Primary focal segmental glomerulosclerosis--long-term outcome after pediatric renal transplantation

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.

Management of proteinuria in the transplanted patient

Proteinuria is a relatively frequent complication in children after renal transplantation (40-80 %). It is usually mild and non-nephrotic in nature and predominantly tubular in origin. The major causes of post-transplant proteinuria are recurrence of primary glomerulonephritis [mostly focal segmental glomerulosclerosis (FSGS)], rejection (acute and chronic), mTOR inhibitors or hypertension. Proteinuria is a risk factor for graft loss and patient death in adults, and even a mild proteinuria (0.1-0.2 g/day) is associated with impaired graft and patient survival. In children, proteinuria seems to be associated with graft but not patient survival. Proteinuria (protein/creatinine ratio) should be assessed regularly in all children. In children with prior chronic kidney disease due to idiopathic FSGS, proteinuria should be assessed daily during the first month after transplantation to enable early diagnosis of recurrence. The cause of proteinuria should be identified, and graft biopsy should be considered in children with unexplained proteinuria, especially with new onset proteinuria or deterioration of previously mild proteinuria. Treatment must be primarily targeted at the cause of proteinuria, and in normotensive children symptomatic antiproteinuric therapy with angiotensin-converting enzyme inhibitors/angiotensin II receptor antagonists should also be initiated. Other antihypertensive drugs should be used to achieve target blood pressure of <75th percentile. Target proteinuria should be <20 mg/mmol creatinine.

Recurrence of idiopathic focal segmental glomerulosclerosis after kidney transplantation: experience of a Korean tertiary center

FSGS is the second most common cause of idiopathic NS in children. It often progresses to ESRD and commonly recurs after KT. To investigate the risk factors and the prognosis of recurrence in pediatric idiopathic FSGS in Korea, retrospective review of 43 KT in 38 children with idiopathic FSGS of last two decades was conducted. The patients presented at the median age of 5.1 yr (range 1.1-13.8 yr) and received KT 5.7 yr later (range 1.3-17.6 yr). FSGS recurred in 20 allografts immediately after transplantation, only in those who presented with NS but not in those who presented with AUA. The risk factors for recurrence were age of onset >5 yr and progression to ESRD within six yr but not sooner than 18 months. CR was achieved in 13 patients with FSGS recurrence and sustained in nine without subsequent relapse over a median of six and a half yr (0.6-20.7 yr). Pediatric idiopathic FSGS presenting with NS recurred in more than half of patients after transplantation. Interestingly, more rapid progression within less than 18 months did not predict recurrence. To identify high-risk patients of recurrence, an international cooperative study would be necessary.

Sequential maintenance therapy with cyclosporin A and mycophenolate mofetil for sustained remission of childhood steroid-resistant nephrotic syndrome

BACKGROUND

There is currently no established standard for maintenance therapy of steroid-resistant nephrotic syndrome (SRNS). We report the long-term clinical course, medication, pharmacokinetic data, and renal function of 23 children with primary, non-familial SRNS with focal segmental glomerulosclerosis (FSGS).

METHODS

To achieve initial remission, patients were treated with high-dose intravenous (i. v.) methylprednisolone and oral cyclosporin A (CsA). Maintenance therapy included transient alternate day oral prednisolone, CsA and angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin receptor blockers. In 18 patients, mycophenolate mofetil (MMF) (adjusted to achieve blood mycophenolic acid trough concentrations > 2 μg/mL) was sequentially added, and 16 patients were converted to MMF monotherapy.

RESULTS

During a mean follow-up time of 7.0 years (1.7-16.5 years; cumulative observation time 161 patient-years), sustained remission could be achieved in all patients. Five of 23 patients (21%) experienced 10 relapses; all responded to relapse therapy. Maintenance therapy could be permanently discontinued in seven patients (30%). After conversion from CsA to MMF, renal function improved significantly; the eGFR at last follow-up was 137 (range 106-198) mL/min × 1.73 m(2). The mean number of anti-hypertensive drugs decreased from 1.86 per patient after initial remission to 0.57 on MMF monotherapy (P < 0.002).

CONCLUSIONS

The data of this uncontrolled retrospective study indicate that in children with SRNS/FSGS achieving initial remission, a sequential steroid-free therapy consisting of a combination of CsA and MMF followed by MMF alone (with the addition of ACE inhibitors and angiotensin receptor blockers), can provide sustained long-term remission, preservation of renal function and better control of blood pressure.

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.

Screening for NPHS2 mutations may help predict FSGS recurrence after transplantation

Steroid-resistant focal segmental glomerulosclerosis (FSGS) often recurs after renal transplantation. In this international survey, we sought to identify genotype-phenotype correlations of recurrent FSGS. We surveyed 83 patients with childhood-onset primary FSGS who received at least one renal allograft and analyzed 53 of these patients for NPHS2 mutations. The mean age at diagnosis was 6.7 years, and the mean age at first renal transplantation was 13 years. FSGS recurred in 30 patients (36%) after a median of 13 days (range, 1.5 to 152 days). Twenty-three patients received a second kidney transplant, and FSGS recurred in 11 (48%) after a median of 16 days (range, 2.7 to 66 days). None of the 11 patients with homozygous or compound heterozygous NPHS2 mutations developed recurrent FSGS compared with 45% of patients without mutations. These data suggest that genetic testing for pathogenic mutations may be important for prognosis and treatment of FSGS both before and after transplantation.

Outcome of living donor renal allograft survival in children with focal segmental glomerulosclerosis

FSGS is the most frequent GN that may recur in a renal allograft. Compared with adults, the impact of FSGS on graft survival appears to be more significant in children. Thus we decided to assess graft survival and complications after renal transplantation in children with FSGS. Outcome of renal transplantation in 25 children with FSGS who received a renal transplant at Labafi Nejad Hospital was studied and compared with 75 patients as a control group. The mean follow-up duration was 68.16 (s.d. = 41.93) months. Other than demographics, variables such as DGF, acute rejection, number of acute rejection episodes, and graft failure in both groups were evaluated. Acute rejection was seen in 22/25 (88%) of FSGS group, compared to 40/75 (53.3%) in the control group. This difference was statistically significant (p = 0.001). DGF was seen in 4/25 (16%) and 13/75 (17.3%) in the FSGS and control groups, respectively (p = N.S.). The mean graft survival time was 115.61 (s.e.m. = 12.56) and 155.56 (s.e.m. = 7.16) month in FSGS and control group, respectively (p = N.S.). We demonstrated that graft function and survival were not significantly different in the FSGS and control patients. However, acute rejection episodes were more common in FSGS patients but without a significant impact on graft survival.

Plasmapheresis for Recurrent Posttransplant Focal Segmental Glomerulosclerosis

The high recurrence rate of focal segmental glomerulosclerosis (FSGS) in kidney transplant recipients suggests that such patients have a circulating factor that alters glomerular capillary permeability. Serum from patients with FSGS increases glomerular permeability to albumin. This permeability factor has been partially identified as a protein. The removal of this protein by plasmapheresis (PP) decreases proteinuria. In this study we report data on the therapeutic effects of PP in FSGS children with recurrence in the transplanted kidney. Three hundred pediatric (age <19 years) renal transplants were performed, including 21 patients (24 transplants) with FSGS as a cause of renal failure. Fourteen (58.3%) subjects experienced disease recurrence (proteinuria >1 g/m(2) per day) within 1 month after transplantation. Mean age patient was 12 +/- 4.3 years, including 83.3% Caucasians and 70.2% recipients of living donor grafts. Nine were treated with 10 cycles of PP (3 cycles/weekly), initiated immediately after recurrence (<48 hours). Immunosuppression included high doses of cyclosporine (C(2) levels of 1700-1800 ng/mL), mycophenolate sodium or mofetil, and prednisone. Thirteen patients were induced with anti-IL2 receptor monoclonal antibody (daclizumab/basiliximab). Among the patients who underwent PP, five (55.5%) achieved a complete remission and one (12%), a partial remission (1 g/24 hours). There were no cases of remission among the five patients who were not treated with PP. Those who achieved remission after PP experienced no recurrences during the 2.6 +/- 1.4 years follow-up. PP appears to be effective to treat recurrent FSGS following kidney transplantation. It should be started as soon as possible.

Computational simulation of renal biopsy accuracy in focal segmental glomerulosclerosis

The goal of this study was to estimate the diagnostic and prognostic accuracy of renal biopsies in focal segmental glomerulosclerosis (FSGS), accounting for the focal nature of affected glomeruli. Computational simulations were performed on a total of 138,600 virtual kidneys, across a range of FSGS involvement. Simulations were designed to address the diagnostic accuracy of renal biopsies, and the biopsy characteristics required to reflect accurately the true degree of involvement of FSGS in the entire kidney or just the juxtamedullary (JM) region. The diagnostic accuracy of renal biopsies for the detection of at least one FSGS glomerulus exceeded 80% when 10-20% of the kidney was affected by FSGS. Hundreds to thousands of biopsy glomeruli were required to characterize reliably the true extent of FSGS when fewer than 75% of the kidney's glomeruli were affected. Renal biopsies with an average of 20 glomeruli did not accurately reflect the extent of FSGS in kidneys until at least 80% of all glomeruli in the kidney were affected. Targeting JM glomeruli did not result in significant improvements in the prognostic performance characteristics of renal biopsies. These findings suggest that conventional renal biopsies might be inadequate for characterizing the extent of FSGS.