The role of vascular endothelial growth factor (VEGF) in renal pathophysiology

Neuroprotective effects of resveratrol on retinal ganglion cells in glaucoma in rodents: A narrative review

Glaucoma, an irreversible optic neuropathy, primarily affects retinal ganglion cells (RGC) and causes vision loss and blindness. The damage to RGCs in glaucoma occurs by various mechanisms, including elevated intraocular pressure, oxidative stress, inflammation, and other neurodegenerative processes. As the disease progresses, the loss of RGCs leads to vision loss. Therefore, protecting RGCs from damage and promoting their survival are important goals in managing glaucoma. In this regard, resveratrol (RES), a polyphenolic phytoalexin, exerts antioxidant effects and slows down the evolution and progression of glaucoma. The present review shows that RES plays a protective role in RGCs in cases of ischemic injury and hypoxia as well as in ErbB2 protein expression in the retina. Additionally, RES plays protective roles in RGCs by promoting cell growth, reducing apoptosis, and decreasing oxidative stress in H2O2-exposed RGCs. RES was also found to inhibit oxidative stress damage in RGCs and suppress the activation of mitogen-activated protein kinase signaling pathways. RES could alleviate retinal function impairment by suppressing the hypoxia-inducible factor-1 alpha/vascular endothelial growth factor and p38/p53 axes while stimulating the PI3K/Akt pathway. Therefore, RES might exert potential therapeutic effects for managing glaucoma by protecting RGCs from damage and promoting their survival.

Prevalence and management of proteinuria associated with vascular endothelial growth factor receptor-targeted tyrosine kinase inhibitor treatment in advanced renal cell carcinoma, hepatocellular carcinoma, and thyroid cancer

Vascular endothelial growth factor receptor-targeted tyrosine kinase inhibitors (VEGFR-TKIs) are often used for treatment of several types of cancer; however, they are associated with an increased risk of proteinuria, sometimes leading to treatment discontinuation. We searched PubMed and Scopus to identify clinical studies examining the incidence and risk factors for proteinuria caused by VEGFR-TKIs in patients with renal cell carcinoma, thyroid cancer, and hepatocellular carcinoma. The global incidence of proteinuria ranged from 6% to 34% for all grades of proteinuria, and from 1% to 10% for grade ≥3 proteinuria. The incidence of proteinuria did not differ significantly by cancer type, but in all three cancer types, there was a trend toward a higher incidence of proteinuria with lenvatinib than with other VEGFR-TKIs. In terms of risk factors, the incidence of proteinuria was significantly higher among Asians (including Japanese) compared with non-Asian populations. Other risk factors included diabetes mellitus, hypertension, and previous nephrectomy. When grade 3/4 proteinuria occurs, patients should be treated according to the criteria for dose reduction or withdrawal specified for each drug. For grade 2 proteinuria, treatment should be continued when the benefits outweigh the risks. Referral to a nephrologist should be considered for symptoms related to decreased renal function or when proteinuria has not improved after medication withdrawal. These management practices should be implemented universally, regardless of the cancer type.

The potential mechanisms underlying the modulating effect of perirenal adipose tissue on hypertension: Physical compression, paracrine, and neurogenic regulation

Hypertension, a prevalent global cardiovascular disease, affects approximately 45.4 % of adults worldwide. Despite advances in therapy, hypertension continues to pose a significant health risk due to inadequate management. It has been established that excessive adiposity contributes majorly to hypertension, accounting for 65 to 75 % of primary cases. Fat depots can be categorised into subcutaneous and visceral adipose tissue based on anatomical and physiological characteristics. The metabolic impact and the risk of hypertension are determined more significantly by visceral fat. Perirenal adipose tissue (PRAT), a viscera enveloping the kidney, is known for its superior vascularisation and abundant innervation. Although traditionally deemed as a mechanical support tissue, recent studies have indicated its contributing potential to hypertension. Hypertensive patients tend to have increased PRAT thickness compared to those without, and there is a positive correlation between PRAT thickness and elevated systolic blood pressure. This review encapsulates the anatomical characteristics and biogenesis of PRAT. We provide an overview of the potential mechanisms where PRAT may modulate blood pressure, including physical compression, paracrine effects, and neurogenic regulation. PRAT has become a promising target for hypertension management, and continuous effort is required to further explore the underlying mechanisms.

Ocular and systemic vascular endothelial growth factor ligand inhibitor use and nephrotoxicity: an update

Tumor growth is intricately linked to the process of angiogenesis, with a key role played by vascular endothelial growth factor (VEGF) and its associated signaling pathways. Notably, these pathways also play a pivotal "housekeeping" role in renal physiology. Over the past decade, the utilization of VEGF signaling inhibitors has seen a substantial rise in the treatment of diverse solid organ tumors, diabetic retinopathy, age-related macular degeneration, and various ocular diseases. However, this increased use of such agents has led to a higher frequency of encountering renal adverse effects in clinical practice. This review comprehensively addresses the incidence, pathophysiological mechanisms, and current evidence concerning renal adverse events associated with systemic and intravitreal antiangiogenic therapies targeting VEGF-A and its receptors (VEGFR) and their associated signaling pathways. Additionally, we briefly explore strategies for mitigating potential risks linked to the use of these agents and effectively managing various renal adverse events, including but not limited to hypertension, proteinuria, renal dysfunction, and electrolyte imbalances.

Central role of podocytes in mediating cellular cross talk in glomerular health and disease

Podocytes are highly specialized epithelial cells that surround the capillaries of the glomeruli in the kidney. Together with the glomerular endothelial cells, these postmitotic cells are responsible for regulating filtrate from the circulating blood with their organized network of interdigitating foot processes that wrap around the glomerular basement membrane. Although podocyte injury and subsequent loss is the hallmark of many glomerular diseases, recent evidence suggests that the cell-cell communication between podocytes and other glomerular and nonglomerular cells is critical for the development and progression of kidney disease. In this review, we highlight these key cellular pathways of communication and how they might be a potential target for therapy in glomerular disease. We also postulate that podocytes might serve as a central hub for communication in the kidney under basal conditions and in response to cellular stress, which may have implications for the development and progression of glomerular diseases.

Biopterin metabolism and nitric oxide recoupling in cancer

Tetrahydrobiopterin is a cofactor necessary for the activity of several enzymes, the most studied of which is nitric oxide synthase. The role of this cofactor-enzyme relationship in vascular biology is well established. Recently, tetrahydrobiopterin metabolism has received increasing attention in the field of cancer immunology and immunotherapy due to its involvement in the cytotoxic T cell response. Past research has demonstrated that when the availability of BH4 is low, as it is in chronic inflammatory conditions and tumors, electron transfer in the active site of nitric oxide synthase becomes uncoupled from the oxidation of arginine. This results in the production of radical species that are capable of a direct attack on tetrahydrobiopterin, further depleting its local availability. This feedforward loop may act like a molecular switch, reinforcing low tetrahydrobiopterin levels leading to altered NO signaling, restrained immune effector activity, and perpetual vascular inflammation within the tumor microenvironment. In this review, we discuss the evidence for this underappreciated mechanism in different aspects of tumor progression and therapeutic responses. Furthermore, we discuss the preclinical evidence supporting a clinical role for tetrahydrobiopterin supplementation to enhance immunotherapy and radiotherapy for solid tumors and the potential safety concerns.

Overexpression of VEGFα as a biomarker of endothelial dysfunction in aortic tissue of α-GAL-Tg/KO mice and its upregulation in the serum of patients with Fabry's disease

Introduction

Fabry's disease is an X-linked lysosomal storage disorder caused by reduced activity of α-galactosidase A (GAL), leading to premature death on account of renal, cardiac, and vascular organ failure. Accumulation of the GAL substrate globotriaosylceramide (Gb3) in endothelial and smooth muscle cells is associated with early vascular cell damage, suggesting endothelial dysfunction as a driver of cardiorenal organ failure. Here, we studied the vascular expression of the key angiogenic factors, VEGFα and its antagonist angiostatin, in Fabry α-GAL-Tg/KO mice and determined circulating VEGFα and angiostatin serum levels in patients with Fabry's disease and healthy controls.

Methods

Cryopreserved aortic vessels from six α-GAL-Tg/KO and six wild-type (WT) mice were obtained and VEGFα and angiostatin levels were determined by performing Western blot analysis. VEGFα expression was visualized by an immunohistochemical staining of paraffin aortic rings. In addition, VEGFα and angiostatin serum levels were measured by using an enzyme-linked immunosorbent assay in 48 patients with genetically verified Fabry's disease (50% male) and 22 healthy controls and correlated with disease severity markers such as lyso-Gb3, albuminuria, NTproBNP, high-sensitive troponin T (hsTNT), and myocardial wall thickness.

Results

It was found that there was a significant increase in VEGFα protein expression (1.66 ± 0.35 vs. 0.62 ± 0.16, p = 0.0009) and a decrease in angiostatin expression (0.024 ± 0.007 vs. 0.053 ± 0.02, p = 0.038) in aortic lysates from α-GAL-Tg/KO compared with that from WT mice. Immunohistochemical staining revealed an adventitial VEGFα signal in α-GAL-Tg/KO mice, whereas no VEGFα signal could be detected in WT mice aortas. No differences in aortic angiostatin expression between α-GAL-Tg/KO- and WT mice could be visualized. The serum levels of VEGFα were significantly upregulated in patients with Fabry's disease compared with that in healthy controls (708.5 ± 426.3 vs. 458.5 ± 181.5 pg/ml, p = 0.048) and positively associated with albuminuria (r = 0.82, p < 0.0001) and elevated NTproBNP (r = 0.87, p < 0.0001) and hsTNT values (r = 0.41, p = 0.048) in male patients with Fabry's disease. For angiostatin, no significant difference was found between patients with Fabry's disease and healthy controls (747.6 ± 390.3 vs. 858.8 ± 599.3 pg/ml).

Discussion

In conclusion, an overexpression of VEGFα and downregulation of its counter player angiostatin in aortic tissue of α-GAL-Tg/KO mice support the hypothesis of an underlying vasculopathy in Fabry's disease. Elevated VEGFα serum levels were also observed in patients with Fabry's disease and were positively associated with elevated markers of organ manifestation in males. These findings suggest that angiogenetic markers, such as VEGFα, may be potentially useful biomarkers for the detection of endothelial dysfunction in classical Fabry's disease.

Toward Precision Medicine: Exploring the Landscape of Biomarkers in Acute Kidney Injury

Acute kidney injury (AKI) remains a complex challenge with diverse underlying pathological mechanisms and etiologies. Current detection methods predominantly rely on serum creatinine, which exhibits substantial limitations in specificity and poses the issue of late-stage detection of kidney injury. In this review, we propose an up-to-date and comprehensive summary of advancements that identified novel biomarker candidates in blood and urine and ideal criteria for AKI biomarkers such as renal injury specificity, mechanistic insight, prognostic capacity, and affordability. Recently identified biomarkers not only indicate injury location but also offer valuable insights into a range of pathological processes, encompassing reduced glomerular filtration rate, tubular function, inflammation, and adaptive response to injury. The clinical applications of AKI biomarkers are becoming extensive and serving as relevant tools in distinguishing acute tubular necrosis from other acute renal conditions. Also, these biomarkers can offer significant insights into the risk of progression to chronic kidney disease CKD and in the context of kidney transplantation. Integration of these biomarkers into clinical practice has the potential to improve early diagnosis of AKI and revolutionize the design of clinical trials, offering valuable endpoints for therapeutic interventions and enhancing patient care and outcomes.

Renal Implications of Long-Term Systemic Bevacizumab for Recurrent Respiratory Papillomatosis

BACKGROUND

Bevacizumab is a vascular endothelial growth factor (VEGF) inhibitor that is used off-label for select cases of recurrent respiratory papillomatosis (RRP) that are severe, involve the distal airway or lung parenchyma, and refractory to other forms of adjuvant therapy. However, there is limited safety data for the use of bevacizumab in children and VEGF inhibitors are reported to have a range of adverse renal effects, including hypertension, proteinuria, and thrombotic microangiopathy (TMA).

CASE-DIAGNOSIS/TREATMENT

This report describes a case of severe juvenile-onset RRP that had an exceptionally high operative burden that was refractory to several adjuvant treatment strategies (including intralesional cidofovir and subcutaneous pegylated interferon). Bevacizumab treatment resulted in a dramatic and sustained improvement in disease control over a 5-year period. However, after 3 years of treatment, the patient developed hypertension and proteinuria and was found to have evidence of a glomerular TMA on kidney biopsy. These complications were successfully managed with a reduction in bevacizumab frequency and angiotensin-converting enzyme inhibitor initiation.

CONCLUSIONS

Clinicians caring for children treated with VEGF inhibitors should be aware of the potential renal complications and their management.

Long-Term Change in Renal Function After Intravitreal Anti-VEGF Treatment for Diabetic Macular Edema: A 2-Year Retrospective Cohort Study

INTRODUCTION

To investigate the longitudinal changes in renal function and associated factors after intravitreal anti-vascular endothelial growth factor (VEGF) administration in diabetic macular edema (DME).

METHODS

A total of 108 patients who had received intravitreal ranibizumab or aflibercept for DME and had follow-up visits for at least 2 years in one hospital were retrospectively enrolled. The estimated glomerular filtration rate (eGFR) at baseline and during the follow-up period and receipt of any renal replacement therapy were recorded. Linear regression and Cox regression models were used to evaluate factors associated with eGFR decline and renal replacement therapy.

RESULTS

After intravitreal anti-VEGF treatment, eGFR showed a mean decline of -10.4 ± 23.2% and -16.5 ± 26.4% at months 12 and 24, respectively. Patients in the eGFR > 120 mL/min and 15-30 mL/min groups had the greatest decline (-32.0 ± 20.6% and -37.4 ± 30.9%, respectively) while those in the 61-90 mL/min group had the smallest decline (-4.3 ± 19.7%) in eGFR after the 2-year treatment. One out of 52 patients (1.9%) receiving ranibizumab and five out of 56 patients (8.9%) receiving aflibercept started hemodialysis or peritoneal dialysis within the 2-year follow-up period (P = 0.21). Baseline eGFR correlated with renal replacement therapy after intravitreal anti-VEGF treatment (hazard ratio = 0.879 per increase of 1 in eGFR, P = 0.018).

CONCLUSIONS

In DME patients receiving intravitreal anti-VEGF treatment, a persistent decline in eGFR was observed during the 2-year treatment course. Patients with extremely high or low eGFR had greater eGFR decline, and those with poor baseline eGFR tended to require dialysis after intravitreal anti-VEGF treatment.

The Association of Intravitreal Anti-VEGF Injections With Kidney Function in Diabetic Retinopathy

Purpose

To examine whether patients with diabetic retinopathy receiving intravitreal anti-VEGF injections are at increased risk of kidney function decline.

Design

Retrospective cohort study.

Participants

Included 187 patients who received intravitreal anti-VEGF injections for proliferative diabetic retinopathy (PDR) and/or diabetic macular edema (DME), and 929 controls with non-PDR who did not receive injections, at a large tertiary care center in Chicago, Illinois.

Methods

We queried our institutional enterprise data warehouse to identify patients with diabetic retinopathy, determined whether they received intravitreal anti-VEGF injections, and followed kidney function for all patients over time.

Main Outcome Measures

We assessed time to sustained 40% decline in estimated glomerular filtration rate (eGFR) from baseline in patients receiving intravitreal anti-VEGF injections and compared it with controls using Kaplan-Meier and multivariable adjusted Cox proportional hazards regression models.

Results

This study included 1116 patients (565 female [50.6%]; mean [standard deviation {SD}] age, 57.3 [13.6] years; mean [SD] eGFR, 65.3 [32.1] ml/min/1.73 m2). Of these, 187 patients received ≥ 1 intravitreal anti-VEGF injection (mean [SD], 11.4 [13.1] injections) for PDR and/or DME, and 929 controls with non-PDR received no injections. Intravitreal anti-VEGF injection use was not associated with an increased risk of kidney function decline (hazard ratio [HR], 1.44; 95% confidence interval [CI], 0.97-2.15). Subgroup analyses revealed that use of intravitreal anti-VEGF injections was associated with increased risk of kidney function decline in male patients (HR, 1.87; 95% CI, 1.11-3.14) but not female patients (HR, 0.97; 95% CI, 0.50-1.89). Intravitreal anti-VEGF injection use was also associated with an increased risk of kidney function decline in patients with baseline eGFR > 30 ml/min/1.73 m2 (HR, 1.86; 95% CI, 1.15-3.01), but not in individuals with baseline eGFR ≤ 30 ml/min/1.73 m2 (HR, 0.97; 95% CI, 0.45-2.10). Among patients who received injections, receiving ≥ 12 injections was not associated with risk of kidney function decline (HR, 1.13; 95% CI, 0.52-2.49).

Conclusions

Intravitreal anti-VEGF injections for patients with diabetic retinopathy are overall well-tolerated with respect to kidney function, but the use of intravitreal anti-VEGF injections was associated with an increased risk of kidney function decline in certain subgroups of patients.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

A novel multiplex biomarker panel for profiling human acute and chronic kidney disease

Acute and chronic kidney disease continues to confer significant morbidity and mortality in the clinical setting. Despite high prevalence of these conditions, few validated biomarkers exist to predict kidney dysfunction. In this study, we utilized a novel kidney multiplex panel to measure 21 proteins in plasma and urine to characterize the spectrum of biomarker profiles in kidney disease. Blood and urine samples were obtained from age-/sex-matched healthy control subjects (HC), critically-ill COVID-19 patients with acute kidney injury (AKI), and patients with chronic or end-stage kidney disease (CKD/ESKD). Biomarkers were measured with a kidney multiplex panel, and results analyzed with conventional statistics and machine learning. Correlations were examined between biomarkers and patient clinical and laboratory variables. Median AKI subject age was 65.5 (IQR 58.5-73.0) and median CKD/ESKD age was 65.0 (IQR 50.0-71.5). Of the CKD/ESKD patients, 76.1% were on hemodialysis, 14.3% of patients had kidney transplant, and 9.5% had CKD without kidney replacement therapy. In plasma, 19 proteins were significantly different in titer between the HC versus AKI versus CKD/ESKD groups, while NAG and RBP4 were unchanged. TIMP-1 (PPV 1.0, NPV 1.0), best distinguished AKI from HC, and TFF3 (PPV 0.99, NPV 0.89) best distinguished CKD/ESKD from HC. In urine, 18 proteins were significantly different between groups except Calbindin, Osteopontin and TIMP-1. Osteoactivin (PPV 0.95, NPV 0.95) best distinguished AKI from HC, and β2-microglobulin (PPV 0.96, NPV 0.78) best distinguished CKD/ESKD from HC. A variety of correlations were noted between patient variables and either plasma or urine biomarkers. Using a novel kidney multiplex biomarker panel, together with conventional statistics and machine learning, we identified unique biomarker profiles in the plasma and urine of patients with AKI and CKD/ESKD. We demonstrated correlations between biomarker profiles and patient clinical variables. Our exploratory study provides biomarker data for future hypothesis driven research on kidney disease.

Potential clinical biomarkers in monitoring the severity of Hantaan virus infection

Hantavirus, which causes hemorrhagic fever with renal syndrome (HFRS) is almost prevalent worldwide. While Hantaan virus (HTNV) causes the most severe form of HFRS with typical clinical manifestations of thrombocytopenia, increased vascular permeability, and acute kidney injury. Although the knowledge of the pathogenesis of HFRS is still limited, immune dysfunction and pathological damage caused by disorders of immune regulation are proposed to play a vital role in the development of the disorder, and the endothelium is considered to be the primary target of hantaviruses. Here, we reviewed the production and function of multiple molecules, mainly focusing on their role in immune response, endothelium, vascular permeability regulation, and platelet and coagulation activation which are closely related to the pathogenesis of HTNV infection. meanwhile, the relationship between these molecules and characteristics of HTNV infection including the hospital duration, immune dysfunction, thrombocytopenia, leukocytosis, and acute kidney injury are also presented, to provide a novel insight into the potential role of these molecules as monitoring markers for HTNV infection.

Risk of antiangiogenic adverse events in metastatic colorectal cancer patients receiving aflibercept in combination with chemotherapy: A meta-analysis

BACKGROUND

Aflibercept has been approved for the treatment of metastatic colorectal cancer for more than a decade, but its antiangiogenesis adverse effect profile during treatment remains unclear. This study is conducted to systematically review the risk of antiangiogenic adverse events in patients with metastatic colorectal cancer receiving aflibercept plus chemotherapy.

METHODS

We searched databases, including PubMed, Embase and the Cochrane Library up to September 9, 2021. Relevant randomized controlled trials (RCTs) and single-arm studies were included in the review. Statistical analyses were performed using R to calculate the summary incidence rate of antiangiogenic-related adverse events, odds ratios and 95% CIs. Heterogeneity among the included studies was assessed by subgroup analysis. Publication bias analysis and sensitivity analysis were performed to confirm the reliability of the results.

RESULTS

A total of 2889 patients from 10 studies met the inclusion criteria. The quality of the included studies was evaluated as qualified for further quantitative synthesis. In part of single-arm studies, the occurrence rates were 44.2% (95%CI, 39.7-48.7%) for hypertension, 31.3% (95% CI, 19.3-43.3%) for proteinuria, 27.3% (95%CI, 21.2-33.4%) for epistaxis, 22.5% (95%CI, 7.8-37.3%) for hemorrhage events, 8.0% (95%CI, 2.0-14 .0%) for venous thromboembolic event in all grades and 22.6% (95%CI, 19.1-26.2%) for grade III/IV hypertension, 7.4% (95%CI, 6.2-8.5%) for grade III/IV proteinuria. In part of RCT, compared to its counterpart, aflibercept containing arm was associated with the increased incidence rate in hypertension (OR:6.30, 95%CI: 3.49-11.36), proteinuria (OR:4.12, 95%CI: 1.25-13.61), epistaxis (OR:3.71, 95%CI: 2.84-4.85), III/IV hypertension (OR:7.20, 95%CI: 5.23-9.92), III/IV proteinuria (OR:5.13, 95%CI: 3.13-8.41). The funnel plot, Begg test and Egger test were carried out on the primary endpoints, III/IV hypertension rate and III/IV proteinuria rate, the result of which detected no obvious publication bias. No significant difference was observed in subgroup analysis in the primary endpoint between the subgroups stratified by treatment line (firstline or non-firstline), chemotherapy regime (FOLFIRI or others) and study design (RCTs or single-arm trials).

CONCLUSION

The available evidence suggests that using aflibercept is associated with an increased risk of antiangiogenic adverse events compared with controls. Further studies are needed to investigate this association. In the appropriate clinical scenario, the use of aflibercept in its approved indications remains justified. However, the results of this study should be interpreted with caution, as some of the evidence comes from single-arm clinical trials.

Targeted VEGFA therapy in regulating early acute kidney injury and late fibrosis

Damage to peritubular capillaries is a key process that contributes to acute kidney injury (AKI) progression. Vascular endothelial growth factor A (VEGFA) plays a critical role in maintaining the renal microvasculature. However, the physiological role of VEGFA in various AKI durations remains unclear. A severe unilateral ischemia‒reperfusion injury model was established to provide an overview of VEGFA expression and the peritubular microvascular density from acute to chronic injury in mouse kidneys. Therapeutic strategies involving early VEGFA supplementation protecting against acute injury and late anti-VEGFA treatment for fibrosis alleviation were analyzed. A proteomic analysis was conducted to determine the potential mechanism of renal fibrosis alleviation by anti-VEGFA. The results showed that two peaks of extraglomerular VEGFA expression were observed during AKI progression: one occurred at the early phase of AKI, and the other occurred during the transition to chronic kidney disease (CKD). Capillary rarefaction progressed despite the high expression of VEGFA at the CKD stage, and VEGFA was associated with interstitial fibrosis. Early VEGFA supplementation protected against renal injury by preserving microvessel structures and counteracting secondary tubular hypoxic insults, whereas late anti-VEGFA treatment attenuated renal fibrosis progression. The proteomic analysis highlighted an array of biological processes related to fibrosis alleviation by anti-VEGFA, which included regulation of supramolecular fiber organization, cell-matrix adhesion, fibroblast migration, and vasculogenesis. These findings establish the landscape of VEGFA expression and its dual roles during AKI progression, which provides the possibility for the orderly regulation of VEGFA to alleviate early acute injury and late fibrosis.

Protease-activated receptors in kidney diseases: A comprehensive review of pathological roles, therapeutic outcomes and challenges

Studies have demonstrated that protease-activated receptors (PARs) with four subtypes (PAR1-4) are mainly expressed in the renal epithelial, endothelial, and podocyte cells. Some endogenous and urinary proteases, namely thrombin, trypsin, urokinase, and kallikrein released during diseased conditions, are responsible for activating different subtypes of PARs. Each PAR receptor subtype is involved in kidney disease of distinct aetiology. PAR1 and PAR2 have shown differential therapeutic outcomes in rodent models of type-1 and type-2 diabetic kidney diseases due to the distinct etiological basis of each disease type, however such findings need to be confirmed in other diabetic renal injury models. PAR1 and PAR2 blockers have been observed to abolish drug-induced nephrotoxicity in rodents by suppressing tubular inflammation and fibrosis and preventing mitochondrial dysfunction. Notably, PAR2 inhibition improved autophagy and prevented fibrosis, inflammation, and remodeling in the urethral obstruction model. Only the PAR1/4 subtypes have emerged as a therapeutic target for treating experimentally induced nephrotic syndrome, where their respective antibodies attenuated the podocyte apoptosis induced upon thrombin activation. Strikingly PAR2 and PAR4 subtypes involvement has been tested in sepsis-induced acute kidney injury (AKI) and renal ischemia-reperfusion injury models. Thus, more studies are required to delineate the role of other subtypes in the sepsis-AKI model. Evidence suggests that PARs regulate oxidative, inflammatory stress, immune cell activation, fibrosis, autophagic flux, and apoptosis during kidney diseases.

K. Sagi S. Hypobaric hypoxia induced renal injury in rats: Prophylactic amelioration by quercetin supplementation

The present study aims at assessing the effect of hypobaric hypoxia induced renal damage and associated renal functions in male SD rats. Further, this study was extended to explore the protective efficacy of quercetin in ameliorating the functional impairment in kidneys of rats under hypobaric hypoxia. Rats were exposed to 7620m (25000 ft.) at 25°C ±2 in a simulated hypobaric hypoxia chamber for different time durations (0h,1h, 3h, 6h, 12h, 24h and 48h) in order to optimize the time at which maximum renal damage would occur. The rats were exposed to hypoxia for 12h duration was considered as the optimum time, due to significant increase in oxidative stress (ROS, MDA) and renal metabolites (creatinine, BUN and uric acid) with remarkable reduction (p<0.001) in antioxidants (GSH) in plasma, as compared to other tested durations. Moreover, these findings were in support with the histopathology analysis of renal tissues. For optimum quercetin dose selection, the rats were administered with different doses of quercetin (25mg, 50mg, 100mg and 200mg/Kg BW) for 12h at 7620 m, 25°C ±2, 1h prior to hypoxia exposure. Quercetin 50mg/kg BW was considered as the optimum dose at which significant (p<0.001) reduction in oxidative stress levels followed by reduction in creatinine and BUN levels were obtained in plasma of the rats compared to hypoxia control rats. Quercetin prophylaxis (50mg/kg BW) stabilized the HIF-1α protein expression followed by reduced VEGF protein expression along with reduced levels of LDH (p<0.001) in the kidneys of rats compared to hypoxia control. Histopathological observations further substantiated these findings in reducing the renal tissue injury. The study findings revealed that, quercetin prophylaxis abrogates the possibility of hypobaric hypoxia induced renal injury by reducing the oxidative stress in rats.

Do intravitreal anti-vascular endothelial growth factor agents lead to renal adverse events? A pharmacovigilance real-world study

Purpose

Intravitreal vascular endothelial growth factor (VEGF) blockade is essential in many macular edema diseases treatment. However, intravitreal VEGF treatment has been reported to lead to deteriorated proteinuria and renal function. This study aimed to explore the relationship between renal adverse events (AEs) and the intravitreal use of VEGF inhibitors.

Method

In the FDA's Adverse Event Reporting System (FAERS) database, we searched for renal AEs of patients receiving various anti-VEGF drugs. We performed statistics on renal AEs in patients treated with Aflibercept, Bevacizumab, Ranibizumab, and Brolucizumab (from January 2004 to September 2022) using disproportionate and Bayesian analysis. We also investigated the time to onset, fatality, and hospitalization rates of renal AEs.

Results

We identified 80 reports. Renal AEs were most frequently associated with Ranibizumab (46.25%) and Aflibercept (42.50%). However, the association between intravitreal anti-VEGFs and renal AEs was insignificant since the reporting odds ratio of Aflibercept, Bevacizumab, Ranibizumab, and Brolucizumab were 0.23 (0.16, 0.32), 0.24 (0.11, 0.49), 0.37 (0.27, 0.51) and 0.15 (0.04, 0.61), respectively. The median time to renal AEs onsets was 37.5 (interquartile range 11.0-107.3) days. The hospitalization and fatality rates in patients who developed renal AEs were 40.24 and 9.76%, respectively.

Conclusion

There are no clear signals for the risk of renal AEs following various intravitreal anti-VEGF drugs based on FARES data.

Urine-Based Detection of Biomarkers Indicative of Chronic Kidney Disease in a Patient Cohort from Ghana

Chronic kidney disease (CKD) is a global health burden with a continuously increasing prevalence associated with an increasing incidence of diabetes and hypertension in aging populations. CKD is characterized by low glomerular filtration rate (GFR) and other renal impairments including proteinuria, thus implying that multiple factors may contribute to the etiology this disease. While there are indications of ethnic differences, it is hard to disentangle these from confounding social factors. Usually, CKD is detected in later stages of the disease when irreversible renal damage has already occurred, thus suggesting a need for early non-invasive diagnostic markers. In this study, we explored the urine secretome of a CKD patient cohort from Ghana with 40 gender-matched patients and 40 gender-matched healthy controls employing a kidney injury and a more general cytokine assay. We identified panels of kidney-specific cytokine markers, which were also gender-specific, and a panel of gender-independent cytokine markers. The gender-specific markers are IL10 and MME for male and CLU, RETN, AGER, EGFR and VEGFA for female. The gender-independent cytokine markers were APOA1, ANGPT2, C5, CFD, GH1, ICAM1, IGFBP2, IL8, KLK4, MMP9 and SPP1 (up-regulated) and FLT3LG, CSF1, PDGFA, RETN and VEGFA (down-regulated). APOA1-the major component of HDL particles-was up-regulated in Ghanaian CKD patients and its co-occurrence with APOL1 in a subpopulation of HDL particles may point to specific CKD-predisposing APOL1 haplotypes in patients of African descent-this, however, needs further investigation. The identified panels, though preliminary, lay down the foundation for the development of robust CKD-diagnostic assays.

VEGFA promotes the occurrence of PLA2R-associated idiopathic membranous nephropathy by angiogenesis via the PI3K/AKT signalling pathway

Background

The M-type phospholipase A2 receptor (PLA2R)-associated idiopathic membranous nephropathy (IMN) is a common immune-related disease in adults. Vascular endothelial growth factor A (VEGFA) is the key mediator of angiogenesis, which leads to numerous kidney diseases. However, the role of VEGFA in IMN is poorly understood.

Methods

In the present study, we downloaded the microarray data GSE115857 from Gene Expression Omnibus (GEO). The differentially expressed genes (DEGs) were identified with R software. The cytoHubba plug-in were used to identify hub genes from the protein–protein interaction network. Gene set enrichment analysis (GSEA) was used to identify signalling pathway in IMN. CCK8 was performed to assess the cell viability in human vascular endothelial cells (HVECs). Then, passive Heymann nephritis (PHN) was induced in rats by a single tail vein injection of anti-Fx1A antiserum. Animals treated with VEGFA inhibitor bevacizumab (BV), with saline as a positive control. Proteinuria was evaluated by biochemical measurements. Immunohistochemistry and immunofluorescence was used to evaluate relative proteins expression. Electron microscopy was performed to observe the thickness of the glomerular basement membrane (GBM).

Results

We revealed 3 hub genes, including one up-regulated gene VEGFA and two down-regulated genes JUN and FOS, which are closely related to the development of PLA2R-associated IMN. Pathway enrichment analysis found that the biological process induced by VEGFA is associated with PI3K/Akt signalling. GSEA showed that the signalling pathway of DEGs in GSE115857 was focused on angiogenesis, in which VEGFA acts as a core gene. We confirmed the high expression of VEGFA, PI3K, and AKT in IMN renal biopsy samples with immunohistochemistry. In HVECs, we found that BV suppresses cell viability in a time and dose dependent manner. In vivo, we found low dose of BV attenuates proteinuria via inhibiting VEGFA/PI3K/AKT signalling. Meanwhile, low dose of BV alleviates the thickening of the GBM.

Conclusion

VEGFA/PI3K/AKT signalling may play significant roles in the pathogenesis of IMN, which may provide new targets for the treatment of IMN.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02936-y.

Cancer Metabolism and Ischemia-Reperfusion Injury: Two Sides of the Same Coin

Cancer cells are characterized by the reprogramming of certain cell metabolisms via activation of definite pathways and regulation of gene signaling. Ischemia-reperfusion injury (IRI) is characterized by tissue damage and death following a lack of perfusion and oxygenation. It is most commonly seen in the setting of organ transplantation. Interestingly, the microenvironments seen in cancer and ischemic tissues are quite similar, especially due to the hypoxic state that occurs in both. As a consequence, there is genetic signaling involved in response to IRI that has common pathways with cancer. Some of these changes are seen across the board with many cancer cells and are known as Hallmarks of Cancer, among which are aerobic glycolysis and the induction of angiogenesis. This literature review aims to compare the metabolic pathways that are altered in cancer tissues and in normal tissues subjected to IRI in order to find common adaptive processes and to identify key pathways that could represent a therapeutic target in both pathologies. By increasing our understanding of this relationship, clinical correlations can be made and applied practically to improve outcomes of transplanted organs, given the known association with acute rejection, delayed graft function, and poor graft survival. The following metabolic pathways are discussed in our review, both in the setting of cancer and IRI: apoptosis, glycolysis, and angiogenesis. The role of the immune system in both pathologies as well as mitochondrial function and the production of reactive oxygen species (ROS) are reviewed.

[Analysis of Factors Affecting Proteinuria Onset Timing in Patients Treated with Bevacizumab]

Bevacizumab (BV) is a recombinant and humanized monoclonal antibody that inhibits vascular endothelial growth factor. BV is used to treat various types of cancer. Proteinuria is a characteristic adverse event that occurs as a result of treatment with BV. However, the onset timing of proteinuria after BV administration remains unclear. In the present study, we examined the risk factors affecting the timing of proteinuria onset upon BV administration. Medical records of 135 patients (62 males and 73 females; mean age: 67.8±10.7 years) treated with BV were reviewed at the Kindai University Nara Hospital from April 2011 to December 2019. Proteinuria was identified in 44.4% (60/135) of the studied patients. The time to the first onset of proteinuria was significantly shorter in the administration of doses of BV (≥10) and history of diabetes mellitus. The median cumulative dose associated with the onset of proteinuria was 30.0 (16.1-58.8) mg/kg. When this cumulative dose was compared with 10 mg/kg, no significant difference was observed (p=0.319). The present study demonstrated that the administration of doses of BV (≥10) and history of diabetes mellitus are one of the main risk factors for early-onset proteinuria. These findings may be useful for the future treatment of early-onset proteinuria in patients treated with BV.

Influence of polymorphisms in the vascular endothelial growth factor gene on allograft rejection after kidney transplantation: a meta-analysis

Background: Reported associations of allograft rejection in kidney transplant patients with VEGF single nucleotide polymorphisms (SNPs) have been inconsistent between studies, which prompted a meta-analysis to obtain more precise estimates.

Methods: Using the PICO elements, kidney transplant patients (P) were compared by genotype data between rejectors (I) and non-rejectors (C) in order to determine the risk of allograft rejection (O) attributed to the VEGF SNPs. Literature search of four databases yielded seven articles. To calculate risks for allograft rejection, four SNPs were examined. Using the allele-genotype model we compared the variant ( var) with the wild-type ( wt) and heterozygous ( var- wt) alleles. Meta-analysis treatments included outlier and subgroup analyses, the latter was based on ethnicity (Indians/Caucasians) and rejection type (acute/chronic). Multiple comparisons were corrected with the Bonferroni test.

Results: Five highly significant outcomes (P ^a < 0.01) survived Bonferroni correction, one of which showed reduced risk for the var allele (OR 0.61, 95% CI 0.45-0.82). The remaining four indicated increased risk for the wt allele where the chronic rejection (OR 2.10, 95% CI 1.36-3.24) and Indian (OR 1.44, 95% CI 1.13-1.84) subgroups were accorded susceptibility status.

Conclusions: Risk associations for renal allograft rejection were increased and reduced on account of the wt and var alleles, respectively. These findings could render the VEGF polymorphisms useful in the clinical genetics of kidney transplantation.

BECLIN1 Is Essential for Podocyte Secretory Pathways Mediating VEGF Secretion and Podocyte-Endothelial Crosstalk

Vascular endothelial growth factor A (VEGFA) secretion from podocytes is crucial for maintaining endothelial integrity within the glomerular filtration barrier. However, until now, the molecular mechanisms underlying podocyte secretory function remained unclear. Through podocyte-specific deletion of BECLIN1 (ATG6 or Becn1), a key protein in autophagy initiation, we identified a major role for this molecule in anterograde Golgi trafficking. The Becn1-deficient podocytes displayed aberrant vesicle formation in the trans-Golgi network (TGN), leading to dramatic vesicle accumulation and complex disrupted patterns of intracellular vesicle trafficking and membrane dynamics. Phenotypically, podocyte-specific deletion of Becn1 resulted in early-onset glomerulosclerosis, which rapidly progressed and dramatically reduced mouse life span. Further, in vivo and in vitro studies clearly showed that VEGFA secretion, and thereby endothelial integrity, greatly depended on BECLIN1 availability and function. Being the first to demonstrate the importance of a secretory pathway for podocyte integrity and function, we identified BECLIN1 as a key component in this complex cellular process. Functionally, by promoting VEGFA secretion, a specific secretory pathway emerged as an essential component for the podocyte-endothelial crosstalk that maintains the glomerular filtration barrier.

Cardiac autonomic neuropathy predicts diabetic retinopathy progression in Asian population with type 2 diabetes mellitus

PURPOSE

To investigate the role of cardiac autonomic neuropathy (CAN), vascular condition, and sensory function in diabetic retinopathy (DR) progression.

METHODS

This 3-year cohort study conducted in a community hospital included 4850 patients over 20 with type 2 diabetes mellitus. Participants were assessed in 2017 at baseline and were followed up in 2020. Patients were divided into two groups based on whether they had DR progression or not and were compared using the chi-square test or two-sample t-test. Beta coefficient and odds ratio (OR) with 95% confidence intervals were calculated using binary logistic regression. The receiver operating characteristic (ROC) curve of various independent variables for DR progression was provided with C-statistics.

RESULTS

Abnormal hemoglobin A1c (HbA1c) level/variation, estimated glomerular filtration rate, urine albumin-to-creatinine ratio, R-R interval variation, standard deviation of the average NN intervals, autonomic nervous system function, power of high-frequency (HF) bands, balance, cardio-ankle vascular index (CAVI), and warm stimulation (WS) were associated with DR progression. Average HbA1c, HF, and proliferative diabetic retinopathy were independent factors for patients developing DR progression. The top three areas under the curve of ROCs were HF + baseline DR grading, WS + baseline DR grading, and CAVI + baseline DR grading. These variable combinations were the most reliable predictors of DR progression.

CONCLUSION

CAN, abnormal vascular condition, and sensory function are associated with DR progression. The combination of HF, WS, and CAVI with baseline DR grading provides the most accurate predictive model for DR progression. Early detection of these factors is important to prevent DR progression.

An in vitro strategy using multiple human induced pluripotent stem cell-derived models to assess the toxicity of chemicals: A case study on paraquat

Most OECD guidelines for chemical risk assessment include tests performed on animals, raising financial, ethical and scientific concerns. Thus, the development of human-based models for toxicity testing is highly encouraged. Here, we propose an in vitro multi-organ strategy to assess the toxicity of chemicals. Human induced pluripotent stem cells (hiPSCs)-derived models of the brain, blood-brain barrier, kidney, liver and vasculature were generated and exposed to paraquat (PQ), a widely employed herbicide with known toxic effects in kidneys and brain. The models showed differential cytotoxic sensitivity to PQ after acute exposure. TempO-Seq™ analysis with a set of 3565 probes revealed the deregulation of oxidative stress, unfolded protein response and Estrogen Receptor-mediated signaling pathways, in line with the existing knowledge on PQ mechanisms of action. The main advantages of this strategy are to assess chemical toxicity on multiple tissues/organs in parallel, exclusively in human cells, eliminating the interspecies bias, allowing a better evaluation of the differential sensitivity of the models representing the diverse organs, and increasing the chance to identify toxic compounds. Furthermore, although we focused on the mechanisms of action of PQ shared by the different models, this strategy would also allow for organ-specific toxicity testing, by including more cell type-specific probes for TempO-Seq analyses. In conclusion, we believe this strategy will participate in the further improvement of chemical risk assessment for human health.

Epoxyeicosatrienoic Acid Analog and 20-HETE Antagonist Combination Prevent Hypertension Development in Spontaneously Hypertensive Rats

Numerous studies indicate a significant role for cytochrome P-450-dependent arachidonic acid metabolites in blood pressure regulation, vascular tone, and control of renal function. Epoxyeicosatrienoic acids (EETs) exhibit a spectrum of beneficial effects, such as vasodilatory activity and anti-inflammatory, anti-fibrotic, and anti-apoptotic properties. 20-Hydroxyeicosatetraenoic acid (20-HETE) is a potent vasoconstrictor that inhibits sodium reabsorption in the kidney. In the present study, the efficiency of EET-A (a stable analog of 14,15-EET) alone and combined with AAA, a novel receptor antagonist of 20-HETE, was tested in spontaneously hypertensive rats (SHR). Adult SHR (16 weeks old) were treated with two doses of EET-A (10 or 40 mg/kg/day). In the following experiments, we also tested selected substances in the prevention of hypertension development in young SHR (6 weeks old). Young rats were treated with EET-A or the combination of EET-A and AAA (both at 10 mg/kg/day). The substances were administered in drinking water for 4 weeks. Blood pressure was measured by telemetry. Once-a-week observation in metabolic cages was performed; urine, blood, and tissue samples were collected for further analysis. The combined treatment with AAA + EET-A exhibited antihypertensive efficiency in young SHR, which remained normotensive until the end of the observation in comparison to a control group (systolic blood pressure, 134 ± 2 versus 156 ± 5 mmHg, respectively; p < 0.05). Moreover the combined treatment also increased the nitric oxide metabolite excretion. Considering the beneficial impact of the combined treatment with EET-A and AAA in young rats and our previous positive results in adult SHR, we suggest that it is a promising therapeutic strategy not only for the treatment but also for the prevention of hypertension.

Dabrafenib- and trametinib-associated glomerular toxicity: A case report

RATIONALE

Combined treatment with dabrafenib, a B-RAF inhibitor, and trametinib, a mitogen-activated protein kinase inhibitor, is an effective option for patients with metastatic melanoma. A few cases of acute kidney injury associated with tubulointerstitial nephritis and 1 case of nephrotic syndrome have been reported in patients on this drug combination; however, progressive renal injury has not been reported. In this case study, we report a patient with metastatic melanoma who developed glomerular capillary endothelial toxicity and progressive glomerular sclerosis during combination therapy.

PATIENT CONCERN

Our patient was an 80-year-old woman with a history of type 2 diabetes and chronic kidney disease.

DIAGNOSIS AND INTERVENTION

She was diagnosed with metastatic melanoma and commenced combination therapy with dabrafenib and trametinib.

OUTCOMES

Her renal function progressively deteriorated; by month 20 after treatment commencement, her serum creatinine level had increased from 1.59 to 3.74 mg/dL. The first kidney biopsy revealed marked glomerular and endothelial cell damage. Her medication was stopped, but no improvement was evident. At 5 months after the first biopsy, her serum creatinine level had increased to 5.46 mg/dL; a second kidney biopsy revealed focal segmental glomerular sclerosis and marked tubulointerstitial fibrosis. She was started on hemodialysis.

LESSONS

We describe a patient with a metastatic melanoma who developed progressive kidney failure during treatment with dabrafenib and trametinib. The most prominent microscopy findings were glomerular endothelial damage in the initial kidney biopsy and accelerated glomerular sclerosis and tubulointerstitial fibrosis in the follow-up biopsy. We hypothesize that a decreased renal reserve and impairment of kidney repair capacity caused by inhibition of B-RAF, a downstream mediator of vascular endothelial growth factor, may explain the progressive kidney injury.

Update on Pathogenesis of Glomerular Hyperfiltration in Early Diabetic Kidney Disease

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

The relationship between renal function and surgical outcomes of patients with proliferative diabetic retinopathy

OBJECTIVES

The relationship between renal function and diabetic retinopathy has been controversial. This study is to investigate the influence of renal function on the complex and surgical outcomes of proliferative diabetic retinopathy (PDR).

METHODS

This was a post hoc analysis of the CONCEPT clinical trial. A total of 45 eyes with PDR underwent vitrectomy were included. Based on the estimated glomerular filtration rate (eGFR), they were divided into abnormal renal function group (ARF group) and normal renal function group (NRG group). Baseline PDR complex, intraoperative outcomes (Intraoperative bleeding, frequency of endodiathermy, surgical time, iatrogenic hole, and tamponade) and postoperative outcomes (logMAR best-corrected visual acuity, vitreous re-hemorrhage, and macular edema, follow up at postoperative 1 month and 3 months) were estimated. Vitreous, aqueous humor and serum were collected at the vitrectomy day and Vascular endothelia growth factor-A levels were quantified for all included patients using liquid chip method.

RESULTS

There was no significant difference in baseline PDR complex, intraoperative and postoperative outcomes between ARF group and NRG group (all P > 0.05). At the vitrectomy day, there was also no difference of Vascular endothelia growth factor-A levels in vitreous, aqueous humor and serum between the two groups (all P > 0.05).

CONCLUSION

Our results showed that the renal function seems not parallel to the severity of PDR, neither to the surgical outcomes. This might be interpreted by the similar Vascular endothelia growth factor-A levels in vitreous, aqueous humor and serum between the two groups.

Meta-Analysis and Bioinformatics Detection of Susceptibility Genes in Diabetic Nephropathy

The latest meta-analysis of genome-wide linkage studies (GWLS) identified nine cytogenetic locations suggestive of a linkage with diabetic nephropathy (DN) due to type 1 diabetes mellitus (T1DM) and seven locations due to type 2 diabetes mellitus (T2DM). In order to gain biological insight about the functional role of the genes located in these regions and to prioritize the most significant genetic loci for further research, we conducted a gene ontology analysis with an over representation test for the functional annotation of the protein coding genes. Protein analysis through evolutionary relationships (PANTHER) version 16.0 software and Cytoscape with the relevant plugins were used for the gene ontology analysis, and the overrepresentation test and STRING database were used for the construction of the protein network. The findings of the over-representation test highlight the contribution of immune related molecules like immunoglobulins, cytokines, and chemokines with regard to the most overrepresented protein classes, whereas the most enriched signaling pathways include the VEGF signaling pathway, the Cadherin pathway, the Wnt pathway, the angiogenesis pathway, the p38 MAPK pathway, and the EGF receptor signaling pathway. The common section of T1DM and T2DM results include the significant over representation of immune related molecules, and the Cadherin and Wnt signaling pathways that could constitute potential therapeutic targets for the treatment of DN, irrespective of the type of diabetes.

Treadmill Exercise Training Ameliorates Functional and Structural Age-Associated Kidney Changes in Male Albino Rats

Aging is a biological process that impacts multiple organs. Unfortunately, kidney aging affects the quality of life with high mortality rate. So, searching for innovative nonpharmacological modality improving age-associated kidney deterioration is important. This study aimed to throw more light on the beneficial effect of treadmill exercise on the aged kidney. Thirty male albino rats were divided into three groups: young (3-4 months old), sedentary aged (23-24 months old), and exercised aged (23-24 months old, practiced moderate-intensity treadmill exercise 5 days/week for 8 weeks). The results showed marked structural alterations in the aged kidney with concomitant impairment of kidney functions and increase in arterial blood pressure with no significant difference in kidney weight. Also, it revealed that treadmill exercise alleviated theses effects in exercised aged group with reduction of urea and cystatin C. Exercise training significantly decreased glomerulosclerosis index, tubular injury score, and % area of collagen deposition. Treadmill exercise exerted its beneficial role via a significant reduction of C-reactive protein and malondialdehyde and increase in total antioxidant capacity. In addition, exercise training significantly decreased desmin immunoreaction and increased aquaporin-3, vascular endothelial growth factor, and beclin-1 in the aged kidney. This study clarified that treadmill exercise exerted its effects via antioxidant and anti-inflammatory mechanisms, podocyte protection, improving aquaporin-3 and vascular endothelial growth factor expression, and inducing autophagy in the aged kidney. This work provided a new insight into the promising role of aerobic exercise to ameliorate age-associated kidney damage.

Anti-VEGF agents: As appealing targets in the setting of COVID-19 treatment in critically ill patients

Recently, the medications used for the severe form of the coronavirus disease-19 (COVID-19) therapy are of particular interest. In this sense, it has been supposed that anti-VEGF compounds would be good candidates in the face of "cytokine storm" and intussuscepted angiogenesis due to having an appreciable anti-inflammatory effect. Therefore, they can be subjected to therapeutic protocols to manage acute respiratory distress syndrome (ARDS). Since the compelling evidence emphasized that VEGFs contribute to the inflammatory process and play a mainstay role in disease pathogenesis, in this review, we aimed to highlight the VEGF's plausible participation in the cytokine storm exacerbation in COVID-19. Next, the recent clinical advances regarding the anti-VEGF medications, including humanized monoclonal antibody, immunosuppressant, a tyrosine kinase inhibitor, and a cytokine inhibitor, have been addressed in the setting of COVID-19 treatment in critically ill patients. Together, retrieving the increased level of VEGF subsets, as well as antagonizing VEGF related receptors, could be helpful for the treatment of COVID-19, especially in those suffering from ARDS.

Vascular Endothelial Cells: Heterogeneity and Targeting Approaches

Forming the inner layer of the vascular system, endothelial cells (ECs) facilitate a multitude of crucial physiological processes throughout the body. Vascular ECs enable the vessel wall passage of nutrients and diffusion of oxygen from the blood into adjacent cellular structures. ECs regulate vascular tone and blood coagulation as well as adhesion and transmigration of circulating cells. The multitude of EC functions is reflected by tremendous cellular diversity. Vascular ECs can form extremely tight barriers, thereby restricting the passage of xenobiotics or immune cell invasion, whereas, in other organ systems, the endothelial layer is fenestrated (e.g., glomeruli in the kidney), or discontinuous (e.g., liver sinusoids) and less dense to allow for rapid molecular exchange. ECs not only differ between organs or vascular systems, they also change along the vascular tree and specialized subpopulations of ECs can be found within the capillaries of a single organ. Molecular tools that enable selective vascular targeting are helpful to experimentally dissect the role of distinct EC populations, to improve molecular imaging and pave the way for novel treatment options for vascular diseases. This review provides an overview of endothelial diversity and highlights the most successful methods for selective targeting of distinct EC subpopulations.

Microvessel Density: Integrating Sex-Based Differences and Elevated Cardiovascular Risks in Metabolic Syndrome

Metabolic syndrome (MetS) is a complex pathological state consisting of metabolic risk factors such as hypertension, insulin resistance, and obesity. The interconnectivity of cellular pathways within various biological systems suggests that each individual component of MetS may share common pathological sources. Additionally, MetS is closely associated with vasculopathy, including a reduction in microvessel density (MVD) (rarefaction) and elevated risk for various cardiovascular diseases. Microvascular impairments may contribute to perfusion-demand mismatch, where local metabolic needs are insufficiently met due to the lack of nutrient and oxygen supply, thus creating pathological positive-feedback loops and furthering the progression of disease. Sexual dimorphism is evident in these underlying cellular mechanisms, which places males and females at different levels of risk for cardiovascular disease and acute ischemic events. Estrogen exhibits protective effects on the endothelium of pre-menopausal women, while androgens may be antagonistic to cardiovascular health. This review examines MetS and its influences on MVD, as well as sex differences relating to the components of MetS and cardiovascular risk profiles. Finally, translational relevance and interventions are discussed in the context of these sex-based differences.

Low-dose rapamycin does not impair vascular integrity and tubular regeneration after kidney transplantation in rats

mTOR inhibitors offer advantages after kidney transplantation including antiviral and antitumor activity besides facilitating low calcineurin inhibitor exposure to reduce nephrotoxicity. Concerns about adverse effects due to antiproliferative and antiangiogenic properties have limited their clinical use particularly early after transplantation. Interference with vascular endothelial growth factor (VEGF)-A, important for physiologic functioning of renal endothelial cells and tubular epithelium, has been implicated in detrimental renal effects of mTOR inhibitors. Low doses of Rapamycin (loading dose 3 mg/kg bodyweight, daily doses 1.5 mg/kg bodyweight) were administered in an allogenic rat kidney transplantation model resulting in a mean through concentration of 4.30 ng/mL. Glomerular and peritubular capillaries, tubular cell proliferation, or functional recovery from preservation/reperfusion injury were not compromised in comparison to vehicle treated animals. VEGF-A, VEGF receptor 2, and the co-receptor Neuropilin-1 were upregulated by Rapamycin within 7 days. Rat proximal tubular cells (RPTC) responded in vitro to hypoxia with increased VEGF-A and VEGF-R1 expression that was not suppressed by Rapamycin at therapeutic concentrations. Rapamycin did not impair proliferation of RPTC under hypoxic conditions. Low-dose Rapamycin early posttransplant does not negatively influence the VEGF network crucial for recovery from preservation/reperfusion injury. Enhancement of VEGF signaling peritransplant holds potential to further improve outcomes.

Hesperidin protects against the chlorpyrifos-induced chronic hepato-renal toxicity in rats associated with oxidative stress, inflammation, apoptosis, autophagy, and up-regulation of PARP-1/VEGF

In this study, we investigated the effects of hesperidin (HSP) on oxidants/antioxidants status, inflammation, apoptotic, and autophagic activity in hepato-renal toxicity induced by chronic chlorpyrifos (CPF) exposure in rats. We used a total of 35 male albino rats in five groups of seven: control, HSP 100, CPF, CPF + HSP50, and CPF + HSP100. After rats were sacrificed, blood, liver, and kidney samples were collected. Serum levels of aspartate aminotransferases (ALT and AST), alkaline phosphatase (ALP), creatinine, and urea were tested. Then, contents of the superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), glutathione peroxidase (GPx), and glutathione (GSH) were measured to detect the level of oxidative stress in rat liver and renal tissues. We measured inflammatory and autophagy markers of chlorpyrifos induced oxidative stress in the liver and kidney tissues including TNF-α, iNOS, IL-1 β, COX-2, NF-κB, MAPK14, and Beclin-1 using ELISA. Histopathological findings were also examined followed by immunohistochemical determination of 8-OHdG expression. Real-time PCR (RT-PCR) was used to examine Cas-3, Bax, Bcl-2, PARP-1, and VEGF, which are associated with apoptosis, autophagy, DNA, and endothelial damage, respectively. In addition, PARP-1 activity was supported by western blot and immunofluorescence, VEGF activity was supported by western blot methods. Treatment with HSP reduced the effect of CPF on ALT, AST, ALP, and total proteins, and increased its effect on tissue antioxidants. PARP/VEGF, apoptotic, pro-apoptotic, anti-apoptotic, and autophagic gene expressions were regulated, and Caspase-3 and Bax expressions were decreased; Bcl-2 expression increased in both the liver and kidney samples, and positivity of 8-OHdG and PARP-1 were reduced in the CPF plus HSP-treated group. Overall, the study demonstrates that HSP may reduce the effects of hepato-renal toxicity caused by CPF by regulating oxidative stress, inflammation, apoptosis, autophagy, and PARP/VEGF genes at biochemical, cellular, and molecular levels.

Predictive and prognostic value of magnesium serum level in FOLFIRI plus cetuximab or bevacizumab treated patients with stage IV colorectal cancer: results from the FIRE-3 (AIO KRK-0306) study

Magnesium wasting is a frequent side effect of epidermal growth factor receptor (EGFR)-antibody treatment as magnesium-absorption mechanisms are dependent on EGFR signaling. EGFR-inhibition results in decreased renal reabsorption. There is evidence that hypomagnesemia during cetuximab treatment correlates with response. The prognostic role of hypomagnesemia during bevacizumab treatment has not been studied yet. Here, we evaluate the prognostic value of hypomagnesemia in patients with metastatic colorectal cancer treated with FOLFIRI plus cetuximab or bevacizumab as first-line therapy. A total of 391 of 752 patients of the firstline irinotecan study population had magnesium levels measured at baseline and for the first three cycles (6 weeks) of treatment. Of those, 240 had Rat Sarkoma wildtype tumors. Overall hypomagnesemia was more common in the cetuximab compared to the bevacizumab arm (80 vs. 43%, P < 0.005). During therapy, magnesium showed a time-dependent decrease to 80% of baseline in the cetuximab and to 89% in the bevacizumab arm. Whereas magnesium continued to decrease over time in the cetuximab-treated patients, it remained stable in the bevacizumab-treated. Overall response rate (ORR) was associated with higher magnesium at week 6 (20.9 vs. 79.1%, P = 0.041). Bevacizumab-treated patients with magnesium levels below the median value at week 6 had a significantly longer progression-free survival (PFS; 11.7 vs. 9.9 months, P = 0.034; hazard ratio 0.73) and a trend towards longer overall survival (OS) (29.6 vs. 23.2 months, P = 0.089; hazard ratio 0.77). Hypomagnesemia at predefined time points and magnesium nadir had no significant effect on ORR, OS and PFS in the cetuximab arm. Our data show different magnesium kinetics in patients with metastatic colorectal cancer treated with cetuximab or bevacizumab. For patients treated with cetuximab, hypomagnesemia did not have an impact on response and survival. Hypomagnesemia might have a prognostic value in bevacizumab treatment.

TAFRO Syndrome with Renal Thrombotic Microangiopathy: Insights into the Molecular Mechanism and Treatment Opportunities

TAFRO syndrome is an extremely rare form of idiopathic MCD, characterized by thrombocytopenia, anasarca, fever, reticulin fibrosis on bone marrow biopsy, and organomegaly. Like idiopathic MCD, renal involvement is also a common presentation in patients with TAFRO syndrome. Furthermore, membranoproliferative glomerulonephritis (MPGN)-like injury and thrombotic microangiopathy (TMA) are the most reported histopathologic findings of renal biopsy. Several molecular mechanisms have been previously postulated in order to explain the TAFRO syndrome symptoms, including abnormal production of interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), etc. The role of these cytokines in renal injury, however, is not well understood. The aim of this review article is to summarize the latest knowledge of molecular mechanisms behind the TAFRO syndrome and their potential role in renal damage.

Renal toxicity of targeted therapies for renal cell carcinoma in patients with normal and impaired kidney function

The introduction of novel targeted therapies during the last 2 decades has led to a significant improvement in patients' clinical outcomes with renal cell carcinoma. However, this improvement came at the price of a whole new spectrum of adverse events, including renal toxicity. Systemic treatment of patients with kidney neoplasms who often present with impairment of kidney function, even prior to treatment, poses an increasing diagnostic and therapeutic challenge for clinicians. Common lifestyle-related comorbidities, i.e., hypertension and diabetes, may contribute to further impairment of kidney function. The lack of official guidelines and the exclusion of patients with reduced kidney function from the clinical trials of recently approved drugs complicate the issue even further. Early detection and correct management of renal toxic effects are crucial to preserve kidney function and ensure the optimal administration of life-prolonging therapies. This review presents detailed information on the renal toxicities of three groups of drugs commonly used in renal cell carcinoma treatment: tyrosine kinase inhibitors, mammalian target of rapamycin inhibitors, and immune checkpoint inhibitors. We outline the incidence and underlying mechanisms of renal adverse effects with a focus on patients on renal replacement therapy, as well as present suggestions for their management.

SYSTEMIC FACTORS AND EARLY TREATMENT RESPONSE TO INTRAVITREAL INJECTION FOR DIABETIC MACULAR EDEMA: The Role of Renal Function

PURPOSE

To investigate the effect of systemic factors on early treatment response to intravitreal bevacizumab injection (IVBI) and intravitreal dexamethasone implant (IVDI) in patients with diabetic macular edema (DME).

METHODS

We reviewed the medical records of 117 treatment naïve DME patients who underwent IVBI. We divided the patients according to their IVBI response. An IVDI was performed in patients with poor response to IVBIs. We investigated the various systemic factors of diabetic patients and examined the relationship between systemic factors and the treatment response to IVBI and IVDI.

RESULTS

In a total of 117 treatment naïve DME eyes, 61 eyes (52.14%) were classified as IVBI responders. An IVDI was performed in 23 of 56 eyes with poor response to IVBI, and 17 eyes (73.91%) had a good response. Among various systemic factors of patients with diabetes, renal function (blood urea nitrogen, creatinine, and estimated glomerular filtration rate) showed a significant negative correlation with central subfield retinal thickness improvement after treatment (P < 0.05). However, there was no difference in HbA1C levels regarding the treatment response to IVBI and IVDI.

CONCLUSION

Renal function was significantly worse in patients with a poor response to IVBI and IVDI. Renal function could be used as a possible predictor for treatment response in certain patients with DME. Furthermore, for patients with DME with poor responses to anti-vascular endothelial growth factor or steroid treatments, assessment of renal function could help explain the poor treatment response.

Nephrotoxicity of Anti-Angiogenic Therapies

The use of inhibitors of vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor 2 (VEGFR2) signaling for the treatment of cancer has increased over the last decade. This signaling pathway plays a fundamental role in angiogenesis and also in kidney physiology. The emergence of anti-angiogenic therapies has led to adverse nephrotoxic effects, despite improving the outcomes of patients. In this review, we will present the different anti-angiogenic therapies targeting the VEGFR pathway in association with the incidence of renal manifestations during their use. In addition, we will discuss, in detail, the pathophysiological mechanisms of frequent renal diseases such as hypertension, proteinuria, renal dysfunction, and electrolyte disorders. Finally, we will outline the cellular damage described following these therapies.

Stem/progenitor cell in kidney: characteristics, homing, coordination, and maintenance

Renal failure has a high prevalence and is becoming a public health problem worldwide. However, the renal replacement therapies such as dialysis are not yet satisfactory for its multiple complications. While stem/progenitor cell-mediated tissue repair and regenerative medicine show there is light at the end of tunnel. Hence, a better understanding of the characteristics of stem/progenitor cells in kidney and their homing capacity would greatly promote the development of stem cell research and therapy in the kidney field and open a new route to explore new strategies of kidney protection. In this review, we generally summarize the main stem/progenitor cells derived from kidney in situ or originating from the circulation, especially bone marrow. We also elaborate on the kidney-specific microenvironment that allows stem/progenitor cell growth and chemotaxis, and comment on their interaction. Finally, we highlight potential strategies for improving the therapeutic effects of stem/progenitor cell-based therapy. Our review provides important clues to better understand and control the growth of stem cells in kidneys and develop new therapeutic strategies.

Machine-perfused donor kidneys as a source of human renal endothelial cells

Renal endothelial cells (ECs) play crucial roles in vasorelaxation, ultrafiltration, and selective transport of electrolytes and water, but also in leakage of the glomerular filtration barrier and inflammatory processes like complement activation and leukocyte recruitment. In addition, they are target cells for both cellular and antibody-mediated rejection in the transplanted kidney. To study the molecular and cellular processes underlying EC behavior in renal disease, well-characterized primary renal ECs are indispensible. In this report, we describe a straightforward procedure to isolate ECs from the perfusion fluid of human donor kidneys by a combination of negative selection of monocytes/macrophages, positive selection by CD31 Dynabeads, and propagation in endothelium-specific culture medium. Thus, we isolated and propagated renal ECs from 102 donor kidneys, representative of all blood groups and major human leukocyte antigen (HLA) class I and II antigens. The obtained ECs were positive for CD31 and von Willebrand factor, expressed other endothelial markers such as CD34, VEGF receptor-2, TIE2, and plasmalemmal vesicle associated protein-1 to a variable extent, and were negative for the monocyte marker CD14 and lymphatic endothelial marker podoplanin. HLA class II was either constitutively expressed or could be induced by interferon-γ. Furthermore, as a proof of principle, we showed the diagnostic value of this renal endothelial biobank in renal endothelium-specific cross-matching tests for HLA antibodies.NEW & NOTEWORTHY We describe a new and widely accessible approach to obtain human primary renal endothelial cells in a standardized fashion, by isolating from the perfusate of machine-perfused donor kidneys. Characterization of the cells showed a mixed population originating from different compartments of the kidney. As a proof of principle, we demonstrated a possible diagnostic application in an endothelium-specific cross-match. Next to transplantation, we foresee further applications in the field renal endothelial research.

Role of sodium glucose cotransporter type 2 inhibitors dapagliflozin on diabetic nephropathy in rats; Inflammation, angiogenesis and apoptosis

AIMS

Diabetic nephropathy is a major cause of chronic kidney disease and end-stage renal failure worldwide. Dapagliflozin Sodium-glucose co-transporter 2 (SGLT2) inhibitor is a new class of diabetic medications prescribed for the treatment of type 2 diabetes. The current study investigates the possible impact of dapagliflozin (DAPA) on inflammations, apoptosis, angiogenesis and fibrosis in early-stage diabetic nephropathy using a rat model of type 2 diabetes.

MAIN METHODS

Rats were divided into five groups, group1: normal vehicle group, group 2: diabetic group, group 3: diabetic+ DAPA (0.75 mg/kg), group 4: diabetic+DAPA (1.5 mg/kg), group 5: diabetic+DAPA (3 mg/kg). At the end of the study, Blood glucose level was measured. Serum insulin, BUN, and SCr were measured. Insulin resistance was determined using the homeostasis model assessment for insulin resistance (HOMA-IR) index. Renal tissue homogenization was done for assessment of inflammatory markers TNF-α, PEDF, and PTX-3, In addition to apoptosis markers BCL-2 and BAX. Histopathological examinations were done for tubular renal cells and immunohistochemical examination for fibrosis marker α-SMA and angiogenic factor VEGF.

KEY FINDINGS

Treatments with dapagliflozin showed improvements in histopathological examinations, inflammatory and apoptotic markers compared to diabetic vehicles in a dose-dependent manner.

SIGNIFICANCE

Thus, dapagliflozin may have renoprotective effects, which be promising in diabetic patients suffered from nephropathy.

Angiogenic markers predict kidney injury and obstetric complications in women with preeclampsia and pregnancy-related acute kidney injury

Pregnancy-related acute kidney injury (PRAKI) particularly on top of preeclampsia (PE) represents a major cause of maternal and fetal morbidity and mortality. Reliable diagnostic tools are needed to further evaluate the diagnosis and prognosis of PRAKI. Our objective was to study the diagnostic and prognostic value of angiogenic markers (e.g., stromal cell-derived factor 1 (SDF-1), vascular endothelial growth factor (VEGF), alarmins as uric acid) in women with PE and PRAKI. This prospective study included three groups; PRAKI, PE patients, and healthy controls that were compared regarding serum levels of the studied markers correlated to renal, maternal, and fetal outcomes. SDF-1, VEGF, and uric acid levels were significantly different between the three included groups and predicted PRAKI diagnosis. Patients with hemolysis, elevated liver enzymes, and low platelet (HELLP) syndrome exhibited the highest titers of SDF-1 and VEGF. A positive correlation was found between SDF-1 and renal recovery. Conclusively, serum assays of SDF-1, VEGF, and uric acid may add a diagnostic value in PRAKI and PE.

Sulfatase 2 Is Associated with Steroid Resistance in Childhood Nephrotic Syndrome

Glucocorticoid (GC) resistance complicates the treatment of ~10-20% of children with nephrotic syndrome (NS), yet the molecular basis for resistance remains unclear. We used RNAseq analysis and in silico algorithm-based approaches on peripheral blood leukocytes from 12 children both at initial NS presentation and after ~7 weeks of GC therapy to identify a 12-gene panel able to differentiate steroid resistant NS (SRNS) from steroid-sensitive NS (SSNS). Among this panel, subsequent validation and analyses of one biologically relevant candidate, sulfatase 2 (SULF2), in up to a total of 66 children, revealed that both SULF2 leukocyte expression and plasma arylsulfatase activity Post/Pre therapy ratios were greater in SSNS vs. SRNS. However, neither plasma SULF2 endosulfatase activity (measured by VEGF binding activity) nor plasma VEGF levels, distinguished SSNS from SRNS, despite VEGF's reported role as a downstream mediator of SULF2's effects in glomeruli. Experimental studies of NS-related injury in both rat glomeruli and cultured podocytes also revealed decreased SULF2 expression, which were partially reversible by GC treatment of podocytes. These findings together suggest that SULF2 levels and activity are associated with GC resistance in NS, and that SULF2 may play a protective role in NS via the modulation of downstream mediators distinct from VEGF.

Time-sequential correlations between diabetic kidney disease and diabetic retinopathy in type 2 diabetes - an 8-year prospective cohort study

PURPOSE

To investigate the time-sequential correlations between progression/remission of diabetic kidney disease (DKD) and development of diabetic retinopathy (DR) or diabetic macular oedema (DME) in type 2 diabetes (T2D).

METHODS

This was an 8-year prospective cohort study in which 576 patients with T2D and microalbuminuria from one medical centre in Taiwan were recruited. Progression of microalbuminuria was defined as shift of urinary albumin/creatinine ratio (ACR) into 300 mg/g or more; remission of microalbuminuria was defined as having a urinary ACR less than 30 mg/g in at least two of three tests over a period of 6 months. Cox regression analysis was used to evaluate the hazard ratios (HRs) for progression or remission of microalbuminuria on development of any DR, proliferative DR (PDR) and DME.

RESULTS

After adjusting for baseline characteristics , remission of microalbuminuria was a significant protecting factor for development of PDR (HR = 0.290, 95% CI: 0.102-0.826, p = 0.020) and DME (HR = 0.404, 95% CI: 0.188-0.864, p = 0.020). After further adjustment for the mean follow-up HbA1c and systolic blood pressure, remission of microalbuminuria was still a significant protecting factor for development of PDR (HR = 0.348, 95% CI: 0.122-0.992, p = 0.048).

CONCLUSIONS

Remission of microalbuminuria was an independent protecting factor for development of PDR and DME. Aggressive treatment for DKD might help prevent the progression of DR.