Process Effacement Research Articles

Anticoagulant-Related Nephropathy in a Patient on Coumadin

Abstract Introduction/Objective Anticoagulant therapy is commonly used to prevent stroke and systemic embolism in patients with atrial fibrillation. However, it carries the risk of bleeding and can lead to serious complications such as anticoagulant-related nephropathy (ARN), a recently described entity characterized by hematuria and acute kidney injury. This report presents a case of a 79-year-old male with a history a patient with a history of atrial fibrillation on coumadin, highlighting the importance of monitoring for anticoagulant-related complications and the need for prompt diagnosis and management to prevent further renal damage. Methods/Case Report The kidney biopsy showed evidence of underlying hypertensive and diabetic nephropathy, with nodular and global glomerulosclerosis, moderate to marked interstitial fibrosis, and tubular atrophy along with many red cell casts of variable ages in the tubules indicative of anticoagulant-related nephropathy. Additionally, one glomerulus had a partial cellular crescent associated with a focus of blood clot, likely related to heavy hematuria. Patient is seronegative for ANCA. The immunofluorescence microscopy is non-contributory due to absence of glomerulus in the sample. Electron microscopy showed diffuse foot process effacement and microvillous transformation of podocytes, increased mesangial matrix, and thickened glomerular basement membranes, but no immune complex deposits. these ultrastructural features confirm the background diabetic nephropathy. Results (if a Case Study enter NA) NA Conclusion Anticoagulant-related nephropathy (ARN) is a rare but serious complication of anticoagulation therapy that can result in hematuria and acute kidney injury. Our case highlights the importance of monitoring for anticoagulant-related complications, especially in high-risk patients with multiple comorbidities. Prompt diagnosis and management of ARN is essential to prevent further renal damage. In this case, despite initial improvement with vitamin K therapy, the patient developed severe renal dysfunction requiring dialysis and renal biopsy. This emphasizes the need for increased awareness and early recognition of ARN in patients on anticoagulant therapy.

Clinical Characteristics and Histopathology in Adults With Focal Segmental Glomerulosclerosis

Rationale & ObjectiveFew 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 DesignReal-world cohort study with data derived from health records. Setting& Participants: Adults with FSGS by kidney biopsies from Arkana Laboratories during 1 January 2016 to 31 May 2020. ExposuresRace, CKD stage, nephrotic proteinuria, age, sex, and hypertension. OutcomesSevere histological disease, defined as global glomerulosclerosis in >50% of glomeruli and >25% interstitial fibrosis and tubular atrophy (IFTA). Analytical ApproachDemographic, clinical, and histological characteristics were compared between race groups. Correlates of severe disease were analyzed by multiple logistic regression. ResultsAmong 2,011 patients with FSGS, 40.6% were White and 23.6% Black. White patients were older (52.8 versus 45.5 years, P < 0.001) with higher estimated glomerular filtration rate (eGFR) than Black patients (53.5 versus 43.1 ml/min/1.73 m2, P < 0.001). A higher proportion of Black patients had global glomerulosclerosis ≥50% (32.1% versus 14.6%, P < 0.001) or IFTA >50% (34.6% versus 14.7%, P < 0.001). Severe histological disease was more likely in Black patients (odds ratio 2.46; 95% confidence interval 1.59, 3.79; P < 0.001). A higher proportion of patients with nephrotic than non-nephrotic proteinuria exhibited diffuse foot process effacement. LimitationsUnequal representation across United States (US) regions, missing demographic and clinical data, and lack of data on primary versus secondary FSGS, treatments, or outcomes. ConclusionsBlack 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.

Acute interstitial nephritis caused by ANCA-associated vasculitis: a case based review.

Antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) typically manifests as rapidly progressive glomerulonephritis with crescent formation. In this report, we present a local case of myeloperoxidase (MPO)-AAV-associated acute interstitial nephritis (AIN), showing slight pauci-immune glomerulonephritis and positive MPO-ANCA. This case is characterized by foot process effacement of podocytes in the glomerulus, a favorable prognosis, and an absence of crescentic formation. To further understand this condition, we conducted a comprehensive literature search on Google Scholar and PubMed, employing both free text words and MeSH terms related to "AAV and AIN." This search yielded 24 cases, which we analyzed for their clinical features, laboratory findings, renal pathological characteristics, and therapeutic outcomes. AAV-associated interstitial nephritis predominantly affects elderly patients and is often associated with anemia, proteinuria, hematuria, and nonspecific manifestations, including fever, anorexia, fatigue, edema, and weight loss. Most of the cases in our review were MPO-ANCA-positive and exhibited isolated interstitial inflammation. These patients typically presented with relatively lower levels of serum creatinine, 24-h urine protein levels, and MPO-ANCA titers. All patients in our study received immunosuppressive therapy, including glucocorticoids, immunosuppressants, and rituximab, with the majority achieving clinical remission. Isolated AIN in the context of AAV is a rare occurrence, but it displays distinct clinical, laboratory, and pathological features. Patients with this presentation show a positive response to immunosuppressive treatment. Nevertheless, the establishment of definitive therapy guidelines for AAV-associated AIN remains uncertain and necessitates further investigation to develop comprehensive treatment guidelines. AIN, particularly when lacking typical glomerulus lesions, may represent a novel subgroup within MPO-AAV warranting additional research and clinical attention. Key Points • This study contributes valuable scientific insights by highlighting that MPO-AAV-associated interstitial nephritis, even without crescentic formation, can exhibit podocyte foot process effacement and respond well to treatment. • The presence of AIN, independent of crescentic glomerulonephritis, suggests the potential emergence of a new subclass within MPA-AAV. • Notably, some cases of MPO-AAV-associated AIN may present with normal levels of Scr (Table 5, cases 5, 6, and 17). • This observation highlights the importance of considering renal biopsy, diagnosis, and therapy in a timely manner to prevent the development of chronic kidney disease (CKD).

Kif21a deficiency leads to impaired glomerular filtration barrier function

The renal glomerulus represents the major filtration body of the vertebrate nephron and is responsible for urine production and a number of other functions such as metabolic waste elimination and the regulation of water, electrolyte and acid–base balance. Podocytes are highly specialized epithelial cells that form a crucial part of the glomerular filtration barrier (GFB) by establishing a slit diaphragm for semipermeable plasma ultrafiltration. Defects of the GFB lead to proteinuria and impaired kidney function often resulting in end-stage renal failure. Although significant knowledge has been acquired in recent years, many aspects in podocyte biology are still incompletely understood. By using zebrafish as a vertebrate in vivo model, we report a novel role of the Kinesin-like motor protein Kif21a in glomerular filtration. Our studies demonstrate specific Kif21a localization to the podocytes. Its deficiency resulted in altered podocyte morphology leading to podocyte foot process effacement and altered slit diaphragm formation. Finally, we proved considerable functional consequences of Kif21a deficiency by demonstrating a leaky GFB resulting in severe proteinuria. Conclusively, our data identified a novel role of Kif21a for proper GFB function and adds another piece to the understanding of podocyte architecture and regulation.

Using Degree of Foot Process Effacement to Predict Outcome in Paediatric Steroid-Resistant Nephrotic Syndrome: A Multi-Centre Analysis

Using Degree of Foot Process Effacement to Predict Outcome in Paediatric Steroid-Resistant Nephrotic Syndrome: A Multi-Centre Analysis

Cure Glomerulonephropathy Pathology Classification and Core Scoring Criteria, Reproducibility, and Clinicopathologic Correlations

Introduction: Cure Glomerulonephropathy (CureGN) is an observational cohort study of patients with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), or IgA nephropathy. We developed a conventional, consensus-based scoring system to document pathologic features for application across multiple pathologists and herein describe the protocol, reproducibility, and correlation with clinical parameters at biopsy. Methods: Definitions were established for glomerular, tubular, interstitial, and vascular lesions evaluated semiquantitatively using digitized light microscopy slides and electron micrographs, and reported immunofluorescence. Cases with curated pathology materials as of April 2019 were scored by a randomly assigned pathologist, with at least 10% of cases scored by a second pathologist. Scoring reproducibility was assessed using Gwet’s agreement coefficient (AC)1 statistic and correlations with clinical variables were performed. Results: Of 800 scored biopsies (134 MCD, 194 FSGS, 206 MN, 266 IgA), 94 were scored twice (11.8%). Of 60 pathology features, 46 (76.7%) demonstrated excellent (AC1>0.8), and 12 (20.0%) had good (AC1 0.6–0.8) reproducibility. Mesangial hypercellularity scored as absent, focal, or diffuse had moderate reproducibility (AC1 = 0.58), but good reproducibility (AC1 = 0.71) when scored as absent or focal versus diffuse. The percent glomeruli scored as no lesions had fair reproducibility (AC1 = 0.34). Strongest correlations between pathologic features and clinical characteristics at biopsy included interstitial inflammation, interstitial fibrosis, and tubular atrophy with estimated glomerular filtration rate, foot process effacement with urine protein/creatinine ratio, and active crescents with hematuria. Conclusions: Most scored pathology features showed excellent reproducibility, demonstrating consistency for these features across multiple pathologists. Correlations between certain pathologic features and expected clinical characteristics show the value of this approach for future studies on clinicopathologic correlations and biomarker discovery.

"Idiopathic" minimal change nephrotic syndrome: a podocyte mystery nears the end.

The discovery of zinc fingers and homeoboxes (ZHX) transcriptional factors and the upregulation of hyposialylated angiopoietin-like 4 (ANGPTL4) in podocytes have been crucial in explaining the cardinal manifestations of human minimal change nephrotic syndrome (MCNS). Recently, uncovered genomic defects upstream of ZHX2 induce a ZHX2 hypomorph state that makes podocytes inherently susceptible to mild cytokine storms resulting from a common cold. In ZHX2 hypomorph podocytes, ZHX proteins are redistributed away from normal transmembrane partners like aminopeptidase A (APA) toward alternative binding partners like IL-4Rα. During disease relapse, high plasma soluble IL-4Rα (sIL-4Rα) associated with chronic atopy complements the cytokine milieu of a common cold to displace ZHX1 from podocyte transmembrane IL-4Rα toward the podocyte nucleus. Nuclear ZHX1 induces severe upregulation of ANGPTL4, resulting in incomplete sialylation of part of the ANGPTL4 protein, secretion of hyposialylated ANGPTL4, and hyposialylation-related injury in the glomerulus. This pattern of injury induces many of the classic manifestations of human minimal change disease (MCD), including massive and selective proteinuria, podocyte foot process effacement, and loss of glomerular basement membrane charge. Administration of glucocorticoids reduces ANGPTL4 upregulation, which reduces hyposialylation injury to improve the clinical phenotype. Improving sialylation of podocyte-secreted ANGPTL4 also reduces proteinuria and improves experimental MCD. Neutralizing circulating TNF-α, IL-6, or sIL-4Rα after the induction of the cytokine storm in Zhx2 hypomorph mice reduces albuminuria, suggesting potential new therapeutic targets for clinical trials to prevent MCD relapse. These studies collectively lay to rest prior suggestions of a role of single cytokines or soluble proteins in triggering MCD relapse.

The Role of Hypoxia on the Trimethylation of H3K27 in Podocytes.

Epigenetic alterations contribute to the pathogenesis of chronic diseases such as diabetes mellitus. Previous studies of our group showed that diabetic conditions reduce the trimethylation of H3K27 in podocytes in a NIPP1- (nuclear inhibitor of protein phosphatase 1) and EZH2- (enhancer of zeste homolog 2) dependent manner. It has been previously reported that in differentiated podocytes, hypoxia decreases the expression of slit diaphragm proteins and promotes foot process effacement, thereby contributing to the progression of renal disease. The exact mechanisms are, however, not completely understood. The aim of this study was to analyze the role of hypoxia and HIFs (hypoxia-inducible factor) on epigenetic changes in podocytes affecting NIPP1, EZH2 and H3K27me3, in vitro and in vivo. In vivo studies were performed with mice exposed to 10% systemic hypoxia for 3 days or injected with 3,4-DHB (dihydroxybenzoate), a PHD (prolyl hydroxylase) inhibitor, 24 h prior analyses. Immunodetection of H3K27me3, NIPP1 and EZH2 in glomerular podocytes revealed, to the best of our knowledge for the first time, that hypoxic conditions and pharmacological HIFs activation significantly reduce the expression of NIPP1 and EZH2 and diminish H3K27 trimethylation. These findings are also supported by in vitro studies using murine-differentiated podocytes.

Introduction of a novel chimeric active immunization mouse model of PLA2R1-associated membranous nephropathy

The phospholipase A2 receptor 1 (PLA2R1) is the major target antigen in patients with membranous nephropathy (MN), an antibody-mediated autoimmune glomerular disease. Investigation of MN pathogenesis has been hampered by the lack of reliable animal models. Here, we overcome this issue by generating a transgenic mouse line expressing a chimeric PLA2R1 (chPLA2R1) consisting of three human PLA2R1 domains (cysteine-rich, fibronectin type-II and CTLD1) and seven murine PLA2R1 domains (CTLD2-8) specifically in podocytes. Mice expressing the chPLA2R1 were healthy at birth and showed no major glomerular alterations when compared to mice with a wild-type PLA2R1 status. Upon active immunization with human PLA2R1 (hPLA2R1), chPLA2R1-positive mice developed anti-hPLA2R1 antibodies, a nephrotic syndrome, and all major histological features of MN, including granular deposition of mouse IgG and complement components in immunofluorescence and subepithelial electron-dense deposits and podocyte foot process effacement in electron microscopy. In order to investigate the role of the complement system in this model, we further crossed chPLA2R1-positive mice with mice lacking the central complement component C3 (C3-/- mice). Upon immunization with hPLA2R1, chPLA2R1-positive C3-/- mice had substantially less severe albuminuria and nephrotic syndrome when compared to chPLA2R1-positive mice with a wild-type C3 status. In conclusion, we introduce a novel active immunization model of PLA2R1-associated MN and demonstrate a pathogenic role of the complement system in this model.

Diagnosis and treatment of Minimal Change Disease in adults-2023

Minimal change disease is aglomerulopathy that clinically manifests as acute onset nephrotic syndrome. Adiagnosis is made by renal biopsy, implying the absence of glomerular lesions on light microscopy but detection of extensive podocyte foot process effacement on electron miscroscopy. Considering the typically excellent response to immunosuppressive measures (especially to glucocorticoids), an autoimmune pathogenesis is assumed. Although general prognosis is overall beneficial, steroid-dependent, steroid-resistant and frequently-relapsing disease courses may complicate the management of these patients and necessitate the use of alternative immunosuppressive treatment strategies. Here, the Austrian Society of Nephrology (ÖGN) provides aconsensus on how to best diagnose and manage adult patients with minimal change disease.

Deletion of protein tyrosine phosphatase SHP-1 restores SUMOylation of podocin and reverses the progression of diabetic kidney disease

Both clinical and experimental data suggest that podocyte injury is involved in the onset and progression of diabetic kidney disease (DKD). Although the mechanisms underlying the development of podocyte loss are not completely understood, critical structural proteins such as podocin play a major role in podocyte survival and function. We have reported that the protein tyrosine phosphatase SHP-1 expression increased in podocytes of diabetic mice and glomeruli of patients with diabetes. However, the invivo contribution of SHP-1 in podocytes is unknown. Conditional podocyte-specific SHP-1-deficient mice (Podo-SHP-1-/-) were generated to evaluate the impact of SHP-1 deletion at four weeks of age (early) prior to the onset of diabetes and after 20 weeks (late) of diabetes (DM; Ins2+/C96Y) on kidney function (albuminuria and glomerular filtration rate) and kidney pathology. Ablation of the SHP-1 gene specifically in podocytes prevented and even reversed the elevated albumin/creatinine ratio, glomerular filtration rate progression, mesangial cell expansion, glomerular hypertrophy, glomerular basement membrane thickening and podocyte foot process effacement induced by diabetes. Moreover, podocyte-specific deletion of SHP-1 at an early and late stage prevented diabetes-induced expression of collagen IV, fibronectin, transforming growth factor-β, transforming protein RhoA, and serine/threonine kinase ROCK1, whereas it restored nephrin, podocin and cation channel TRPC6 expression. Mass spectrometry analysis revealed that SHP-1 reduced SUMO2 post-translational modification of podocin while podocyte-specific deletion of SHP-1 preserved slit diaphragm protein complexes in the diabetic context. Thus, our data uncovered a new role of SHP-1 in the regulation of cytoskeleton dynamics and slit diaphragm protein expression/stability, and its inhibition preserved podocyte function preventing DKD progression.

Short-term use of ceftriaxone sodium leads to intestinal barrier disruption and ultrastructural changes of kidney in SD rats

Objective Antibiotic treatments are known to disturb gut microbiota, but their effects on the mucosal barrier and extraintestinal diseases are rarely discussed. The aim of this study was to evaluate and visualize the impact of antibiotics on colonic mucus and the microbial community, and to assess whether intestinal dysbacteriosis is involved in the pathogenesis and progression of extraintestinal diseases in vivo. Materials and Methods Twenty-one SD rats were randomly assigned into three groups followed by different experimental treatments. The albumin–creatinine ratio, urinary protein and occult blood semi-quantified test were tested. Fecal samples were collected at different time points (0,4, and 12 weeks) for 16S rRNA gene sequencing. Colon and kidney specimens were examined using light microscopy and transmission electron microscopy (TEM) to identify morphological changes. Results Ceftriaxone intervention for one week did not cause any symptoms of diarrhea or weight loss, but the alpha and beta diversities of gut microbiota decreased quickly and significantly, a lower Firmicutes/Bacteroidetes (F/B) ratio was observed. At week 12, although the alpha and beta diversities increased to a level similar to that of the control (CON) group, LEfSe analysis indicated that the microbial community composition still differed significantly in each group. In addition, KEGG metabolic prediction revealed different metabolic functions in each group. TEM examination of colon revealed that dramatic morphological changes were observed in the ceftriaxone (Cef) group, wherein microvilli were misaligned and shortened significantly and morphologically intact bacteria were seen on the epithelial cell surface. TEM examination of kidneys from the Cef group showed characteristic glomerular changes in the form of widely irregularly thickened glomerular basement membrane (GBM) and foot process fusion or effacement; mild thickening of the GBM and foot process fusion was detected when ceftriaxone and Resatorvid (TAK242, an inhibitor of TLR4 signaling) are used together in the ceftriaxone + TAK242 (TAK) group. Conclusions Short-term use of ceftriaxone induced dynamic changes of gut microbiota and lead to intestinal barrier disruption and ultrastructural changes of kidneys in the SD rats. Moreover, interference with the TLR4-dependent signaling pathway can alleviate the damage to the intestinal barrier and kidney.

Patient-Specific Pharmacokinetics and Dasatinib Nephrotoxicity.

Dasatinib has been associated with nephrotoxicity. We sought to examine the incidence of proteinuria on dasatinib and determine potential risk factors that may increase dasatinib-associated glomerular injury. We examined glomerular injury through urine albumin-creatinine ratio (UACR) in 82 patients with chronic myelogenous leukemia who were on tyrosine-kinase inhibitor therapy for at least 90 days. t tests were used to compare mean differences in UACR, while regression analysis was used to assess the effects of drug parameters on proteinuria development while on dasatinib. We assayed plasma dasatinib pharmacokinetics using tandem mass spectroscopy and further described a case study of a patient who experienced nephrotic-range proteinuria while on dasatinib. Participants treated with dasatinib ( n =32) had significantly higher UACR levels (median 28.0 mg/g; interquartile range, 11.5-119.5) than participants treated with other tyrosine-kinase inhibitors ( n =50; median 15.0 mg/g; interquartile range, 8.0-35.0; P < 0.001). In total, 10% of dasatinib users exhibited severely increased albuminuria (UACR >300 mg/g) versus zero in other tyrosine-kinase inhibitors. Average steady-state concentrations of dasatinib were positively correlated with UACR ( ρ =0.54, P = 0.03) and duration of treatment ( P = 0.003). There were no associations with elevated BP or other confounding factors. In the case study, kidney biopsy revealed global glomerular damage with diffuse foot process effacement that recovered on termination of dasatinib treatment. Exposure to dasatinib was associated with a significant chance of developing proteinuria compared with other similar tyrosine-kinase inhibitors. Dasatinib plasma concentration significantly correlated with higher risk of developing proteinuria while receiving dasatinib. This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_09_08_CJN0000000000000219.mp3.

Huangqi decoction ameliorates kidney injury in db/db mice by regulating the BMP/Smad signaling pathway

PurposeThis study aims to investigate the mechanism underlying the beneficial effects of Huangqi decoction (HQD) on Diabetic kidney disease (DKD) in diabetic db/db mice.MethodsEight-week-old male diabetic db/db mice were randomly divided into four groups: Model (1% CMC), HQD-L (0.12 g/kg), HQD-M (0.36 g/kg), and HQD-H (1.08 g/kg) groups. Non-diabetic db/m mice were served as the control group. These mice received HQD treatment for 8 weeks. After treatment, the kidney function, histopathology, micro-assay, and protein expression levels were assessed.ResultsHQD treatment improved the albumin/creatine ratio (ACR) and 24 h urinary albumin excretion, prevented the pathological phenotypes of increased glomerular volume, widened mesangial areas, the of mesangial matrix proliferation, foot process effacement, decreased nephrin expression and reduced number of podocytes. Expression profiling analysis revealed global transcriptional changes that predicted related functions, diseases and pathways. HQD treatment activated protein expressions of BMP2, BMP7, BMPR2, and active-Rap1, while inhibiting Smad1 and phospho-ERK. In addition, HQD was associated with improvements in lipid deposition in the kidneys of db/db mice.ConclusionHQD ameliorated the progression of DKD in db/db mice by regulating BMP transcription and downstream targets, inhibiting the phosphorylation of ERK and the expression of Smad1, promoting Rap1 binding to GTP, and regulating the lipid metabolism. These findings provide a potential therapeutic approach for treating DKD.

Dual deletion of guanylyl cyclase-A and p38 mitogen-activated protein kinase in podocytes with aldosterone administration causes glomerular intra-capillary thrombi

Natriuretic peptides exert not only blood-lowering but also kidney-protective effects through guanylyl cyclase-A (GC-A), a natriuretic peptide receptor. Signaling through GC-A has been shown to protect podocytes from aldosterone-induced glomerular injury, and a p38 mitogen-activated protein kinase (MAPK) inhibitor reduced glomerular injury in aldosterone-infused podocyte-specific GC-A knockout mice. To explore the role of p38 MAPK in podocytes, we constructed podocyte-specific p38 MAPK and GC-A double knockout mice (pod-double knockout mice). Unexpectedly, aldosterone-infused and high salt-fed (B-ALDO)-treated pod-double knockout mice resulted in elevated serum creatinine, massive albuminuria, macrophage infiltration, foot process effacement, nephrin and podocin reduction, and additionally, intra-capillary fibrin thrombi, indicating endothelial injury. Microarray analysis showed increased plasminogen activator inhibitor-1 (PAI-1) in glomeruli of B-ALDO-treated pod-double knockout mice. In B-ALDO-treated pod-double knockout mice, PAI-1 increased in podocytes, and treatment with PAI-1 neutralizing antibody ameliorated intra-capillary thrombus formation. Invitro, deletion of p38 MAPK by the CRISPR/Cas9 system and knockdown of GC-A in human cultured podocytes upregulated PAI-1 and transforming growth factor- β1 (TGF-β1). When p38 MAPK knockout podocytes, transfected with a small interfering RNA to suppress GC-A, were co-cultured with glomerular endothelial cells in a transwell system, the expression of TGF-β1 was increased in glomerular endothelial cells. PAI-1 inhibition ameliorated both podocyte and endothelial injury in the transwell system signifying elevated PAI-1 in podocytes is a factor disrupting normal podocyte-endothelial crosstalk. Thus, our results indicate that genetic dual deletion of p38 MAPK and GC-A in podocytes accelerates both podocyte and endothelial injuries, suggesting these two molecules play indispensable roles in podocyte function.

#4694 AUTOMATIC SEGMENTATION OF GLOMERULAR SUBSTRUCTURES BY DEEP LEARNING

Abstract Background and Aims Electron microscopy (EM) complements light microscopy (LM) evaluation of the kidney biopsy. Foot process effacement, as assessed by EM, helps in diagnosing podocytopathies. However, human interpretation of EM images is time-intensive and often subjective. In this pilot, we investigate how deep learning techniques can help in adequate segmentation of the glomerular basement membranes (GBM) and podocytes in EM images. The ultimate goal would be to design an automatic tool for reliable and fast assessment of foot process effacement. Method Podocytes and glomerular basement membranes (GBM) of 10 patients, 5 with podocyte disease and 5 without glomerular changes (where biopsy showed tubulointerstitial pathology on LM) were annotated with a combination of manual annotation and thresholding for providing ground truth. After data preprocessing including splitting, flipping, rotating and tiling, a modified U-net architecture was applied (‘baseline model’). This baseline model was compared to a combination of U-net and a self-supervised contrastive learning approach with pretraining on 100 additional images (SimCLR framework, ‘fine-tuned model’). Segmentation performance was measured by IoU score. Results Segmentation of the glomerular basement membrane was best achieved by the baseline model and resulted in an IoU score of 0.711±0.089 compared to a IoU score of 0.675 ±0.093 in the fine-tuned model Segmentation of the podocytes was most successful in the fine-tuned model, with a IoU score of 0.609±0.118 compared to a IoU score of 0.591 ±0.118 in the baseline model Conclusion This study pioneers in segmenting glomerular substructures on EM images by means of a modified U-net architecture. The next step is training and validation in larger datasets. Data annotation remains a challenge. Inclusion of more images is expected to greatly improve the performance of the model. Guideline 1500-3600 characters

#5400 CLINICAL PROFILE, MICROSCOPIC FEATURES AND OUTCOMES OF PATIENTS WITH MINOR GLOMERULAR ABNORMALITIES AT NKTI: A 10-YEAR DESCRIPTIVE CROSS-SECTIONAL STUDY

Abstract Background and Aims Minor Glomerular Abnormality (MGA) is a kidney biopsy diagnosis characterized by the presence of minor structural abnormalities which, are not sufficient to be classified under the other known glomerular diseases. Although usually considered a benign renal problem, few literatures mentioned it may cause deterioration of kidney function in the long term. The objective of this study is to describe the clinical profile, microscopy findings, treatment outcome and renal survival of patients diagnosed with Minor Glomerular Abnormalities in NKTI from 2005 to 2015. Method This is a Retrospective, Descriptive, Cross-sectional study which included 190 patients who were diagnosed with MGA. Demographic, clinical profile, CKD classification and treatment outcomes were presented using descriptive statistics while renal survival was analysed using Fisher's Exact Test. Based on the level of proteinuria and serum creatinine, treatment outcomes of the patients were classified as either with (1) complete response [if with reduction in proteinuria to ≤ 300 mg/day (&amp;lt;/ = 0.3 g/day) and a creatinine clearance ≥ 80 ml/min with no reduction from baseline] (2) partial response [proteinuria between 300 mg and 3 g/day OR by at least 50% from baseline level and with no deterioration in creatinine clearance], (3) relapse[patients whom (a) after a complete response to treatment (baseline proteinuria ≤ 300 mg/day), there is an increase in proteinuria to ≥ 1.0 g/day or (b) after a partial response (baseline proteinuria between 300 mg and 3 g/day), there is an increase in proteinuria to ≥ 3 g/day or increase in proteinuria by ≥ 50%, or (c) after a partial response (baseline proteinuria &amp;gt; 3 g/day), there is an increase in proteinuria by ≥ 50%], or (4) unsatisfactory response to treatment if complete or partial response is not met. Renal survival was assessed by classifying the renal status of the patients as either with (1) Normal or Mildly Decreased GFR [CKD 1-2] or (2) with moderately decreased kidney function to renal failure [CKD 3-5]. Results The mean age of the MGA patients at diagnosis was 37 years old. Of the 190 subjects of this study, 53.68% were female and 73.16% has no comorbidities. Proteinuria was the most common reason for consult (66.32%), followed by hematuria (38.42%) and worsening renal function (14.21%). Most of the patients had Nephrotic Syndrome (39%) before biopsy. The top three Electron Microscopy findings were Minimal Change Disease (24.4%) Segmental Podocyte Foot Processes Effacement (True MGA) at 27.4% and Thin Basement Membrane Disease (22.6%). At one year and five years, 13.68% and 4.74% respectively have complete response to treatment while 22.10% and 13.15% respectively have either partial or unsatisfactory response to treatment. Eighty patients (86.02%) at one year and 33 patients (78.57%) at 5 years remain at CKD 1-2. When the renal survival of the True MGA and Non-MGA patients were compared using Fisher Exact Test, there was no significant difference between the two groups (p values of 0.080 at 1 year and 0.99 at 5 years). Conclusion Minimal Change Disease is the most common Electron Microscopy diagnosis. Majority have good renal survival, but few progressed to CKD 3-5. Survival between MGA and Non-MGA patients are similar.

#3939 EFFECTIVENESS OF IMATINIB FOR MCTO NEPHROPATHY

Abstract Background and Aims MAFB is a podocyte-specific transcription factor. Point mutations in the MAFB transactivation domain in humans result in multicentric carpometacarpal-tarsal osteolysis (MCTO). MCTO patients show focal segmental glomerulosclerosis (FSGS) due to podocyte damage, known as MCTO nephropathy. Effective treatment for MCTO has not been found. Imatinib is a tyrosine kinase inhibitor (TKI), which inhibits PI3K-Akt pathway, and is in long-term use for the treatment of chronic myeloid leukemia. Method In order to develop a new treatment for MCTO, we generated disease model mice using the CRISPR-Cas9 system. These animals have the same genetic mutation as human MCTO patients. Albuminuria was evaluated at 4 weeks of age, and renal histological analysis was performed at 26 weeks of age. In addition, RNA-seq for isolated glomeruli of 10-week-old MCTO mice and wild-type animal was performed for genetic and pathway analysis. Results MCTO mice exhibited growth retardation, and presented albuminuria from 4 weeks of age. Foot process effacement and FSGS-like renal histological changes were shown. Nephropathy symptoms were similar to that of human MCTO patients. Interestingly, the upregulated genes in RNA-seq analysis were a group of receptor genes associated with PI3K-Akt signaling, including lpar1 and csfr1.Transesophageal administration of imatinib, a PI3K-Akt pathway inhibitor, treatment for 5 consecutive weeks decreased albuminuria and ameliorated histological renal damage. RNA-seq of isolated glomeruli of MCTO mice after imatinib treatment showed decreased expression of genes associated with TGFβ-related signaling pathways compared to the non-treated group. Recently, enhanced PI3K-Akt signaling in podocytes has been linked to several renal diseases associated with podocyte injury. In addition, lpar1 inhibition in glomeruli is known to suppress TGFβ. Imatinib suppressed PI3K-Akt signaling, which is enhanced in podocytes of MCTO mice. This may have shown a podocyte-protective effect by suppressing fibrosis-related genes such as TGFβ. Imatinib is classified as a TKI, but frequency of podocyte toxicity is lower than other TKIs. Conclusion The podocyte injury mechanism of MCTO nephropathy is associated with enhanced PI3K-Akt signaling in podocytes. Imatinib inhibits this pathway and suppresses TGFβ. Imatinib may become a therapeutic agent for MCTO nephropathy.

#2907 ASYMPTOMATIC NEPHROTIC SYNDROME: AN INTERESTING PRESENTATION OF ADULT ONSET MINIMAL CHANGE DISEASE

Abstract Background and Aims Minimal change disease (MCD), a predominantly pediatric disease, is less common in adults. Patients often present with florid hypervolemia, manifested by significant lower extremity edema, anasarca, pericardial effusion or pleural effusion. Herein, we present a case of newly diagnosed MCD in an elderly gentleman with an atypical presentation. Method A 69 year old male with hypertension and benign prostate hypertrophy presented to the emergency department (ED). He was noted to have abnormal labs at an outside clinic on routine testing and was directed to the ED. In the ED, he was found to have a serum creatinine (SCr) of 10.89 mg/dL. Initial urine studies also revealed proteinuria of 11g/g with 6.5 g/g of albuminuria. Other initial labs were significant for a potassium of 4.5 mEq/L, BUN 126 mg/dL and albumin 2.2 g/dL with normal liver enzymes. Renal ultrasound was unremarkable. Upon further discussion with the patient, he endorsed long term daily use of diclofenac for many months. He stated that he stopped diclofenac three weeks prior to presentation. He denied any proton pump inhibitor or recent antibiotic use. He denied any fevers, nights sweats or weight loss to suggest Type B symptoms. There was no personal kidney disease history nor family history of kidney disease. He was a non-alcoholic and non-smoker. We continued to hold further non-steroidal anti-inflammatory medications as well as other nephrotoxic medications. Although patient had elevated SCr and azotemia, he did not meet any acute indications for dialysis and we continued to manage the patient conservatively. Serologies were negative for ANA, ANCA, Anti-GBM, HIV, hepatitis B and C, as well as antiPLA2R. Serum protein electrophoresis, kappa to lambda ratio, complements 3 and 4 were all within normal values. A kidney biopsy was revealing for patchy interstitial inflammatory infiltrate containing mononuclear cells admixed with few eosinophils on light microscopy as well as diffuse foot process effacement on electron microscopy (Figure 2). The patient had a one-week hospital stay with improvement of SCr to 2.29 mg/dL without any prednisone or treatment for MCD. Spot urine protein improved to 7.4 g/g by time of discharge. At clinic follow up 2 weeks later his creatinine had improved to 1.1 mg/dL with UPCR of 0.4 g/g. Results MCD is a podocytopathy that can occur in up to 10% of adults with nephrotic syndrome [1]. Secondary MCD has been reported with NSAIDs. Steroids are the first line therapy for MCD and can lead to remission in the majority of the cases. In patients who do not respond to steroids, calcineurin inhibitors or mycophenolate can be used. Conclusion Our patient presented with biopsy proven-MCD that was presumed to be secondary to diclofenac. His clinical presentation was not characteristic of nephrotic syndrome with no edema. Few reports exist of spontaneous remission in these patients with most of the patient requiring steroids. While it is uncommon for patients with MCD to spontaneously resolve, not all patients with NSAID-induced MCD require treatment and these patients could be monitored conservatively.

#4013 LIPIDOMIC ANALYSIS OF PFSGS PATIENTS' SERUM TO IDENTIFY POTENTIAL CANDIDATES FOR THE CIRCULATING PERMEABILITY FACTOR(S) IN THE LIPID DOMAIN

Abstract Background and Aims Patients with primary focal segmental glomerulosclerosis (pFSGS) present with nephrotic syndrome. Whereas the exact pathogenesis is largely unknown, there is strong evidence that one or more circulating permeability factors in the circulation induce podocyte injury. Podocyte injury eventually leads to foot process effacement, massive proteinuria and kidney function loss. Historically, research into the cause of pFSGS has focused primarily on identifying the circulating factor in the protein domain, but reports of successful treatment with lipid apheresis suggest that it could also be a lipid compound. Here, we set out to investigate the lipidome of pFSGS patients’ serum to identify potential candidates for the circulating permeability factor(s) in the lipid domain. Method For this lipidomics study, we included 5 patients with pFSGS in whom serum had been collected at the time they presented at our center with active nephrotic syndrome. We compared the serum lipidome of the pFSGS patients with age matched healthy controls (n = 5), and with age matched patients with familial hypercholesterolemia (n = 5) who, like pFSGS patients, have significantly elevated lipid values. Serum was analyzed using the Shotgun Lipidomics platform by Lipotype GmbH (Dresden, Germany), as previously described [1]. The amount of lipids were normalized to the total amount of lipids present within the sample. Results The lipidomic profile of patients with pFSGS was markedly different from the profile of healthy controls and patients with hypercholesterolemia. We found differences in various lipid classes in pFSGS patients, including cholesterol esters (CE), lyso-phophatidylcholine (LPC), phophatidylethanolamine (PE), diacylglycerol (DAG) and triacylglycerol (TAG) that were significantly changes compared to both healthy controls and FH patients. Diacylglycerols (DAG) were identified as the most significantly increased lipid species in pFSGS. By analyzing the subspecies we discovered that DAGs with carbon chains greater than 38 carbon atoms in both chains combined (long carbon chain DAGs, lccDAGs) were exclusively present in patients with pFSGS. Conclusion Our lipidomics data show that patients with pFSGS have a substantially different lipid profile than healthy controls and patients with familial hypercholesterolemia. We identified lccDAGs as unique lipids in patients with pFSGS, that were not present in controls. This is an interesting finding since the DAG-analogue 1-oleoyl-2-acetyl-sn-glycerol (OAG) is known to be able to induce podocyte injury in vitro [2]. In further research, we will focus on confirming whether lccDAGs are unique to pFSGS patients, whether it is suitable as a biomarker, and whether it plays a causal role in the disease process.