Outcome of infantile nephropathic cystinosis depends on early intervention, not genotype: A multicenter sibling cohort study.

Infantile nephropathic cystinosis (INC) is an inheritable lysosomal storage disorder characterized by lysosomal cystine accumulation, progressive kidney disease, and multiple extrarenal complications (ERCs). Cysteamine postpones the onset of end-stage kidney disease (ESKD) and reduces the incidence of ERCs; however, cysteamine is generally initiated upon establishment of the renal Fanconi syndrome (FS) and partial loss of kidney function, whereas data on long-term effects of cysteamine administered from neonatal age are lacking. An international multicenter retrospective cohort study of siblings with INC was set up to investigate the outcome in relation to age at initiation of cysteamine versus CTNS genotype, with attention to patients treated with cysteamine from neonatal age. None of the siblings treated from neonatal age (n = 9; age 10 ± 6 years) had reached ESKD, while 22% of their index counterparts (n = 9; age 14 ± 5 years) had commenced renal replacement therapy. Siblings treated with cysteamine from the onset of symptoms at a younger age compared with their index counterparts, reached ESKD at a significant older age (13 ± 3 vs. 10 ± 3 years, p = 0.002). In contrast, no significant difference in ERCs was observed between sibling and index patients, independently from the age at initiation of cysteamine. The CTNS genotype had no impact on the overall outcome in this cohort. In INC, presymptomatic treatment with cysteamine results in a better renal outcome in comparison to treatment initiated from the onset of symptoms. This justifies including cystinosis into newborn screening programs. SYNOPSIS: In infantile nephropathic cystinosis, presymptomatic treatment with cysteamine improves the renal outcome which justifies the inclusion of cystinosis into newborn screening programs.

Hemolytic-Uremic Syndrome in Children.

Hemolytic uremic syndrome is characterized by a triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney failure. Most cases are caused by Shiga-toxin-producing bacteria, especially Escherichia coli. Transmission occurs through ground beef and unpasteurized milk. STEC-HUS is the main cause of acute renal failure in children. Management remains supportive. Immediate outcome is most often. Atypical HUS represents about 5% of cases, has a relapsing course with more than half of the patients progressing to end-stage kidney failure. Most cases are due to variants in complement regulators of the alternative pathway. Complement inhibitors, such as eculizumab, have considerably improved the prognosis.

An international cohort study spanning five decades assessed outcomes of nephropathic cystinosis.

Nephropathic cystinosis is a rare disease secondary to recessive mutations of the CTNS gene encoding the lysosomal cystine transporter cystinosin, causing accumulation of cystine in multiple organs. Over the years, the disease has evolved from being a fatal condition during early childhood into a treatable condition, with patients surviving into adulthood. Data on cystinosis are limited by the rarity of the disease. Here, we have investigated factors associated with kidney and growth outcome in a very large cohort of 453 patients born between 1964 and 2016 and followed in Belgium, Germany, Austria, France, Italy, Spain, The Netherlands, Turkey and United Kingdom. From the 1970s to the 1990s, the median increase in kidney survival was 9.1 years. During these years, cysteamine, a cystine-depleting agent, was introduced for the treatment of cystinosis. Significant risk factors associated with early progression to end-stage kidney disease assessed by Cox proportional multivariable analysis included delayed initiation of cysteamine therapy and higher mean leucocyte cystine levels. No significant effect on kidney function was observed for gender, pathogenic variant of the CTNS gene, and the prescription of indomethacin or renin angiotensin system blockers. Significantly improved linear growth was associated with early use of cysteamine and lower leukocyte cystine levels. Thus, our study provides strong evidence in favor of early diagnosis and optimization of cystine depletion therapy in nephropathic cystinosis.

Association between 25(OH) vitamin D and graft survival in renal transplanted children.

BACKGROUND: In children, vitamin D deficiency is common after renal transplantation. Besides promoting bone and muscle development, vitamin D has immunomodulatory effects, which could protect kidney allografts. The purpose of this study was to assess the association between vitamin D status and the occurrence of renal rejection. METHODS: We studied a retrospective cohort of 123 children, who were transplanted at a single institution between September 2008 and April 2019. Patients did not receive vitamin D supplementation systematically. In addition, factors influencing vitamin D status were analyzed using univariate and multivariate analyses. RESULTS: Median 25-hydroxy-vitamin D (25-OH-D) concentration was close to reference values at the time of transplantation (30 ng/mL (min-max 5-100)), but rapidly decreased within the first 3 months to 19 ng/mL (min-max 3-91) (P < .001). The overall acute rejection rate was 7%. The clinical rejection rate (5% vs 9%), subclinical rejection (12% vs 36%), and borderline changes (21% vs 28%) were not statistically different during the follow-up between the 3-month 25-OH-D < 20 ng/mL and 3-month 25-OH-D > 20 ng/mL groups. There was a correlation between the 25-OH-D levels and PTH concentration at 3 months (r = -.2491, P = .01), but no correlation between the 3-month 25-OH-D and the season of the year (F = 0.19, P = .90; F = 1.34, P = .27, respectively). Multivariate analyses revealed that age and mGFR at 3 months, were independent predictors of mGFR at 12 months. CONCLUSION: Our data show that vitamin D deficiency can develop rapidly after transplantation; vitamin D levels at 3 months are not associated with lower mGFR or a higher rejection rate at 1 year in children as opposed to adult recipients.

Treatment and outcome of congenital nephrotic syndrome.

BACKGROUND: Recommendations for management of Finnish-type congenital nephrotic syndrome (CNS) followed by many teams include daily albumin infusions, early bilateral nephrectomy, dialysis and transplantation. We aimed to assess the treatment and outcome of patients with CNS in France. METHODS: We conducted a nationwide retrospective study on 55 consecutive children born between 2000 and 2014 treated for non-infectious CNS. RESULTS: The estimated cumulative incidence of CNS was 0.5/100 000 live births. The underlying defect was biallelic mutations in NPHS1 (36/55, 65%), NPHS2 (5/55, 7%), PLCE1 (1/55, 2%), heterozygous mutation in WT1 (4/55, 7%) and not identified in nine children (16%). Fifty-three patients (96%) received daily albumin infusions from diagnosis (median age 14 days), which were spaced and withdrawn in 10 patients. Twenty children (35%) were managed as outpatients. Thirty-nine patients reached end-stage kidney disease (ESKD) at a median age of 11 months. The overall renal survival was 64% and 45% at 1 and 2 years of age, respectively. Thirteen children died during the study period including four at diagnosis, two of nosocomial catheter-related septic shock, six on dialysis and one after transplantation. The remaining 13 patients were alive with normal renal function at last follow-up [median 32 months (range 9-52)]. Renal and patient survivals were longer in patients with NPHS1 mutations than in other patients. The invasive infection rate was 2.41/patient/year. CONCLUSIONS: Our study shows: (i) a survival free from ESKD in two-thirds of patients at 1 year and in one-half at 2 years and (ii) a significant reduction or even a discontinuation of albumin infusions allowing ambulatory care in a subset of patients. These results highlight the need for new therapeutic guidelines for CNS patients.

Acute kidney injury complicating nephrotic syndrome of minimal change disease.

Minimal change disease accounts for 70% to 90% of cases of nephrotic syndrome in children. It also causes nephrotic syndrome in adults, including patients older than age 60. Renal function is altered moderately in approximately 20% to 30% of patients because foot-process fusion impairs filtration of water and solutes. The glomerular filtration rate is reduced by approximately 20% to 30% and returns to baseline with remission of proteinuria. Over the past 50 years, a number of publications have reported cases of acute kidney injury occurring in approximately one-fifth to one-third of adult cases in the absence of prior or concomitant renal disease. Clinical attributes point to a male predominance, age >50, massive proteinuria, severe hypoalbuminemia, a background of hypertension and vascular lesions on kidney biopsy, along with ischemic tubular necrosis. Acute kidney injury may require dialysis for weeks or months until remission of proteinuria allows resolution of oliguria. In some cases, renal function does not recover. An effect of endothelin-1-induced vasoconstriction at the onset of proteinuria has been proposed to explain tubular cell ischemic necrosis. The main factors causing acute kidney injury in patients with minimal change disease are diuretic-induced hypovolemia and nephrotoxic agents. Acute kidney injury is uncommon in children in the absence of intercurrent complications. Infection, nephrotoxic medication, and steroid resistance represent the main risk factors. In all patients, the goal of supportive therapy is essentially to buy time until glucocorticoids obtain remission of proteinuria, which allows resolution of renal failure.

A randomized clinical trial indicates that levamisole increases the time to relapse in children with steroid-sensitive idiopathic nephrotic syndrome.

Levamisole has been considered the least toxic and least expensive steroid-sparing drug for preventing relapses of steroid-sensitive idiopathic nephrotic syndrome (SSINS). However, evidence for this is limited as previous randomized clinical trials were found to have methodological limitations. Therefore, we conducted an international multicenter, placebo-controlled, double-blind, randomized clinical trial to reassess its usefulness in prevention of relapses in children with SSINS. The efficacy and safety of one year of levamisole treatment in children with SSINS and frequent relapses were evaluated. The primary analysis cohort consisted of 99 patients from 6 countries. Between 100 days and 12 months after the start of study medication, the time to relapse (primary endpoint) was significantly increased in the levamisole compared to the placebo group (hazard ratio 0.22 [95% confidence interval 0.11-0.43]). Significantly, after 12 months of treatment, six percent of placebo patients versus 26 percent of levamisole patients were still in remission. During this period, the most frequent serious adverse event (four of 50 patients) possibly related to levamisole was asymptomatic moderate neutropenia, which was reversible spontaneously or after treatment discontinuation. Thus, in children with SSINS and frequent relapses, levamisole prolonged the time to relapse and also prevented recurrence during one year of treatment compared to prednisone alone. However, regular blood controls are necessary for safety issues.

Clinical and genetic heterogeneity in familial steroid-sensitive nephrotic syndrome.

BACKGROUND: Familial steroid-sensitive nephrotic syndrome (SSNS) is a rare condition. The disease pathophysiology remains elusive. However, bi-allelic mutations in the EMP2 gene were identified, and specific variations in HLA-DQA1 were linked to a high risk of developing the disease. METHODS: Clinical data were analyzed in 59 SSNS families. EMP2 gene was sequenced in families with a potential autosomal recessive (AR) inheritance. Exome sequencing was performed in a subset of 13 families with potential AR inheritance. Two variations in HLA-DQA1 were genotyped in the whole cohort. RESULTS: Transmission was compatible with an AR (n = 33) or autosomal dominant (AD, n = 26) inheritance, assuming that familial SSNS is a monogenic trait. Clinical features did not differ between AR and AD groups. All patients, including primary (n = 7) and secondary steroid resistant nephrotic syndrone (SRNS), (n = 13) were sensitive to additional immunosuppressive therapy. Both HLA-DQA1 variations were found to be highly linked to the disease (OR = 4.34 and OR = 4.89; p < 0.001). Exome sequencing did not reveal any pathogenic mutation, neither did EMP2 sequencing. CONCLUSIONS: Taken together, these results highlight the clinical and genetic heterogeneity in familial SSNS. Clinical findings sustain an immune origin in all patients, whatever the initial steroid-sensitivity. The absence of a variant shared by two families and the HLA-DQA1 variation enrichments suggest a complex mode of inheritance.

Age-Dependent Risk of Graft Failure in Young Kidney Transplant Recipients.

BACKGROUND: The risk of graft failure in young kidney transplant recipients has been found to increase during adolescence and early adulthood. However, this question has not been addressed outside the United States so far. Our objective was to investigate whether the hazard of graft failure also increases during this age period in France irrespective of age at transplantation. METHODS: Data of all first kidney transplantation performed before 30 years of age between 1993 and 2012 were extracted from the French kidney transplant database. The hazard of graft failure was estimated at each current age using a 2-stage modelling approach that accounted for both age at transplantation and time since transplantation. Hazard ratios comparing the risk of graft failure during adolescence or early adulthood to other periods were estimated from time-dependent Cox models. RESULTS: A total of 5983 renal transplant recipients were included. The risk of graft failure was found to increase around the age of 13 years until the age of 21 years, and decrease thereafter. Results from the Cox model indicated that the hazard of graft failure during the age period 13 to 23 years was almost twice as high as than during the age period 0 to 12 years, and 25% higher than after 23 years. CONCLUSIONS: Among first kidney transplant recipients younger than 30 years in France, those currently in adolescence or early adulthood have the highest risk of graft failure.

A randomised Phase I/II trial to evaluate the efficacy and safety of orally administered Oxalobacter formigenes to treat primary hyperoxaluria.

BACKGROUND: Primary hyperoxaluria (PH) is a rare, genetic disorder which involves the overproduction of endogenous oxalate, leading to hyperoxaluria, recurrent urolithiasis and/or progressive nephrocalcinosis and eventually resulting in kidney failure and systemic oxalosis. The aim of this trial was to investigate whether treatment involving an oxalate-metabolising bacterium (Oxalobacter formigenes) could reduce urinary oxalate excretion in PH patients. METHODS: The efficacy and safety of O. formigenes (Oxabact® OC5; OxThera AB, Stockholm, Sweden) was evaluated in a randomised, placebo-controlled, double-blind study for 8 weeks. The primary objective was reduction in urinary oxalate excretion (Uox). Secondary objectives included faecal O. formigenes count and decrease in plasma oxalate concentration (Pox). RESULTS: Twenty-eight patients randomised 1:1 to the treatment group (OC5) or the placebo group completed the study. After 8 weeks of treatment, there was no significant difference in the change in Uox (mmol/24 h/1.73 m2) between the groups (OC5: +0.042, placebo: -0.140). Post-hoc analysis showed a statistically significant increase in Uox per urinary creatinine excretion in the OC5 group (OC5: +5.41, placebo: -15.96; p = 0.030). Change in Pox from baseline was not significantly different between groups (p = 0.438). The O. formigenes cell count was significantly increased in OC5-treated patients (p < 0.001) versus placebo. The treatment response to O. formigenes was related to individual stage of kidney deterioration, and Pox was directly correlated to kidney function, even for early-stage patients (chronic kidney disease stage 1). No safety issues were observed. CONCLUSIONS: Treatment with OC5 did not significantly reduce Uox or Pox over 8 weeks of treatment. The treatment was well tolerated and successfully delivered to the gastrointestinal tract.

Observations of a large Dent disease cohort.

Dent disease classically combines low-molecular-weight proteinuria, hypercalciuria with nephrocalcinosis, and renal failure. Nephrotic range proteinuria, normal calciuria, and hypokalemia have been rarely reported. It is unknown whether the changes in phenotype observed over time are explained by a decrease in glomerular filtration rate (GFR) or whether there is any phenotype-genotype relationship. To answer this we retrospectively analyzed data from 109 male patients with CLCN5 mutations (Dent-1) and 9 patients with mutation of the OCRL gene (Dent-2). In Dent-1 disease, the estimated GFR decreased with age, by 1.0 to 1.6 ml/min per 1.73 m(2)/yr in the absence and presence of nephrocalcinosis, respectively, with no significant difference. Median values of low-molecular-weight proteinuria were in the nephrotic range and remained at the same level even in late renal disease. End-stage renal disease occurred in 12 patients, at a median age of 40 years. Hypercalciuria decreased with glomerular filtration and was absent in 40% of the patients under 30 and 85% of those over the age of 30. Hypophosphatemia did not resolve with age and calcitriol concentrations were in the upper normal range. Kalemia decreased with age, with half of the patients over the age of 18 presenting with hypokalemia. Thus, no phenotype/genotype correlation was observed in this cohort of patients with Dent disease.

Excellent long-term outcome of renal transplantation in cystinosis patients.

BACKGROUND: Cystinosis is a rare lysosomal disorder leading to end stage renal disease in more than 90 % of patients before 20 years of age. Data about safety and efficiency of renal transplantation in patients with cystinosis is scarce. We evaluated long-term outcomes of renal transplantation in adult patients with cystinosis. METHODS: Data of renal transplantation (n = 31) in 30 adult patients with cystinosis in 5 French university transplant centers between 1980 and 2013 were retrospectively analyzed. A control cohort of 93 patients was matched for age, graft date, living/deceased donor status and transplant center. RESULTS: Median age at transplantation was 20.4 years (7-36.5). At transplantation, all patients with cystinosis had corneal cystine deposits, 3 had diabetes and 7 had hypothyroidism. Graft survival was better in patients with cystinosis than in control patients (p = 0.013). Multivariate analysis confirmed that cystinosis was an independent protective factor for graft survival (Hazard Ratio (HR) 0.11; CI95 [0.02-0.61]). Specific complications of cystinosis occurred during follow up: diabetes mellitus (n = 4), hypothyroidism (n = 1), liver involvement (n = 1), neurologic involvement (n = 2). Proportion of post-transplant diabetes mellitus (PTDM) was not statistically different in cystinosis group compared to control group: 4 (13.0 %) compared to 5 (5.0 %), respectively (p = 0.25), with no differences regarding calcineurin inhibitors and steroids treatments during follow-up. CONCLUSIONS: Renal transplantation appears to be safe with excellent long-term outcomes in patients with cystinosis. These patients may receive standard immunosuppressive regimens with steroids and calcineurin inhibitors.

Long-term results of combined liver-kidney transplantation for primary hyperoxaluria type 1: the French experience.

Primary hyperoxaluria type 1 (PH1) is a hepatic metabolic defect leading to end-stage renal failure. The posttransplant recurrence of kidney disease can suggest a need for combined liver-kidney transplantation (LKT). However, the risk of LKT is theoretically far higher than the risk of kidney-alone transplantation (KAT). An unselected consecutive series of 54 patients with PH1 was analyzed according to the type of transplantation initially performed between May 1979 and June 2010 at 10 French centers. The duration of dialysis, extrarenal lesions, age, and follow-up were similar between the groups. Postoperative morbidity and mortality did not differ between the groups, and 10-year patient survival rates were similar for the LKT (n = 33) and KAT groups (n = 21; 78% versus 70%). Kidney graft survival at 10 years was better after LKT (87% versus 13%, P < .001) . Four patients (12.1%) lost their first kidney graft in the LKT group, whereas 19 (90%) did in the KAT group (P < .001). The recurrence of oxalosis occurred in 11 renal grafts (52%) in the KAT group but in none in the LKT group (P < .001). End-stage renal failure resulting from rejection was also higher in the KAT group (19% versus 9%, P < 0.0001). A second kidney transplant was performed for 15 patients (71%) in the KAT group versus 4 patients (12%) in the LKT group (P < 0.001). In conclusion, LKT for PH1 provides better kidney graft survival, less rejection, and similar long-term patient survival and is not associated with an increased short-term mortality risk. LKT must be the first-line treatment for PH1 patients with end-stage renal disease.

Nephropathic cystinosis: an international consensus document.

Cystinosis is caused by mutations in the CTNS gene (17p13.2), which encodes for a lysosomal cystine/proton symporter termed cystinosin. It is the most common cause of inherited renal Fanconi syndrome in young children. Because of its rarity, the diagnosis and specific treatment of cystinosis are frequently delayed, which has a significant impact on the overall prognosis. In this document, we have summarized expert opinions on several aspects of the disease to improve knowledge and provide guidance for diagnosis and treatment.

Fanconi syndrome and severe polyuria: an uncommon clinicobiological presentation of a Gitelman syndrome.

BACKGROUND: Gitelman syndrome is an autosomal recessive tubulopathy characterized by hypokalemia, hypomagnesemia, metabolic alkalosis and hypocalciuria. The majority of patients do not present with symptoms until late childhood or adulthood, and the symptoms are generally mild. We report here the first case of Gitelman syndrome presenting with the biological features of Fanconi syndrome and an early polyuria since the neonatal period. We discuss in this article the atypical electrolytes losses found in our patient, as well as the possible mechanisms of severe polyuria. CASE PRESENTATION: A 6-year-old Caucasian girl was admitted via the Emergency department for vomiting, and initial laboratory investigations found hyponatremia, hypokalemia, metabolic acidosis with normal anion gap, hypophosphatemia, and hypouricemia. Urinalysis revealed Na, K, Ph and uric acid losses. Thus, the initial biological profile was in favor of a proximal tubular defect. However, etiological investigations were inconclusive and the patient was discharged with potassium chloride and phosphorus supplementation. Three weeks later, further laboratory analysis indicated persistent hypokalemia, a metabolic alkalosis, hypomagnesemia, and hypocalciuria. We therefore sequenced the SLC12A3 gene and found a compound heterozygosity for 2 known missense mutations. CONCLUSIONS: Gitelman syndrome can have varying and sometimes atypical presentations, and should be suspected in case of hypokalemic tubular disorders that do not belong to any obvious syndromic entity. In this case, the proximal tubular dysfunction could be secondary to the severe hypokalemia. This report emphasizes the need for clinicians to repeat laboratory tests in undiagnosed tubular disorders, especially not during decompensation episodes.

Quality of life is improved and kidney function preserved in patients with nephropathic cystinosis treated for 2 years with delayed-release cysteamine bitartrate.

OBJECTIVES: To determine the long-term effects of delayed-release cysteamine bitartrate (DR-CYS) based on our previous work that established the short-term noninferiority of DR-CYS every 12 hours compared with immediate-release cysteamine bitartrate every 6 hours. STUDY DESIGN: We conducted a prospective, controlled, open label, single-arm study of DR-CYS for 2 years in 40 patients to assess efficacy in depletion of cystine in peripheral white blood cells, to assess the dose required to maintain white blood cell content of cystine <1 nmol ½ cystine/mg protein, to measure quality of life using the Pediatric Quality of Life Inventory, change in estimated glomerular filtration rate, and change in height Z-score. RESULTS: Through 24 months of study, the mean white blood cell content of cystine was always <1 nmol ½ cystine/mg protein, and the dose of DR-CYS decreased from 43.5-40.1 mg/kg/d (P = .05), and the significant improvement in social function, school function, and in total function scores on the Pediatric Quality of Life Inventory remained. The estimated glomerular filtration rate was maintained and growth velocity was maintained at 24 months compared with the baseline height Z-score. CONCLUSIONS: The use of a DR-CYS administered every 12 hours to patients with cystinosis is of great benefit to their quality of life and to important biomarkers of disease control, when studied in a prospective, controlled fashion. We suggest that DR-CYS should be considered for substrate depletion in patients with cystinosis.

A new gel formulation of topical cysteamine for the treatment of corneal cystine crystals in cystinosis: the Cystadrops OCT-1 study.

OBJECTIVE: To establish the safety and efficacy of a new gel formulation of cysteamine hydrochloride (CH) eye drops, for the treatment of corneal complications of nephropathic cystinosis. DESIGN: Open label dose response clinical trial. PARTICIPANTS: Eight patients with infantile nephropathic cystinosis including 4 children, 3 adolescents, and 1 adult (mean age at inclusion, 12.1 ± 4.6 years) treated with CH 0.1% eye drops. INTERVENTION: Patients were treated, in both eyes, with the control CH 0.1% eye drop formulation on average 4 times daily for one month and then switched to Cystadrops® at the same dose frequency. Based on clinical ocular findings, the dose regimen was adapted at D30 and D90 in order to decrease the frequency of instillation. After D90, this dose frequency was maintained, except in cases of crystal density worsening. Patients had a follow-up visit every 6 months during 48 months. MAIN OUTCOME MEASURES: Safety assessment consisted of adverse event and serious adverse event monitoring and recording at each visit. For the efficacy study, the primary endpoint was the corneal cystine crystal density measured with an in vivo confocal microscopy (IVCM) score. RESULTS: All patients completed the study. During the 4-year study period, neither serious adverse events nor significant adverse events related to the study drug were reported. After switching to Cystadrops®, the IVCM total score decreased from baseline to D90 by a mean of 28.6 ± 17.5% (p<0.001). From D90 to M48, the IVCM total score remained stable and significantly decreased as compared to that at D1 despite a reduced dose regimen from D90. At M48, the mean IVCM total score was 8.13 ± 4.15, decreased by a mean 29.9 ± 26.29% from D1 (p = 0.001), with a reduced number of instillations compared to that at D1. The IVCM total score and photophobia were significantly correlated (p = 0.04). CONCLUSION: This study provides evidence that Cystadrops® gel is superior to the CH 0.1% formulation in terms of efficacy and has a good safety profile over a long follow-up period.

Allo-immune membranous nephropathy and recombinant aryl sulfatase replacement therapy: a need for tolerance induction therapy.

Nephrotic syndrome was reported in a highly-sensitized patient receiving enzyme replacement therapy (ERT) for Pompe disease, but the prevalence of ERT-induced renal complications and mechanisms to facilitate readministration of ERT in these patients remain unexplored. This work identifies a new antigen responsible for secondary membranous nephropathy (MN) in a patient with mucopolysaccharidosis type VI caused by aryl sulfatase B (ASB) deficiency. ERT (recombinant human ASB [rhASB]; 1 mg/kg per week) started at the age of 4 years led to a high anti-rhASB titer and dramatically improved clinical manifestations. However, 16 months later, the patient suddenly developed nephrotic syndrome resistant to steroid therapy 1 week after orthopedic surgery. Examination of the kidney biopsy specimen revealed glomerular deposition of IgG (mostly IgG4, C3, and C5b-9) in a granular pattern typical of MN. Double immunofluorescence staining showed that subepithelial granular deposits contained rhASB colocalized with IgG. Ig eluted from the patient's biopsy specimen reacted specifically with rhASB. On discontinuation of ERT, proteinuria progressively decreased, but the patient's clinical condition markedly deteriorated. Induction of tolerance to rhASB was initiated by coadministration of low-dose corticosteroids, rituximab, intravenous Igs, and oral methotrexate. ERT was resumed 8 weeks after starting immunosuppressive therapy without inducing a rebound of antibody titer or an increase in proteinuria. We conclude that the allo-immune response to the recombinant rhASB caused the nephropathy. Considering the critical requirement for ERT in patients with such enzyme deficiencies, immune tolerance induction should be advocated in the patients with allo-immune MN.

Long-term remission of atypical HUS with anti-factor H antibodies after cyclophosphamide pulses.

BACKGROUND: Anti-complement factor H (CFH) autoantibody (Ab)-associated atypical hemolytic uremic syndrome (aHUS) has a poor prognosis, but no consensus exists on its treatment. METHODS: We report the follow-up of four children with anti-CFH Ab (8,000 to >32,000 arbitrary units)-associated aHUS after plasma exchanges (PEs), prednisone, and cyclophosphamide pulse therapy with the evolution of anti-CFH Ab titers and kidney function. RESULTS: Patient 1 received PEs + prednisone + cyclophosphamide pulses after two relapses following PEs and then PEs + rituximab. The other three patients were treated with PEs + prednisone + cyclophosphamide pulses as a first-line therapy. In our four patients, the induction protocol combining PEs + prednisone + cyclophosphamide pulses led to a rapid and sustained remission up to 6 years, 4 years and 4 months without any maintenance therapy. Kidney function was normal and anti-CFH Ab titer decreased, but remained detectable during remission without any clinical or biological signs of relapse. CONCLUSIONS: We demonstrate the long-term efficiency and safety of cyclophosphamide pulses combined with PEs and prednisone in anti-CFH Ab-associated aHUS leading to a prolonged decrease in anti-CFH Ab titers and prevention of relapses without the need for maintenance therapy.