Diagnosis Of Focal Segmental Glomerulosclerosis Research Articles

Clinical and genetic analysis of a child with Focal segmental glomerulosclerosis due to a novel variant of PLCE1 gene

To explore the genetic basis and clinical phenotype of a Chinese pedigree affected with Focal segmental glomerulosclerosis (FSGS). A male patient who was admitted to the First Affiliated Hospital of Zhengzhou University on July 26, 2018 was selected as the study subject. Clinical data of the patient was collected. Next generation sequencing and Sanger sequencing were carried out to detect the variant sites. Bioinformatic software was used to simulate the effect of candidate variant on the protein functions. Ultrasound exam of the patient showed enhanced echo for the renal parenchyma. Kidney biopsy had confirmed the pathological diagnosis of FSGS (non-specific). Electronic microscopy displayed segmental sclerosis of the glomeruli, mild hyperplasia of mesangial cells and matrix. The proband was found to harbor two novel variants of the PLCE1 gene, namely c.3199delA (p.N1067Mfs*15) and c.4441_4443delATC (p.1481_1481del), which were respectively inherited from his mother and father. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), both variants were rated as pathogenic (PVS1+PM2_Supporting+PP3; PM2_Supporting+PM3+PP3). Bioinformatic simulation suggested that both variants could significantly affect the tertiary structure of the PLCE1 protein. The c.4441_4443delATC and c.3199delA variants of the PLCE1 gene probably underlay the pathogenesis of the FSGS in this pedigree.

Prophylactic treatment of FSGS recurrence in patients who relapsed in a previous kidney graft.

Recurrence of focal segmental glomerulosclerosis (FSGS) is common after kidney transplantation and is classically associated with a significant decrease in graft survival. A major risk factor is a prior history of FSGS recurrence on a previous graft. This analysis reports the impact of a prophylactic treatment of FSGS recurrence in very high-risk patients who experienced a recurrence on a previous graft. We performed a retrospective multicentre observational study in 25 French transplantation centres. The inclusion criteria were patients aged more than 18 years who had undergone kidney transplant between December 31, 2004, and December 31, 2020, and who had a history of FSGS recurrence on a previous graft. We identified 66 patients: 40 received prophylactic treatment (PT+), including intravenous cyclosporine and/or rituximab and/or plasmapheresis, and 26 did not receive any prophylactic treatment (PT-). The time to progression to end-stage kidney disease was similar between groups. The PT+group was younger at FSGS diagnosis and at the time of kidney retransplantation and lost their previous graft faster. The overall recurrence rate was 72.7% (76.9% in the PT- group and 70.0% in the PT+group, P=0.54). At least partial remission was achieved in 87.5% of patients. The 5-year graft survival was 67.7% (95% CI: 53.4 to 78.4%): 65.1% (95%CI: 48.7 to 77.4%) in patients with FSGS recurrence vs. 77.3% (95% CI: 43.8 to 92.3%) in patients without recurrence (P=0.48). Our study suggests that prophylactic treatment should not be used routinely in patients receiving a second transplantation after recurrence of FSGS on a previous graft. The recurrence rate is high regardless of the use of prophylactic treatment. However, the 5-year graft survival remains satisfactory.

#735 The clinicopathologic prognostic factors to estimate ESRD in patients with FSGS from national wide cohort of renal biopsy

Abstract Background and Aims Focal segmental glomerulosclerosis (FSGS) is one of the leading causes of glomerulonephritis in Korea. FSGS can be caused by heterogenous aetiologies with subdivided by primary, secondary, and genetical forms. The proposed clinicopathologic classification is dependent on amount of proteinuria, laboratory findings of possible secondary causes, and genetic profiles, however, that may not provide definite subtypes of FSGS. Therefore, it is important to search for prognostic markers of any form of FSGS. Method We enrolled a total of 20,404 adult patients who underwent native renal biopsy from 1979 to 2018 in 18 hospitals in Korea. Clinical, demographic, and laboratory data were collected in conjunction with pathologic findings. Among diagnosis of FSGS by pathologists of each hospital, we selected patients with definite segmental sclerosis by light microscopic examination including ≥10 glomeruli and without electron dense deposits by electron microscopic examination. We excluded patients with other forms of pathologic diagnosis except FSGS, with diabetes mellitus, or with follow-up period < 6 months after renal biopsy. We evaluated prognostic factors to estimate the risk of ESRD which event was found from ESRD registry of the Korean Society of Nephrology or the data from each hospital. Results Among 511 selected FSGS patients, 314 (61.4%) men were included. Mean age was 45.0 ± 17.9 years at biopsy. The laboratory finding of serum creatinine, estimated GFR, and urine protein to creatinine ratio (UPCR) was 1.38 ± 0.85 mg/dl, 71.8 ± 36.6 ml/min/1.73 m2, and 4.32 ±4.84 g/g creatinine, respectively (there were no missing data). GFR <60 ml/min/1.73 m2 was found in 41.5 % of patients and UPCR ≥ 3.0 g/g creatinine in 41.1 % of patients. During 117.5 ± 100.1 months of follow-up period, there were 97 (19.0%) patients with incident ESRD. Clinical prognostic factors to incident ESRD were estimated GFR, diastolic blood pressure, and year of renal biopsy. Pathologic prognostic factors were glomerular size, amount of global sclerosis and segmental sclerosis, severity of increase in glomerular matrix, interstitial fibrosis, interstitial inflammation, and tubular atrophy, and presence of artherosclerosis of intrarenal vessels. Adjusted with clinicopathologic factors related to incident ESRD, Cox's proportional hazard models revealed only pathologic findings of amount of glomerular global sclerosis and segmental sclerosis and presence of tubular atrophy were the independent prognostic factors (Model with 3.5 % of missing cases and -2 log likelihood ratio is 956.9, p < 0.001). GFR and UPCR showed significant relationship with incidence of ESRD, however, the significance was gone in the model adjusted with pathologic findings. AUC by ROC to estimate the event of ESRD by percentage of global sclerosis (GS) was 0.601 (range; 0.538-0.663, p = 0.002) and, by percentage of segmental sclerosis (SS), 0.679 (range; 0.616-0.743, p < 0.001). We grouped patients with three pathology categorical variables of a criterion of GS 30.9%, SS 10.5 %, and moderate degree in severity of tubular atrophy (TA), resulted in 8 groups, and summarized into 4 groups according to the relative risk to develop ESRD (Fig. 1). UPCR was a significant risk factor to estimate ESRD only in Group 4 with the criterion of 2 g/g creatinine by the Kaplan-Meier test (p = 0.034). GFR was not a prognostic factor in any pathology subgroup. Conclusion Important prognostic factors to estimate incident ESRD were pathologic findings of global sclerosis, segmental sclerosis, and tubular atrophy in FSGS patients. Significance of UPCR and GFR as prognostic factors was varied according to pathologic findings. We need to reconsider the criterion of UPCR to initiate immunosuppressive treatment and to break down the effect of immunosuppressive treatments for FSGS according to pathologic findings at renal biopsy.

Kidney outcomes in children with primary focal segmental glomerulosclerosis from a low- and middle- income country.

Limited data exists regarding the clinical course and outcomes of children with primary focal segmental glomerulosclerosis (FSGS) from low- and middle- income countries. Children aged 1-18years with biopsy-proven primary FSGS followed from January 2010-June 2023 in a tertiary-care center were enrolled and their clinical profile, histological characteristics, kidney outcomes, and predictors of adverse outcomes were determined. Over 13years, 73 (54.8% boys) children with median (IQR) age at FSGS diagnosis 6.7 (3,10) years were recruited and followed up for median 4 (2.5,8) years. FSGS-not otherwise specified (NOS) was the most common histological subtype, in 64 (87.6%) children, followed by collapsing variant in 5 (6.8%) children. At last follow-up, 43 (58.9%), 2 (2.7%) and 28 (38.3%) children were in complete remission (CR), partial remission (PR), and no remission (NR) respectively. Calcineurin inhibitors led to CR or PR in 39 (62%) children. Overall, 21 (28.7%) children progressed to chronic kidney disease (CKD) stage 2-5 (19 from NR vs. 2 from PR group; p = 0.03); with 41% of those NR at 12months progressing to CKD 4-5 by last follow-up. On multivariable analysis, collapsing variant [adjusted HR 2.5 (95%CI 1.5, 4.17), p = 0.001] and segmental sclerosis > 25% [aHR 9.9 (95%CI 2.2, 45.2), p = 0.003] predicted kidney disease progression. In children with FSGS, response to immunosuppression predicts kidney survival as evidenced by nil to lower progression to CKD 2-5 by median follow-up of 4 (2.5,8) years in children with CR and PR, comparedto those with no remission at 12months from diagnosis. Segmental sclerosis > 25% and collapsing variant predicted progression to advanced CKD.

Evaluation of C4d expression and staining patterns by immunohistochemistry in renal biopsy samples with focal segmental glomerulosclerosis and minimal change disease

IntroductionC4d is an activation product of lectin pathway of complement. Glomerular deposition of C4d is associated with poor prognosis in different types of immune-related glomerulonephritis. The present study was conducted to investigate expression level of C4d and its staining pattern in renal biopsy of patients with focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD) by immunohistochemistry method. Materials and methodsIn this retrospective cross-sectional study, renal biopsy specimens from 46 samples of MCD, 47 samples of FSGS, and 15 samples without glomerular disease as the controls, were subjected to immunohistochemistry staining with C4d. Demographic characteristics and information obtained from light and electron microscopy (EM) of patients were also extracted from their files. ResultsC4d positive staining was observed in 97.9 % of FSGS and 43.5 % of MCD samples, which showed a statistically significant difference (P < 0.001). The sensitivity and specificity of C4d expression for diagnosing FSGS were 97.9 % and 56.5 %, respectively. There was no significant correlation between C4d expression and any of the light and electron microscopy findings, including presence of foam cells, mesangial matrix expansion, interstitial fibrosis and tubular atrophy, and basement membrane changes in MCD patients. Also, no significant correlation was observed between C4d expression and clinical symptoms of proteinuria or prolonged high level of creatinine in patients with MCD. Discussion and conclusionThe expression of C4d marker had a good sensitivity and negative predictive value in the diagnosis of FSGS.

Precision medicine for focal segmental glomerulosclerosis.

Focal segmental glomerulosclerosis (FSGS) is one of the common causes of nephrotic syndrome in adults and children worldwide. FSGS consists of a group of kidney diseases classified based on specific histopathological features. The current classification of FSGS makes it difficult to distinguish individual differences in pathogenesis, disease progression, and response to treatment. In recent years, the spread of next-generation sequencing, updates in biological techniques, and improvements of treatment have changed our understanding of FSGS. In this review, we will discuss the use of genetic testing in patients with FSGS, explore its clinical significance from a genetic identification perspective, and introduce several new biomarkers, that may help in the early diagnosis of FSGS and guide the development of specific or targeted therapies, so as to understand the biological characteristics in FSGS. This will certainly help develop more effective and safer treatments and advance precision medicine.

The most common founder pathogenic variant c.868G > A (p.Val290Met) in the NPHS2 gene in a representative adult Czech cohort with focal segmental glomerulosclerosis is associated with a milder disease and its underdiagnosis in childhood.

Genetic focal segmental glomerulosclerosis (FSGS) is caused by pathogenic variants in a broad spectrum of genes that have a variable representation based on subjects' ethnicity and/or age. The most frequently mutated autosomal recessive gene in FSGS is NPHS2. In this study, we analyzed the spectrum of NPHS2 variants and their associated phenotype in Czech adult FSGS patients. A representative cohort of 234 adult patients with FSGS, derived from 225 families originating from all regions of Czechia, was analyzed by massively parallel sequencing. In this study, we focused on the comprehensive analysis of the NPHS2 gene. The histological classification of FSGS followed the Columbia classification. We detected seven (3%) cases bearing homozygous or compound heterozygous pathogenic NPHS2 variants. A single pathogenic variant c.868G > A (p.Val290Met) was found in the majority of NPHS2-positive cases (86%; 6 out of 7) in histologically confirmed instances of FSGS. Its allele frequency among unrelated NPHS2-associated FSGS patients was 50% (6/12), and Haplotype analysis predicted its origin to be a result of a founder effect. There is an identical V290M-related haplotype on all V290M alleles spanning a 0,7 Mb region flanking NPHS2 in Central European FSGS populations. The phenotype of the p.Val290Met NPHS2-associated FSGS demonstrated a later onset and a much milder course of the disease compared to other NPHS2 pathogenic variants associated with FSGS. The mean age of the FSGS diagnosis based on kidney biopsy evaluation was 31.2 ± 7.46 years. In 50% of all cases, the initial disease manifestation of proteinuria occurred only in adulthood, with 83% of these cases not presenting with edemas. One-third (33%) of the studied subjects progressed to ESRD (2 out of 6) at the mean age of 35.0 ± 2.82 years. We identified the most prevalent pathogenic variant, p.Val290Met, in the NPHS2 gene among Czech adult FSGS patients, which has arisen due to a founder effect in Central Europe. The documented milder course of the disease associated with this variant leads to the underdiagnosis in childhood. We established the histopathological features of the NPHS2-associated adult FSGS cases based on the Columbia classification. This might improve patient stratification and optimize their treatment.

Urinary SPP1 has potential as a non-invasive diagnostic marker for focal segmental glomerulosclerosis.

Focal segmental glomerulosclerosis (FSGS) is a type of chronic glomerular nephropathy showing characteristic glomerular sclerosis, diagnosed by kidney biopsy. However, it is difficult and expensive to monitor disease progression with repeated renal biopsy in clinical practice, and thus here we explored the feasibility of urine biomarkers as non-invasive diagnostic tools. We downloaded scRNA-seq datasets of 20 urine cell samples and 3 kidney tissues and obtained two gene lists encoding extracellular proteins for bioinformatic analysis; in addition, we identified key EP-Genes by immunohistochemical staining and performed bulk RNA sequencing with 12 urine samples. We report that urine cells and kidney cells were correlated. A total of 64 EP-Genes were acquired by intersecting genes of distal tubular cluster with extracellular proteins. Function enrichment analysis showed that EP-Genes might be involved in the immune response and extracellular components. Six key EP-Genes were identified and correlated with renal function. IMC showed that key EP-Genes were located mainly in tubules. Cross verification and examination of a urine RNAseq dataset showed that SPP1 had diagnostic potential for FSGS. The presence of urine SPP1 was primarily associated with macrophage infiltration in kidney, and the pathogenesis of FSGS may be related to innate immunity. Urinary cells seemed to be strongly similar to kidney cells. In summary, SPP1 levels reflect renal function and may have potential as a biomarker for non-invasive diagnosis of FSGS.

Caracterización y tratamiento de los pacientes adultos con glomeruloesclerosis focal y segmentaria.

Introduction: Glomerulopathies constitute the third cause of chronic kidney disease. Within these, focal segmental glomerulosclerosis (FSGS) is one of the most prevalent in Latin America. Each patient has a varied clinical presentation and etiology, as well as different treatments and evolution. The study aimed to characterize patients with histological diagnosis of FSGS based on their clinical presentation, evolution, and treatment in three public nephrology reference hospitals in Quito-Ecuador. Methods: The present observational, longitudinal, retrospective study was conducted from January 2012 to December 2020 at the Hospitals Carlos Andrade Marín, Eugenio Espejo, and Hospital de las Fuerzas Armadas N1. The variables were demographic, clinical, laboratory, and treatment. Descriptive statistics, proportions, and confidence intervals for a proportion are used. A follow-up of 6, 12, and 24 months was carried out. Results: 98 FSGS records were analyzed, constituting 15.2% of all kidney pathologies. This pathology was more frequent in men (60.2%) and Hispanics (98%), with a median age of 40. 95.9% and 67.3% of the patients had no history of diabetes or hypertension, respectively. The main symptom at diagnosis was non-nephrotic proteinuria (65.3%), and 7.1% of patients required dialysis at the onset of the disease. At six months, only 24% of patients achieved remission. The most common first-line treatments were corticosteroids, followed by mycophenolate, while the most frequently used second-line drug was cyclosporine.

A novel risk score for predicting prolonged length of stay following pediatric kidney transplant.

Kidney transplants (KT) are accepted as the kidney replacement therapy of choice for children with kidney failure. The surgery itself may be more difficult especially in small children, and often leads to significant hospital stays. There is little research on predicting prolonged length of stay (LOS) in children. We aim to examine the factors associated with prolonged LOS following pediatric KT to help clinicians make informed decisions, better counsel families, and potentially reduce preventable causes of prolonged stay. We retrospectively analyzed the United Network for Organ Sharing database for all KT recipients less than 18years old between January 2014 and July 2022 (n = 3693). Donor and recipient factors were tested in univariate and multivariate logistic analysis using stepwise elimination of non-significant factors to create a final regression model predicting LOS longer than 14days. Values were assigned to significant factors to create risk scores for each individual patient. In the final model, only primary diagnosis of focal segmental glomerulosclerosis, dialysis prior to KT, geographic region, and recipient weight prior to KT were significant predictors of LOS longer than 14days. The C-statistic of the model is 0.7308. The C-statistic of the risk score is 0.7221. Knowledge of the risk factors affecting prolonged LOS following pediatric KT can help identify patients at risk of increased resource use and potential hospital-acquired complications. Using our index, we identified some of these specific risk factors and created a risk score that can stratify pediatric recipients into low, medium, or high risk groups. A higher resolution version of the Graphical abstract is available as Supplementary information.

#6681 MT-TL1 M.3243A&amp;gt;G MITOCHONDRIAL DNA VARIANT DETECTED FROM WHOLE EXOME SEQUENCING CAN EXPLAIN CASES OF ADULT UNKNOWN NEPHROPATHIES

Abstract Background and Aims In a population-based study, mainly constituted of unknown nephropathies (cohort Sorbonne University, Paris, France N = 1197 patients), beyond reporting the diagnostic yield of nuclear genes, we also investigated the incidence of the mtDNA pathogenic variant MT-TL1 m.3243A&amp;gt;G. This variation was systematically searched from whole exome sequencing (WES) data. In retrospect, we described the renal phenotype and studied the heteroplasmy level of the mtDNA variation in urine or kidney tissues compared to its blood fraction. The prevalence of m.3243A&amp;gt;G has been estimated ranging from 0.08% to up to 0.25%. Method From September 2018, to February 2023, WES has been prospectively performed, as a first exploration of adult's nephropathies of unknown origin or when a genetic renal disease was clinically suggested. As off-target result, we retrieved m.3243A&amp;gt;G variation in blood DNA and then determined the mtDNA heteroplasmic level respective from urine sample or kidney tissue when available with an orthogonal method. Results We report a molecular diagnosis in 294 over 1197 adult patients sequenced (diagnostic yield: 24%, Age 43 y/o in average). Among these 294 patients with molecular diagnoses, 48 were distinct monogenic disorders, out of which 8 accounted for 52% of the genetic diagnoses. MT-TL1 m.3243A&amp;gt;G pathogenic variant was detected in 1,7% of the patients (20 patients over 1197 patients). An orthogonal method confirmed the presence of m.3243A&amp;gt;G variant in 10 patients supporting the possibility to diagnose from blood DNA analysed by WES. In all cases, the presence of m.3243A&amp;gt;G had major clinical implications for the patients and their families: living related donor aborted for two patients, a molecular diagnosis in three patients with unknown nephropathies and in three patients with histological diagnosis of focal segmental glomerulosclerosis. Other mitochondrial diseases appeared less likely involved in our adult cohort (only one patient with COQ2 pathogenic variants). Conclusion This population-based study reinforces the place of WES as first-tier exploration for adult patients with chronic kidney disease in whom phenotypes are often poor and/or atypical. The mitochondrial genome analysis with the same assay allowed the detection of yet unsuspected MT-TL1 m.3243A&amp;gt;G variant in 1,7% of patients suggesting enrichment compared to current prevalence observed in other population. Our data suggest that the entity “mitochondrial nephropathy” can represent a significant part of adult unknown nephropathies.

Incorporation of Genetic Studies in the Kidney Transplant Evaluation Clinic: The Value of a Multidisciplinary Approach.

Recent studies identified underlying genetic causes in a proportion of patients with various forms of kidney disease. In particular, genetic testing reclassified some focal segmental glomerulosclerosis (FSGS) cases into collagen type 4 (COL4)-related nephropathy. This knowledge has major implications for counseling prospective transplant recipients about recurrence risk and screening biologically related donors. We describe our experience incorporating genetic testing in our kidney transplant multidisciplinary practice. Patients' DNA was analyzed using whole exome sequencing for a comprehensive kidney gene panel encompassing 344 genes associated with kidney diseases and candidate genes highly expressed in the kidney. Results were correlated with phenotype by a multidisciplinary committee of nephrologists, renal pathologists, geneticists, and genetic counselors. Between October 2018 and July 2020, 30 recipient and 5 donor candidates completed testing. Among recipient candidates, 24 (80%) carried the diagnosis of FSGS, 2 (6.7%) tubulointerstitial nephritis, and 1 (3.3%) nephrolithiasis, and 3 (10%) had an unknown cause of kidney disease. The yield for pathogenic/likely pathogenic variants was 43.3%, with majority being COL4 variants (53.8%). Among those with FSGS diagnosis, the yield was 10 of 24 (41.6%), with 29% reclassified into a COL4-related nephropathy. Family history of kidney disease was the only clinical characteristic difference between recipients with positive and negative results (76.9 versus 29.4%; P = 0.025). One of 5 donors tested positive for a pathogenic/likely pathogenic variant and was excluded from donation. We conclude that thoughtful use of genetic testing can be valuable for kidney donor selection and transplant recipient management.

Potential Urine Proteomic Biomarkers for Focal Segmental Glomerulosclerosis and Minimal Change Disease.

Primary focal segmental glomerulosclerosis (FSGS), along with minimal change disease (MCD), are diseases with primary podocyte damage that are clinically manifested by the nephrotic syndrome. The pathogenesis of these podocytopathies is still unknown, and therefore, the search for biomarkers of these diseases is ongoing. Our aim was to determine of the proteomic profile of urine from patients with FSGS and MCD. Patients with a confirmed diagnosis of FSGS (n = 30) and MCD (n = 9) were recruited for the study. For a comprehensive assessment of the severity of FSGS a special index was introduced, which was calculated as follows: the first score was assigned depending on the level of eGFR, the second score—depending on the proteinuria level, the third score—resistance to steroid therapy. Patients with the sum of these scores of less than 3 were included in group 1, with 3 or more—in group 2. The urinary proteome was analyzed using liquid chromatography/mass spectrometry. The proteome profiles of patients with severe progressive FSGS from group 2, mild FSGS from group 1 and MCD were compared. Results of the label free analysis were validated using targeted LC-MS based on multiple reaction monitoring (MRM) with stable isotope labelled peptide standards (SIS) available for 47 of the 76 proteins identified as differentiating between at least one pair of groups. Quantitative MRM SIS validation measurements for these 47 proteins revealed 22 proteins with significant differences between at least one of the two group pairs and 14 proteins were validated for both comparisons. In addition, all of the 22 proteins validated by MRM SIS analysis showed the same direction of change as at the discovery stage with label-free LC-MS analysis, i.e., up or down regulation in MCD and FSGS1 against FSGS2. Patients from the FSGS group 2 showed a significantly different profile from both FSGS group 1 and MCD. Among the 47 significantly differentiating proteins, the most significant were apolipoprotein A-IV, hemopexin, vitronectin, gelsolin, components of the complement system (C4b, factors B and I), retinol- and vitamin D-binding proteins. Patients with mild form of FSGS and MCD showed lower levels of Cystatin C, gelsolin and complement factor I.

Epidemiology and clinicopathological characteristics of native kidney disease in children in Flanders, Belgium.

The Flemish Collaborative Glomerulonephritis Group (FCGG) registry is a population-based kidney biopsy registry that has been including all native kidney biopsies performed in children in Flanders (Belgium), since 2017. From 2017 to 2020, 148 pediatric (< 18years) native kidney biopsies were included. Each biopsy received a histopathological and final nephrological diagnosis, and concordance between both was assessed. Disease chronicity, summarized by the Mayo Clinic Chronicity Score, was determined on 122 biopsies with > 5 glomeruli. Kidney biopsy rate was high (29.0 biopsies per million children per year), median age was 10.0years (IQR 5.8-14.7), and boys predominated (56.1% males). A total of 140 biopsies (94.6%) showed a representative pathology result. Glomerular disease was most prevalent, with IgA nephropathy/IgA vasculitis (43 biopsies, 29.1%) and minimal change disease (MCD) (29 biopsies, 19.6%) being the overall most frequent diagnoses. In general, diagnostic concordance was high (80.7%). In Alport syndrome and focal segmental glomerulosclerosis (FSGS), concordance was lower, as the nephrological diagnosis was often determined by results of genetic analysis. Nephrotic syndrome was the most frequent indication for kidney biopsy (31.8%) and was mainly caused by MCD and FSGS. The degree of disease chronicity on kidney biopsies was generally low, although 27.3% of biopsies with a diagnosis of FSGS showed moderate-to-severe chronic damage. The presented epidemiological findings validate data from previous European registry studies and may inspire kidney biopsy registries worldwide to implement novel features such as clinicopathological concordance and chronicity grading. A higher resolution version of the Graphical abstract is available as Supplementary information.

Marked reduction of proteinuria after removal of a growth hormone-producing pituitary adenoma in a patient with focal segmental glomerulosclerosis: a case report and literature review.

Focal segmental glomerulosclerosis is a rare complication of acromegaly. A 74-year-old man was found to have acromegaly features such as enlargement of the forehead, nose, and hands. Laboratory tests showed a urine protein/creatinine ratio of 3.16g/gCr and serum creatinine of 1.34mg/dL. The levels of growth hormone and insulin-like growth factor I were markedly elevated, and the growth hormone level was not suppressed after 75g oral glucose loading. Magnetic resonance imaging revealed a pituitary tumor with a diameter of 1.2cm. Renal biopsy confirmed the diagnosis of focal segmental glomerulosclerosis. Transsphenoidal resection of the pituitary tumor led to remission of acromegaly and reduction in proteinuria highlighting the causal link between growth hormone overproduction and proteinuria. Treatment of acromegaly may be effective for acromegaly-associated focal segmental glomerulosclerosis.

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.

Renal tubular gen e biomarkers identification based on immune infiltrates in focal segmental glomerulosclerosis

Objective The present study identified novel renal tubular biomarkers that may influence the diagnosis and treatment of focal segmental glomerulosclerosis (FSGS) based on immune infiltration. Methods Three FSGS microarray datasets, GSE108112, GSE133288 and GSE121211, were downloaded from the Gene Expression Omnibus (GEO) database. The R statistical software limma package and the combat function of the sva package were applied for preprocessing and to remove the batch effects. Differentially expressed genes (DEGs) between 120 FSGS and 15 control samples were identified with the limma package. Disease Ontology (DO) pathway enrichment analysis was conducted with statistical R software to search for related diseases. Gene set enrichment analysis (GSEA) was used to interpret the gene expression data and it revealed many common biological pathways. A protein-protein interaction (PPI) network was built using the Search Tool for the Retrieval of Interacting Genes (STRING) database, and hub genes were identified by the Cytoscape (version 3.7.2) plug-in CytoHubba. The plug-in Molecular Complex Detection (MCODE) was used to screen hub modules of the PPI network in Cytoscape, while functional analysis of the hub genes and hub nodes involved in the submodule was performed by ClusterProfiler. The least absolute shrinkage and selection operator (LASSO) regression and support vector machine recursive feature elimination (SVM-RFE) analysis were used to screen characteristic genes and build a logistic regression model. Receiver operating characteristic (ROC) curve analyses were used to investigate the logistic regression model and it was then validated by an external dataset GSE125779, which contained 8 FSGS samples and 8 healthy subjects. Cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT) was used to calculate the immune infiltration of FSGS samples. Results We acquired 179 DEGs, 79 genes with downregulated expression (44.1%) and 100 genes with upregulated expression (55.9%), in the FSGS samples. The DEGs were significantly associated with arteriosclerosis, kidney disease and arteriosclerotic cardiovascular disease. GSEA revealed that these gene sets were significantly enriched in allograft rejection signaling pathways and activation of immune response in biological processes. Fifteen genes were demonstrated to be hub genes by PPI, and three submodules were screened by MCODE linked with FSGS. Analysis by machine learning methodologies identified nuclear receptor subfamily 4 group A member 1 (NR4A1) and dual specificity phosphatase 1 (DUSP1) as sensitive tubular renal biomarkers in the diagnosis of FSGS, and they were selected as hub genes, as well as hub nodes which were enriched in the MAPK signaling pathway. Immune cell infiltration analysis revealed that the genetic biomarkers were both correlated with activated mast cells, which may amplify FSGS biological processes. Conclusion DUSP1 and NR4A1 were identified as sensitive potential biomarkers in the diagnosis of FSGS. Activated mast cells have a decisive effect on the occurrence and development of FSGS through tubular lesions and tubulointerstitial inflammation, and they are expected to become therapeutic targets in FSGS.

Precise clinicopathologic findings for application of genetic testing in pediatric kidney transplant recipients with focal segmental glomerulosclerosis/steroid-resistant nephrotic syndrome.

Establishing a molecular genetic diagnosis of focal segmental glomerulosclerosis (FSGS)/steroid-resistant nephrotic syndrome (SRNS) can be useful for predicting post-transplant recurrence. Monogenic causes are reportedly present in approximately 20-30% of patients with FSGS/SRNS. However, the characteristics of patients who are likely to have a monogenic cause remain to be determined. Pediatric recipients with SRNS and/or biopsy-proven FSGS who underwent their first kidney transplantation at our center between 1999 and 2019 were analyzed. Patients with secondary FSGS/SRNS were excluded. The recipients were divided into three groups: familial/syndromic, presumed primary, and undetermined FSGS/SRNS. Patients who met all of the following criteria were categorized as having presumed primary FSGS/SRNS: (i) nephrotic syndrome, (ii) complete or partial remission with initial steroid therapy and/or additional immunosuppressive therapies, and (iii) diffuse foot process effacement on electron microscopy in the native kidney biopsy. All patients underwent genetic testing using next-generation sequencing. Twenty-four patients from 23 families were analyzed in this study. Pathogenic or likely pathogenic variants in FSGS/SRNS-related genes were identified in four of four families, zero of eight families, and 10 of 11 families with familial/syndromic, presumed primary, and undetermined FSGS/SRNS, respectively. Post-transplant recurrence only occurred in patients with presumed primary FSGS/SRNS. Our systematic approach based on precise clinicopathological findings including nephrotic syndrome, treatment responses, and diffuse foot process effacement might be useful to differentiate pediatric kidney transplant recipients with FSGS/SRNS who are likely to have a monogenic cause from patients who are not, and to predict post-transplant recurrence. A higher resolution version of the Graphical abstract is available as Supplementary information.

A Case of Focal Segmental Glomerulosclerosis in a Young Girl with a Very Low Birth Weight

In Japan, the prevalence of low birth weight (LBW) has been estimated to be approximately 10%, which is the highest among developed countries. This high prevalence might affect the occurrence of LBW-associated diseases in the adult population of Japan. LBW has been recognized as a contributing factor to post-adaptive focal segmental glomerulosclerosis (FSGS) in adulthood; however, few reports to date have evaluated the clinical and pathological characteristics of post-adaptive FSGS. A 13-year-old girl was referred to our hospital owing to mild proteinuria, which was detected at a school urinary screening. She was born at a gestational age of 23 weeks, with a very LBW of 630 g. Dipstick urinalysis revealed grade (2+) proteinuria. Her serum creatinine level was 1.02 mg/dL, and she was diagnosed as having stage 2 chronic kidney disease (CKD). Her serum uric acid level was 7 mg/dL. Furthermore, her mother and 16-year old brother had hyperuricemia. A percutaneous renal biopsy leads to a diagnosis of FSGS. After 3 years of treatment with an angiotensin receptor blocker, her proteinuria decreased. However, her serum creatinine level was 1.07 mg/dL, and she still had stage 2 CKD. We considered that in this patient, the first hit was her LBW, and the second hit was hyperuricemia. The second hit might be associated with the development of CKD. The birth history of patients is not usually confirmed by nephrologists. Our case demonstrates that obtaining information regarding the preterm birth and LBW of patients is important in the diagnosis of noncommunicable diseases because school urinary screening is not routinely performed in countries other than Japan.

Clinical, pathological, and genetic characteristics of cases with asymptomatic proteinuria not manifesting nephrotic syndrome at onset: a single-center retrospective study.

Cases with asymptomatic proteinuria (ASP) not manifesting nephrotic syndrome often pathologically show focal segmental glomerulosclerosis (FSGS). However, characteristics of those cases had not been intensively studied so far. We retrospectively reviewed clinical, pathological, and genetic characteristics of 37 children (median age, 9.3years) who underwent renal biopsy for persistent isolated proteinuria (urine protein-to-creatinine ratio: UP/C, > 0.2g/g) between 2003 and 2019. Targeted next-generation sequencing (NGS) was utilized for all patients with FSGS, excluding those with secondary FSGS. At biopsy, all patients with FSGS (N = 14) had UP/C ≥ 0.5g/g and the median UP/C was significantly higher in those with FSGS than those with minor glomerular abnormalities (MGA) (N = 23) (1.49 vs. 0.53g/g, P < 0.001). Causative variants were found in seven patients with FSGS (TRPC6, WT1, ACTN4, and INF2 in 3, 2, 1, and 1 patient, respectively): all gene variants were in genes manifesting autosomal dominant inheritance mode. The proportion of the perihilar variant was significantly higher in the genetic FSGS patients than in the non-genetic FSGS patients (4/7 vs. 0/7, P < 0.05). Kaplan-Meier analysis showed that the renal survival rate after ASP diagnosis was significantly lower in the genetic FSGS patients than in the non-genetic FSGS and the MGA patients (P < 0.001). UP/C was a simple and useful predictive parameter for the diagnosis of FSGS. APS without nephrotic syndrome at onset may be associated with autosomal dominant causes of FSGS, especially in those with the perihilar variant.