Focal And Segmental Glomerulosclerosis Research Articles

The role of matrix metalloproteinase inhibitor (doxycycline) in the treatment of primary focal segmental glomerulosclerosis

Background Focal and segmental glomerulosclerosis (FSGS) is a histological pattern used in clinical practice to define a podocytopathy that develops with nephrotic-range proteinuria and segmental obliteration or collapse of glomerular capillary loops with increased extracellular matrix in some glomeruli. The major concerns of idiopathic FSGS are the poor renal prognosis with an absence of response to immunosuppressive therapies or relapses and its recurrence after kidney transplantation in ⁓30–50% of patients, which leads to renal graft failure. The aim of this work is to study the possible role of matrix metalloproteinase inhibitor (doxycycline) in the treatment of primary FSGS. Patients and methods This prospective cohort study was conducted on 100 patients with FSGS. Patients were randomly divided into two equal groups: group 1: patients with FSGS under conventional therapy as a control group. Group 2: patients with FSGS under conventional therapy and doxycycline 100 mg/day for 3 months. Patients were closely monitored for treatment effects and adverse reactions. Clinical, laboratory, and radiological parameters were assessed. Treatment outcomes, including remission of proteinuria and adverse effects, were evaluated. Results Group 2 showed significantly lower levels of triglycerides and fasting blood glucose compared with group 1. Doxycycline-related side effects were observed in some group 2 patients. Both groups showed increased hemoglobin levels and decreased C-reactive protein levels at follow-up. Kidney function tests improved in both groups, with group 2 demonstrating superior outcomes. Group 2 showed higher rates of improvement and lower incidence of end-stage renal disease requiring hemodialysis. Conclusion Adding doxycycline to conventional therapy holds promise for treating primary FSGS. Patients receiving combined therapy exhibited enhanced renal function, reduced proteinuria, and better treatment outcomes.

#1290 Adverse proinflammatory responses in the kidney after FGF23 administration in three murine kidney disease models

Abstract Background and Aims The hormone FGF23 is a biomarker associated with morbidity and mortality in individuals with and without kidney disease, but the role of FGF23 excess as a pathogenic factor is incompletely understood. Here, we investigated renal FGF23 signaling in kidney disease models. Method This study used three independent disease models: i) Male C57BL/6 mice (n = 16) were treated with Freud's adjuvant and nephrotoxic serum (NTS) to induce anti-glomerular basement membrane (anti-GBM) disease. ii) Female BALB/c mice (n = 8) were treated with adriamycin (doxorubicin) 10.5 mg/kg to induce focal and segmental glomerulosclerosis (FSGS). iii) Male DBA/2J mice (n = 20) were fed a diet containing adenine 0.2%. Control mice of the respective same strain and sex received vehicle injections. Mice of the anti-GBM and FSGS models and controls received intravenous injections of recombinant FGF23 1 µg or vehicle for six consecutive days (anti-GBM) or once (FSGS), with dissection 24 h after the last injection. Mice of the adenine model were dissected after 15 weeks. Following dissection, ex vivo precision-cut kidney slices (PCKS) were obtained from n = 4 mice and maintained for 24 at 37°C, 95% O2 and 5% CO2, followed by a 1 h treatment with recombinant FGF23 200 ng/ml or vehicle. Glomerular filtration rate (GFR) or renal retention parameters in serum and albuminuria were assessed. Kidneys underwent histological assessment using hematoxylin & eosin or Masson's trichrome. Renal RNA was isolated for bulk RNAseq. Differential gene expression was assessed to determine the effect of FGF23 treatment in disease-free controls, in each disease model, and the interaction between FGF23 X disease effect for the anti-GBM and FSGS groups. Gene set enrichment analysis was performed with a focus on the immune system. Results Anti-GBM mice showed a 45 ± 27% GFR decline (mean ± SD) compared to baseline, whereas controls showed an GFR increase of 11 ± 36% (p < 0.01). Kidney histology revealed an interstitial infiltrate. The FSGS model showed elevated serum creatinine and albuminuria, and hypercellularity in some glomeruli. Mice of the adenine model showed progressively increased blood urea nitrogen concentrations starting after 2 weeks, up to a 3-fold increase at week 14. Histology revealed interstitial fibrosis and tubular atrophy. Bulk RNAseq revealed proinflammatory transcriptional signatures after FGF23 treatment in all disease models, regardless of which timepoint or model: In the anti-GBM model, Hallmark gene sets of inflammatory response, interferon-α response, interferon-β response and allograft rejection were significantly increased after 6 days of FGF23 treatment, whereas disease-free controls showed no significantly changed immune gene sets after 6 days of FGF23. In FSGS mice, none of the Hallmark gene sets were changed after 1 FGF23 injection, but top individual gene expression affected by 1 FGF23 injection were an increased proinflammatory transcription factor Cebpb and an increased DNA damage transcript Dclre1b. Finally, the PCKS of adenine model revealed no significant Hallmark gene sets, but the two genes with differential expression were a proinflammatory macrophage/fibroblast chemokine Ccl4 (increased) and an immunoglobulin heavy variable Ighv2-2 (decreased). Conclusion FGF23-driven patterns of proinflammatory gene expression were observed in three experimental models of kidney disease, both in vivo and ex vivo assessment of FGF23 signaling, thus excluding effects of FGF23 on other organs. As these findings were limited to transcriptional analyses, the present data warrant further confirmation and exploration of FGF23 as a pathogenic agent in kidney disease.

#1644 Prognostic significance of hematuria on kidney survival in podocytopathies

Abstract Background and Aims Hematuria is common in podocytopathies, but its prognostic impact on kidney survival in these proteinuric diseases is not well-established. Our study examines the prevalence of hematuria at podocytopathy diagnosis and its association with renal survival. Method In our retrospective study, we analyzed 236 patients (median age 50 years, 60% male, median eGFR 65.5 mL/min/1.73 m2, median proteinuria 3.9g/g) with biopsy proven podocytopathies—48% membranous nephropathy (MN), 32% minimal change disease (MCD), 20% focal and segmental glomerulosclerosis (FSGS)—diagnosed at a tertiary center from 2010 to 2015. Hematuria was defined as the presence of 5 or more red blood cells (RBCs) per high-power field in 3 of 3 consecutive centrifuged urine specimens obtained at least 1 week apart. The follow-up period extended until the onset of end-stage kidney disease (ESKD: start of kidney replacement therapy or renal transplantation), death, or January 2022, with a median duration of 8.5 (95% CI: 8.1, 8.8) years. Results In our patient cohort, 31% (n = 73) presented with hematuria, having a median of 120 (IQR: 40-220) red blood cells (RBCs). Those with hematuria more frequently exhibited arterial hypertension (55% vs 36%, p 0.007) and had higher levels of proteinuria (5.3 vs 3.2g/g, p 0.01). However, no significant differences were noted in terms of age (53 vs 48 years, p 0.08), Charlson comorbidity score (2 vs 2, p 0.9), type of podocytopathy (MN 52 vs 47%, MCD 27 vs 34%, FSGS 21 vs 19%, p 0.5), eGFR (62.1 vs 68.8 mL/min, p 0.08), serum albumin levels (3.3 vs 3.4g/dL, p 0.6), total renal chronicity score on histology (0 vs 0, p 0.6), and treatment with ACE inhibitors/angiotensin receptor blockers (43% vs 50%, p 0.4) or immunosuppression (81% vs 74%, p 0.4). Thirty-two percent of the patients with hematuria reached ESKD versus 9% in the group without hematuria (p 0.001); there were no differences regarding mortality between the two groups. Mean kidney survival time for the entire cohort was 10.3 (95% CI: 9.9, 10.8) years; renal survival at 1, 3, 5 and 10 years were 97%, 92%, 88% and 82%, respectively. Patients with hematuria at diagnosis had a significant shorter kidney survival time (9.0 (95% CI: 8.0, 10.0) vs 11.0 (95% CI: 10.6, 11.4) years, p 0.001). In a multivariate Cox proportional hazard model (backward Wald), presence of hematuria at diagnosis (HR 3.64, 95% CI: 1.87, 7.07), lower eGFR (HR 0.96, 95% CI: 0.94, 0.97) and higher total renal chronicity score on histology (HR 1.10, 95% CI: 1.00, 1.22) were independent predictors of reduced kidney survival. Conclusion Hematuria is prevalent in the three podocytopathies and independently correlates with poorer kidney survival outcomes. This underscores the possible need for personalized treatment strategies in patients with podocytopathies presenting with hematuria.

#3084 Familial nephropathy associated with a combined mutations of Alport and Nail Patella syndrome genes in the same family

Abstract Introduction Alport syndrome is a genetic condition stemming from mutation in Type IV collagen and is characterized by kidney disease and frequently hearing loss and ocular abnormalities. Renal involvement is from an abnormality of the glomerular basement membrane with hematuria and proteinuria progressing eventually to renal failure. In the vast majority, the inheritance is X- linked affecting the alpha 5 chain of type IV collagen while in about 15 percent of the patients the inheritance is autosomal recessive or dominant with mutations affecting alpha 3 or 4 chains of type IV collagen. Sensorineural deafness is common and ocular abnormalities may include lenticonus, corneal opacities, fleck retinopathy and temporal retinal thinning. Nail Patella syndrome (NPS) is a rare genetic condition from mutation in the LMX1B gene on chromosome 9 with an autosomal dominant inheritance. Glomerular disease is from characteristic glomerular basement membrane changes and is associated with nail, pelvic girdle and limb abnormalities. A forme fruste with glomerular lesions but lacking extrarenal features is recognized but uncommon. We present a family with mutations in both COL4A5 and LMX1B presenting with hematuria and proteinuria Case Presentation A 23 year old female was evaluated for hematuria and proteinuria. Her history was notable for kidney biopsy at the age thirteen showing focal and segmental glomerulosclerosis (FSGS). She was treated with tacrolimus for four years from age thirteen through seventeen. Patient was reportedly diagnosed with Nail Patella Syndrome after genetic testing. Her family history was notable for hematuria in her brother and hematuria and proteinuria in her mother. On physical examination she was noted to have no nail or skeletal abnormalities associated with Nail Patella Syndrome. Her labs were notable for a serum creatinine of 0.6 mg/dl and proteinuria of 155 mg/g creatinine of proteinuria. Urine microscopy revealed dysmorphic hematuria. Radiological imaging did not show skeletal abnormalities observed in Nail Patella Syndrome but genetic testing identified a pathogenic variant in COL4A5 c.919G>A (p.Gly307Ser) in addition to a variant of uncertain significance in LMX1B c.349G>A (p.Gly117Ser). Her brother aged 20 had a creatinine of 0.87 mg/dl with dysmorphic hematuria and no proteinuria. Genetic testing showed the same pathogenic variant in COL4A5 as in his sibling. His mother aged 55 was subsequently evaluated and had a creatinine 0.73 mg/dl with dysmorphic hematuria and 152 mg/g of proteinuria. Genetic testing was with the same variant in COL4A5 noted in her two children. Renal biopsy was extensive thinning and segmental lamellation of the glomerular basement membrane with eight percent FSGS. The typical “moth-eaten” appearance of the glomerular basement membrane characteristic of NPS was not evident. Segmental staining was observed with alpha 5 unit of Type IV collagen. Audiology and retinal optical coherence optometry studies are pending. Discussion Alport syndrome and Nail Patella Syndrome are rare genetic disorders that cause variable degrees of renal insufficiency from glomerular base membrane defects and are associated with characteristic extra renal manifestations. This is the first report of an inherited nephritis with combined mutations in COL4A5 and LMX1B. The clinical features and renal biopsy are compatible with Alport Syndrome and the significance of the mutation in LMX1B is uncertain. Conclusion This is the first case report of a combined mutation in COL4A5 and LMX1B gene presenting with hematuria and minimal proteinuria with preserved kidney function.

Inhibition of RAC attenuates Adriamycin-induced podocyte injury

Minimal Change Disease (MCD), which is associated with podocyte injury, is the leading cause of nephrotic syndrome in children. A considerable number of patients experience relapses and require prolonged use of prednisone and immunosuppressants. Multi-drug resistance and frequent relapses can lead to disease progression to focal and segmental glomerulosclerosis (FSGS).To identify potential targets for therapy of podocyte injury, we examined microarray data of mRNAs in glomerular samples from both MCD patients and healthy donors, obtained from the GEO database. Differentially expressed genes (DEGs) were used to construct the protein-protein interactions (PPI) network through the application of the search tool for the retrieval of interacting genes (STRING) tool. The most connected genes in the network were ranked using cytoHubba. 16 hub genes were selected and validated by qRT-PCR. RAC2 was identified as a potential therapeutic target for further investigation. By downregulating RAC2, Adriamycin (ADR)-induced human podocytes (HPCs) injury was attenuated. EHT-1864, a small molecule inhibitor that targets the RAC (RAC1, RAC2, RAC3) family, proved to be more effective than RAC2 silencing in reducing HPCs injury. In conclusion, our research suggests that EHT-1864 may be a promising new molecular drug candidate for patients with MCD and FSGS.

Protective Role of the Podocyte IL-15 / STAT5 Pathway in Focal Segmental Glomerulosclerosis

IntroductionDuring glomerular diseases, podocyte-specific pathways can modulate the intensity of histological disease and prognosis. The therapeutic targeting of these pathways could thus improve the management and prognosis of kidney diseases. The Janus Kinase/ Signal Transducer and Activator of Transcription (JAK/STAT) pathway, classically described in immune cells, has been recently detailed in intrinsic kidney cells. MethodsWe describe STAT5 expression in human kidney biopsies from patients with focal and segmental glomerulosclerosis (FSGS) and studied mice with a podocyte-specific Stat5 deletion in experimental glomerular diseases. ResultsHere, we show, for the first time, that STAT5 is activated in human podocytes in FSGS. Additionally, podocyte-specific Stat5 inactivation aggravates the structural and functional alterations in a mouse model of FSGS. This could be due, at least in part, to an inhibition of autophagic flux. Finally, Interleukin 15 (IL-15), a classical activator of STAT5 in immune cells, increases STAT5 phosphorylation in human podocytes and its administration alleviates glomerular injury in vivo by maintaining autophagic flux in podocytes. ConclusionIn conclusion, activating podocyte STAT5 with commercially available IL-15 represents a potential new therapeutic avenue for FSGS.

Podocyte number and glomerulosclerosis indices are associated with the response to therapy for primary focal segmental glomerulosclerosis.

Corticosteroid therapy, often in combination with inhibition of the renin-angiotensin system, is first-line therapy for primary focal and segmental glomerulosclerosis (FSGS) with nephrotic-range proteinuria. However, the response to treatment is variable, and therefore new approaches to indicate the response to therapy are required. Podocyte depletion is a hallmark of early FSGS, and here we investigated whether podocyte number, density and/or size in diagnostic biopsies and/or the degree of glomerulosclerosis could indicate the clinical response to first-line therapy. In this retrospective single center cohort study, 19 participants (13 responders, 6 non-responders) were included. Biopsies obtained at diagnosis were prepared for analysis of podocyte number, density and size using design-based stereology. Renal function and proteinuria were assessed 6 months after therapy commenced. Responders and non-responders had similar levels of proteinuria at the time of biopsy and similar kidney function. Patients who did not respond to treatment at 6 months had a significantly higher percentage of glomeruli with global sclerosis than responders (p < 0.05) and glomerulosclerotic index (p < 0.05). Podocyte number per glomerulus in responders was 279 (203-507; median, IQR), 50% greater than that of non-responders (186, 118-310; p < 0.05). These findings suggest that primary FSGS patients with higher podocyte number per glomerulus and less advanced glomerulosclerosis are more likely to respond to first-line therapy at 6 months. A podocyte number less than approximately 216 per glomerulus, a GSI greater than 1 and percentage global sclerosis greater than approximately 20% are associated with a lack of response to therapy. Larger, prospective studies are warranted to confirm whether these parameters may help inform therapeutic decision making at the time of diagnosis of primary FSGS.

Inhibition of the glucocorticoid receptor attenuates proteinuric kidney diseases in multiple species.

Glucocorticoids are the treatment of choice for proteinuric patients with minimal change disease (MCD) and primary focal segmental glomerulosclerosis (FSGS). Immunosuppressive as well as direct effects on podocytes are believed to mediate their actions. In this study, we analyzed the anti-proteinuric effects of inhibition of the glucocorticoid receptor (GR) in glomerular epithelial cells, including podocytes. We employed genetic and pharmacological approaches to inhibit the GR. Genetically, we used Pax8-Cre/GRfl/fl mice to specifically inactivate the GR in kidney epithelial cells. Pharmacologically, we utilized a glucocorticoid antagonist called mifepristone. Genetic inactivation of GR, specifically in kidney epithelial cells, using Pax8-Cre/GRfl/fl mice, ameliorated proteinuria following protein overload. We further tested the effects of pharmacological GR inhibition in three models and species: the puromycin aminonucleoside-induced nephrosis model in rats, the protein overload model in mice and the inducible transgenic NTR/MTZ zebrafish larvae with specific and reversible podocyte injury. In all three models, both pharmacological GR activation and inhibition consistently and significantly ameliorated proteinuria. Additionally, we translated our findings to humans, where three nephrotic adult patients with MCD or primary FSGS with contraindications or insufficient responses to corticosteroids were treated with mifepristone. This treatment resulted in a clinically relevant reduction of proteinuria. Thus, across multiple species and proteinuria models, both genetic and pharmacological GR inhibition was at least as effective as pronounced GR activation. While the mechanism remains perplexing, GR inhibition may be a novel and targeted therapeutic approach to treat glomerular proteinuria potentially bypassing adverse actions of steroids.

Phellinus igniarius ameliorates renal aging in a rat model of focal and segmental glomerulosclerosis

Objective: To comparatively investigate the ameliorative effect of Phellinus igniarius (P. igniarius) on renal aging in a rat model of focal and segmental glomerulosclerosis (FSGS). Methods: The FSGS model was established in rats by uninephrectomy combined with tail vein injection of doxorubicin. The FSGS rats were randomly divided into the model group, the P. igniarius decoction group, the P. igniarius polysaccharides group, and the P. igniarius polyphenols group. Molecular indicators of cell senescence, renal function indexes, and podocyte injury markers were tested after ten weeks of intragastric administration. Besides, the pathological renal lesions and the ultrastructural changes were observed. Results: FSGS developed in the model group within ten weeks and showed segmental glomerular scarring and renal aging. Following the 10-week intervention, 24 h proteinuria, serum creatinine, blood urea nitrogen, P16INK4α, thrombospondin-1, and transforming growth factor-β1 were decreased in each treatment group, whereas albumin, erythropoietin, nephrin, and podocin were increased; the pathological renal injury was alleviated, and the number of senescent cells was reduced, especially in rats treated with P. igniarius decoction. Conclusions: P. igniarius ameliorates renal aging and renal injury in the FSGS rat model. Compared with the effective constituents (polysaccharides and polyphenols), P. igniarius decoction has a better curative effect, which is expected to provide a new therapeutic idea for FSGS.

Proteomics of Plasma and Plasma-Treated Podocytes: Application to Focal and Segmental Glomerulosclerosis.

Focal and segmental glomerulosclerosis (FSGS) is a severe form of idiopathic nephrotic syndrome (INS), a glomerulopathy of presumably immune origin that is attributed to extrarenal pathogenic circulating factors. The recurrence of FSGS (rFSGS) after transplant occurs in 30% to 50% of cases. The direct analysis of patient plasma proteome has scarcely been addressed to date, mainly due to the methodological difficulties associated with plasma complexity and dynamic range. In this study, first, we compared different methods of plasma preparation, second, we compared the plasma proteomes of rFSGS and controls using two preparation methods, and third, we analyzed the early proximal signaling events in podocytes subjected to patient plasma, through a combination of phosphoproteomics and lipid-raft proteomics (raftomics). By combining immunodepletion and high pH fractionation, we performed a differential proteomic analysis of soluble plasma proteins and of extracellular vesicles (EV) obtained from healthy controls, non-INS patient controls, and rFSGS patients (n = 4). In both the soluble- and the EV-protein sets from the rFSGS patients, we found a statistically significant increase in a cluster of proteins involved in neutrophil degranulation. A group of lipid-binding proteins, generally associated with lipoproteins, was found to be decreased in the soluble set from the rFSGS patients. In addition, three amino acid transporters involved in mTORC1 activation were found to be significantly increased in the EV from the rFSGS. Next, we incubated human podocytes for 30 min with 10% plasma from both groups of patients. The phosphoproteomics and raftomics of the podocytes revealed profound differences in the proteins involved in the mTOR pathway, in autophagy, and in cytoskeleton organization. We analyzed the correlation between the abundance of plasma and plasma-regulated podocyte proteins. The observed changes highlight some of the mechanisms involved in FSGS recurrence and could be used as specific early markers of circulating-factor activity in podocytes.

High Rate of Mutations of Adhesion Molecules and Extracellular Matrix Glycoproteins in Patients with Adult-Onset Focal and Segmental Glomerulosclerosis.

(1) Background: Focal and segmental glomerulosclerosis (FSGS) is a pattern of injury that results from podocyte loss in the setting of a wide variety of injurious mechanisms. These include both acquired and genetic as well as primary and secondary causes, or a combination thereof, without optimal therapy, and a high rate of patients develop end-stage renal disease (ESRD). Genetic studies have helped improve the global understanding of FSGS syndrome; thus, we hypothesize that patients with primary FSGS may have underlying alterations in adhesion molecules or extracellular matrix glycoproteins related to previously unreported mutations that may be studied through next-generation sequencing (NGS). (2) Methods: We developed an NGS panel with 29 genes related to adhesion and extracellular matrix glycoproteins. DNA was extracted from twenty-three FSGS patients diagnosed by renal biopsy; (3) Results: The average number of accumulated variants in FSGS patients was high. We describe the missense variant ITGB3c.1199G>A, which is considered pathogenic; in addition, we discovered the nonsense variant CDH1c.499G>T, which lacks a Reference SNP (rs) Report and is considered likely pathogenic. (4) Conclusions: To the best of our knowledge, this is the first account of a high rate of change in extracellular matrix glycoproteins and adhesion molecules in individuals with adult-onset FSGS. The combined effect of all these variations may result in a genotype that is vulnerable to the pathogenesis of glomerulopathy.

#6930 TOO ELDERLY FOR A KIDNEY BIOPSY?

Abstract Background and Aims As we age, we lose kidney function and accumulate risk factors and comorbidities that predispose to kidney damage. However, kidney disease can develop at any time. Life expectancy continues to improve worldwide. For that reason, more elderly patients are undergoing diagnostic kidney biopsies (KB). There is a general reluctance in performing KB in those patients. It is important to know if a diagnosis KB in elderly patients can have a positive therapeutic impact. Method In this retrospective cohort study, we analyzed the medical charts of all patients aged ≥ 80years who underwent a native kidney biopsy (KB) between January and December 2021, in a central hospital in Portugal. Results Between January and December 2021, 59 patients underwent a native KB, 6 of them over 80 years of age (10% of all patients). Between those elderly patients, the median age was 82 years. The indications for KB were chronic kidney disease with a nephrotic range proteinuria in 3 patients, nephrotic syndrome, acute glomerulonephritis and acute kidney injury in 1 patient each. Median serum creatinine was 2.27 mg/dL (minimum 0.8 and maximum 5.4 mg/dL) and median protein-to-creatinine ratio was 5.7g/g (minimum 3.3 and maximum 13g/g). The pathological diagnoses found were focal and segmental glomerulosclerosis (FSGS) (n=2), pauci-immune crescentic glomerulonephritis (n=1), membranous nephropathy in a patient with a follicular lymphoma (n=1), acute interstitial nephritis (AIN) (n=1), and diabetic glomerulosclerosis in a patient with a monoclonal gammopathy of undetermined significance (n=1). 3 patients have received a kidney-specific treatment – the patient with AIN started corticosteroids, one patient with FSGS was submitted to corticosteroids plus tacrolimus, and the patient with pauci-imune crescentic glomerulonephritis to corticosteroids plus rituximab. The patient with membranous nephropathy and follicular lymphoma received a specific chemotherapy regimen according with lymphoproliferative disease. An improvement in kidney function occurred only in one patient and the other three developed adverse effects (particularly corticosteroids induced diabetes and infections). One year later, one of patients who received treatment was dead, another one was on hemodialysis, and the other two patients had a glomerular filtration rate lower than 15mL/min/1.73 m2. Conclusion Elderly patients have a higher risk of adverse effects from the kidney-specific treatment. It is important to assess the therapeutic risk/benefit when considering performing a renal biopsy in these patients.

#6883 PROTECTIVE ROLE OF THE PODOCYTE IL-15 / STAT5 PATHWAY IN EXPERIMENTAL FOCAL AND SEGMENTAL GLOMERULOSCLEROSIS

Abstract Background and Aims During glomerular diseases, podocyte-specific pathways can modulate the intensity of histological disease and prognosis. The therapeutic targeting of these pathways could thus improve the management and prognosis of kidney diseases. The Janus Kinase/ Signal Transducer and Activator of Transcription (JAK/STAT) pathway, classically described in immune cells, has been recently detailed in intrinsic kidney cells. We previously evidenced a protective role for a podocyte-expressed immune receptor such as the common gamma chain (ΓC) during glomerulonephritis (1). We also found that STAT5, a transcriptional factor classically described and activated downstream ΓC in T cells is upregulated in podocytes during glomerulonephritis. Method Using a mice model with a podocyte-specific deletion of Stat5, we analyzed the role of STAT5 in two experimental models of glomerular diseases. Results Here, we show, for the first time, that STAT5 is activated in human podocytes in focal and segmental glomerulosclerosis (FSGS). Additionally, podocyte-specific Stat5 inactivation aggravates the structural and functional alterations in a mouse model of FSGS (Figure 1). This could be due, at least in part, to an inhibition of autophagic flux and an alteration of mitochondrial function. Finally, Interleukin 15 (IL-15), a classical activator of STAT5 in immune cells, increases STAT5 phosphorylation in human podocytes and its administration alleviates glomerular injury in vivo by maintaining autophagic flux in podocytes. Conclusion In conclusion, activating podocyte STAT5 with commercially available IL-15 represents a potential new therapeutic avenue for FSGS.

Egyptian pediatric clinical practice adapted guidelines: evidence-based [2] steroid-resistant nephrotic syndrome (SRNS) 2022

BackgroundNephrotic syndrome is one of the most common chronic kidney diseases in children. Steroid sensitive type (SSNS) constitutes about 85–90%, whereas steroid-resistant type (SRNS) only 15–20% (Mickinney et al. Pediatr Nephrol 16:1040-1044, 2001). While MCD is the most common histopathology in SS type, children with SRNS have MCD, mesangial proliferative glomerulonephritis, or focal and segmental glomerulosclerosis (FSGS) (International Study Kidney Disease in children, Kidney Int 20;765-771, 1981). SRNS is defined as those who do not show remission after 6 weeks and standard dose of oral steroids ± 3 IV MPD doses (Trautmann et al. Pediatr Nephrol 35:1529-1561, 2020).ObjectivesThese national adapted guidelines aim to frame evidence-based recommendations adopted or adapted from the IPNA 2020, KDIGO 2021, and Japanese 2014 de novo guidelines for diagnosis and management of nephrotic children to be presented in two manuscripts: (1) steroid sensitive (SSNS) and (2) steroid-resistant nephrotic syndrome (SRNS).MethodologyFormulation of key questions was followed with a review of literature guided by our appraised guidelines using AGREE plus appraisal tool. Virtual monthly meetings all through the year 2021 were activated for reviewing and validation of final adaptation evidence-based draft, considering all comments of external reviewers including KDIGO assigned reviewer.DiscussionRationale behind the selection of adopted statements and tailoring of others to suit our local facilities, expertise, and our local disease profile was discussed in the text with reasons.ConclusionThe provided guidelines aim to optimize patient care and outcome and suggest research areas lacking validated research recommendations.

A Study of Focal and Segmental Glomerulosclerosis according to the Columbia Classification and Its Correlation with the Clinical Outcome.

Introduction Focal and segmental glomerulosclerosis (FSGS) is a leading cause of nephrotic syndrome in both adults and children. The "Columbia classification of FSGS" includes five variants; not otherwise specified (NOS), tip, perihilar, cellular, and collapsing variants that may have different prognostic and therapeutic implications. Materials and Methods This is a retrospective study and was carried out in the Department of Histopathology, Apollo Hospitals, Hyderabad. Of a total of 11,691 kidney biopsies over a 7-year period, from 2006 to 2012, 824 cases were diagnosed as FSGS, of which 610 cases in which detailed clinical findings were available were included in this study. FSGS was then categorized according to the Columbia classification. Results FSGS, NOS was the predominant histomorphological variant. Serum creatinine was significantly high in the collapsing variant, followed by NOS. Follow-up data was available for 103 cases,72.8% had complete remission, 10.6% had partial remission, and in 16.5 % there was no remission. Relapses were observed in 6.7% cases, two patients (1.9%) succumbed, and 4.8% cases progressed to chronic kidney disease. Conclusion This study showed that perihilar variant was less prevalent, with tip and cellular variants being more prevalent in Indian subcontinent compared to Western literature. Collapsing variant was also less common.

Determination of Anti-Phospholipase A2 and Anti-Thrombospondin Type 1 Domain-Containing Protein 7A in Latin Patients with Membranous Nephropathy

Primary membranous nephropathy (MN) is caused by antibodies against podocyte antigens, especially the type M receptor of phospholipase A2 (PLA2R) and thrombospondin type-1 domain containing 7 A (THSD7A). This study's aim was the determination of anti-PLA2R, anti-THSD7A serum antibodies, and anti-PLA2R renal tissue staining prevalence in a Latin population with MN, as well as evaluating their role as biomarkers for disease activity. The performance of the two anti-PLA2R serum diagnostic methods-ELISA and indirect immunofluorescence (IFI)-was evaluated for the diagnosis of MN. Fifty-nine patients, including 29 with MN, 18 with lupus membranous nephropathy (LMN) and 12 with focal and segmental glomerulosclerosis (FSGS), were evaluated for serum antibodies. Renal biopsies were also evaluated for the presence of anti-PLA2R staining. Twenty-one patients with MN were followed for 1 year. Patients with LMN and FSGS were negative for both antibodies. All 29 MN patients were negative for anti-THSD7A; 16 MN patients were positive for anti-PLA2R by ELISA and/or IFI, and 3 MN patients were positive for anti-PLA2R only by IFI. Thus, the anti-PLA2R ELISA test demonstrated 45% sensitivity and 97% specificity, while the IFI test showed, respectively, 55% and 100% in our MN patients. Among the 28 MN renal biopsies, 20 presented anti-PLA2R positive staining, corresponding to a 72% sensitivity. Positive correlations were observed between the anti-PLA2R ELISA titer and proteinuria. In conclusion, determination of anti-PLA2R antibodies in the MN Latin population showed similar rates to those reported for other populations. The anti-PLA2R serum levels correlated with MN disease activity.

Mesangial Injury and Capillary Ballooning Precede Podocyte Damage in Nephrosclerosis

The development of focal and segmental glomerulosclerosis (FSGS) as a consequence of glomerular hypertension resulting from arterial hypertension is widely considered a podocyte disease. However, the primary damage is encountered in the mesangium. In acute settings, mesangial cells disconnect from their insertions to the glomerular basement membrane, causing a ballooning of capillaries and severe changes of the folding pattern of the glomerular basement membrane, of the arrangement of the capillaries, and thereby of the architecture of the tuft. The displacement of capillaries led to contact of podocytes and parietal epithelial cells, initiating the formation of tuft adhesions to Bowman's capsule, the committed lesion to progress to FSGS. In addition, the displacement of capillaries also caused an abnormal stretching of podocytes, resulting in podocyte damage. Thus, the podocyte damage that starts the sequence to FSGS is predicted to develop secondary to the mesangial damage. This sequence was found in two hypertensive rat models of FSGS and in human hypertensive nephrosclerosis.

TRPC6 Inactivation Reduces Albuminuria Induced by Protein Overload in Sprague Dawley Rats.

Canonical transient receptor potential-6 (TRPC6) channels have been implicated in familial and acquired forms of focal and segmental glomerulosclerosis (FSGS), and in renal fibrosis following ureteral obstruction in mice. TRPC6 channels also appear to play a role in driving glomerular disease in aging and in autoimmune glomerulonephritis. In the present study, we examine the role of TRPC6 in the proteinuric state caused by prolonged albumin overload (AO) in Sprague Dawley rats induced by daily injections of exogenous albumin. This was assessed in rats with a global and constitutive inactivation of TRPC6 channels (Trpc6del/del rats) and in wild-type littermates (Trpc6wt/wt rats). AO for 14 and 28 days caused increased urine albumin excretion that was significantly attenuated in Trpc6del/del rats compared to Trpc6wt/wt controls. AO overload did not induce significant glomerulosclerosis or azotemia in either genotype. AO induced mild tubulointerstitial disease characterized by fibrosis, hypercellularity and increased expression of markers of fibrosis and inflammation. Those changes were equally severe in Trpc6wt/wt and Trpc6del/del rats. Immunoblot analysis of renal cortex indicated that AO increased the abundances of TRPC3 and TRPC6, and caused a nearly complete loss of TRPC5 in Trpc6wt/wt rats. The increase in TRPC3 and the loss of TRPC5 occurred to the same extent in Trpc6del/del rats. These data also suggest that TRPC6 plays a role in the normal function of the glomerular filtration barrier. However, whether TRPC6 inactivation protects the tubulointerstitial compartments in Sprague Dawley rats depends on the disease model examined.

MO203: Minimal Change Disease Secondary to SARS-COV-2 (COVID-19) Infection: A Report of 2 Cases and Review of Related Literature

Abstract &amp;gt;BACKGROUND AND AIMS The COVID-19 pandemic has brought to the forefront a wide spectrum of renal injuries that included glomerulopathies, some of which were recently highlighted in various case reports. These consist of focal and segmental glomerulosclerosis (FSGS) and minimal change disease (MCD).1 These changes were found among seemingly vulnerable populations such as the African American and Caucasian ethnicities with paucity of reports among other races. We present two cases of biopsy-confirmed MCD secondary to COVID-19 infection among adult Filipino patients. METHODS Case Report RESULTS: Case 1 A 40-year-old Filipino female with a history of right total mastectomy 2 years prior for a low-grade phyllodes tumor and no other medical comorbidities was admitted due to stillbirth. She was noted to have bipedal edema with a positive COVID-19 RT-PCR swab. Further workup revealed a serum creatinine 1.04 mg/dL, urine RBC 1/HPF and a 24-h urine protein of 9.22 g with hypoalbuminemia and dyslipidemia. Serologic workup was noted to be negative. She was started on Losartan, Atorvastatin, and Furosemide. A kidney biopsy was performed which demonstrated unremarkable light microscopy and immunofluorescence and widespread podocyte-foot process effacement. These biopsy findings were interpreted to be consistent with minimal change disease. She was started on Prednisone at 1 mg/kg/day with continuation of both Losartan and Atorvastatin. Six weeks after, the patient achieved complete remission with resolution of both hypoalbuminemia and dyslipidemia. She also reports no further recurrence of edema. Case 2 A 61-year-old Filipino male with a history of type 2 diabetes mellitus, hypertension, dyslipidemia and mild COVID-19 infection 4 months prior now presented with diarrhea. A routine COVID-19 RT-PCR swab revealed a re-infection. Physical examination noted bipedal edema. Further workup demonstrated a serum creatinine 3.39 mg/dL, urine RBC 2/HPF and urine ACR 2.6 g/g. Serologic tests were negative. He was diagnosed with Nephrotic Syndrome and underwent kidney biopsy. Findings showed an unremarkable light microscopy and immunofluorescence with widespread podocyte-foot process effacement. These findings were found to be consistent with minimal change disease and acute tubular injury. He was started on Prednisone (1 mg/kg/day), Losartan, Furosemide and Atorvastatin. Eight weeks later, the patient achieved complete remission with resolution of edema. CONCLUSION It is currently suspected that APOL1 risk variants found in reported cases of COVID-19-associated glomerulopathies are underlying toxic gain-of-function mutations that drive kidney disease.2 It is interesting to note that APOL1 renal risk variants are found exclusively in African-derived chromosomes and are rarely found among European or Asian chromosomes.3 Even though an APOL1 genotyping was not performed, our case reports provide the first examples of MCD among individuals without a high-risk genotype (APOL1) by epidemiology and enlarge the literature on MCD in COVID-19. We posit that there may be other underlying predispositions or mechanisms that may be driving glomerulopathy formation among COVID-19 patients aside from their inherent APOL 1 risk. Both of our patients were started on steroid therapy with a tapering regimen and achieved complete remission on subsequent follow-up. Existing reports suggest that most cases of COVID-19-associated MCD will often achieve resolution of AKI and proteinuria with steroid therapy, even in those with high-risk APOL1 genotype, emphasizing the need for an accurate histologic classification.4

Treatment of post-transplant recurrent FSGS in children using plasmapheresis and augmentation of immunosuppression

BackgroundUp to 60% of pediatric renal transplant recipients with end-stage renal disease due to primary focal and segmental glomerulosclerosis (FSGS) may develop recurrent disease. Such recurrence is associated with poor prognosis if no remission is achieved. We report a single center experience with a protocol based on plasmapheresis and increased immunosuppression that resulted in a high long-lived remission rate.MethodsThis retrospective cohort study included consecutive pediatric renal transplant patients with recurrent FSGS treated with a standardized protocol using plasmapheresis and cyclophosphamide to supplement usual post-transplant immunosuppression with calcineurin inhibitors and steroids. Relapse was defined as urinary protein/creatinine ratio > 1.0 g/g and remission as < 0.5 g/g.ResultsSeventeen patients with FSGS recurrence post-transplant were treated. All had therapy resistant FSGS in native kidneys and had been on dialysis from 4 to 10 years. Of the 17, one died perioperatively from a pulmonary thromboembolism. Fifteen others achieved a complete remission within 3 months of treatment for FSGS recurrence. After a median follow-up period of 4 years, there were no recurrences of significant proteinuria. One patient achieved remission with rituximab.ConclusionThe addition of plasmapheresis and cyclophosphamide to a calcineurin- and steroid-based immunosuppression regime was highly successful in inducing high remission rates with recurrent FSGS. Prospective trials are needed to evaluate further the efficacy of increased immunosuppression along with plasmapheresis in this setting.