Recurrent Focal And Segmental Glomerulosclerosis Research Articles

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.

Re-transplantation in pediatric patients with failure of primary transplant due to recurrent focal segmental glomerulosclerosis: A pediatric nephrology research consortium study.

Recurrent focal and segmental glomerulosclerosis (FSGS) in kidney transplant recipients is associated with lower graft survival and increased morbidity. There are limited data to guide the decision to re-transplant patients with transplant failure due to FSGS recurrence. We aimed to evaluate outcomes in patients re-transplanted after having initial graft failure due to recurrent FSGS and to study physician attitudes and practice patterns. Retrospective data from 10 centers were collected on 20 patients transplanted between January 1997 and September 2018. A survey was sent to nephrologist members of the Pediatric Nephrology Research Consortium. Mean patient age (years) was 9.8±4.8 at first transplant and 15.9±4.9 at re-transplantation. Pre-transplant plasmapheresis was used in 1 (5.3%) primary transplant vs. 7 (38.9%) re-transplants (p=.03). Nephrotic syndrome recurred in 14 patients (70%) after re-transplantation and was severe in 21.1% vs. 64.7% after first transplant (p=.04). Graft survival was significantly higher in the second transplant (p .009) with 70% having functioning grafts at a median of 25.2months. Thirty-one physicians from 21 centers completed the survey, 94% indicated they would re-transplant such patients, 44.4% preferred a minimum waiting period before re-transplantation, 36.4% preferred living donors, and 22.2% indicated having protocols for re-transplantation at their centers. Consideration for re-transplantation is high among pediatric nephrologists. Pre-transplant plasmapheresis was more frequent in re-transplanted patients. Nephrotic syndrome recurrence was less severe, with better graft survival. More data and a larger population are necessary to further evaluate outcome determinants and best practices in this special population.

RAGE and αVβ3-integrin are essential for suPAR signaling in podocytes

The soluble urokinase plasminogen activator receptor (suPAR) has been implicated in the pathogenesis of kidney diseases including primary and recurrent focal and segmental glomerulosclerosis (FSGS), diabetic nephropathy, and acute kidney injuries (AKI). Elevated serum suPAR concentration is a negative prognostic indicator in multiple critical clinical conditions. This study has examined the initial transduction steps used by suPAR in cultured mouse podocytes. We now report that the receptor for advanced glycation end-products (RAGE) co-immunoprecipitates with αV and β3 integrin subunits, which have been previously shown to initiate suPAR signal transduction at the podocyte cell surface. siRNA knock-down of RAGE attenuated Src phosphorylation evoked by either suPAR or by glycated albumin (AGE-BSA), a prototypical RAGE agonist. suPAR effects on Src phosphorylation were also blocked by the structurally dissimilar RAGE antagonists FPS-ZM1 and azeliragon, as well as by cilengitide, an inhibitor of outside-in signaling through αV-integrins. FPS-ZM1 also blocked Src phosphorylation evoked by AGE-BSA. FPS-ZM1 blocked increases in cell surface TRPC6 abundance, cytosolic reactive oxygen species (ROS) and activation of the small GTPase Rac1 evoked by either suPAR or AGE-BSA. In addition, FPS-ZM1 inhibited Src phosphorylation evoked by serum collected from a patient with recurrent FSGS during a relapse. The magnitude of this inhibition was indistinguishable from the effect produced by a neutralizing antibody against suPAR. These data suggest that orally bioavailable small molecule RAGE antagonists could represent a useful therapeutic strategy for a wide range of clinical conditions associated with elevated serum suPAR, including primary FSGS and AKI.

CASK, the Soluble Glomerular Permeability Factor, Is Secreted by Macrophages in Patients With Recurrent Focal and Segmental Glomerulo-Sclerosis.

Introduction: Focal and segmental glomerulosclerosis (FSGS) is a frequent form of glomerulonephritis that may be caused by a soluble permeability factor and regulated by the immune system. We previously described a soluble form of calcium/calmodulin-dependent serine/threonine kinase (CASK) acting as a permeability factor in patients with recurrent FSGS (rFSGS). Here, we aimed to identify the immune cells associated with CASK secretion in patients with rFSGS.Methods: FACS, western blotting and immunoprecipitation were performed to detect CASK in peripheral blood mononuclear cells, including CD3+, CD20+, and CD14+subsets, from patients with rFSGS, healthy donors, transplant patients and patients with nephrotic syndrome due to diabetes mellitus, and in KHM2 cells.Results: CASK was produced mostly by monocytes in patients with rFSGS but not by T or B lymphocytes. It was not detectein cells from control patients. CASK was also produced and secreted by M2 polarized macrophages and KMH2 cells, but not by M1 polarized macrophages. CASK secretion was not not inhibited by brefeldin A, suggesting an absence of classical secretion pathway involvement. Within cells, CASK was partly colocalized with ALIX, a molecule involved in exosome development, and these two molecules were coprecipitated from M2 macrophages. Moreover, exosomes derived from M2 macrophages induced podocyte cytoskeleton alterations and increased podocyte motility.Conclusion: These results suggest that the soluble permeability factor CASK is secreted by monocytes and M2 macrophages, via exosomes, to alter the glomerular filtration barrier in rFSGS.

Immunoadsorption for Recurrent Primary Focal Segmental Glomerulosclerosis on Kidney Allografts: A Single-Center Experience and Literature Review

Introduction: Primary focal and segmental glomerulosclerosis (FSGS) frequently reoccurs on kidney transplants and may lead to premature allograft loss. There are no guidelines for treating FSGS recurrence on allografts; treatment is based on apheresis (plasma exchange plasmapheresis [PP], semi-specific immunoadsorption [IA] with reusable columns) plus rituximab. Objective: We aimed to assess the efficacy of IA to treat recurrent FSGS. Methods: We report on 7 patients with recurrent FSGS on kidney allograft (proteinuria ≥3 g/g of urinary creatinine or ≥3 g/day); they all received IA. Our primary objective was to reduce proteinuria by >50%. Patients’ mean age was 45 ± 10 years. Postoperative immunosuppression relied on steroids, mycophenolate mofetil, tacrolimus, with an induction therapy of basiliximab or antithymocyte globulins. Prophylaxis to prevent FSGS recurrence was either rituximab alone (n = 3), rituximab plus either PP or IA (n = 3), or no treatment (n = 1). Mean follow-up was 20 ± 13 months. There was a median of 72 (14–101) IA sessions per patient, that is, a mean of 14 ± 1 sessions per IA column. Results: At 12 months after starting IA, all patients had partial (n = 6) or complete (n = 1) remission, and allograft survival was 100%. The mean reduction in proteinuria within an IA session was 45 ± 15%. At last follow-up, 2 patients are in remission without IA, 3 patients are in partial remission that is IA dependent, and 2 patients lost their allograft due to FSGS recurrence. The most frequent adverse event was cytomegalovirus reactivation (n = 13), which subsided after valganciclovir therapy. Conclusions: We show that recurrence of FSGS can be controlled long term with IA plus rituximab. However, some patients remained dependent on IA.

Circulating CASK is associated with recurrent focal segmental glomerulosclerosis after transplantation.

IntroductionFocal and Segmental GlomeruloSclerosis (FSGS) can cause nephrotic syndrome with a risk of progression to end-stage renal disease. The idiopathic form has a high rate of recurrence after transplantation, suggesting the presence of a systemic circulating factor that causes glomerular permeability and can be removed by plasmapheresis or protein-A immunoadsorption.ResultsTo identify this circulating factor, the eluate proteins bound on therapeutic immunoadsorption with protein-A columns were analyzed by comparative electrophoresis and mass spectrometry. A soluble form of calcium/calmodulin-dependent serine protein kinase (CASK) was identified. CASK was immunoprecipitated only in the sera of patients with recurrent FSGS after transplantation and not in control patients. Recombinant-CASK (rCASK) induced the reorganization of the actin cytoskeleton in immortalized podocytes, a redistribution of synaptopodin, ZO-1,vinculin and ENA. rCASK also induced alterations in the permeability of a monolayer of podocytes and increased the motility of pdodocytes in vitro. The extracellular domain of CD98, a transmembrane receptor expressed on renal epithelial cells, has been found to co-immunoprecipitated with rCASK. The invalidation of CD98 with siRNA avoided the structural changes of rCask treated cells suggesting its involvement in physiopathology of the disease. In mice, recombinant CASK induced proteinuria and foot process effacement in podocytes.ConclusionOur results suggest that CASK can induce the recurrence of FSGS after renal transplantation.

Changes in podocyte TRPC channels evoked by plasma and sera from patients with recurrent FSGS and by putative glomerular permeability factors

Primary forms of focal and segmental glomerulosclerosis (FSGS) are driven by circulating factors that cause dysfunction or loss podocytes. Rare genetic forms of FSGS can be caused by mutations in TRPC6, which encodes a Ca2+-permeable cationic channel expressed in mesangial cells and podocytes; and NPHS2, which encodes podocin, a TRPC6-binding protein expressed in podocyte slit diaphragm domains. Here we observed that exposing immortalized mouse podocytes to serum or plasma from recurrent FSGS patients for 24h increased the steady-state cell-surface abundance of TRPC6, accompanied by an increase in currents through endogenous TRPC6 channels evoked by a hypoosmotic stretch stimulus. These effects were mimicked by the soluble urokinase receptor (suPAR) and by tumor necrosis factor (TNF), circulating factors implicated in nephrotic syndromes. Most but not all of the recurrent FSGS plasma samples that we examined also caused a loss of podocin over a period of several hours. The loss of podocin was also seen following exposure to suPAR but not TNF. However, TNF increased the effects of suPAR on TRPC6 and podocin, and TNF and suPAR are required for the full effects of one of the recurrent FSGS plasma samples. The actions of FSGS plasma, suPAR and TNF on surface abundance of TRPC6 were blocked by cilengitide, an inhibitor of αvβ3-integrin signaling. These data suggest that primary FSGS is a heterogeneous condition mediated by multiple circulating factors, and support TRPC6 and αvβ3-integrin as potential therapeutic targets.

Complete Remission of Post-transplantation Recurrence of Focal Segmental Glomerulosclerosis With the Use of Adrenocorticotrophic Hormone Gel: Case Report

BackgroundPost-transplantation recurrence of primary focal and segmental glomerulosclerosis (FSGS) is estimated to occur in 30%–50% of cases and doubles the risk of allograft failure. Treatment of recurrent FSGS is challenging because specific pathogenic targets are unknown and available therapeutic options have limited efficacy. Case ReportWe report a case of recurrent FSGS with nephrotic-range proteinuria (urine protein creatinine ratio [UPCR], >50) and debilitating edema that was resistant to rituximab and plasmapheresis. The patient had a remarkable response to adrenocorticotropic hormone (ACTH) gel and achieved complete remission (UPCR, 0.5; serum albumin, 4.1 g/dL; serum creatinine, 1.0 mg/dL) which was maintained over 10 months on this treatment. ConclusionsWe conclude that ACTH gel is a potential therapeutic option for post-transplantation recurrence of FSGS and warrants further evaluation.

Rituximab therapy prevents focal and segmental glomerulosclerosis recurrence after a second renal transplantation

Preventive treatment of focal and segmental glomerulosclerosis (FSGS) allograft recurrence in high risk recipients having a prior history of graft loss caused by FSGS recurrence is still a challenging question. We retrospectively identified four patients who underwent a second renal transplantation because of recurrent FSGS and who received Rituximab therapy as a prophylactic treatment. Loss of their first allograft was directly related to an early (<3 months) recurrence of FSGS that was either resistant to plasmapheresis therapy in two cases or had escaped to this therapeutic management in the two others. After the second renal transplantation, all patients were free of FSGS recurrence during follow-ups that were between 12 and 54 months long. These preliminary results demonstrate for the first time that Rituximab therapy may constitute an attractive prophylactic option for patients being considered for a second renal transplantation because of recurrent FSGS in their first graft.

Successful paediatric ABO incompatible renal transplantation with quadruple immunosuppression and B lymphocyte depletion

<h3>Aims</h3> ABO incompatible renal transplantation has been reported as a successful form of renal replacement therapy in children and adults. Antibody removal is required with options of B lymphocyte depletion with splenectomy, plasma exchange, double filtration plasmapheresis or immunoadsorption. <h3>Methods</h3> To report the successful outcome of ABO incompatible renal transplantation using quadruple immunosuppression (basiliximab at days 0 and 4, mycophenolate mofetil and tacrolimus from one week pretransplantation and corticosteroids) with only B lymphocyte depletion (intravenous rituximab 375 mg/m² at one month pretransplantation). A 14-year-old young man received a living related renal transplantation from his mother for end-stage renal failure (ESRF) on haemodialysis for steroid resistant nephrotic syndrome due to focal and segmental glomerulosclerosis (FSGS) who had a living related renal transplant from his father 18 months previously, which had failed due to a vascular event. <h3>Results</h3> The recipient and donor (mother) blood groups were A and B Rhesus positive, respectively, with anti-B titres of one in four rising to one in eight pretransplantation. His renal transplant was performed successfully without further antibody removal or surgical complications and immediate renal allograft function. Three months posttransplant his renal function has stabilised with a plasma creatinine of 114μmol/l giving an estimated glomerular filtration rate of 62 ml/min/1.73 m². He does not have clinical evidence of recurrent FSGS posttransplantation (normal serum albumin levels without albuminuria) with negative anti-B titres and donor specific antibodies and no evidence of EBV, BK or CMV viraemia (having required oral valganciclovir as CMV mismatch). He had a normal transplant renal biopsy at ten days post-transplant without evidence of acute rejection and one focal segmental sclerotic lesion seen on protocol biopsy at three months. <h3>Conclusion</h3> In view of the reported success of ABO incompatible renal transplantation, clinicians must consider this option in ESRF patients whose parents have been excluded as living donors in view of ABO blood group incompatibility.

Effect of protein A immunoadsorption in nephrotic syndrome of various etiologies.

Protein A immunoadsorption (IA) has proved effective in reducing proteinuria in patients with nephrotic syndrome after recurrence of focal and segmental glomerulosclerosis (FSGS) in kidney transplants. The effect of IA in nephrotic syndrome of other etiologies remains unknown. Nine patients with nephrotic syndrome secondary to membranous nephropathy (four cases), diabetes mellitus (one case), IgA nephropathy (two cases), and amyloidosis (two cases) had three to five IA of 2.5 plasma volumes over 4 to 8 d. Patients received no concomitant immunosuppressive treatment, and antihypertensive drugs were left unchanged. Proteinuria decreased from 12.64 +/- 5.49 to 3.35 +/- 2.2 g/24 h (mean +/- SD) in all patients after three to five IA. Hematocrit decreased from 37.32 to 32.64% (12.5% hemodilution) and serum albumin from 25.43 to 18.6 g/L (26.4% decrease). Proteinuria returned to baseline levels within 1 mo, as described in recurrent FSGS following transplantation. When serum albumin balance was controlled by albumin infusion after IA in two patients, comparable decreases in proteinuria were observed. Therefore, IA is effective in producing short-term reduction of proteinuria in nephrotic syndromes related not only to FSGS but also to membranous and IgA nephropathies, diabetes mellitus, and amyloidosis, which suggests that IA removes a nonspecific circulating hemodynamic-altering or permeability-increasing factor.

Recurrent nephrotic syndrome in a renal allograft recipient with focal and segmental glomerulosclerosis: Efficacy of plasmapheresis

Summary: We report a 29‐year‐old man with renal failure due to focal and segmental glomerulosclerosis (FSGS) who received a well‐matched cadaveric renal allograft and had the early appearance of the nephrotic syndrome and renal insufficiency. His condition responded dramatically to plasmapheresis. the pathogenesis of FSGS recurring in a renal allograft may involve a recently identified circulating factor. the possible efficacy of plasmapheresis in the treatment of recurrent FSGS may be attributable to the removal of this factor.