animals. Treatment with losartan and enalapril in monotherapy or combination increased the expression of podocin, cubilin, and ClC-5. However, only the combined therapy normalized podocin, cubilin, and ClC-5 protein abundance in the non-clipped kidney of 2K-1C rats. Renovascular hypertensive 2K-1C rats had a lower concentration of plasma potassium compared to 2K rats. Single RAS blockade normalized potassium plasma concentration, whereas 2K-1C rats treated with dual RAS blockade exhibited hyperkalemia. Hypokalemia in 2K-1C rats was accompanied by an increase in the cleaved activated forms of α-ENaC and γ-ENaC and the expression of β-ENaC. Combined RAS blockade but not monotherapy significantly reduced the expression of these ENaC subunits in 2K-1C rats. Indeed, double RAS blockade reduced the abundance of cleaved-α-ENaC to levels lower than those of 2K rats. Collectively, these results demonstrate that the antiproteinuric effect of dual RAS blockade in 2K-1C rats is associated with the restored abundance of podocin and cubilin, and ClC-5. Moreover, double RAS blockade-induced hyperkalemia may be due, at least partially, to an exaggerated downregulation of cleaved α-ENaC in the non-clipped kidney of renovascular hypertensive rats.

Common genetic variants and pathways in diabetes and associated complications and vulnerability of populations with different ethnic origins

Diabetes mellitus is a complex and heterogeneous metabolic disorder which is often pre- or post-existent with complications such as cardiovascular disease, hypertension, inflammation, chronic kidney disease, diabetic retino- and nephropathies. However, the frequencies of these co-morbidities vary among individuals and across populations. It is, therefore, not unlikely that certain genetic variants might commonly contribute to these conditions. Here, we identified four single nucleotide polymorphisms (rs5186, rs1800795, rs1799983 and rs1800629 in AGTR1, IL6, NOS3 and TNFA genes, respectively) to be commonly associated with each of these conditions. We explored their possible interplay in diabetes and associated complications. The variant allele and haplotype frequencies at these polymorphic loci vary among different super-populations (African, European, admixed Americans, South and East Asians). The variant alleles are particularly highly prevalent in different European and admixed American populations. Differential distribution of these variants in different ethnic groups suggests that certain drugs might be more effective in selective populations rather than all. Therefore, population specific genetic architectures should be considered before considering a drug for these conditions.

KLF4 initiates sustained YAP activation to promote renal fibrosis in mice after ischemia-reperfusion kidney injury

Acute renal injury (AKI) causes a long-term risk for progressing into chronic kidney disease (CKD) and interstitial fibrosis. Yes-associated protein (YAP), a key transcriptional cofactor in Hippo signaling pathway, shuttles between the cytoplasm and nucleus, which is required for the renal tubular epithelial cells repair in the acute phase of AKI. In this study we investigated the role of YAP during ischemia-reperfusion (IR)-induced AKI to CKD. Mice were subjected to left kidney IR followed by removal of the right kidney on the day before tissue harvests. Mouse shRNA expression adenovirus (Ad-shYAP or Ad-shKLF4) and mouse KLF4 expression adenovirus (Ad-KLF4) were delivered to mice by intrarenal injection on D7 after IR. We showed that the expression and nucleus distribution of YAP were persistently increased until the end of experiment (D21 after IR). The sustained activation of YAP in post-acute phase of AKI was accompanied by renal dysfunction and interstitial fibrosis. Knockdown of YAP significantly attenuated IR-induced renal dysfunction and decreased the expression of fibrogenic factors TGF-β and CTGF in the kidney. We showed that the expression of the transcription factor KLF4, lined on the upstream of YAP, was also persistently increased. Knockdown on KLF4 attenuated YAP increase and nuclear translocation as well as renal functional deterioration and interstitial fibrosis in IR mice, whereas KLF4 overexpression caused opposite effects. KLF4 increased the expression of ITCH, and ITCH facilitated YAP nuclear translocation via degrading LATS1. Furthermore, we demonstrated in primary cultured renal tubular cells that KLF4 bound to the promoter region of YAP and positively regulates YAP expression. In biopsy sample from CKD patients, we also observed increased expression and nuclear distribution of YAP. In conclusion, the activation of YAP in the post-acute phase of AKI is implicated in renal functional deterioration and fibrosis although it exhibits beneficial effect in acute phase. Reprogramming factor KLF4 is responsible for the persistent activation of YAP. Blocking the activation of KLF4-YAP pathway might be a way to prevent the transition of AKI into CKD.

TGF-β: The missing link in obesity-associated airway diseases?

Obesity is emerging as a global public health epidemic. The co-morbidities associated with obesity significantly contribute to reduced quality of life, mortality, and global healthcare burden. Compared to other asthma comorbidities, obesity prominently engenders susceptibility to inflammatory airway diseases such as asthma and chronic obstructive pulmonary disease (COPD), contributes to greater disease severity and evokes insensitivity to current therapies. Unlike in other metabolic diseases associated with obesity, the mechanistic link between obesity and airway diseases is only poorly defined. Transforming growth factor-β (TGF-β) is a pleiotropic inflammatory cytokine belonging to a family of growth factors with pivotal roles in asthma. In this review, we summarize the role of TGF-β in major obesity-associated co-morbidities to shed light on mechanisms of the diseases. Literature evidence shows that TGF-β mechanistically links many co-morbidities with obesity through its profibrotic, remodeling, and proinflammatory functions. We posit that TGF-β plays a similar mechanistic role in obesity-associated inflammatory airway diseases such as asthma and COPD. Concerning the role of TGF-β on metabolic effects of obesity, we posit that TGF-β has a similar mechanistic role in obesity-associated inflammatory airway diseases in interplay with different comorbidities such as hypertension, metabolic diseases like type 2 diabetes, and cardiomyopathies. Future studies in TGF-β-dependent mechanisms in obesity-associated inflammatory airway diseases will advance our understanding of obesity-induced asthma and help find novel therapeutic targets for prevention and treatment.

The Blockade of TACE-Dependent EGF Receptor Activation by Losartan-Erlotinib Combination Attenuates Renal Fibrosis Formation in 5/6-Nephrectomized Rats Under Vitamin D Deficiency

Chronic kidney disease (CKD) has been considered a major public health issue. In addition to cardiovascular diseases and infections, hypovitaminosis D has been considered a non-traditional aggravating factor for CKD progression. Interstitial fibrosis is a hallmark of CKD strongly correlated with deterioration of renal function. Transforming growth factor β (TGF-β) is the major regulatory profibrotic cytokine in CKD. Many injurious stimuli converge on the TGF-β pathway, which has context-dependent pleiotropic effects and interacts with several related renal fibrosis formation (RFF) pathways. Epidermal growth factor receptor (EGFR) is critically involved in CKD progression, exerting a pathogenic role in RFF associated with TGF-β-related fibrogenesis. Among others, EGFR pathway can be activated by a disintegrin and a metalloproteinase known as tumor necrosis factor α-converting enzyme (TACE). Currently no effective therapy is available to completely arrest RFF and slow the progression of CKD. Therefore, we investigated the effects of a double treatment with losartan potassium (L), an AT1R antagonist, and the tyrosine kinase inhibitor erlotinib (E) on the alternative pathway of RFF related to TACE-dependent EGFR activation in 5/6-nephrectomized rats under vitamin D deficiency (D). During the 90-day protocol, male Wistar rats under D, were submitted to 5/6 nephrectomy (N) on day 30 and randomized into four groups: N+D, no treatment; N+D+L, received losartan (50 mg/kg/day); N+D+E, received erlotinib (6 mg/kg/day); N+D+L+E received losartan+erlotinib treatment. N+D+L+E data demonstrated that the double treatment with losartan+erlotinib not only blocked the TACE-dependent EGF receptor activation but also prevented the expression of TGF-β, protecting against RFF. This renoprotection by losartan+erlotinib was corroborated by a lower expression of ECM proteins and markers of phenotypic alteration as well as a lesser inflammatory cell infiltrate. Although erlotinib alone has been emerging as a renoprotective drug, its association with losartan should be considered as a potential therapeutic strategy on the modulation of RFF.

Role of TGF-β signalling in PCOS associated focal segmental glomerulosclerosis

Research on polycystic ovarian syndrome (PCOS) remains intense due to its evolving impact on metabolism, reproduction and cardiovascular function. Changes in metabolic pathways can also significantly impact renal function including the development of Focal Segmental Glomerulosclerosis (FSGS), one of the most highly investigated renal diseases. In FSGS, scarring of the glomerulus vascular tuft damages the kidneys. Onset of FSGS may either be congenital or due to other disorders that affect the metabolism and normal kidney function. Both PCOS and FSGS appear to be associated with Transforming Growth Factor-β (TGF-β) signalling. Over-expression of TGF-β may be due to the activation of the thrombospondin 1 (TSP1) gene, which increases the probability of developing renal disorders. Higher androgen levels in PCOS may also cause podocyte damage thus directly impacting development of FSGS. This article reviews the role of TGF-β's in PCOS and FSGS and explores the inter-relationship between these two disorders.

Renal disorders in rheumatologic diseases: the spectrum is changing (part 2. Arthridides)

This review is devoted to rheumatologic diseases mainly characterized by different types of arthritis. They may involve also different organs, including the kidney, but renal disease is more frequently caused by the nephrotoxicity of drugs to relieve pain or to interfere with the pathophysiology of the underlying disease. Rheumatoid arthritis is the prototype of arthropathies. This autoimmune disease mainly attacks joints, tendons and ligaments but can also involve internal organs including the kidney. Psoriatic arthritis is a complex disease in which psoriasis, a chronic inflammatory disease, is associated with the development of peripheral arthritis or spondylitis. The disease or its treatment may lead to kidney complications. Gout is a form of inflammatory arthritis which is characterized by an increase in the serum uric acid deposits in and around the joints of the extremities, the so called tophi. The disease is often associated with a metabolic syndrome with diabetes, obesity, hypertension, and cardiovascular disease. Kidney injury is frequent. It may be caused by kidney stones, urinary tract obstruction, tubulointerstitial and vascular lesions leading to CKD and renal failure.

Alisol B 23-acetate attenuates CKD progression by regulating the renin-angiotensin system and gut-kidney axis

BACKGROUND

Increasing evidence suggests a link between the gut microbiome and various diseases including hypertension and chronic kidney disease (CKD). However, studies examining the efficacy of controlling blood pressure and inhibiting the renin-angiotensin system (RAS) in preventing CKD progression are limited.

METHODS

In the present study, we used 5/6 nephrectomised (NX) and unilateral ureteral obstructed (UUO) rat models and cultured renal tubular epithelial cells and fibroblasts to test whether alisol B 23-acetate (ABA) can attenuate renal fibrogenesis by regulating blood pressure and inhibiting RAS.

RESULTS

ABA treatment re-established dysbiosis of the gut microbiome, lowered blood pressure, reduced serum creatinine and proteinuria, suppressed expression of RAS constituents and inhibited the epithelial-to-mesenchymal transition in NX rats. Similarly, ABA treatment inhibited expression of collagen I, fibronectin, vimentin, α-smooth muscle actin and fibroblast-specific protein 1 at both mRNA and protein levels in UUO rats. ABA was also effective in suppressing activation of the transforming growth factor-β (TGF-β)/Smad3 and preserving Smad7 expression in both NX and UUO rats. In vitro experiments demonstrated that ABA treatment inhibited the Wnt/β-catenin and mitochondrial-associated caspase pathways.

CONCLUSION

These data suggest that ABA attenuated renal fibrosis through a mechanism associated with re-establishing dysbiosis of the gut microbiome and regulating blood pressure, and Smad7-mediated inhibition of Smad3 phosphorylation. Thus, we demonstrate ABA as a promising candidate for treatment of CKD by improving the gut microbiome and regulating blood pressure.

Prognostic value of urinary TGF-β1 in hemolytic uremic syndrome: A pilot study

BACKGROUND

Transforming growth factor β1 (TGF-β1) is the main profibrotic cytokine. Its urinary excretion reflects intrarenal production; thus, we conjectured that it is elevated during hemolytic uremic syndrome related to Shiga-toxin-producing Escherichia coli (STEC-HUS). In this pilot study, we explored the ability of baseline TGF-β1 excretion (exposure variable) to predict renal prognosis at 6 months (outcome variable). In a secondary investigation, we compared changes in cytokine levels during the study period between patients with opposite renal outcomes.

METHODS

Urinary TGF-β1 concentrations were measured prospectively in 24 children with STEC-HUS on admission, and at 15, 30, 60, 90, and 180 days. Normal values were obtained from 20 healthy subjects.

RESULTS

Baseline TGF-β1 concentrations predicted renal outcomes with an area under the curve of 1 (95%CI 0.85-1; sensitivity 100%, specificity 100%) with the best cutoff level >293.7 pg/mg uCr. All patients with high TGF-β1 levels developed persistent renal impairment, unlike none with low concentrations (4/4 vs. 20/0 respectively, P = 0.0001). The latter had higher cytokine levels (P < 0.05) at each time point without reaching normal concentrations (<45 pg/mg uCr).

CONCLUSIONS

Baseline urinary TGF-β1 levels accurately predicted short-term renal outcomes in STEC-HUS children, and cytokine excretion during the first 6 months after diagnosis was higher among those with worse evolution. Larger studies are needed to validate these findings.

Mangiferin Alleviates Renal Interstitial Fibrosis in Streptozotocin-Induced Diabetic Mice through Regulating the PTEN/PI3K/Akt Signaling Pathway

Renal interstitial fibrosis is considered to be the typical manifestation of diabetic nephropathy (DN). Mangiferin has shown positive effect on the prevention or treatment of diabetes and its complications. The aim of this study was to explore the inhibitive effect and mechanism of mangiferin on renal interstitial fibrosis in diabetic mice. Streptozotocin- (STZ-) induced diabetic mice were treated with mangiferin (15, 30, and 60 mg/kg/d) for 4 weeks. The morphology of kidneys was observed by Masson's trichrome staining, and the biochemical parameters (fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), blood urea nitrogen (BUN), serum creatinine (SCr), and urine protein) were determined by kits. In addition, the levels of inflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin- (IL-) 6, and IL-1β), antioxidant enzymes (SOD, CAT, and GSH-Px), MDA, and ROS were assessed. Furthermore, the expressions of fibronectin (FN), collagen I (Col I), and α-SMA were measured by immunohistochemistry. Regulations of TGF-β1 and the PTEN/PI3K/Akt pathway were detected by Western blotting. Treatment with mangiferin significantly ameliorated renal dysfunction in diabetic mice, as evidenced by the increase in body weight and decreases in FBG, TG, TC, BUN, SCr, urine protein, and the kidney to body weight ratio (KW/BW). Furthermore, mangiferin treatment prevented renal interstitial fibrosis evidenced by decreases in the positive expression of FN, Col I, and α-SMA, in comparison with morphological changes in the renal tissue. Meanwhile, mangiferin increased antioxidant enzymes, reduced the TNF-α, IL-6, and IL-1β, as well as MDA and ROS. Additionally, mangiferin administration also downregulated TGF-β1, upregulated PTEN, and decreased the phosphorylation of both PI3K and Akt. These findings demonstrate that mangiferin may reduce inflammation and oxidative stress in DN, thereby inhibiting the renal interstitial fibrosis by reducing the TGF-β1-mediated elevation of Col I, FN, and α-SMA through the PTEN/PI3K/Akt pathway.

Overexpression of microRNA-21 mediates Ang II-induced renal fibrosis by activating the TGF-β1/Smad3 pathway via suppressing PPARα

Angiotensin II (Ang II) is an important profibrotic factor, and the tumor-promoting microRNA miR-21 was recently linked to fibrotic disorders. We aimed to investigate whether and how miR-21 mediates Ang II-induced renal fibrosis. In renal tubular epithelial cells, Ang II upregulated miR-21 and fibrosis-related indicators but decreased PPARα expression. miR-21 overexpression promoted PPARα downregulation, activated the TGF-β1/Smad3 pathway and induced fibrogenesis, while miR-21 suppression exerted opposite effects. In Ang II-treated cells, reduced PPARα expression, TGF-β1/Smad3 pathway activation and fibrogenesis were all exacerbated by miR-21 upregulation but alleviated by miR-21 inhibition. The dual-luciferase assay confirmed PPARα as the target of miR-21. PPARα silencing alone could overactivate the TGF-β1/Smad3 pathway in the presence or absence of Ang II. Importantly, the regulatory effects of miR-21 knockdown and the angiotensin type 1 receptor blocker losartan alone or in combination on the PPARα/TGF-β1/Smad3 pathway in Ang II-treated cells were almost the same. More crucially, PPARα restoration abolished the profibrotic effect of miR-21 overexpression. In addition, inhibiting miR-21 in Ang II-treated mice effectively ameliorated the abnormally activated PPARα/TGF-β1/Smad3 pathway, albuminuria, and renal fibrosis without lowering blood pressure. These results demonstrated that miR-21 extensively mediates Ang II-induced kidney fibrosis via amplifying the TGF-β1/Smad3 pathway by targeting PPARα.

Effect of (-)-epicatechin on the modulation of progression markers of chronic renal damage in a 5/6 nephrectomy experimental model

Aims

To evaluate the effects of (-)-epicatechin (Epi) in the progression of kidney damage.

Material and methods

We assessed the effects of Epi [0.01-20 mg/kg of body weight/day] during 14 days, in a 5/6 nephrectomy model in mice.

Key findings

Nephrectomy-induced systolic arterial hypertension was significantly reduced in a dose dependent manner with Epi treatment. Increased serum creatinine and urea were reduced almost to normal values. The concentration of tetrahydrobiopterin (BH4), used as subrogate of endothelial dysfunction, decreased in nephrectomyzed animals, Epi treatment increased BH4 levels almost reaching normal values. The expression of angiotensin II receptor (AT₁-R) and NADPH oxidase-4 (NOX-4) and 3-nitrotyrosine levels increased with nephrectomy and were reduced with Epi treatment. Renal tissue morphology in the remaining tissue was conserved with Epi treatment in a dose dependent manner.

Significance

Chronic kidney disease (CKD) is an independent cardiovascular risk factor associated with a mortality rate 10 to 20 times higher than that of the general population. High blood pressure, endothelial dysfunction and oxidative stress are important factors determining kidney damage progression. Findings of this study indicate that Epi is able to counteract the deleterious effects of subtotal nephrectomy and the structural and functional changes in the remnant kidney tissue, decreasing the progression of CKD. These results warrant the possibility of implement clinical trials to limit the progression of CKD in humans.

Angiotensins and rheumatoid arthritis

At present, the role of the renin-angiotensin system (RAS) in regulating the cardiovascular system and maintaining water and electrolyte homeostasis has been well studied. However, over the past decades, new components of the RAS have been identified, suggesting a wider range of its potential effects on the body. It is of fundamentally importance for rheumatologists to affect inflammation, including rheumatoid inflammation, through blockade of angiotensin (AT) II formation via the effects of AT 1–7 and angiotensin-converting enzyme inhibitors, as well as through suppression of angiogenesis, primarily by reducing the production of endothelial growth factor. The organ-protective and antiinflammatory potential of drugs that reduce the production of AT, which has been proven in in vitro and in vivo experiments, allows us to consider them as first-line angiotropic agents in patients with rheumatoid arthritis, especially in the presence of concomitant hypertension and/or nephropathy.

Biomarkers of Atrial Fibrillation in Metabolic Syndrome

Whether the increased atrial fibrillation (AF) risk in metabolic syndrome (MetS) patients is due to the syndrome as a whole or simply the sum of the risks of its individual component parts is still obscure. These two clinical entities share many pathophysiological links and thus distinction between a casual observation and a significant association is difficult. Biomarkers associated with pathogenesis of AF in the context of MetS have the ability to refine future risk prediction. In the present review we identify circulating substances that could be regarded as potential biomarkers for prediction of incident AF, or of cardiovascular events in the setting of AF in patients with MetS. Cardiac myocyte injury and stress markers (troponin and natriuretic peptides), markers of renal function (glomeral filtration rate, cystatin-C), and inflammation markers/mediators (interleukin- 6, CRP) are promising biomarkers of patients with AF and MetS.

Short-term dexamethasone treatment transiently, but not permanently, attenuates fibrosis after acute-to-chronic kidney injury

Background

Acute kidney injury (AKI) is an underestimated, yet important, risk factor for the development of chronic kidney disease (CKD). Persistence of inflammation after a renal ischemic injury has been observed, both in experimental models and patients, and is thought to be an important mechanisms underlying progression of acute-to-chronic renal injury. Temporary suppression of inflammation immediately after AKI might therefore be a good first-line therapeutic strategy towards a better long term outcome.

Methods

Male C57Bl/6 J mice (Charles River, 10–12 weeks of age) underwent warm (36 °C body temperature) unilateral ischemia-reperfusion of the kidney for 21 min, after which treatment with intraperitoneal injection of the corticosteroid dexamethasone (10 mg/kg) was initiated for 3 weeks. Both at that time point and after an additional 3 week post-treatment follow up period, fibrosis was quantified by collagen I gene expression and immunostaining, as well as gene expression analysis of fibrosis-related genes Tgfβ, Ccn2 (Ctgf), Pai-1 and Ccn3. Furthermore, inflammation was evaluated by Tnfα gene expression and protein expression of the F4/80 macrophage marker and the α-SMA fibroblast marker. Lastly, renal histopathology was quantified by a morphometric analysis of the tubulointerstitial area.

Results

Treatment with dexamethasone attenuated development of fibrosis, as evidenced by reduced collagen I gene expression and immunostaining, in combination with reduced gene expression of the pro-fibrotic Ccn2 and increased expression of the anti-fibrotic Ccn3. The effects of dexamethasone on renal fibrosis persisted during the 3 week follow up period, as evidenced by stagnation of collagen I deposition in the ischemic kidney, in contrast to vehicle-treatment, where progression of fibrosis was observed. However, expression levels of the pro-fibrotic genes re-approached those of vehicle-treated injured kidneys suggesting that the effects of dexamethasone on fibrosis beyond the treatment period are temporary.

Conclusion

A short term anti-inflammatory therapy with dexamethasone only transiently attenuates ischemia induced fibrosis. Prolonged or persistent anti-inflammatory treatment seems warranted to achieve long term benefit.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1151-7) contains supplementary material, which is available to authorized users.

Natural products for the prevention and treatment of kidney disease

BACKGROUND

Chronic kidney disease (CKD) is one of the common causes resulting in a high morbidity and mortality. Renal fibrosis is the main pathological features of CKD. Natural products have begun to gain widely popularity worldwide for promoting healthcare and preventing CKD, and have been used as a conventional or complementary therapy for CKD treatment.

PURPOSE

The present paper reviewed the therapeutic effects of natural products on CKD and revealed the molecular mechanisms of their anti-fibrosis.

METHODS

All the available information on natural products against renal fibrosis was collected via a library and electronic search (using Web of Science, Pubmed, ScienceDirect, Splinker, etc.).

RESULTS

Accumulated evidence demonstrated that natural products exhibited the beneficial effects for CKD treatment and against renal fibrosis. This review presents an overview of the molecular mechanism of CKD and natural products against renal fibrosis, followed by an in-depth discussion of their molecular mechanism of natural products including isolated compounds and crude extracts against renal fibrosis in vitro and in vivo. A number of isolated compounds have been confirmed to retard renal fibrosis.

CONCLUSION

The review provides comprehensive insights into pathophysiological mechanisms of CKD and natural products against renal fibrosis. Particular challenges are presented and placed within the context of future applications of natural products against renal fibrosis.

Tea Polypeptide Ameliorates Diabetic Nephropathy through RAGE and NF-κB Signaling Pathway in Type 2 Diabetes Mice

Diabetic nephropathy (DN) is a major complication of type 2 diabetes (T2D), which is a key determinant of mortality in diabetic patients. Developing new therapeutic drugs which can not only control T2D but also prevent the development of DN is of great significance. We studied the therapeutic potential of Cuiyu tea polypeptides (TP), natural bioactive peptides isolated from a type of green tea, against DN and its underlying molecular mechanisms. TP (1000 mg/kg bw/day, p.o.) administration for 5 weeks significantly reduced the fasting blood glucose by 52.04 ± 9.23% in the high fat diet/streptozocin (HFD/STZ)-induced (30 mg/kg bw) diabetic mice. Compared to the model group, the serum insulin level of the TP group was decreased by 25.54 ± 6.06%, while at the same time, the HOMA-IR, HOMA-IS, and lipid levels showed different degrees of recovery ( p < 0.05). Moreover, in TP group mice the total urinary protein, creatinine, and urine nitrogen, all which can reflect the damage degree of the glomerular filtration function to a certain extent, dramatically declined by 34.51 ± 2.65%, 42.24 ± 15.24%, and 80.30 ± 6.01% compared to the model group, respectively. Mechanistically, TP stimulated the polyol PKCζ/JNK/NF-κB/TNF-α/iNOS and AGEs/RAGE/TGF-β1 pathways, upregulated the expression of podocin in the glomeruli, and decreased the release of pro-inflammatory cytokines. These results strongly indicate the therapeutic potential of TP against DN.

Aberrant DNA methylation of Tgfb1 in diabetic kidney mesangial cells

Epigenetic modulation may underlie the progression of diabetic nephropathy (DN). Involvement of TGFB1 in mesangial fibrosis of DN led us to hypothesize that Tgfb1 DNA demethylation contributes to progression of DN. In primary mesangial cells from diabetic (db/db) mouse kidneys, demethylation of Tgfb1 DNA and upregulation of Tgfb1 mRNA progressed simultaneously. USF1 binding site in Tgfb1 promoter region were demethylated, and binding of USF1 increased, with decreased binding of DNMT1 in db/db compared with control. Given downregulation of Tgfb1 expression by folic acid, antioxidant Tempol reversed DNA demethylation, with increased and decreased recruitment of DNMT1 and USF1 to the promoter, resulting in decreased Tgfb1 expression in db/db mice. Addition of H₂O₂ to mesangial cells induced DNA demethylation and upregulated Tgfb1 expression. Finally, Tempol attenuated mesangial fibrosis in db/db mice. We conclude that aberrant DNA methylation of Tgfb1 due to ROS overproduction play a key to mesangial fibrosis during DN progression.

Sex dimorphism in ANGII-mediated crosstalk between ACE2 and ACE in diabetic nephropathy

Angiotensin-converting enzyme (ACE) and ACE2 play a critical role in the renin-angiotensin system (RAS) by altering angiotensin II (ANGII) levels, thus governing its deleterious effects. Both enzymes are altered by sex and diabetes, and play an important role in the development of diabetic nephropathy (DN). Importantly, previous evidence in diabetic and ACE2-deficient (ACE2KO) males suggest a sex-dependent crosstalk between renal ACE and ACE2. In the present work, we aimed to study the sex-specific susceptibility to diabetes and direct infusion of ANGII in kidney disease progression, with a special focus on its link to ACE2 and ACE. In our mouse model, ANGII promoted hypertension, albuminuria, reduced glomerular filtration, and glomerular histological alterations. ANGII adverse effects were accentuated by diabetes and ACE2 deficiency, in a sex-dependent fashion: ACE2 deficiency accentuated ANGII-induced hypertension, albuminuria, and glomerular hypertrophy in diabetic females, whereas in diabetic males exacerbated ANGII-mediated glomerular hypertrophy, mesangial expansion, and podocyte loss. At the molecular level, ANGII downregulated renal ACE gene and enzymatic activity levels, as well as renin gene expression in ACE2KO mice. Interestingly, male sex and diabetes accentuated this effect. Here we show sex dimorphism in the severity of diabetes- and ANGII-related renal lesions, and demonstrate that ACE2- and ACE-related compensatory mechanisms are sex-specific. Supporting our previous findings, the modulation and ANGII-mediated crosstalk between ACE2 and ACE in DN progression was more evident in males. This work increases the understanding of the sex-specific role of ACE2 and ACE in DN, reinforcing the necessity of more personalized treatments targeting RAS.

Bone mesenchymal stem cells pretreated with erythropoietin enhance the effect to ameliorate cyclosporine A-induced nephrotoxicity in rats

An increasing number of experiments and clinical trials have demonstrated the safety, feasibility, and efficacy of mesenchymal stem cells (MSCs)-based therapies for the treatment of various diseases. The main drawbacks of MSC therapy are the lack of specific homing after systemic infusion and early death of injected cells because of the injury micro-environment. We pretreated bone mesenchymal stem cells (BMSCs) with erythropoietin (EPO) to investigate their positive effect on cyclosporine A (CsA)-induced nephrotoxicity. BMSCs were incubated with different concentrations of EPO (10, 100, 500, and 1000 IU/mL) for 24 and 48 h, and their proliferation rate, cytoskeletal morphology, migration ability, and the expression of CXCR4 were evaluated to determine the optimal pretreatment conditions. To investigate the therapeutic effects of BMSCs pretreated with EPO in CsA-induced nephrotoxicity, we established CsA-induced in vitro and in vivo toxicity models. In our in vitro study, preconditioning of BMSCs with 500 IU/mL EPO for 48 h induced a marked increase in their proliferation rate, cytoskeletal rearrangement, migration in the scrape-healing assay, and migration toward injured HK2 cells. In vivo, EPO-BMSCs showed higher ability to improve renal function than BMSCs, and in CsA-induced rats treated with EPO-BMSCs, interstitial lymphocyte infiltration, tubular swelling, necrosis, and interstitial fibrosis decreased. We demonstrated that pretreatment with 500 IU/mL EPO before infusion markedly increased the homing ability of BMSCs, and obviously ameliorate CsA-induced nephrotoxicity in rats.