FSGS: Diagnosis and Diagnostic Work-Up

Clinical Characteristics and Histopathology in Adults With Focal Segmental Glomerulosclerosis

Rationale & Objective

Few data are available regarding histological features at the time of focal segmental glomerulosclerosis (FSGS) diagnosis among diverse real-world populations. This study describes clinical and histological characteristics and correlates of histological disease severity in adults with FSGS who underwent a clinical kidney biopsy.

Study Design

Real-world cohort study with data derived from health records.

Setting & Participants

Adults with FSGS by kidney biopsies from Arkana Laboratories from January 1, 2016 to May 31, 2020.

Exposure

Race, chronic kidney disease stage, nephrotic proteinuria, age, sex, and hypertension.

Outcomes

Severe histological disease, defined as global glomerulosclerosis in >50% of glomeruli and >25% interstitial fibrosis and tubular atrophy (IFTA).

Analytical Approach

Demographic, clinical, and histological characteristics were compared between race groups. Correlates of severe disease were analyzed using multiple logistic regression.

Results

Among 2,011 patients with FSGS, 40.6% were White, and 23.6% Black. White patients were older (52.8 vs 45.5 years, P < 0.001) with a higher estimated glomerular filtration rate (eGFR) than Black patients (53.5 vs 43.1 mL/min/1.73 m2, P < 0.001). A higher proportion of Black patients had global glomerulosclerosis ≥50% (32.1% vs 14.6%, P < 0.001) or IFTA >50% (34.6% vs 14.7%, P < 0.001). Severe histological disease was more likely in Black patients (OR, 2.46; 95% CI, 1.59-3.79; P < 0.001). A higher proportion of patients with nephrotic than nonnephrotic proteinuria exhibited diffuse foot process effacement.

Limitations

Unequal representation across United States regions, missing demographic and clinical data, and lack of data on primary versus secondary FSGS, treatments, or outcomes.

Conclusions

Black patients were more frequently diagnosed at younger age with lower eGFR and more severe histological disease compared with White patients. Timelier identification of FSGS could increase the opportunity for therapeutic intervention, especially for high-risk patients, to mitigate disease progression and complications.

Plain-Language Summary

Focal segmental glomerulosclerosis (FSGS) accounts for around one-quarter of diagnoses derived from clinical kidney biopsies in the United States. Limited data are available regarding the classes and distribution of histological features at FSGS diagnosis among diverse real-world populations. Analyzing data from US patients who underwent kidney biopsy and were diagnosed with FSGS, we showed that up to half of patients had features of severe histological disease. Of this overall population, Black patients were more frequently diagnosed at a younger age but with more severe histological disease than White patients. The work highlights the need for timelier diagnosis of FSGS to enable intervention at an earlier disease stage.

A Case of COVID-19-Associated Focal Segmental Glomerulosclerosis

This case report details a 43-year-old female diagnosed with the collapsing variant of focal segmental glomerulosclerosis (FSGS) post-infection with coronavirus disease 2019 (COVID-19). The patient contracted COVID-19 after returning from a trip to Florida and initially presented to the emergency department with gastrointestinal symptoms. Thereafter, the patient was diagnosed with COVID-19 and was admitted for acute kidney injury and worsening COVID-19 infection. FSGS is a glomerulopathy that consists of glomerular scarring that leads to nephrotic syndrome, secondary to podocyte effacement. FSGS has many causes, as well as distinct variants, but is noted to have an association with some viruses, most notably HIV and cytomegalovirus (CMV). Although the association between FSGS and HIV or CMV is well established, the evidence is minimal in regard to other viruses. This case report serves to highlight the potential association of COVID-19 with FSGS.

MicroRNA-155-5p Aggravates Adriamycin-Induced Focal Segmental Glomerulosclerosis through Targeting Nrf2

INTRODUCTION

Focal segmental glomerulosclerosis (FSGS) is characterized by focal and segmental obliteration of glomerular capillary tufts with increased matrix and usually associated with nephrotic range proteinuria. FSGS is a huge burden to society; however, the mechanisms remain unclear and treatment is still lacking.

METHODS

Adriamycin nephropathy was induced by Adriamycin injection and some mice were also injected with Anti-miR-155-5p LNA or YC-1 (a pharmacological inhibitor of HIF-1). At 6 weeks, the mice were sacrificed, and kidneys, blood and urine samples were collected for further analysis.

RESULTS

We demonstrated a significant increase of miR-155-5p in kidney tissues in Adriamycin-induced FSGS mouse models. We also found Adriamycin treatment led to the activation of HIF-1, and inhibition of HIF-1 using YC-1 partly prevented the induction of miR-155-5p. Functionally, anti-miR-155-5p attenuated kidney injury and delayed the progression of renal fibrosis. Further, anti-miR-155-5p also enhanced the expression of Nrf2 following Adriamycin treatment. Further, our luciferase microRNA target reporter assay verified Nrf2 as a direct target of miR-155-5p. Our further results indicated anti-miR-155-5p could suppress kidney oxidative stress and inflammation, also supporting Nrf2 was the direct target of miR-155-5p. Finally, we also found miR-155-5p did not increase in serum but significantly increased in urine, indicating urinary miR-155-5p may be useful for FSGS diagnosis.

CONCLUSION

This study identified a HIF-1/miR-155-5p/Nrf2 axis which can promote kidney oxidative stress and inflammation, finally aggravating kidney injury and accelerating the progression of renal fibrosis in FSGS. Moreover, the increase in urinary miR-155-5p may be useful for the diagnosis of FSGS.

STAT-3 signaling role in an experimental model of nephropathy induced by doxorubicin

The focal segmental glomerulosclerosis (FSGS) is one of the most frequent glomerulopathy in the world, being considered a significative public health problem worldwide. The disease is characterized by glomerular loss mainly due to inflammation process and collagen fibers deposition. STAT-3 is a transcription factor associated with cell differentiation, migration and proliferation and in renal cells it has been related with fibrosis, acting on the progression of the lesion. Considering this perspective, the present study evaluated the involvement of STAT-3 molecule in an experimental model of FSGS induced by Doxorubicin (DOX). DOX mimics primary FSGS by causing both glomerular and tubular lesions and the inhibition of the STAT3 pathway leads to a decrease in fibrosis and attenuation of kidney damage. We described here a novel FSGS experimental model in a strain of genetically heterogeneous mice which resembles the reality of FSGS patients. DOX-injected mice presented elevated indices of albuminuria and glycosuria, that were significantly reduced in animals treated with a STAT-3 inhibitor (STATTIC), in addition with a decrease of some inflammatory molecules. Moreover, we detected that SOCS-3 (a regulator of STAT family) was up-regulated only in STATTIC-treated mice. Finally, histopathological analyzes showed that DOX-treated group had a significant increase in a tubulointerstitial fibrosis and tubular necrosis, which were not identified in both control and STATTIC groups. Thus, our results indicate that STAT-3 pathway possess an important role in experimental FSGS induced by DOX and may be an important molecule to be further investigated.

Focal Segmental Glomerulosclerosis and Recurrence in Living Donor Recipients

Purpose

Focal segmental glomerulosclerosis (FSGS) is a common cause for end-stage renal disease that can recur in the graft after kidney transplantation. The incidence of FSGS recurrence is reported in up to 47% of patients, predisposing those to possible poorer transplantation outcomes. Hence, we examined the incidence of FSGS recurrence and the effect on graft outcome in our patient cohort of living donor kidney transplantations (LDKT).

Patients and Methods

We analyzed 194 adult patients who received a LDKT between 2011 and 2017 of which 22 (11%) had FSGS as underlying disease. Demographic data and clinical outcomes, especially regarding recurrence of FSGS, were evaluated.

Results

FSGS recurrence was identified in three (14%) patients within three months after transplantation, of whom two patients (9%) lost their graft. There was no significant difference in graft survival comparing FSGS to other reasons for end-stage renal disease.

Conclusion

Incidence of FSGS recurrence in the present patient cohort was within the range reported in the literature and comparatively low. Our data support LDKT as a treatment option in patients with end-stage renal disease due to FSGS.

Next-generation sequencing in patients with familial FSGS: first report of collagen gene mutations in Tunisian patients

Focal segmental glomerulosclerosis (FSGS) is a histological lesion with many causes, including inherited genetic defects, with significant proteinuria being the predominant clinical finding at presentation. FSGS is considered as a podocyte disease due to the fact that in the majority of patients with FSGS, the lesion results from defects in the podocyte structure. However, FSGS does not result exclusively from podocyte-associated genes. In this study, we used a genetic approach based on targeted next-generation sequencing (NGS) of 242 genes to identify the genetic cause of FSGS in seven Tunisian families. The sequencing results revealed the presence of eight distinct mutations including seven newly discovered ones: the c.538G>A (p.V180M) in NPHS2, c.5186G>A (p.R1729Q) in PLCE1 and c.232A>C (p.I78L) in PAX2 and five novel mutations in COL4A3 and COL4A4 genes. Four mutations (c.209G>A (p.G70D), c.725G>A (p.G242E), c.2225G>A (p.G742E), and c. 1681_1698del) were detected in COL4A3 gene and one mutation (c.1424G>A (p.G475D)) was found in COL4A4. In summary, NGS of a targeted gene panel is an ideal approach for the genetic testing of FSGS with multiple possible underlying etiologies. We have demonstrated that not only podocyte genes but also COL4A3/4 mutations should be considered in patients with FSGS.

Case Report: Glucocorticoids Combined With Immunosuppressant in the Treatment of Acromegaly Complicated With Focal Segmental Glomerulosclerosis

Background: Acromegaly is a chronic disease caused by excessive secretion of growth hormone (GH), which circulates and stimulates the liver and body tissues to produce insulin-like growth factor type 1 (IGF-1). Experimental studies have shown that excessive secretion of GH is related to glomerular sclerosis, and elevated IGF-1 levels may be involved in the occurrence of glomerular hypertrophy. But relevant clinical cases are rare. Here, we reported a case of acromegaly complicated with focal segmental glomerulosclerosis (FSGS). Case Presentation: A 49-year-old man was admitted to our hospital because of acromegaly for more than 10 years and proteinuria for more than 3 years. Acromegaly was confirmed by contrast-enhanced magnetic resonance imaging, minimally invasive surgery and pathology. The results of renal biopsy showed FSGS-NOS (not otherwise specified) with ischemic renal injury and mesangial IgA deposition. One month after transnasal transsphenoidal space occupying resection, GH and urinary protein decreased significantly, and nephropathy was partially relieved. In the next 4 months, GH stabilized at the normal level, while urinary protein gradually increased. When the urinary protein increased to 4.2 g/d, the dosage of glucocorticoids increased to 20 mg/d, and tacrolimus 1 mg/d were added, and the urinary protein decreased again. However, when the urinary protein decreased to 0.43 g/d, the patient stopped taking glucocorticoids and tacrolimus, and the urinary protein increased to 2.85 g/d after 8 months, but the GH was still in the normal range. Conclusion: In this case, GH is partially involved in the formation of FSGS. Not only does surgery reduce the effects of GH, but low doses of glucocorticoids and immunosuppressant are effective in slowing the progression of kidney disease, at least in reducing urinary protein.

Collapsing focal segmental sclerosis in an HIV-negative patient

Collapsing focal segmental glomerulosclerosis (FSGS) is classically seen in HIV-infected patients and carries a dismal prognosis. It can also occur in HIV-negative patients in which case, early aggressive treatment with glucocorticoids may be helpful with improvement in both proteinuria and renal function.

Challenges in primary focal segmental glomerulosclerosis diagnosis: from the diagnostic algorithm to novel biomarkers

Primary or idiopathic focal segmental glomerulosclerosis (FSGS) is a kidney entity that involves the podocytes, leading to heavy proteinuria and in many cases progresses to end-stage renal disease. Idiopathic FSGS has a bad prognosis, as it involves young individuals who, in a considerably high proportion (∼15%), are resistant to corticosteroids and other immunosuppressive treatments as well. Moreover, the disease recurs in 30–50% of patients after kidney transplantation, leading to graft function impairment. It is suspected that this relapsing disease is caused by a circulating factor(s) that would permeabilize the glomerular filtration barrier. However, the exact pathologic mechanism is an unsettled issue. Besides its poor outcome, a major concern of primary FSGS is the complexity to confirm the diagnosis, as it can be confused with other variants or secondary forms of FSGS and also with other glomerular diseases, such as minimal change disease. New efforts to optimize the diagnostic approach are arising to improve knowledge in well-defined primary FSGS cohorts of patients. Follow-up of properly classified primary FSGS patients will allow risk stratification for predicting the response to different treatments. In this review we will focus on the diagnostic algorithm used in idiopathic FSGS both in native kidneys and in disease recurrence after kidney transplantation. We will emphasize those potential confusing factors as well as their detection and prevention. In addition, we will also provide an overview of ongoing studies that recruit large cohorts of glomerulopathy patients (Nephrotic Syndrome Study Network and Cure Glomerulonephropathy, among others) and the experimental studies performed to find novel reliable biomarkers to detect primary FSGS.

Recurrence of FSGS after Kidney Transplantation in Adults

BACKGROUND AND OBJECTIVES

FSGS recurrence after kidney transplantation is a major risk factor for graft loss. However, the natural history, clinical predictors, and response to treatment remain unclear because of small sample sizes and poor generalizability of single-center studies, and disease misclassification in registry-based studies. We therefore aimed to determine the incidence, predictors, and treatment response of recurrent FSGS in a large cohort of kidney transplant recipients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Post-Transplant Glomerular Disease (TANGO) project is an observational, multicenter, international cohort study that aims to investigate glomerular disease recurrence post-transplantation. Transplant recipients were screened for the diagnosis of idiopathic FSGS between 2005 and 2015 and details were recorded about the transplant, clinical outcomes, treatments, and other risk factors.

RESULTS

Among 11,742 kidney transplant recipients screened for FSGS, 176 had a diagnosis of idiopathic FSGS and were included. FSGS recurred in 57 patients (32%; 95% confidence interval [95% CI], 25% to 39%) and 39% of them lost their graft over a median of 5 (interquartile range, 3.0-8.1) years. Multivariable Cox regression revealed a higher risk for recurrence with older age at native kidney disease onset (hazard ratio [HR], 1.37 per decade; 95% CI, 1.09 to 1.56). Other predictors were white race (HR, 2.14; 95% CI, 1.08 to 4.22), body mass index at transplant (HR, 0.89 per kg/m²; 95% CI, 0.83 to 0.95), and native kidney nephrectomies (HR, 2.76; 95% CI, 1.16 to 6.57). Plasmapheresis and rituximab were the most frequent treatments (81%). Partial or complete remission occurred in 57% of patients and was associated with better graft survival.

CONCLUSIONS

Idiopathic FSGS recurs post-transplant in one third of cases and is associated with a five-fold higher risk of graft loss. Response to treatment is associated with significantly better outcomes but is achieved in only half of the cases.

A bigenic mouse model of FSGS reveals perturbed pathways in podocytes, mesangial cells and endothelial cells

Focal segmental glomerulosclerosis is a major cause of end stage renal disease. Many patients prove unresponsive to available therapies. An improved understanding of the molecular basis of the disease process could provide insights leading to novel therapeutic approaches. In this study we carried out an RNA-seq analysis of the altered gene expression patterns of podocytes, mesangial cells and glomerular endothelial cells of the bigenic Cd2ap+/-, Fyn-/- mutant mouse model of FSGS. In the podocytes we observed upregulation of many genes related to the Tgfβ family/pathway, including Gdnf, Tgfβ1, Tgfβ2, Snai2, Vegfb, Bmp4, and Tnc. The mutant podocytes also showed upregulation of Acta2, a marker of smooth muscle and associated with myofibroblasts, which are implicated in driving fibrosis. GO analysis of the podocyte upregulated genes identified elevated protein kinase activity, increased expression of growth factors, and negative regulation of cell adhesion, perhaps related to the observed podocyte loss. Both podocytes and mesangial cells showed strong upregulation of aldehyde dehydrogenase genes involved in the synthesis of retinoic acid. Similarly, the Cd2ap+/-, Fyn-/- mesangial cells, as well as podocytes in other genetic models, and the glomeruli of human FSGS patients, all show upregulation of the serine protease Prss23, with the common thread suggesting important functionality. Another gene with strong upregulation in the Cd2ap+/-, Fyn-/- mutant mesangial cells as well as multiple other mutant mouse models of FSGS was thrombospondin, which activates the secreted inactive form of Tgfβ. The Cd2ap+/-, Fyn-/- mutant endothelial cells showed elevated expression of genes involved in cell proliferation, angioblast migration, angiogenesis, and neovasculature, all consistent with the formation of new blood vessels in the diseased glomerulus. The resulting global definition of the perturbed molecular pathways in the three major cell types of the mutant glomerulus provide deeper understanding of the molecular pathogenic pathways.

Importance of Genetic Diagnostics in Adult-Onset Focal Segmental Glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a histological pattern of podocyte and glomerulus injury. FSGS can be primary and secondary to other diseases or due to a genetic cause. Strikingly, genetic causes for adult-onset FSGS are often overlooked, likely because identifying patients with genetic forms of FSGS based on clinical presentation and histopathology is difficult. Yet diagnosing genetic FSGS does not only have implications for prognostication and therapy but also for family and family planning. In this case series, we present 3 adult patients who presented with advanced renal disease with the histological picture of FSGS and proved to have a genetic cause of the disease, namely, variants in INF2, COL4A4 and HNF1B, respectively. We show the possibilities of identifying genetic FSGS based on clinical clues of a positive family history, early age at onset of disease, and/or severe therapy-resistant disease. We discuss ways to select the method of genetic testing for individual patients. Finally, we examine how the judicious use of genetic investigations can obviate potential harmful diagnostic procedures and direct clinical decisions in patients and their relatives.

Increased Serum Soluble Urokinase-Type Plasminogen Activator Receptor (suPAR) Levels in FSGS: A Meta-Analysis

Introduction

The soluble urokinase-type plasminogen activator receptor (suPAR) has been found to be elevated in primary focal segmental glomerulosclerosis (pFSGS). However, its usefulness as a biomarker for FSGS remains controversial. We conducted a meta-analysis aiming at investigating the significance of suPAR in diagnosing pFSGS.

Methods

Electronic databases (PubMed and EMBASE) were searched to identify studies comparing suPAR levels in FSGS patients and controls, from the earliest available date to May 1, 2018. A random-effects model with standardized mean difference (SMD) was used for meta-analyses. Risk of bias was assessed using the Newcastle-Ottawa quality assessment scale.

Results

A total of 187 articles were screened, and the final analysis included 13 articles. In comparison to healthy controls, serum suPAR levels were significantly increased in pFSGS patients (SMD, 1.07, 95% confidence interval (CI) 0.65 to 1.48; participants = 814; studies = 9, I ² = 85%). Higher suPAR levels were also found in patients with pFSGS compared to those with minimal change disease (SMD 0.53, 95% CI 0.22 to 0.84). Of note, such a difference was not found in pediatric groups (SMD 0.42, 95% CI -0.13 to 0.96) while it was more evidently noted in adult patients (SMD 1.32, 95% CI 0.90 to 1.74). Serum suPAR levels did not differ between pFSGS patients in remission compared to those in active proteinuric state (SMD 0.29, 95% CI -0.30 to 0.88). Comparison with membranous nephropathy and IgA nephropathy showed no significant difference.

Conclusions

Our meta-analysis demonstrated that, in comparison to both healthy controls and controls with minimal change disease, suPAR levels were significantly higher in adult patients with pFSGS. suPAR levels did not differ between pFSGS patients during the initial period of diagnosis and those in remission.

Electron microscopic findings suggestive of focal and segmental glomerulosclerosis in patients with steroid-resistant nephrotic syndrome

Distinction between minimal change disease and unsampled Focal Segmental Glomerulosclerosis is a challenging concept in kidney biopsy of patients with nephrotic syndrome with minimal histopathological findings. This study was performed to compare electron microscopic findings in patients with steroid-resistant nephrotic syndrome with minimal histopathological abnormalities and cases with Focal Segmental Glomerulosclerosis. This Cohort study was conducted in Cancer Institute, Imam Khomeini Hospital Complex, Tehran, Iran. Twenty patients with steroid-resistant nephrotic syndrome and minimal changes on the light microscopic study were selected as case group. Similarly, 20 patients with Focal Segmental Glomerulosclerosis were selected as the control group. Ultrastructural findings were re-evaluated and scored qualitatively (0-3+). In patients with minimal changes on light microscopic evaluation, clinical course of the disease was followed after 5 years. Mean ages of the patients (8 women and 12 men) in case and control groups were 12.9 and 15.9 years, respectively (p > 0.05). There was no significant difference in number of examined glomeruli and sampling from cortico-medullary junction area between the groups. The mean percentage of sclerotic glomeruli in control group was 15.4%. Tubular atrophy and interstitial fibrosis were more frequent in control patients. Podocyte proliferation, GBM duplication (involving more than 10% of capillary walls), and moderate to severe multifocal expansion of mesangial matrix were significantly more obvious in FSGS patient samples (p < 0.05). No statistically significant difference was found in severity of cytoplasmic vacuolization, GBM wrinkling and splitting between the groups. Most of (80%) the patients with minimal changes improved during the 5-year follow-up. Generally, we concluded that Podocyte proliferation, GBM remodeling, and moderate to severe mesangial matrix expansion are the most reliable findings on electron microscopic examination in favor of FSGS.

Development of a novel cell-based assay to diagnose recurrent focal segmental glomerulosclerosis patients

Definitive diagnosis of glomerular disease requires a kidney biopsy, an invasive procedure that may not be safe or feasible to perform in all patients. We developed a noninvasive, accurate, and economical diagnostic assay with easy commercial adaptability to detect recurrent focal segmental glomerulosclerosis (rFSGS) after kidney transplant. Since FSGS involves podocyte damage and death, our approach involved mRNA profiling of cultured podocytes treated with plasma from patients with rFSGS to identify upregulated genes involved in podocyte damage. For concept validation, three upregulated pro-apoptotic candidate genes (IL1β, BMF, and IGFBP3) were selected, and their promoter regions were cloned into a luciferase-based reporter vector and transfected into podocytes to generate stable podocyte cell lines. Strikingly, when exposed to rFSGS patient plasma, these cell lines showed increased reporter activity; in contrast, no reporter activity was noted with plasma from patients with non-recurrent FSGS or membranous nephropathy. Area under the receiver operating characteristics curves (AUCs) for models discriminating between rFSGS and other nephropathies (non-recurrent FSGS and membranous nephropathy) and between rFSGS and non-recurrent FSGS ranged from 0.81 to 0.86, respectively. Estimated sensitivities and specificities for the diagnosis of rFSGS were greater than 80% for the IL1β and BMF cell lines, and were slightly lower for the IGFBP3 cell line. Importantly, the novel approach outlined here for the diagnosis of rFSGS is widely applicable to the design of sensitive and specific diagnostic/prognostic assays for other glomerular diseases.

Successful Treatment of Focal Segmental Glomerulosclerosis Recurrence in a Second Kidney Transplant Patient: A Case Report

BACKGROUND

Recurrence of focal segmental glomerulosclerosis (FSGS) in renal allograft recipients after first transplant occurs in the second graft in virtually all patients. There is little evidence regarding optimal treatment.

CASE PRESENTATION

A 55-year-old man with primary FSGS and disease recurrence in both the first and the second kidney grafts is presented. In 1999, the patient developed FSGS 3 years after transplant, which was treated with plasmapheresis and cyclophosphamide. Hemodialysis was started at 8 years from the onset of relapse. In February 2014, the patient received a second kidney transplant, and after 2 weeks laboratory analysis showed nephrotic proteinuria (5.9 g/d) with increased serum creatinine. Biopsy results revealed recurrence of FSGS. At that time, he was treated with steroids and plasmapheresis with partial efficacy, achieving a serum creatinine level of 1.1 mg/dL with decreased proteinuria (1 g/d). After 4 months, creatinine worsened (1.6 mg/dL) with new evidence of proteinuria. Second biopsy results showed evidence of FSGS progression. The patient then received plasmapheresis and 2 doses of rituximab. Follow-up was characterized by progressive remission up to complete resolution. The patient is currently free from relapses after 3 years with good renal function and almost no proteinuria.

CONCLUSIONS

More evidence and prospective studies are needed to better understand the role of rituximab in FSGS in order to obtain an optimized therapeutic protocol for recurrence of FSGS in renal transplant recipients.

Fetal Renal Echogenicity Associated with Maternal Focal Segmental Glomerulosclerosis: The Effect of Transplacental Transmission of Permeability Factor suPAR

We report a case of a pregnant woman with nephrotic syndrome due to biopsy-proven focal segmental glomerulosclerosis (FSGS) whose fetus developed echogenic kidneys and severe oligohydramnios by 27 weeks of gestation. Maternal treatment with prednisone resulted in normalization of the amniotic fluid indices and resolution of fetal renal echogenicity. The newborn was noted to have transient renal dysfunction and proteinuria, resolving by 6 weeks postpartum. The transplacental passage of permeability factors is postulated to have caused both the fetal and newborn renal presentation, with significantly elevated levels of soluble urokinase-type plasminogen activator receptor (suPAR) noted in the cord blood. This case documents the transplacental maternal-fetal transmission of suPAR, demonstrating the potential for maternal-fetal transmission of deleterious, disease-causing entities, and adds to the differential diagnosis of fetal echogenic kidneys. Further, this is the first documentation of a fetal response to maternal systemic therapy.

Diagnosis and primary care management of focal segmental glomerulosclerosis in children

Focal segmental glomerulosclerosis (FSGS) is a pattern of kidney damage that can occur in individuals at any age, including children. Pediatric patients with FSGS require medication monitoring, growth, and psychological health. This article discusses the NP's role in the clinical presentation, diagnostic workup, and treatment of FSGS in pediatric patients.

Activation of mineralocorticoid receptor by ecdysone, an adaptogenic and anabolic ecdysteroid, promotes glomerular injury and proteinuria involving overactive GSK3β pathway signaling

Ecdysone is an arthropod molting hormone and has been marketed as a non-androgenic natural anabolic and adaptogen. However, the safety profile of ecdysone is largely undetermined. After ecdysone treatment for 2 weeks, mice developed albuminuria with histologic signs of glomerular injury, including hypertrophy, mesangial expansion, mild glomerulosclerosis and podocyte injury. A direct glomerulopathic activity of ecdysone seems to contribute, since addition of ecdysone to cultured glomerular cells induced cytopathic changes, including apoptosis, activation of mesangial cells, podocyte shape changes and a decreased expression of podocyte markers. To explore the molecular target responsible for the pathogenic actions, we employed an in silico modeling system of compound-protein interaction and identified mineralocorticoid receptor (MR) as one of the top-ranking proteins with putative interactions with ecdysone. The molecular structure of ecdysone was highly homologous to mineralocorticoids, like aldosterone. Moreover, ecdysone was capable of both inducing and activating MR, as evidenced by MR nuclear accumulation in glomerular cells both in vitro and in vivo following ecdysone treatment. Mechanistically, glycogen synthase kinase (GSK) 3β, which has been recently implicated in pathogenesis of glomerular injury and proteinuria, was hyperactivated in glomeruli in ecdysone-treated mice, concomitant with diverse glomerulopathic changes. In contrast, spironolactone, a selective blockade of MR, largely abolished the cytopathic effect of ecdysone in vitro and attenuated albuminuria and glomerular lesions in ecdysone treated mice, associated with a mitigated GSK3β overactivity in glomeruli. Altogether, ecdysone seems able to activate MR and thereby promote glomerular injury and proteinuria involving overactive GSK3β pathway signaling.

Pharmacological inhibition of focal segmental glomerulosclerosis-related, gain of function mutants of TRPC6 channels by semi-synthetic derivatives of larixol

BACKGROUND AND PURPOSE

Gain of function mutations in TRPC6 channels can cause autosomal dominant forms of focal segmental glomerulosclerosis (FSGS). Validated inhibitors of TRPC6 channels that are biologically active on FSGS-related TRPC6 mutants are eagerly sought.

EXPERIMENTAL APPROACH

We synthesized new TRPC6-inhibiting modulators from larixol, a resiniferous constituent of Larix decidua, and tested the potency and selectivity in cell lines stably expressing various TRPC channel isoforms. Channel activation was followed by Ca²⁺ influx analyses and electrophysiological recordings. The most promising compound larixyl carbamate (LC) was tested on native TRPC6 channels and TRPC6 constructs carrying FSGS-related point mutations.

KEY RESULTS

LC exhibited an about 30-fold preference for TRPC6 over TRPC3 channels and a fivefold preference for TRPC6 over TRPC7 channels. Six FSGS-related TRPC6 mutants, including the highly active M132T and R175Q variants, were strongly inhibited by 1 μM LC. Surprisingly, no TRPC6-related Ca²⁺ signals were detectable in primary murine podocytes, or in acutely isolated glomeruli. in these preparations. Quantitative PCR revealed a 20-fold to 50-fold lower abundance of TRPC6 transcripts in rat or mouse podocytes, compared with pulmonary artery smooth muscle cells from the same species. Accordingly, electrophysiological recordings demonstrated that DAG-induced currents in murine podocytes are very small, but sensitive to LC.

CONCLUSIONS AND IMPLICATIONS

In spite of their low abundance in native podocytes, native TRPC6 channels are targetable using larixol-derived TRPC6 inhibitors. As observed with wild-type TRPC6 channels, FSGS-related TRPC6 mutants were sensitive to the newly developed inhibitors, paving the way for experimental therapies.

Resveratrol Attenuates Adriamycin-Induced Focal Segmental Glomerulosclerosis through C3aR/C5aR- Sphingosine Kinase 1 Pathway

Background/Aim: Focal segmental glomerulosclerosis (FSGS) typically presents with nephrotic range proteinuria, which could eventually develop into end-stage renal disease. Resveratrol (RSV) is a natural polyphenol compound, which has been reported to suppress inflammatory response and renal interstitial fibrosis. This study is aimed at evaluating the renoprotective effect of RSV treatment on adriamycin-induced FSGS. Methods: In Balb/c mice, adriamycin nephropathy was induced by adriamycin (10 mg/kg body weight, diluted in normal saline) via a tail vein on day 0. Then the mice were treated with RSV (40 mg/kg body weight) once daily by oral gavage, again starting on the day of adriamycin injection and continued for 6 weeks. At 6 weeks, the mice were sacrificed; kidneys and blood samples were collected for further analysis. Results: When treated with adriamycin, the expressions of C3aR, C5aR, sphingosine kinase 1 (Sphk1), and soluble urokinase-type plasminogen activator receptor (suPAR) were upregulated, while RSV treatment could inhibit the expressions of C3aR, C5aR, Sphk1, and suPAR, eventually leading to anti-inflammatory and anti-fibrosis conditions. Conclusion: RSV attenuates adriamycin-induced FSGS through C3aR/C5aR-Sphk1 pathway.

Does copy number variation of APOL1 gene affect the susceptibility to focal segmental glomerulosclerosis?

Background: APOL1 risk variants (G1 and G2) are associated with increased susceptibility to focal segmental glomerulosclerosis (FSGS) in African population. However, the two risk mutations were not found in Chinese FSGS patients. In this study, we explored the association between the copy number variation (CNV) of APOL1 gene and FSGS.

Methods: APOL1 copy number variations were detected by quantitative real-time PCR with TaqMan probes and compared between 133 FSGS patients and 123 controls. The association between CNV of APOL1 gene and clinical parameters was also investigated.

Results: The distribution of APOL1 CNV did not show significant difference between FSGS patients and controls. The creatinine and proteinuria in the high copy number group (CN ≥ 3) were higher than the other two groups, but the difference was not significant (p > .05). The FSGS pathological types were different among the three groups.

Conclusion: There was no significant difference in the distribution of APOL1 gene copy variants between FSGS patients and normal controls, and there was no significant correlation between the APOL1 gene CNV and the FSGS patients’ clinical manifestations. APOL1 CNVs may be not associated with susceptibility to FSGS.