Plasma exchange improves graft survival in patients with recurrent focal glomerulosclerosis after renal transplantation

Primary Focal Segmental Glomerulosclerosis Plasmas Increase Lipid Droplet Formation and Perilipin-2 Expression in Human Podocytes

Many patients with primary focal segmental glomerulosclerosis (FSGS) develop recurrence of proteinuria after kidney transplantation. Several circulating permeability factors (CPFs) responsible for recurrence have been suggested, but were never validated. We aimed to find proteins involved in the mechanism of action of CPF(s) and/or potential biomarkers for the presence of CPF(s). Cultured human podocytes were exposed to plasma from patients with FSGS with presumed CPF(s) or healthy and disease controls. Podocyte proteomes were analyzed by LC-MS. Results were validated using flow cytometry, RT-PCR, and immunofluorescence. Podocyte granularity was examined using flow cytometry, electron microscopy imaging, and BODIPY staining. Perilipin-2 protein expression was increased in podocytes exposed to presumed CPF-containing plasmas, and correlated with the capacity of plasma to induce podocyte granularity, identified as lipid droplet accumulation. Elevated podocyte perilipin-2 was confirmed at protein and mRNA level and was also detected in glomeruli of FSGS patients whose active disease plasmas induced podocyte perilipin-2 and lipid droplets. Our study demonstrates that presumably, CPF-containing plasmas from FSGS patients induce podocyte lipid droplet accumulation and perilipin-2 expression, identifying perilipin-2 as a potential biomarker. Future research should address the mechanism underlying CPF-induced alterations in podocyte lipid metabolism, which ultimately may result in novel leads for treatment.

Novel mouse strains to study circulating permeability factor(s) in primary focal segmental glomerulosclerosis

Recurrence of proteinuria after kidney transplantation in primary focal segmental glomerulosclerosis (FSGS) is unpredictable. Several putative circulating permeability factors (CPFs) have been suggested, but none have been validated. A clinically relevant experimental model is required that demonstrates the presence of CPF(s) in patient material, to study CPF(s) and possibly predict recurrence in patients. We aimed to develop a FSGS-prone Thy-1.1 transgenic mouse model with accelerated proteinuria after injection of samples from patients with FSGS. The Thy-1.1 transgene was backcrossed into 5 mouse strains. The age of onset and severity of spontaneous proteinuria varied between the different genetic backgrounds. 129X1/Sv^Thy-1.1 and 129S2/SvPas^Thy-1.1 mice displayed proteinuria at 4 weeks, whereas Balb/c^Thy-1.1 and C57BL/6J^Thy-1.1 mice developed proteinuria from 6 weeks, and were used further. We determined the maximum protein dose that could be injected without causing protein overload in each background. Balb/c^Thy-1.1 and C57BL/6J^Thy-1.1 males and females were injected with presumably CPF-containing plasmapheresis effluent from 6 FSGS patients, which induced albuminuria particularly in Balb/c^Thy-1.1 males. Unfortunately, no response could be detected when using sera instead of plasmapheresis effluent, serum being more clinically relevant in the context of predicting FSGS recurrence. Considering the differences between responses elicited by serum and plasmapheresis effluent, simultaneously collected serum, plasma, and plasmapheresis effluent were tested. Whereas we could detect responses using a validated in vitro model, none of these presumably CPF-containing samples induced proteinuria in Balb/c^Thy-1.1 males. Thus, we have extensively tested the Thy-1.1 mouse model on different genetic backgrounds with proteinuria after injection of FSGS patient material as clinically relevant readout. The Balb/c^Thy-1.1 male mouse strain demonstrated the most promising results, but to detect CPF activity in FSGS serum e.g. prior to kidney transplantation, this strain clearly lacks sensitivity and is therefore not yet clinically applicable. It could, however, still be used as research tool to study CPFs in patient samples that did induce proteinuria.

Management of recurrent focal segmental glomerulosclerosis (FSGS) post renal transplantation

BACKGROUND

One of the common GN causing ESKD is focal segmental glomerulosclerosis (FSGS). Recurrence of FSGS post-transplantation can lead to graft loss. Data on management either prophylactically or once recurrence occurs are limited. This review article aims to assess the effective management of patients with FSGS recurrence post-transplantation, looking mainly at recurrence post prophylactic treatment and remission in case of treatment post recurrence.

METHODS

Twenty-three studies were included using the search MeSH terms "FSGS" "recurrence" "adults" "transplantation" "treatment". Search engines used were Pubmed, clinical key, Scopus and Cochrane library. Inclusion criteria were articles covered adult patients with recurrent FSGS post renal transplantation, treatment with rituximab and plasmapheresis, and articles published from 2000 tt2021. Excluded articles were paediatric population, studies with no reported outcomes of the treatment of FSGS, and Patients who received stem cell transplantation or galactose therapy.

RESULTS

Prophylactic PP did not show a reduction in recurrence of FSGS in 2/3 studies. Prophylactic rituximab was shown to reduce recurrence of FSGS in one-study and case reports. Treatment of recurrent FSGS with PP showed responses ranging from 41% to 100%. Only one study did not show improvement with PP use as treatment having a 27% remission. Treatment with rituximab showed variable results, with reports showing remission ranging from 57% to 100%. Whereas other reports showing no response at all. PP prescription reporting was variable. One study suggested intensified PP regimen while in most other studies PP was guided by the response reflected by the reduction of proteinuria.

DISCUSSION

Reviewing the treatment of recurrent FSGS is crucial, as there no consensus on treating FSGS as the disease is not very common in the adult population. The evidence of different modalities is based on small cohort studies. This paper supports the use of PP and RTX as treatment of recurrent FSGS.

CONCLUSIONS

In conclusion, PP and RTX are the main modalities to treat recurrent FSGS with varying response rates. Prophylactic PP does not play a role in preventing recurrent FSGS. Prophylactic rituximab might play a role in preventing FSGS post-transplantation. PP and RTX, when used as a treatment, show variable response rates. Larger RCTs are needed to have a strong level of evidence to base our clinical management on.

Novel in vitro assays to detect circulating permeability factor(s) in idiopathic focal segmental glomerulosclerosis

BACKGROUND

Many patients with idiopathic focal segmental glomerulosclerosis (FSGS) develop recurrence of proteinuria after kidney transplantation (TX). Although several circulating permeability factors (CPFs) responsible for recurrence have been suggested, there is no consensus. To facilitate CPF identification and predict recurrence after TX, there is a need for robust methods that demonstrate the presence of CPFs.

METHODS

Cultured human podocytes (hPods) and human and mouse glomerular endothelial cells (ciGEnC, mGEnC) were exposed to plasmas of FSGS patients with presumed CPFs, and of (disease) controls. A visual scoring assay and flow cytometry analysis of side scatter were used to measured changes in cellular granularity after exposure to plasma.

RESULTS

Nine out of 13 active disease plasmas of 10 FSGS patients with presumed CPFs induced granularity in hPod in a dose- and time-dependent manner. Corresponding remission plasmas induced no or less granularity in hPod. Similar results were obtained with ciGEnC and mGEnC, although induced granularity was less compared with hPod. Notably, foetal calf serum, healthy plasma and a remission plasma partially blocked FSGS plasma-induced hPod granularity.

CONCLUSIONS

We developed a novel assay in which active disease, presumably CPF-containing, FSGS plasmas induced granularity in cultured hPod. Our results may indicate the presence of CPF inhibitor(s) in healthy and remission plasma. We suggest the presence of a delicate balance between CPF and a CPF inhibitory factor, which is disturbed in patients with active disease. Our novel assays can be applied in future research to identify CPF and CPF inhibitors, and possibly to predict recurrence after TX.

Novel diagnostic and therapeutic techniques reveal changed metabolic profiles in recurrent focal segmental glomerulosclerosis

Idiopathic forms of Focal Segmental Glomerulosclerosis (FSGS) are caused by circulating permeability factors, which can lead to early recurrence of FSGS and kidney failure after kidney transplantation. In the past three decades, many research endeavors were undertaken to identify these unknown factors. Even though some potential candidates have been recently discussed in the literature, "the" actual factor remains elusive. Therefore, there is an increased demand in FSGS research for the use of novel technologies that allow us to study FSGS from a yet unexplored angle. Here, we report the successful treatment of recurrent FSGS in a patient after living-related kidney transplantation by removal of circulating factors with CytoSorb apheresis. Interestingly, the classical published circulating factors were all in normal range in this patient but early disease recurrence in the transplant kidney and immediate response to CytoSorb apheresis were still suggestive for pathogenic circulating factors. To proof the functional effects of the patient's serum on podocytes and the glomerular filtration barrier we used a podocyte cell culture model and a proteinuria model in zebrafish to detect pathogenic effects on the podocytes actin cytoskeleton inducing a functional phenotype and podocyte effacement. We then performed Raman spectroscopy in the < 50 kDa serum fraction, on cultured podocytes treated with the FSGS serum and in kidney biopsies of the same patient at the time of transplantation and at the time of disease recurrence. The analysis revealed changes in podocyte metabolome induced by the FSGS serum as well as in focal glomerular and parietal epithelial cell regions in the FSGS biopsy. Several altered Raman spectra were identified in the fractionated serum and metabolome analysis by mass spectrometry detected lipid profiles in the FSGS serum, which were supported by disturbances in the Raman spectra. Our novel innovative analysis reveals changed lipid metabolome profiles associated with idiopathic FSGS that might reflect a new subtype of the disease.

Response to plasma exchange and graft survival in recurrent focal and segmental glomerulosclerosis after transplantation: does the time of recurrence matter? A retrospective study

Recurrence of primary focal and segmental glomerulosclerosis following kidney transplantation (rFSGS) is a frequent and severe disease. We studied the time to recurrence of FSGS and its impact on the response to plasma exchange (PE) and graft survival. Between 1990 and 2013, 2730 kidney transplants were performed, including 52 patients with a primary diagnosis of FSGS. Of these patients with primary FSGS, 34 (67%) developed rFSGS. We retrospectively divided these patients into two groups depending on the time to recurrence: early (up to three months after transplantation, n = 26) or late (more than three months after transplantation, n = 8). Survival did not significantly differ between the two groups. In cases of late recurrence, PE was started later and was performed less frequently, and remission was achieved after more PE sessions and longer PE treatment than for the early group (P = 0.01). In early recurrence, resistance to PE at 40 days was associated with no long-term response to PE. PE should be performed as soon as possible after rFSGS. Patients with late rFSGS need to be offered the same treatment regime as those with early rFSGS.

Combination of High-Dose Intravenous Cyclosporine and Plasma Exchange Treatment Is Effective in Post-Transplant Recurrent Focal Segmental Glomerulosclerosis: Results of Case Series

BACKGROUND

Idiopathic focal segmental glomerulosclerosis (FSGS) commonly recurs in the early post-transplant period. The treatment protocols and results are conflictive in recurrent FSGS. We aimed to present the results of our treatment protocol and basic approach to the disease recurrences.

METHODS

This prospective, single-center study was conducted between the years 2015 and 2018. Twelve patients who fit completely the diagnosis of idiopathic FSGS by clinical, laboratory, and biopsy findings were included. A specific treatment protocol which consists of plasma exchange and high dose intravenous cyclosporine was delivered to the patients independently of induction protocols. Twenty-four months of outcomes of graft functions were evaluated.

RESULTS

Nine patients completed the treatment protocol and were documented for evaluation. All patients achieved a complete or partial remission in an average 24 months of follow-up period.

CONCLUSION

Idiopathic FSGS is more commonly recurrent than thought to be. The early detection of proteinuria is crucial because the administration of a plasma exchange-based treatment protocol can reverse proteinuria. We think our treatment protocol is a well-established, efficient, and safe choice for post-transplant recurrent FSGS in adults.

Diagnostic and Prognostic Value of Soluble Urokinase-type Plasminogen Activator Receptor (suPAR) in Focal Segmental Glomerulosclerosis and Impact of Detection Method

The plasma soluble urokinase-type plasminogen activator receptor (suPAR) is a biomarker for focal segmental glomerulosclerosis (FSGS), but its value is under discussion because of ambiguous results arising from different ELISA methods in previous studies. The aim of this study was to compare diagnostic performance of two leading suPAR ELISA kits and examine four objectives in 146 subjects: (1) plasma suPAR levels according to glomerular disease (primary, secondary and recurrent FSGS after kidney transplantation, other glomerulonephritis) and in healthy controls; (2) suPAR levels based on glomerular filtration rate; (3) sensitivity and specificity of suPAR for FSGS diagnosis and determination of optimal cut-offs; (4) suPAR as prognostic tool. Patients with FSGS showed significant higher suPAR values than patients with other glomerulonephritis and healthy individuals. This applied to subjects with and without chronic kidney disease. Although both suPARnostic™ assay and Quantikine Human uPAR ELISA Kit exerted high sensitivity and specificity for FSGS diagnosis, their cut-off values of 4.644 ng/mL and 2.789 ng/mL were significantly different. Higher suPAR was furthermore predictive for progression to end-stage renal disease. In summary, suPAR values must be interpreted in the context of population and test methods used. Knowing test specific cut-offs makes suPAR a valuable biomarker for FSGS.

Clinical features and outcomes of kidney transplant recipients with focal segmental glomerulosclerosis recurrence

AIM

Focal segmental glomerulosclerosis recurs in up to 30% and up to 80% of adult and pediatric kidney transplant recipients, respectively. There is no standard of care treatment. The purpose of this study was to evaluate clinical characteristics, treatments and outcomes of patients with focal segmental glomerulosclerosis recurrence (FSGSr).

METHODS

This was a retrospective single-center cohort study including FSGSr patients treated with plasmapheresis (PP) and combinations of high dose steroids, cyclosporine and rituximab.

RESULTS

Among 61 patients included in this analysis the median time to diagnosis was 19 days. The incidence of first biopsy-confirmed FSGSr was 18% reaching 52.4% with follow-up biopsies. During PP treatment 54% of the patients developed infectious complications. PP was discontinued in 37% of patients due to treatment failure (no remission or graft loss) and in 26% due to an adverse event. All patients who discontinued PP due to adverse event did not show clinical response or lost the allograft. The incidence of acute rejection was 34.4%. The incidences of partial and complete remissions were 16.4% and 27.8%, respectively. Overall 6-years patient and graft survivals were 90.7% and 64.5%, respectively.

CONCLUSION

This analysis confirms the low, variable and unpredictable rate of FSGSr remission, inconsistencies among available therapeutic options and its high rate of adverse events, and the negative impact on graft survival.

The Incidence of Primary vs Secondary Focal Segmental Glomerulosclerosis: A Clinicopathologic Study

OBJECTIVES

To describe the change in the incidence rates of primary and secondary focal segmental glomerulosclerosis (FSGS) from 1994 through 2013 in Olmsted County, Minnesota, and to identify the clinical and biopsy characteristics that distinguish primary from secondary FSGS.

PATIENTS AND METHODS

Olmsted County adult residents with native kidney biopsy from January 1, 1994, through December 31, 2013, and FSGS as the only glomerulopathy were identified. The clinical and pathologic characterstics of primary and secondary FSGS were described and compared, and incidence rates were calculated.

RESULTS

Of 370 adults biopsied, 281 had glomerular diseases, of which 46 (16%) had FSGS. From 1994-2003 to 2004-2013, there were significant increases in kidney biopsy rates (14.7 [95% CI, 12.1-17.3] vs 22.9 [95% CI, 20.0-25.7] per 100,000 person-years, 17% increase per 5 years; P<.001) and total FSGS rates (1.4 [95% CI, 0.6-2.2] vs 3.2 [95% CI, 2.1-4.3] per 100,000 person-years, 41% increase per 5 years; P=.02). Compared with patients with limited foot process effacement (<80%), patients with diffuse effacement (≥80%) without an identifiable cause had lower serum albumin levels (P<.001), had higher proteinuria (P<.001), and were more likely to have nephrotic syndrome (100% vs 4%; P<.001). Patients with diffuse effacement without an identifiable cause were classified as primary FSGS, which accounted for 3 of 12 patients (25%) during 1994-2003 and 9 of 34 (26%) during 2004-2013.

CONCLUSION

Although the incidence of FSGS has increased, the proportions of primary and secondary FSGS have remained stable.

Rituximab for Recurrence of Primary Focal Segmental Glomerulosclerosis After Kidney Transplantation: Clinical Outcomes

BACKGROUND

Rituximab has shown encouraging results for the treatment of kidney transplantation recipients with focal segmental glomerulosclerosis (FSGS) recurrence. However, the correct, opportune, and safe use of rituximab for this indication remains to be determined.

METHODS

This multicenter retrospective study reports on 19 new cases aged 35 (15-66) years who developed FSGS recurrence at 12 (1.5-27) days posttransplantation. Initial treatment consisted of plasma exchanges (PE), high doses of calcineurin inhibitors, and steroids. Rituximab was introduced either immediately (N = 6) or after failure of the initial treatment (N = 10) or failed attempted weaning from PE (N = 3).

RESULTS

Overall, we observed 9 of 19 complete remissions and 3 of 19 partial remissions. Estimated glomerular filtration rates (Modification of Diet in Renal Disease 4) were significantly higher in the responding patients than in nonresponding patients at month (M)12, M36, and M60. Overall, kidney survival at 5 years was 77.4% (95% range, 41.9-92.7). The 5-year graft survival rates in the responding patients and the nonresponding patients were 100% and 36.5%, respectively (P = 0.01). A further course of rituximab was required for 4 patients as a result of FSGS relapse, with good results. During the first year after renal transplantation, 14 patients developed severe infections (16 bacterial, 4 viral, 1 parasitic).

CONCLUSIONS

In kidney transplantation recipients with recurrent FSGS, rituximab therapy may be a recommended treatment for cases that have failed either the initial treatment or weaning from PE.

The role of plasma exchange in treating post-transplant focal segmental glomerulosclerosis: A systematic review and meta-analysis of 77 case-reports and case-series

Background

Evidence on the role of plasma exchange for treating recurrent post-transplant focal segmental glomerulosclerosis (FSGS) comes largely from individual cases and uncontrolled series. We conducted a systematic review and meta-analysis to estimate the remission rate after treatment with plasma exchange, and to determine if remission varied with patient or treatment characteristics.

Methods

We searched MEDLINE, EMBASE, Science Citation Index Expanded, and the Conference Proceedings Citation Index (Science and BIOSIS) for studies of patients with post-transplant recurrent FSGS who were treated with plasma exchange after recurrence (1950–2012). Of 678 studies screened, 77 met our inclusion criteria: 34 case reports (45 patients) and 43 case series (378 patients). We extracted patient-level data from each study and used random-effects models to calculate remission, defined as proteinuria <3.5 g/day (partial) or <0.5 g/day (complete).

Results

The overall remission rate in 423 patients with outcome data was 71 % (95 % CI: 66 % to 75 %). In 235 patients with data on age, remission was similar for adults and children: 69.1 % (95 % CI: 59.6 % to 77.2 %) and 70.2 % (95 % CI: 61.1 % to 77.9 %). Males were more likely to achieve remission (OR = 2.85; 95 % CI: 1.44 to 5.62) and patients treated within 2 weeks of recurrence showed a trend towards higher likelihood of remission (OR = 2.16; 95 % CI: 0.93 to 5.01). Proteinuria >7 g/day at recurrence was inversely associated with remission (OR = 0.43; 95 % CI: 0.19 to 0.97). Age and type of kidney transplant (living vs. deceased) did not associate with remission.

Conclusion

In this systematic review of patients with recurrent post-transplant FSGS, 71 % of patients achieved full or partial remission after treatment with plasma exchange; however, extensive missing data and lack of a control group limit any conclusions on causality.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-016-0322-7) contains supplementary material, which is available to authorized users.

Recurrent Primary Focal Segmental Glomerulosclerosis Managed With Intensified Plasma Exchange and Concomitant Monitoring of Soluble Urokinase-Type Plasminogen Activator Receptor-Mediated Podocyte β3-integrin Activation

BACKGROUND

Primary focal segmental glomerulosclerosis (FSGS) often causes nephrotic proteinuria and frequently results in end-stage renal disease and recurrence after kidney transplantation. Recent studies describe soluble urokinase-type plasminogen activator receptor (suPAR) as a circulating factor implicated in FSGS.

METHODS

This single-center study included 12 adult patients with histologically proven primary FSGS (n = 2) or recurrent FSGS after transplantation (n = 10). The effect of plasma exchange (PE) on clinical outcome, suPAR levels, and in vitro podocyte β3-integrin activation was investigated over a median of 11 (6-18) sessions of PE.

RESULTS

The course of treatment was monitored in a total of 70 sessions of PE, which partly eliminated suPAR, with a mean reduction of 37 ± 12% of serum concentration per session. However, a substantial rebound was observed between sessions, with suPAR levels reaching 99 ± 22% of the pretreatment levels after a median of 4 days. Podocyte β3-integrin activation dropped significantly after PE but rebounded within 4 days concomitant with a rising suPAR level. In 11 of 12 patients, multimodal treatment (including extensive PE) reduced proteinuria significantly (from 5.3 [2.0-7.8] to 1.0 [0.4-1.6] g/d), indicating clinical efficacy of the therapy. One patient suffered allograft loss due to FSGS recurrence. A persisting response was independent of a lasting reduction in the level of total suPAR because there was no sustained significant change in suPAR levels before and after the course of intensified treatment (3814 ± 908 to 3595 ± 521 pg/mL; P = 0.496).

CONCLUSIONS

We conclude that multimodal therapy including extensive PE was associated with stabilization of recurrent FSGS and a temporary lowering of plasma suPAR as well as podocyte β3-integrin activation. Whether a sustained lowering of total suPAR results in further improved outcomes requires additional study.

Focal segmental glomerular sclerosis recurrence with massive proteinuria and anuria immediately after kidney transplantation

Here, we report a case of focal segmental glomerular sclerosis (FSGS) recurrence immediately (47 minutes) after transplantation. A 1-hour biopsy specimen showed large periodic acid-Schiff-positive granules within the cells of the swollen proximal tubule, while electron microscopy revealed podocyte swelling and partial foot process effacement. These findings were worse on day 2 biopsy. Massive proteinuria and anuria were then observed. Two courses (2 × 2 times) of plasmapheresis and rituximab were administered, and the graft function gradually recovered. A day 22 biopsy specimen showed improvement in findings compared to those observed on day 2. One year after transplantation, no signs of FSGS recurrence are evident, and graft function remains good.

Plasma Exchange for the Recurrence of Primary Focal Segmental Glomerulosclerosis in Adult Renal Transplant Recipients: A Meta-Analysis

Background. Posttransplant recurrence of primary focal segmental glomerulosclerosis (rFSGS) in the form of massive proteinuria is not uncommon and has detrimental consequences on renal allograft survival. A putative circulating permeability factor has been implicated in the pathogenesis leading to widespread use of plasma exchange (PLEX). We reviewed published studies to assess the role of PLEX on treatment of rFSGS in adults. Methods. Eligible manuscripts compared PLEX or variants with conventional care for inducing proteinuria remission (PR) in rFSGS and were identified through MEDLINE and reference lists. Data were abstracted in parallel by two reviewers. Results. We detected 6 nonrandomized studies with 117 cases enrolled. In a random effects model, the pooled risk ratio for the composite endpoint of partial or complete PR was 0,38 in favour of PLEX (95% CI: 0,23–0,61). No statistical heterogeneity was observed among included studies (I² = 0%, p = 0,42). On average, 9–26 PLEX sessions were performed to achieve PR. Renal allograft loss due to recurrence was lower (range: 0%–67%) in patients treated with PLEX. Conclusion. Notwithstanding the inherent limitations of small, observational trials, PLEX appears to be effective for PR in rFSGS. Additional research is needed to further elucidate its optimal use and impact on long-term allograft survival.

Recurrent focal segmental glomerulosclerosis after kidney transplantation

Focal segmental glomerulosclerosis (FSGS) is an important cause of glomerular disease in children and adolescents and nearly 50 % of affected patients will progress to end-stage kidney disease over a 5 to 10-year period. Unfortunately, there is no established treatment for disease in the native kidney. Moreover, up to 55 % of patients develop recurrent disease after receiving a kidney transplant, with a substantially higher risk in patients who have already experienced recurrent disease in a prior transplant. A number of clinical and laboratory factors have been identified as risk factors for this complication. In addition, new investigations into podocyte biology and circulating permeability factors have shed light on the cause of recurrent the disease. While a number of novel therapeutic agents have been applied in the management of this problem, there still is no proven treatment. In this review, we summarize recent advances in the epidemiology, pathophysiology, and treatment of recurrent FSGS in pediatric patients who have received a kidney transplant.

Permeability factors in idiopathic nephrotic syndrome: historical perspectives and lessons for the future

The term idiopathic nephrotic syndrome (iNS) traditionally covers minimal change disease and primary focal segmental glomerulosclerosis (FSGS), now thought to be separate disease entities. Clinical and experimental evidence suggest that circulating permeability factors are involved in their pathogenesis. In the past four decades, many investigators have searched for the responsible factors, thus far with little success. The recent report of the soluble urokinase plasminogen activator receptor as a causative factor in FSGS has received much attention, but again the initially promising findings were not confirmed. We describe the history of the search for permeability factors, discuss the pitfalls that are likely responsible for the lack of success and propose criteria that should be used in future studies when evaluating candidate permeability factors.

Focal segmental glomerulosclerosis: towards a better understanding for the practicing nephrologist

Focal and segmental glomerulosclerosis (FSGS) is a common histopathological lesion that can represent a primary podocytopathy, or occur as an adaptive phenomenon consequent to nephron mass reduction, a scar from a healing vasculitic lesion, direct drug toxicity or viral infection among other secondary causes. Thus, the presence of an FSGS lesion in a renal biopsy does not confer a disease diagnosis, but rather represents the beginning of an exploratory process, hopefully leading ultimately to identification of a specific etiology and its appropriate treatment. We define primary FSGS as a 'primary' podocytopathy characterized clinically by the presence of nephrotic syndrome in a patient with an FSGS lesion on light microscopy and widespread foot process effacement on electron microscopy (EM). Secondary FSGS is commonly characterized by the absence of nephrotic syndrome and the presence of segmental foot process effacement on EM. Failure to accurately differentiate between the primary and secondary forms of FSGS has resulted in many patients undergoing unnecessary immunosuppressive treatment. Here, we review some key points that may assist the practicing nephrologist to distinguish between primary and secondary FSGS.

Plasma exchange for kidney disease: what is the best evidence?

Therapeutic plasma exchange (TPE) has been used as adjunctive therapy for various kidney diseases dating back to the 1970s. In many cases, support for TPE was on mechanistic grounds given the potential to remove unwanted large molecular-weight substances such as autoantibodies, immune complexes, myeloma light chains, and cryoglobulins. More recently, growing evidence from randomized controlled trials, meta-analyses, and prospective studies has provided insights into more rational use of this therapy. This report describes the role of TPE for the 6 most common kidney indications in the 2013 Canadian Apheresis Group (CAG) registry and the evidence that underpins current recommendations and practice. These kidney indications include thrombotic microangiopathy, antiglomerular basement membrane disease, anti-neutrophil cytoplasmic antibody-associated vasculitis, cryoglobulinemia, recurrence of focal and segmental glomerulosclerosis in the kidney allograft, and kidney transplantation.

A multicenter cross-sectional study of circulating soluble urokinase receptor in Japanese patients with glomerular disease

Elevated serum-soluble urokinase receptor (suPAR) levels have been described in patients with focal segmental glomerulosclerosis (FSGS) in several different cohorts. However, it remains unclear whether this is the case for Japanese patients and whether circulating suPAR can be clinically useful as a diagnostic marker. To determine this, we measured serum suPAR levels in 69 Japanese patients with biopsy-proven glomerular diseases in a cross-sectional manner. The serum suPAR levels showed a significant inverse correlation with renal function by univariate (R(2) of 0.242) and multivariate (β=0.226) analyses. Even after excluding patients with renal dysfunction, no significant difference in the suPAR levels was detected among the groups. Receiver operating characteristic analysis and measures of the diagnostic test performance showed that suPAR was not a useful parameter for differentiating FSGS from the other glomerular diseases (AUC-ROC: 0.621), although a small subgroup analysis showed that patients with FSGS, treated with steroids and/or immunosuppressants, had significantly lower suPAR levels. Patients with ANCA-associated glomerulonephritis had significantly higher levels of suPAR compared with the other disease groups, which may be owing to their lower renal function and systemic inflammation. Thus, suPAR levels are significantly affected by renal function and have little diagnostic value even in patients with normal renal function.

Issues in solid-organ transplantation in children: translational research from bench to bedside

In this review, we identify important challenges facing physicians responsible for renal and cardiac transplantation in children based on a review of the contemporary medical literature. Regarding pediatric renal transplantation, we discuss the challenge of antibody-mediated rejection, focusing on both acute and chronic antibody-mediated rejection. We review new diagnostic approaches to antibody-mediated rejection, such as panel-reactive antibodies, donor-specific cross-matching, antibody assays, risk assessment and diagnosis of antibody-mediated rejection, the pathology of antibody-mediated rejection, the issue of ABO incompatibility in renal transplantation, new therapies for antibody-mediated rejection, inhibiting of residual antibodies, the suppression or depletion of B-cells, genetic approaches to treating acute antibody-mediated rejection, and identifying future translational research directions in kidney transplantation in children. Regarding pediatric cardiac transplantation, we discuss the mechanisms of cardiac transplant rejection, including the role of endomyocardial biopsy in detecting graft rejection and the role of biomarkers in detecting cardiac graft rejection, including biomarkers of inflammation, cardiomyocyte injury, or stress. We review cardiac allograft vasculopathy. We also address the role of genetic analyses, including genome-wide association studies, gene expression profiling using entities such as AlloMap®, and adenosine triphosphate release as a measure of immune function using the Cylex® ImmuKnow™ cell function assay. Finally, we identify future translational research directions in heart transplantation in children.

Therapeutic plasma exchange for the treatment of pediatric renal diseases in 2013

Therapeutic plasma exchange is an extracorporeal treatment modality that removes systemic circulating pathologic factors or replaces absent plasma components and plays a role in many nephrologic conditions. It presents a number of technical challenges in the pediatric population but has become an increasingly common practice in pediatric nephrology over the past several decades. While prospective evidence is often lacking, our increased understanding of the molecular pathogenesis underlying many pediatric renal diseases provides sound reasoning for the use of plasma exchange in treating these conditions. This review will present the currently accepted indications for plasma exchange in children, the technical aspects of the procedure and its potential complications.

Serum suPAR in patients with FSGS: trash or treasure?

The urokinase-type plasminogen activator receptor (uPAR) has important functions in cell migration. uPAR can be shed from the cell membrane resulting in soluble uPAR (suPAR). Further cleavage gives rise to shorter fragments with largely unknown functions. Recent studies have demonstrated that both overexpression of uPAR on podocytes and the administration of suPAR cause proteinuria in mice. The common pathogenic mechanism involves the activation of podocyte β3-integrin. Increased activation of β3-integrin is also observed in patients with focal and segmental glomerulosclerosis (FSGS). These observations form the basis for the hypothesis that suPAR may be the circulating factor causing FSGS. A recent study fosters this idea by demonstrating increased suPAR levels in the serum of patients with FSGS and reporting an association with recurrence after transplantation and response to plasmapheresis. However, this study was heavily biased, and subsequent studies have given conflicting results. Although the experimental work is very suggestive, at present there is no proof that any known human suPAR fragment causes FSGS in humans. We therefore suggest that the measurement of suPAR using currently available assays has absolutely no value at the present time in decision-making in routine clinical practice.

A retrospective study of focal segmental glomerulosclerosis: clinical criteria can identify patients at high risk for recurrent disease after first renal transplantation

Background

Focal segmental glomerulosclerosis (FSGS) is a frequent cause of end-stage renal disease. Renal transplantation in patients with FSGS is often complicated by disease recurrence, which is associated with poor outcome. There are no tests that reliably predict recurrence of FSGS after transplantation. The aim of this study was to evaluate if clinical criteria can identify patients at high risk for recurrent disease.

Methods

We retrospectively studied 94 patients who received a first renal transplant at a median age of 37 years (range 5–69 years). Patients were assigned to one of three groups: familial or genetic FSGS (group I; n=18), secondary FSGS (group II; n=10) and idiopathic FSGS (group III; n=66). Pretransplant clinical characteristics were analyzed to determine predictors of a recurrence after transplantation.

Results

FSGS only recurred in patients with idiopathic FSGS (group III; 42%). Patients with a recurrence had a significantly lower serum albumin, higher 24-hour proteinuria and higher estimated glomerular filtration rate at diagnosis. Serum albumin at diagnosis was the only independent predictor of a recurrence in patients with idiopathic FSGS. Patients with recurrent FSGS had more acute rejection episodes (54% vs. 27%, P =0.02) and lower five year graft survival compared to patients without a recurrence (50 vs. 82%, P <0.01).

Conclusions

Clinical criteria allow identification of patients at high risk of recurrent FSGS after renal transplantation. This information can be used in the counseling and management of patients with FSGS.

Plasmapheresis in immunologic renal disease

Plasmapheresis has been used in the management of immunologic renal disease for the last 40 years. The rationale behind this approach is to remove pathogenic immune mediators, such as autoantibodies and immune complexes, from the circulation. There may also be benefit in depleting proinflammatory molecules, such as complement components and coagulation factors. Initial experience was gained in Goodpasture's disease, in which antiglomerular basement membrane antibodies were known to be pathogenic. More recently, a role for autoantibodies has become clear in small-vessel systemic vasculitis and some cases of hemolytic uremic syndrome/thrombotic thrombocytopenic purpura. Removal of immune complexes is thought to be important in cryoglobulinemia and systemic lupus erythematosus. Plasmapheresis is used in renal transplantation for the treatment of acute antibody-mediated rejection, and for desensitization of patients with preformed anti-HLA antibodies or those receiving an ABO-incompatible transplant. Although many of the early studies were uncontrolled, there has been an increasing number of randomized controlled trials in recent years. The aim of this article is to summarize current indications for the use of plasmapheresis in immunologic renal disease.

Focal segmental glomerulosclerosis after renal transplantation

Focal segmental glomerulosclerosis (FSGS) is a clinicopathologic syndrome of proteinuria, usually of nephrotic range, associated with focal and segmental sclerotic glomerular lesions. Therefore, FSGS is diagnosed by clinical features and histopathological examination of renal biopsy. The natural history of the condition varies, and although it may respond to treatment, FSGS is an important disease in the etiology of end-stage renal disease (ESRD). Furthermore, after kidney transplantation, approximately 30% of patients with FSGS develop recurrent FSGS. The risk factors for recurrence of FSGS include childhood onset and age <15 yr, rapid progression of the primary FSGS to ESRD, recurrence of FSGS in a previous allograft, diffuse mesangial hypercellularity in the native kidney, collapsing FSGS, and podocin gene mutation. In addition, after kidney transplantation, de novo FSGS also develops in approximately 10-20% of allografts, associated with a complication of hyperfiltration injury, chronic transplant glomerulopathy, and calcineurin inhibitor toxicity. FSGS is considered a podocyte disease, and the pathology is characterized by segmental FSGS lesion with glomerular epithelial hypercellularity. The pathological diagnosis of FSGS is based on the 2004 Columbia classification system. In the present minireview, we discuss the pathology of recurrence and de novo FSGS after kidney transplantation.

Preemptive plasmapheresis and recurrence of focal segmental glomerulosclerosis in pediatric renal transplantation

  FSGS has a high recurrence rate after renal transplantation. To examine the effects of the use of preemptive and post-transplant PP on recurrence and graft outcome, we conducted a retrospective study on 34 pediatric patients (mean age 13±5 yr) with biopsy-proven pretransplant FSGS and who underwent a renal transplantation between 1996 and 2007. Recurrence was defined as a serum albumin level of <3.0g/L in the presence of nephrotic-range proteinuria (>40mg/m(2) /h). Total response to PP therapy was defined as the resolution of the nephrotic-range proteinuria and partial response as persistent proteinuria despite PP but not in the nephrotic range. Fifteen patients received a LD renal transplantation and 19 patients received a DD renal transplantation. Nineteen patients received CsA and 14 patients received tacrolimus. Nineteen patients (56%) had FSGS recurrence. There was no difference in the recurrence rate between patients receiving CsA vs. tacrolimus. Among the 15 LD patients, 13 received preemptive PP (1-10 sessions) and seven patients (47%) had subsequent FSGS recurrence. Among the 19 DD patients, four received preemptive PP and 12 (63%) had FSGS recurrence. The number of preemptive PP did not affect the recurrence rate. In a group of patients with a previous graft loss secondary to recurrence, the rate of recurrence was lower than expected (40%) and two of the three patients who did not recur had three or more sessions of preemptive PP. Of the 19 patients with recurrence, 17 were treated with PP therapy and 88% of the patients fully or partially responded. Only five patients had graft loss at three yr post-transplant: two from FSGS recurrence and three from non-compliance. These results suggest that preemptive PP does not decrease the rate of recurrence after transplantation but might be beneficial in treating high-risk patients with documented recurrence. Patients with FSGS recurrence post-transplant can achieve good graft survival with both LD and DD transplantation.

Protocol biopsies for focal segmental glomerulosclerosis treated with plasma exchange and rituximab in a renal transplant patient

We discuss a renal transplant patient with focal segmental glomerulosclerosis (FSGS) treated with plasma exchange and rituximab. A 45-yr-old woman underwent cadaveric renal transplantation in May 2008. She had started hemodialysis support in 1991. Immediately after transplantation, massive proteinuria (1-5 g/d) appeared. Graft biopsy at one h showed minor glomerular abnormalities with partial foot process effacement on electric microscopy. Protocol biopsy at three months after transplantation for persistent proteinuria showed obvious FSGS under light microscopy. Plasma exchange and rituximab administration were subsequently initiated in August 2008, and proteinuria disappeared within a month after starting these treatments. Protocol graft biopsy one yr after transplantation (2009) showed increased global sclerosis and a decrease in segmental sclerosis. In addition, foot process effacement had recovered by one yr after transplantation. Plasma exchange and subsequent rituximab administration led to clinical remission of post-transplant FSGS with improvement in podocyte structure. Rituximab should be considered soon after several sessions of plasmapheresis in transplant patients with recurrent FSGS.

Long-term outcome of renal transplantation in adults with focal segmental glomerulosclerosis

SUMMARY

Little information is available about the long-term results of kidney transplantation in adults with focal segmental glomerulosclerosis (FSGS). The outcomes of 52 renal transplants performed between 1988 and 2008 in 47 adults with FSGS were compared with those of 104 matched controls (median follow-up 93.4 vs. 109.4 months respectively). At 15 years, patient survival was 100% and graft survival 56% in FSGS patients vs. 88.3% and 64% respectively in controls (P = NS). FSGS recurred in 12 out of 52 grafts (23%) and led to graft failure in seven within 10 months (median). In the other five cases, proteinuria remitted and grafts are functioning 106 months (median) after transplantation. A second recurrence developed in five out of eight re-transplanted patients (62.5%) who lost their first graft because of recurrence; only one graft was lost. Patients with recurrence were more frequently male subjects (83% vs. 40%, P = 0.02), younger at diagnosis of FSGS (16.3 +/- 6.8 vs. 24.1 +/- 11.5 years, P = 0.03) and of younger age at transplantation (28.4 +/- 7.8 vs. 35.8 +/- 12.2 years, P = 0.05). Treatment with plasmapheresis plus ACE inhibitors achieved either complete or partial remission in 80% of the cases. Long-term patient and renal allograft survivals of adults with FSGS were comparable to those of controls. Recurrence was more frequent in young patients and in patients who lost a previous graft from recurrence. Graft loss resulting from a second recurrence is lower than expected.

Kidney transplantation for primary focal segmental glomerulosclerosis: outcomes and response to therapy for recurrence

BACKGROUND

For a subset of adults and children with primary focal segmental glomerulosclerosis (FSGS), proteinuria and renal dysfunction recur after kidney transplantation (KTx). Predicting recurrence and response to plasmapheresis (PP) or other interventions remains problematic.

METHODS

The prevalence, recurrence rate, outcomes, and treatment responses of patients with FSGS were determined among 1573 KTx recipients. Although 5.0% carried some diagnosis of FSGS, only 1.9% (n=30) met strict diagnostic criteria for primary FSGS including biopsy-proven FSGS, lack of secondary factors, negative family history, and progression to end-stage renal disease within 10 years.

RESULTS

Of these, 47% had recurrent FSGS compared with 8% of those not meeting strict criteria (P<0.001). Recurrence was more common in children compared with adults (86% vs. 35%, P=0.01). Graft survival was lower for recipients with primary FSGS compared with all others and inferior graft survival was attributable to recurrent FSGS. Fourteen patients received PP preemptively (pre-KTx) or therapeutically (post-KTx) for recurrent disease. Four pediatric patients additionally received anti-CD20 (rituximab) therapy. Of the different treatment approaches, only PP combined with rituximab was associated with prolonged remission of proteinuria.

CONCLUSIONS

The results indicate that patients at high risk for FSGS recurrence can be identified and may benefit from carefully planned peritransplant interventions.

Intensive and prolonged treatment of focal and segmental glomerulosclerosis recurrence in adult kidney transplant recipients: a pilot study

No treatment has consistently induced long-term remission of proteinuria in adult patients with focal segmental glomerulosclerosis (FSGS) recurrence after kidney transplantation. We undertook an open-label, nonrandomized pilot trial of intensive and prolonged treatment of FSGS recurrence. Over an 18-month period, 10 adult kidney transplant recipients with FSGS recurrence received concomitantly high-dose steroids, intravenous cyclosporine for 14 days followed by oral cyclosporine therapy, and an intensive and prolonged course of plasma exchanges (PE). We compared this treatment with those of a control group of 19 patients with a FSGS recurrence transplanted between 1997 and 2005. Complete, rapid (mean 23 +/- 7 days) and sustained remission was obtained in 9/10 patients (90%) as opposed to 27% in the control group. At month 3 and month 12, proteinuria was 0.16 g/day (range 0.05-0.3 g/day) and 0.19 g/day (range 0.05-1 g/day) respectively. Only one patient remained in partial remission at month 12 but he had already lost two previous grafts due to FSGS recurrence. PEs were stopped at month 9 in all patients except for the patient with a partial remission who remains PE-dependent. This small pilot study provides very encouraging results demonstrating that this treatment rapidly achieves complete and sustained remission in a high proportion of patients.

What are the indications for plasma exchanges in autoimmune diseases?: The registry of the Société Française d’Hémaphérèse

The use of plasma exchange (PE) in the autoimmune diseases is encouraged in France. Since 1990, the national registry of PE allows an analysis of the evolution of the coverage of these pathologies. The variation of the number of patients treated by PE is correlated in respect to the results of the therapeutic studies. After a decrease of PE activity in these indications during the 90s, one observes a new increase of the patients treated because of the validation of new indications. Autoimmune diseases represent the third cause of morbidity in developed countries, with a global prevalence of 5%, and concerns four groups of pathologies of organs or systems (neurology, haematology, nephrology and vasculitis). In 1976, Lockwood demonstrated the place of plasma exchanges (PE) in Goodpasture's syndrome [Lockwood CM, Rees AJ, Pearson TA, Evans DJ, Peters DK, Wilson CB. Immunosuppression and plasma exchange in the treatment of Goopasture's syndrome. Lancet 1976;1(7962):723-6. [1]], with a significant decrease of antibodies during large volume exchanges. In the 80s, several prospective studies began to estimate the efficiency of PE in other autoimmune diseases. The national registry of the Société Française d' Hémaphérèse, has collected the epidemiological and technical data of PE since 1985. This work analyses the evolution of the validated indications, between 1990 and 2005 in France.

Focal Segmental Glomerulosclerosis and Renal Transplantation

Primary focal segmental glomerulosclerosis (FSGS) is a major cause of nephrotic syndrome and eventual end-stage renal disease. It is known to be due to an abnormality of the visceral epithelial cells (podocytes) of the glomerulus. The morphological hallmark of primary FSGS is diffuse effacement of podocyte foot processes. The etiology of the podocyte damage is not been clearly established. FSGS can also be a secondary process due to underlying conditions including obesity and heroin use. In the secondary processes, the mechanism appears to be a decreased ratio of podocytes to the glomerular filtration surface area. Familial forms of FSGS also exist due to alterations of several different podocyte proteins. Primary FSGS is an increasing cause of end-stage renal disease. Recurrence of severe FSGS in renal allograft recipients presents a major challenge to transplant physicians. The incidence of recurrence is generally accepted to be between 20% and 30%. Risk factors for and characteristics of recurrence include a rapid progression of the primary disease to end-stage renal failure, early onset of nephrotic range proteinuria after allografting, frequent loss of the allograft, a high frequency of recurrence in subsequent allografts, and children less than 15 years of age. Some investigators have identified a circulating factor called the FSGS factor that appears to be associated with recurrence after transplantation. This factor has been shown to be a protein between 30 and 50 kd molecular weight. Logically, the possibility of a circulating factor associated with recurrence of FSGS led investigators to treat patients with plasmapheresis. Several studies have been reported with varying success. The response of patients to plasmapheresis seems to be completely individual. Other studies have added cyclophosphamide and/or mycophenolate mofetil to the plasmapheresis protocol. Again success in these studies has been variable. However, because some patients show complete recovery with plasmapheresis, individuals who develop recurrent FSGS after transplantation usually are given a trial of plasmapheresis therapy.