Primary Focal Segmental Glomerular Sclerosis Research Articles

#2862 Genetics and electron microscopy: complementary tools for management of focal segmental glomerulosclerosis?

Abstract Background and Aims Focal segmental glomerular sclerosis (FSGS) defines a histologic lesion that represents a pattern of injury associated to different pathologic conditions affecting both children and adults. It is classified into primary forms, presumably immune-mediated, secondary forms, determined by a maladaptive response to different conditions, genetic and undetermined forms. According to Mayo Clinic classification, primary and secondary forms can de differentiated using electron microscopy (EM), with a podocytes foot process effacement (FPE) ≥80% identifying primary forms. Better understanding the role of Genetics in FSGS and response to treatment in different forms is of vital importance in this rare and multifaceted condition. We analyzed a discrete cohort of patients with FSGS examined both with EM and genetic testing (GT). Main aims of our study were: 1) assessment of GT in primary and secondary forms; 2) analysis of response to therapy according to histologic and genetic classification. Method This is a retrospective observational study on patients that received a histological diagnosis of FSGS, including EM, and underwent NGS genetic testing from January 2020 to June 2023. Primary and secondary forms of FSGS were distinguished by degree of pedicle fusion at EM, according to Mayo Clinic classification. Clinical, laboratory, genetic data and used therapies were recorded. Complete response (CR) to therapy was defined as a reduction of proteinuria to 0.3 g/day, with normalization of albuminemia. Partial response (PR) was defined as halving proteinuria into a sub-nephrotic range and increasing albuminemia up to 3.5 g/dL. Absent response was defined as a persisting nephrotic range proteinuria. Results In the study period, 33 patients receiving a histologic diagnosis of FSGS with EM examination underwent NGS testing. Of these, 25 had available genetic results and were included. Ten patients (40%) were females, 15 (60%) were males; mean age was 40.8 years (SD ±14.5); 20 (80%) were Caucasian, 4 (16%) Black, 1 (4%) Asian. Based on EM, 11 (44%) were classified as primary forms, 14 (56%) as secondary forms. Twelve (48%) patients presented with nephrotic syndrome. Of these, 10 had a primary form. Seven (28%) had nephrotic-range proteinuria without hypoalbuminemia, 6 (24%) had subnephrotic range proteinuria. Six (54.5%) of the primary forms and 8 (57.1%) of the secondary forms had a positive genetic testing (p = 0.78). Among secondary forms, through GT, one diagnosis of Fabry disease and one of Tuberous Sclerosis were made in patients without clear systemic symptoms. Fabry disease was confirmed by presence of zebra bodies at EM. All primary forms received immunosuppressive therapies, all being rituximab-based regimens; all secondary forms received support therapy. Nine (81.1%) primary forms and 9 (64.3%) secondary forms had at least a PR to treatment (4 CR in primary group and 1 CR in secondary group) (p = 0.33). Among primary forms, 5 of 6 patients (83%) with a positive GT had at least a PR with a strong immunosuppressive therapy. In secondary forms group 4 of 8 patients (50%) had at least PR with offered support therapy. Fabry and Tuberous Sclerosis were offered specific treatments with benefit. Conclusion Percentage of positive GT did not differ in primary and secondary forms of FSGS as defined by Mayo Clinic classification. Thus a positive GT should not be considered a unique feature of secondary forms. GT was critical for an unexpected diagnosis of systemic hereditary diseases, thus enabling adequate target therapies. We believe GT should be offered to all patients with FSGS. In primary FSGS, defined according to EM, more than 80% of patients had at least a PR following immunosuppressive therapy, even in patients with positive GT. In conclusion, as clinical presentation and light microscopy are not sufficient for an accurate diagnosis, combining EM and GT is of utmost importance in proper classification and management of FSGS.

Glomerular capillary C3 deposition as a risk factor for unfavorable renal outcome in pediatric primary focal segmental glomerular sclerosis.

Some patients with primary focal segmental sclerosis (FSGS) demonstrate complement 3 (C3) deposition in glomerular capillary loops (Cap-C3) and/or mesangial area (Mes-C3). The clinicopathological and prognostic significance of C3 deposition remains incompletely investigated, especially in the pediatric cohort. We retrospectively analyzed 264 children of biopsy-proven primary FSGS between January 2003 and December 2020. The correlation between Cap-C3 and renal outcome was evaluated by the Kaplan-Meier method and Cox multivariate regression analysis. Renal end-point event was defined as the development of end-stage renal disease, death for renal disease, or an estimated glomerular filtration rate reduction by at least 50% from baseline. Among the 264 patients, 30 (11.4%) had Cap-C3. Kaplan-Meier analysis showed that patients with Cap-C3 had significantly lower renal survival rates than patients without Cap-C3 (60.17% vs. 84.71% at 5 years, 39.49% vs. 65.55% at 10 years, P < 0.01). Cox multivariate regression analysis showed that Cap-C3 was an independent risk factor for poor renal outcome (HR 3.53, 95% CI 1.22-10.19, P = 0.02). Glomerular capillary C3 deposition was an independent risk factor for unfavorable renal outcome in children with primary FSGS.

The Role of Rituximab in Primary Focal Segmental Glomerular Sclerosis of the Adult

IntroductionPrimary focal segmental glomerular sclerosis (FSGS) is a rare, likely immune-mediated disease. Rituximab (RTX) may play a role in management, although data in adults are scanty.MethodsWe collected cases of RTX-treated primary FSGS within the Italian Society of Nephrology Immunopathology Working Group and explored response rate (24-hour proteinuria <3.5 g and <50% compared with baseline, stable estimated glomerular filtration rate).ResultsA total of 31 patients were followed for at least 12 months; further follow-up (median 17 months, interquartile range [IQR] 15–33.5) was available for 11. At first RTX administration, median creatinine and 24-hour proteinuria were 1.17 mg/dl (IQR 0.83–1.62) and 5.2 g (IQR 3.3–8.81), respectively. Response rate at 3, 6, and 12 months was 39%, 52%, and 42%, respectively. In the first 12 months, creatinine level remained stable whereas proteinuria and serum albumin level improved, with an increase in the proportion of patients tapering other immunosuppressants. There were 6 patients who were retreated with RTX within 12 months, either for proteinuria increase or refractory disease; only the 2 responders to the first RTX course experienced a further response. At univariate analysis, 6-month response was more frequent in steroid-dependent patients (odds ratio [OR] 7.7 [95% CI 1.16–52.17]) and those with proteinuria <5 g/24 h (OR 8.25 [1.45–46.86]). During long-term follow-up, 4 of 5 responders at 12 months maintained a sustained response, either without further immunosuppression (2 of 4) or with pre-emptive RTX (2 of 4); 1 relapsed and responded to RTX retreatment.ConclusionRTX may be an option in primary FSGS, especially in steroid-dependent patients, with 24-hour proteinuria <5 g and previously responders to RTX. Optimal long-term management for responders is unclear, with some patients experiencing sustained remission and others requiring RTX retreatment, either preemptive or after rising proteinuria.

Effective Treatment of a Post-renal Transplantation Patient with Early Recurrent Focal Segmental Glomerulosclerosis and Concomitant Hemolytic Uremic Syndrome, a Case Report

While recurrence of primary Focal Segmental Glomerular Sclerosis (FSGS) is common post renal transplantation (30%-80%), a concomitant presentation of hemolytic uremic syndrome (HUS) and recurrent FSGS has never been reported. In addition, treatment of recurrent FSGS and HUS post-renal transplantation is challenging; and usually individualized based on center's experience. Here, we reported a case of a pediatric patient with early recurrence of FSGS and concomitant HUS post-renal transplantation. This patient had a complete hematological and renal response following the administration of Eculizumab and Rituximab, respectively. Withdrawal of Tacrolimus as well as plasmapheresis did not improve kidney function. Therefore, we concluded that both Eculizumab and Rituximab could achieve remission in comparable cases when administered at fixed intervals.

Efficacy of Rituximab in Treatment-Resistant Focal Segmental Glomerulosclerosis With Elevated Soluble Urokinase-Type Plasminogen Activator Receptor and Activation of Podocyte β3 Integrin

IntroductionSevere, nonresponsive, primary focal segmental glomerular sclerosis (FSGS) can progress to end-stage kidney disease (ESKD) in <5 years. Soluble urokinase-type plasminogen activator receptor (suPAR) may contribute to podocyte effacement by activating podocyte β3 integrin. It has been reported as a potential permeability factor and biomarker for primary FSGS. Rituximab was found to have efficacy in case reports and small series. Whether rituximab is efficacious in patients with treatment-resistant FSGS in the context of high suPAR levels and evidence of podocyte B3 integrin activation remains unknown.MethodsIn this nonblinded, open-label pilot study, the safety and efficacy of rituximab were evaluated in treatment-resistant adult patients with primary FSGS and a suPAR level > 3500 pg/ml with evidence of β3 integrin activation. Rituximab (1 g) was given on days 1 and 15. The primary outcome was proteinuria at 12 months.ResultsOnly 13 of 38 screened patients qualified for the study, of whom 9 consented to participate. The baseline proteinuria and glomerular filtration rate (GFR) levels were 7.70 ± 4.61 g/d and 67 ± 38 ml/min, respectively. A transient response at 6 months was noted in 2 patients without a parallel change in suPAR level. At 12 months, there was no statistically significant improvement in proteinuria level with all participants remaining nephrotic (7.27 ± 7.30 g/d). GFR level marginally declined to 60 ± 38 ml/min with one patient progressing to ESKD. There were 2 serious infections, an infusion-related reaction and leucopenia attributed to rituximab.ConclusionRituximab was ineffective when administered to adult patients with treatment-resistant primary FSGS with a high suPAR and evidence of podocyte activation.

Later Response to Corticosteroids in Adults With Primary Focal Segmental Glomerular Sclerosis Is Associated With Favorable Outcomes

IntroductionGuidelines advise initial therapy with corticosteroids (CSs) in patients with presumed primary focal segmental glomerular sclerosis (pFSGS). Many patients do not achieve complete remission (CR) after 8 or 16 weeks. Although these patients are considered steroid resistant, clinical outcomes are ill defined.MethodsA retrospective cohort study of patients with pFSGS who were referred between January 1995 and December 2014. Data of clinical presentation until last follow-up were collected from patient records.ResultsA total of 51 patients (median age 47 years, 20 female/31 male) were included (median follow-up 7.1 years). There were 10 patients who achieved partial response (PR) at 8 weeks. High-dose CS monotherapy was continued for a median of 17 weeks (interquartile range [IQR] 11–21 weeks) (total duration 56 weeks [IQR 28–83 weeks]). With CSs, the cumulative incidence of CR + PR was 18% and 35%, respectively. Of 24 patients with persistent nephrotic-range proteinuria, 22 received additional immunosuppressive (IS) therapy, resulting in CR in 3 (14%) and PR in 11 patients (50%). A decrease of >20% of proteinuria at 8 weeks predicted response. In addition, 8 patients (36%) were considered primary nonresponders. A genetic cause was found in 2 patients. Proteinuria at end of follow-up was 1.2 g (IQR 0.4–3.0 g/24 hours or g/10 mmol creatinine). Renal survival at 3, 5, and 10 years was 92%, 87%, and 64%, respectively.ConclusionPatients with presumed pFSGS often respond late to IS therapy. A decrease in proteinuria of >20% after 8 weeks of therapy is a predictor of responsiveness. Regardless of CR in some patients, improved biomarkers are needed to predict response/outcomes in patients with pFSGS.

Renal transplant outcomes in primary FSGS compared with other recipients and risk factors for recurrence: A national review of the Irish Transplant Registry.

Primary focal segmental glomerular sclerosis (p-FSGS) is commonly complicated by recurrence (r-FSGS) post-transplantation. Our objective was to describe Irish outcomes for transplantation after end-stage renal disease (ESRD) due to p-FSGS, specifically rates of, and treatments for, r-FSGS. Irish patients with biopsy-proven FSGS were identified from the Irish National Kidney Transplant database (1982-2015). Medical record review was performed to identify predictors of r-FSGS and treatments for r-FSGS. Transplant outcomes were compared to outcomes in all renal transplants performed during the same time period using registry data. Demographic and clinical predictors of r-FSGS were identified. Statistical analysis was performed using Stata (version 13, College Station, TX, USA). Thirty-eight transplant recipients had biopsy-proven p-FSGS, 16 received a second transplant. A total of 3846 transplants formed the comparator group. r-FSGS complicated 60.5% (23/38) of first transplants. Eighty-six percent (10/12) of patients with previous r-FSGS developed recurrent disease after further transplantation. Patients with p-FSGS receiving a first renal transplant had higher rate of graft failure than those with another cause of ESRD (HR 1.9, 95% CI 1.152-3.139). Sixteen patients received immunotherapy for r-FSGS; 12 (86%) had at least partial response, but two (14%) developed significant complications. We demonstrate high rates of r-FSGS and describe modest success from with treatments for r-FSGS.

Glomerular disease recurrence in second and subsequent kidney transplants

Primary glomerular diseases such as primary focal segmental glomerular sclerosis (FSGS), IgA Nephropathy and membrano-proliferative glomerulonephritis (MPGN) may recur in renal transplants, and can potentially lead to graft failure. The rate of recurrence in second and subsequent renal transplants, following failure of the first graft due to recurrence, is unclear. A retrospective review of the Irish transplant database from 1982 to 2009 was performed. Patients were included for analysis if their first graft failed due to biopsy-confirmed recurrent glomerular disease (primary FSGS, IgA nephropathy or MPGN) and they underwent subsequent re-transplantation. 3,330 deceased and living renal transplants were performed during the time period in question. 33 patients had a deceased donor renal transplant following recurrence of primary FSGS, IgA nephropathy or MPGN causing first graft failure. Clinically significant disease recurrence was seen in 44% of re-transplants at 10 years. Median second graft survival in this group was 9.1 years. The median graft survival was 10.5 years for all other re-transplants performed in Ireland during the same time period. Clinically significant disease recurrence does not necessarily affect re-transplants following loss of the first graft to disease recurrence. Selected patients who experience first graft failure due to recurrent glomerular disease should not be precluded from receiving a second transplant.

Treatment of Recurrent Focal Segmental Glomerular Sclerosis Posttransplant With a Multimodal Approach Including High-Galactose Diet and Oral Galactose Supplementation

Treatment of Recurrent Focal Segmental Glomerular Sclerosis Posttransplant With a Multimodal Approach Including High-Galactose Diet and Oral Galactose Supplementation

Current status and issues of C1q nephropathy

C1q nephropathy, first proposed by Jennette and Hipp [Am J Clin Pathol 83:415-420, 1985; Am J Kidney Dis 6:103-110, 1985], was described as a distinct glomerular disease entity characterized by extensive mesangial deposition of C1q, with associated mesangial immune complexes, and the absence of any clinical and laboratory evidence of systemic lupus erythematosus. Now, 20 years since the first report, the disease entity is gradually attaining recognition, particularly in the field of pediatrics. C1q is the subcomponent of C1 in the classical pathway of complement activation. Generally, C1q deposition is caused by the activation of C1 by immunoglobulin G (IgG) and IgM; therefore, C1q nephropathy is considered as an immune complex glomerulonephritis. However, in C1q nephropathy, it remains unclear whether the deposition of C1q in the glomeruli is in response to the deposition of immunoglobulin or immune complex, or whether deposition is non-specific trapping that accompanies increased glomerular protein trafficking associated with proteinuria. Since not only the pathogenesis of C1q deposition in glomeruli but also its significance are still uncertain, it has not yet been established as an independent disease. From recent publications of the clinical and pathological characterizations, C1q nephropathy has been thought to be a subgroup of primary focal segmental glomerular sclerosis. However, many reports describe different symptoms, histopathologies, therapeutic responses and prognoses, suggesting that C1q nephropathy is not a single disease entity, but that it may be a combination of several disease groups. There are many uncertain areas requiring further investigation, though it is hoped that a detailed examination of future cases will clarify the subgroups making up C1q nephropathy and their clinicopathological characteristics, and will lead to the establishment of C1q nephropathy as an independent disease entity.

Treatment of focal segmental glomerular sclerosis with rituximab: 2 case reports

Primary focal segmental glomerular sclerosis (FSGS) recurs in 20 - 40% of patients after kidney transplantation. Rituximab has been used to treat several glomerular diseases. We treated two renal-transplant patients with recurrence of FSGS with rituximab. Despite a prophylactic perioperative therapy of plasmapheresis (PE) and i.v. cyclosporine A, Patient 1 developed significant proteinuria, at 1 day after his first kidney transplantation. After two infusions of rituximab (375 mg/m2) he had complete remission. A second relapse, which occurred on Day 40, was also successfully treated by PE and one additional infusion of rituximab. 10 months after transplantation, he still has complete remission from recurrent nephrotic syndrome. Patient 2 also developed significant proteinuria, but 1 day after a second kidney transplantation. Nephrotic syndrome persisted despite 27 sessions of PE and cyclophosphamide therapy. At 13 months after transplantation, he received four infusions of rituximab (375 mg/m(2)), but this was ineffective. There is a need to demonstrate whether or not rituximab therapy is of interest to prevent and to treat nephritic syndrome in renal-transplant patients who suffer from FSGS.

Primary focal segmental glomerular sclerosis in children: clinical course and prognosis

To review the clinical course and identify prognostic factors, we retrospectively analyzed 92 children with steroid-resistant primary focal segmental glomerulosclerosis (FSGS). The mean age of onset was 80.4+/-42.4 months. The mean follow-up duration was 98.2+/-63.3 months. Eighty-five patients presented with nephrotic syndrome and seven presented with asymptomatic proteinuria. Thirty-three patients were initial responders to steroid treatment (late non-responders) and 59 were initial nonresponders. At last follow-up, 36 patients (39.1%) were in complete remission, and 29 (31.5%) progressed to chronic renal failure (CRF). Renal survival rates at 5, 10, and 15 years were 84, 64, and 53%, respectively. By morphological classification, there were tip variants (6.1%), collapsing variants (10.6%), cellular variants (1.5%), perihilar variants (9.1%), and NOS (not otherwise specified, 72.7%). Among the variants, there were no significant differences in age of onset, degree of proteinuria, response to treatment, or progression to CRF. Poor prognostic factors for CRF included: asymptomatic proteinuria at presentation, initial renal insufficiency, higher segmental sclerosis (%), severe tubulointerstitial change, initial nonresponse, and absence of remission. In the multivariate analysis, an increase in the initial serum creatinine and resistance to treatment were independent risk factors for CRF. A more prolonged use of corticosteroid therapy and early introduction of cyclosporin A (CsA) may improve the prognosis for primary FSGS in patients with initial steroid nonresponsiveness.

Role of cyclosporin A in remitting nephrotic syndrome in a Japanese patient infected with human immunodeficiency virus type 1

We report here the case of a 57-year-old Japanese man who developed nephrotic syndrome during the course of human immunodeficiency virus type 1 (HIV-1) infection. Histological examination revealed focal segmental glomerular sclerosis (FSGS), suggesting that HIV-associated nephropathy (HIVAN) was a possible diagnosis. However, he was initially treated with glucocorticoid plus immunosuppressants for primary FSGS, without knowledge that he was seropositive for HIV-1. Of importance, the nephrotic syndrome entered remission after treatment with cyclosporin A (CsA), and there was no recurrence of the nephropathy over the following 4 years. The patient eventually died due to opportunistic infection. This case is the first report of FSGS in a Japanese HIV patient, and also serves to illustrate the potential risks and benefits of CsA for the treatment of nephrotic syndrome associated with HIV-1 infection.

Podocytes undergo phenotypic changes and express macrophagic-associated markers in idiopathic collapsing glomerulopathy

Podocytes undergo phenotypic changes and express macrophagic-associated markers in idiopathic collapsing glomerulopathy

Primary focal segmental glomerular sclerosis in adults: Prognostic value of histologic variants

Primary focal segmental glomerular sclerosis (FSGS) is a clinicopathologic syndrome in which variable amounts of proteinuria are associated with the renal biopsy finding of segmental glomerular scarring in some, but not all, of the glomeruli. Additional histologic features have been described in FSGS, including the position of the scar relative to the vascular and tubular pole of the glomerulus, foam cells, hyalinosis, mesangial deposits of immunoglobulin M, diffuse mesangial hypercellularity, glomerular visceral epithelial cell hyperplasia and hypertrophy, and the extent of associated interstitial fibrosis and tubular atrophy. We performed a retrospective study on 81 patients with biopsy-proven, primary FSGS to determine whether any of the histologic features of FSGS correlated with renal function at the time of biopsy and the incidence of end-stage renal disease at follow-up. Sixty patients were nephrotic and 21 had nonnephrotic proteinuria. Only the degree of interstitial fibrosis correlated with the initial serum creatinine ( r = 0.536) and none of the histologic features predicted the presence of nephrotic-range proteinuria at the time of biopsy. Segmental scars involved 21% ± 14% of the glomeruli per biopsy specimen, but their position within the glomerulus was uniform in only 13% of the cases. Diffuse mesangial hypercellularity was present in 17% of the biopsy specimens, and glomerular epithelial cell lesions were present in 57% of the biopsy specimens. Multivariate analysis showed that only the degree of interstitial fibrosis predicted end-stage renal disease in all 81 patients and in the 60 patients with nephrotic-range proteinuria. The current data do not support different therapeutic approaches in primary FSGS based on histologic subtypes.

Focal segmental glomerular sclerosis in adults: Presentation, course, and response to treatment

The authors performed a retrospective clinicopathologic study in 81 patients with primary focal segmental glomerular sclerosis (FSGS) to determine whether they could identify clinical or histologic features at presentation that could be predictive of outcome and response to therapy. Males constituted 58% of patients, and 53% were black. At biopsy the patients were 40 ± 17 years old; 74% were nephrotic, and renal insufficiency was present in 62%. The average time from presentation to biopsy was 16 months, and the average total follow-up was 62 months. Nephrotic patients had a significantly poorer prognosis as compared with nonnephrotic patients (5- and 10-year survivals of 76% and 57% v 92% and 92%; P < 0.05). A multivariate analysis was done on histologic and clinical features at biopsy, assessing for risk factors leading to end-stage renal disease, showing only the serum creatinine and the degree of interstitial fibrosis to have a significant correlation. Thirty nephrotic patients received prednisone, with a treatment time of 5.5 ± 4 months and a total dose of 5.9 ± 2.9 g per course of treatment. Fifteen of these patients (50%) achieved a remission by 3.7 ± 2 months (10 complete remission and 5 partial remissions), with all patients responding within 9 months. Only two patients had spontaneous remissions (both partial). The 5- and 10-year survival for patients in remission were both 100% as compared with 66% and 41% ( P < 0.01), respectively, for nephrotic patients not in remission. No clinical feature at presentation or biopsy was predictive of response to therapy when a multivariate analysis was performed. Nephrotic patients responding to therapy have a significantly better prognosis than nonresponsive patients. Response to therapy requires at least 3 to 4 months of treatment with prednisone. Unfortunately, no clinical feature at presentation or biopsy predicts which patients are more likely to respond to treatment. This experience suggests that nephrotic patients with primary FSGS may benefit from a more prolonged course of therapy with prednisone. Furthermore, these findings underscore the need for a controlled trial in nephrotic patients with FSGS to confirm the response to and establish guidelines for therapy.