Renal transplantation in 4 patients with methylmalonic aciduria: a cell therapy for metabolic disease.

INTRODUCTION: Patients with methylmalonic acidemia (MMA) may develop many complications despite medical treatment, in particular, severe central nervous system damage and chronic kidney disease (CKD). A kidney transplant may partially correct the metabolic dysfunctions. Liver, kidney and combined liver-kidney transplantations have been advocated but no guidelines are available to identify the most suitable organ to transplant. PATIENTS AND METHODS: Four patients with MMA (mut° phenotype) received a kidney graft because of repeated metabolic decompensations, with progression to CKD in 3 patients (end-stage kidney disease in two patients and CKD stage III in one patient with an estimated glomerular filtration rate [eGFR] of 40ml/min/1.73m(2)) but normal renal function in one (eGFR of 93ml/min/1.73m(2)) before transplantation. RESULTS: The medium age at transplantation was 7.9y (5-10.2) and the median follow-up was 2.8years (1.8-4.6). Renal transplantation improved the relevant metabolic parameters in 4/4 patients and renal function in the patients with CKD. Plasma and urinary MMA levels immediately decreased and remained normal or subnormal (mean values of plasma MMA before transplantation 1530µmol/L versus 240µmol/L after transplantation, and mean values of urine MMA before transplantation 4700mmol/mol creatinine versus 2300mmol/mol creatinine after transplantation). No further acute metabolic decompensation was observed and protein-intake was increased from 0.60 to 0.83g/Kg/day. One patient transplanted at age 9.7years developed a hepatoblastoma at age 11years with subsequent neurological complications and eventually died. The three other patients are alive. Two of them remained neurologically stable. The 3rd patient who displayed choreoathetosis transiently improved his neurological condition immediately after transplantation and then remained stable. CONCLUSION: Kidney transplantation represents an interesting alternative therapeutic option in methylmalonic aciduria, for renal complications but also as a "cellular therapy" that may significantly reduce metabolic decompensations and hospitalizations. However, further neurological impairment remains possible.

NPHS2, encoding the glomerular protein podocin, is mutated in autosomal recessive steroid-resistant nephrotic syndrome.

Familial idiopathic nephrotic syndromes represent a heterogeneous group of kidney disorders, and include autosomal recessive steroid-resistant nephrotic syndrome, which is characterized by early childhood onset of proteinuria, rapid progression to end-stage renal disease and focal segmental glomerulosclerosis. A causative gene for this disease, NPHS2, was mapped to 1q25-31 and we report here its identification by positional cloning. NPHS2 is almost exclusively expressed in the podocytes of fetal and mature kidney glomeruli, and encodes a new integral membrane protein, podocin, belonging to the stomatin protein family. We found ten different NPHS2 mutations, comprising nonsense, frameshift and missense mutations, to segregate with the disease, demonstrating a crucial role for podocin in the function of the glomerular filtration barrier.

A mutant mitochondrial respiratory chain assembly protein causes complex III deficiency in patients with tubulopathy, encephalopathy and liver failure.

Complex III (CIII; ubiquinol cytochrome c reductase of the mitochondrial respiratory chain) catalyzes electron transfer from succinate and nicotinamide adenine dinucleotide-linked dehydrogenases to cytochrome c. CIII is made up of 11 subunits, of which all but one (cytochrome b) are encoded by nuclear DNA. CIII deficiencies are rare and manifest heterogeneous clinical presentations. Although pathogenic mutations in the gene encoding mitochondrial cytochrome b have been described, mutations in the nuclear-DNA-encoded subunits have not been reported. Involvement of various genes has been indicated in assembly of yeast CIII (refs. 8-11). So far only one such gene, BCS1L, has been identified in human. BCS1L represents, therefore, an obvious candidate gene in CIII deficiency. Here, we report BCS1L mutations in six patients, from four unrelated families and presenting neonatal proximal tubulopathy, hepatic involvement and encephalopathy. Complementation study in yeast confirmed the deleterious effect of these mutations. Mutation of BCS1L would seem to be a frequent cause of CIII deficiency, as one-third of our patients have BCS1L mutations.

Donor splice-site mutations in WT1 are responsible for Frasier syndrome.

Frasier syndrome (FS) is a rare disease defined by male pseudo-hermaphroditism and progressive glomerulopathy. Patients present with normal female external genitalia, streak gonads and XY karyotype and frequently develop gonadoblastoma. Glomerular symptoms consist of childhood proteinuria and nephrotic syndrome, characterized by unspecific focal and segmental glomerular sclerosis, progressing to end-stage renal failure in adolescence or early adulthood. No case of Wilms' tumour has been reported, even in patients with extended follow-up. In contrast with FS patients, most individuals with Denys-Drash syndrome (DDS; refs 6,7) have ambiguous genitalia or a female phenotype, an XY karyotype and dysgenetic gonads. Renal symptoms are characterized by diffuse mesangial sclerosis, usually before the age of one year, and patients frequently develop Wilms' tumour. Mutations of the Wilms'-tumour gene, WT1, cause different pathologies of the urogenital system, including DDS. WT1 is composed of ten exons and encodes a protein with four zinc-finger motifs and transcriptional and tumour-suppressor activities. Alternative splicing generates four isoforms: the fifth exon may or may not be present, and an alternative splice site in intron 9 allows the addition of three amino acids (KTS) between the third and fourth zinc fingers of WT1 (ref. 17). Here we demonstrate that FS is caused by mutations in the donor splice site in intron 9 of WT1, with the predicted loss of the +KTS isoform. Examination of WT1 transcripts indeed showed a diminution of the +KTS/-KTS isoform ratio in patients with FS.

Renal transplantation under prophylactic eculizumab in atypical hemolytic uremic syndrome with CFH/CFHR1 hybrid protein.

We report the first observation of successful kidney transplantation under pre-emptive eculizumab treatment in a 7-year-old boy with atypical hemolytic uremic syndrome (aHUS) and a known hybrid CFH/CFHR1 gene, who was dependent on plasma therapy during the 3-year dialysis period. The hybrid CFH/CFHR1 protein has an altered C3b/C3d binding, is incapable to protect cells from complement attack and is directly implicated in aHUS pathogenesis. There was no evidence of recurrence during the first 16-month follow-up period. We conclude that eculizumab alone, without plasma therapy (plasma infusion and/or plasma exchange), is sufficient to prevent recurrence of aHUS and to maintain long-term graft function.

Eculizumab for atypical hemolytic uremic syndrome recurrence in renal transplantation.

Eculizumab (anti-C5) has been sporadically reported as an efficient therapy for atypical hemolytic uremic syndrome (aHUS). However, the lack of series precludes any firm conclusion about the optimal use of anti-C5 for preventing or treating aHUS posttransplant aHUS recurrence. We thoroughly studied 22 renal transplant recipients with aHUS who received off-label therapy with anti-C5, including 12 cases, which have not been reported yet. Nine patients, all carrying a complement genetic abnormality associated with a high risk of aHUS recurrence, received prophylactic anti-C5 therapy to prevent posttransplant recurrence. Eight of them had a successful recurrence-free posttransplant course and achieved a satisfactory graft function, while the remaining patient experienced early arterial thrombosis of the graft. Thirteen renal transplant recipients were given anti-C5 for posttransplant aHUS recurrence. A complete reversal of aHUS activity was obtained in all of them. Importantly, the delay of anti-C5 initiation after the onset of the aHUS episode inversely correlated with the degree of renal function improvement. Three patients in whom anti-C5 was subsequently stopped experienced a relapse. Altogether these data suggest that long-term eculizumab is highly effective for preventing and treating posttransplant aHUS recurrence. Our study also indicates that anti-C5 should be promptly started if a recurrence occurs.

Anti-Factor H autoantibodies in a fifth renal transplant recipient with atypical hemolytic and uremic syndrome.

Hemolytic uremic syndrome (HUS) associated with anti-Factor H (anti-FH) autoantibodies is a recently described pathophysiological entity. Monitoring of anti-FH IgG titer may be a sensitive marker of disease activity and guide treatment to eliminate circulating anti-FH antibodies. We report here a case of atypical HUS (aHUS) in which anti-FH autoantibodies were detected during the course of a fifth kidney transplant, 30 years after the first flare of aHUS. This exceptional case suggests that early, specific management based on immunosuppressive therapy and plasma exchanges monitored by anti-FH IgG titer may result in long-term graft survival.

Long-term outcome in methylmalonic aciduria: a series of 30 French patients.

OBJECTIVE: To better delineate the natural history of patients with methylmalonic aciduria (MMA). STUDY DESIGN: Thirty patients with vitamin-B12-unresponsive MMA (25 aged 1.5 to 22.0 years (y) at the end of the study and 5 who died during a metabolic crisis) were managed following standardized guidelines and studied retrospectively. The median follow-up was 8.3 y (range: 1.4-19.5). Patients were investigated with neuropsychological testing, brain MRIs, inulin clearances, biochemical and genetic studies. RESULTS: Fifteen patients had a neonatal onset. Thirteen patients (43%) had significant neurological impairment. Chronic renal disease (CRD) occurred in 14 patients (47%) with a median age of onset of 6.5 y (range 1.5-18.6). Renal function further deteriorated in 4 patients within a median period of 5.8 y (range 2-7.4). Of 25 patients investigated at the enzymatic level, 17 were classified mut(o), 3 mut- and 5 cblA. Mortality, number of acute decompensations (p=0.031), median MMA urinary excretion (p=0.006) and neurological impairment (p<0.0001) were higher in mut degrees patients compared to mut-/cblA patients. Concerning the CRD, no difference incidence was found although the onset of CRD occurred earlier in mut(o) patients and was more severe. CONCLUSIONS: Our study provides unique data concerning the progression of renal disease in MMA. Patients with mut(o) phenotype have a more severe phenotype and probably an earlier and more severe CRD than patients with mut-/cblA phenotype.

Liver hepatoblastoma and multiple OXPHOS deficiency in the follow-up of a patient with methylmalonic aciduria.

A boy who was diagnosed with methylmalonic aciduria (MMA) at the age of 10 days developed persistent hepatomegaly and raised transaminases from the age of 4 years. He was subsequently diagnosed with Leigh syndrome and required a kidney transplantation for end-stage renal failure. A massive hepatoblastoma led to his death by the age of 11 years. Methylmalonyl-CoA mutase activity was undetectable on both cultured skin fibroblasts and kidney biopsy and multiple respiratory chain deficiency was demonstrated in the kidney. Mitochondrial dysfunction and/or post-transplant immunosuppressive therapy should be considered as a possible cause of liver cancer in this patient.

Long-term follow-up of ifosfamide renal toxicity in children treated for malignant mesenchymal tumors: an International Society of Pediatric Oncology report.

The renal function of 74 children with malignant mesenchymal tumors in complete remission and who have received the same ifosfamide chemotherapy protocol (International Society of Pediatric Oncology Malignant Mesenchymal Tumor Study 84 [SIOP MMT 84]) were studied 1 year after the completion of treatment. Total cumulative doses were 36 or 60 g/m2 of ifosfamide (six or 10 cycles of ifosfamide, vincristine, and dactinomycin [IVA]). None of them had received cisplatin chemotherapy. Ages ranged from 4 months to 17 years; 58 patients were males and 42 females. The most common primary tumor site was the head and neck. Renal function was investigated by measuring plasma and urinary electrolytes, glucosuria, proteinuria, aminoaciduria, urinary pH, osmolarity, creatinine clearance, phosphate tubular reabsorption, beta 2 microglobulinuria, and lysozymuria. Fifty-eight patients (78%) had normal renal tests, whereas 16 patients (22%) had renal abnormalities. Two subsets of patients were identified from this latter group: the first included four patients (5% of the total population) who developed major toxicity resulting in Fanconi's syndrome (TDFS); and the second group included five patients with elevated beta 2 microglobulinuria and low phosphate reabsorption. The remaining seven patients had isolated beta 2 microglobulinuria. Severe toxicity was correlated with the higher cumulative dose of 60 g/m2 of ifosfamide, a younger age (less than 2 1/2 years old), and a predominance of vesicoprostatic tumor involvement. This low percentage (5%) of TDFS must be evaluated with respect to the efficacy of ifosfamide in the treatment of mesenchymal tumors in children.

Molecular identification of human T-lymphocyte antigens defined by the OKT5 and OKT8 monoclonal antibodies.

Three human lymphocyte differentiation antigens, specific of the entire T-cell population, of the helper/inducer T-cell subset, and of the cytotoxic/suppressor T-cell subset have been identified, using mouse monoclonal antibodies obtained from Dr. P. Kung. Various T-cell populations were radio-labelled, the antigens were isolated by immunoprecipitation with the monoclonal antibodies and the resulting immune complexes subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The OKT3 antigen, present on peripheral T-lymphocytes and on functionally mature thymocytes has been identified as an oligomeric protein, composed of 23,000 mol. wt subunits. The OKT4 antigen, specific for the helper/inducer subset, is a single protein of 53,000 mol. wt. The OKT8/OKT5 antigen, defining the cytotoxic/suppressor subpopulation is composed of two subunits of 31,000 and 33,000. From co-capping experiments and biochemical data, the hypothesis is established that OKT5 recognizes a dimer of 140,000 mol. wt and OKT8 recognizes a determinant present on both the monomer 70,000 and the dimer. This hypothesis could explain the OKT5- OKT8+ phenotype of some T-cells.

The IgE humoral response in OKT3-treated patients. Incidence and fine specificity.

We recently described a case of anaphylaxis occurring at the time of retreatment with OKT3 of a renal allograft recipient in whom, for the first time, high anti-OKT3 IgE levels were documented. This led us to examine a large series of sera from 181 OKT3-treated patients to better define the frequency of IgE sensitization, its fine specificity (anti-isotypic and/or anti-idiotypic) and its relation to the appearance of IgG anti-OKT3 antibodies (Abs). Six patients out of the 181 assayed have developed anti-OKT3 IgE Abs as detected by ELISA. The earliest time of appearance of IgE anti-OKT3 Abs was 10 days after starting OKT3 (range, 10-25). The IgE response peaked by day 18 (range, 11-35) and had usually disappeared at 3 months after treatment. A more careful dissection of the fine specificity of the IgE response revealed that three of the four patients tested had developed an exclusive anti-idiotypic response. In the last patient, an anti-isotypic component was present since anti-OKT3 IgE Abs also reacted with control IgG2a, IgG2b, and IgG3 monoclonal antibodies. Importantly, anti-OKT3 IgE Abs were only detected in heavily sensitized patients also showing high titers of IgG specific Abs by ELISA (> or = 1/1000) as well as "blocking" anti-OKT3 antibodies, as assessed by immunofluorescence. We conclude that (1) exposure to OKT3 may lead to specific IgE sensitization that, however, only appears in about 38% of the patients; (2) IgE Abs mostly appear in patients also showing high levels of conventional IgG anti-OKT3 Abs including the presence of "blocking" anti-idiotypic Abs, and (3) IgE Abs may be directed to both idiotypic and isotypic determinants of the monoclonal antibody.

Multicentric Kaposi's sarcoma in a 5-year-old human immunodeficiency virus-negative renal allograft recipient.

We describe the clinical and pathologic features of a case of pediatric multicentric Kaposi's sarcoma (KS) associated with allograft transplantation in a human immunodeficiency virus (HIV)-negative child. A lethal polyadenopathic and visceral KS occurred in a 5-year-old Caribbean boy who had undergone an allogenic renal transplantation for diffuse mesangial sclerosis with end-stage renal failure 4 months previously. The HIV-1 and HIV-2 serologies were negative. Despite its rarity, KS must be considered as a differential diagnosis in posttransplantation polyadenopathic or multisystemic syndromes in children.

Immunological factors in organ transplantation.

Several immunological factors affect the outcome of human kidney transplants. HLA-A, -B and -DR matching improves kidney graft survival rate, especially matching for HLA-DR antigens. The beneficial effect of pretransplant blood transfusion has been confirmed although the mechanisms of the beneficial effect are not clear. Donor specific transfusion prior to living related donor kidney transplantation improve graft survival but some 30% of potential recipients become sensitized to the donor during the transfusion process. Major improvements in the results of organ transplantation have been achieved during the past few years with the use of new immunosuppressive agents, namely cyclosporin and monoclonal antibodies reacting with T lymphocytes. Both agents act selectively on T lymphocytes. However, nephrotoxicity of cyclosporin may limit its use.

Detection of antilineage specific leucocyte antibodies by a quantitative immunocytometry method in sera from candidates for renal allografts.

A sensitive and quantitative flow cytometry method for detecting antileucocyte antibodies was developed to study retrospectively samples from candidates using frozen donor cells and frozen recipient sera. This immunofluorescence method was used to compare levels of reactivities of serum antibodies before and after donor specific blood transfusion treatment and after renal transplantation. The results demonstrate that the flow cytometry crossmatch is a sensitive and accurate method which should be used prospectively before precluding transplantation in the presence of a positive B cell standard crossmatch. Antibodies detected by flow cytometry before transplantation could be responsible for an early acute rejection episode. Finally, combination of flow cytometry crossmatch and standard crossmatch assays might thus be useful before precluding transplantation in living related donors.

Cyclosporine in the therapy of steroid-resistant idiopathic nephrotic syndrome.

Steroid-resistant nephrotic syndrome with either minimal changes or focal and segmental glomerular sclerosis on initial biopsy is a severe condition as more than 50% of patients with the disease progress to end-stage renal failure within 10 years. We recently identified a distinct form of idiopathic nephrotic syndrome with an autosomal recessive mode of inheritance and were able to map the gene on the long arm of chromosome 1. The absence of recurrence of the disease after renal transplantation suggest a primary defect in a glomerular basement membrane protein. Several reports suggest that cyclosporine is effective in a proportion of patients with steroid-resistant idiopathic nephrotic syndrome, particularly when used in combination with corticosteroids. There are also data suggesting that high doses of cyclosporine may be necessary in patients with severe hypercholesterolemia. However, cyclosporine treatment should be carefully monitored in view of the high risk of nephrotoxicity, as shown by the results of repeat renal biopsies. The beneficial role of cyclosporine in recurrent steroid-resistant nephrotic syndrome is still debated. Preliminary observations suggest that the early use of intravenous cyclosporine may be effective in these patients.

Management of oxalosis.

Oxalosis is the final stage of primary hyperoxaluria type I (PHI) when reduction of GFR produces oxalate accumulation. It involves bones, arteries, eyes, heart, nerves, etc. The management of oxalosis starts with prevention of nephrocalcinosis and renal failure by diluting urine and by inhibiting oxalate crystal formation either by increasing the urinary citrate or the urinary pyrophosphate. At endstage renal disease (ESRD) there is no dialysis modality for avoiding the progression of oxalosis. Combined liver/kidney transplantation (LKT) represents the most effective approach. The European PHI transplant registry recently reported 64 LKT with a five-year patient survival of 80% and progressive healing of oxalosis. Four children who received LKT in our unit are reported, all of whom are alive with a follow-up of three months to five years. Bone disease completely healed in one case after three years, but retinal deposits persisted despite improvement of visual acuity. A special perioperative protocol must be applied for protecting the graft from oxalate released from the stores. Laboratory follow-up including oxalemia and urinary crystal volume helps to adjust the individual prescriptions. This intensive management must be continued as long as oxalate stores persist.

Nutritional and metabolic studies in children on continuous ambulatory peritoneal dialysis.

A study was done of 15 children and adolescents, aged 2.5 to 17.5 years, who were treated by continuous ambulatory peritoneal dialysis (CAPD) for 6 to 24 months. Plasma albumin concentration decreased from 34.4 +/- 4.8 g/liter at the onset of therapy to 31.3 +/- 5.3 g/liter after 19 to 24 months. Children less than 6 years old had lower albumin levels (29.4 +/- 1.7 g/liter) than did the older group (36.3 +/- 4.2 g/liter). The lower plasma albumin was related to peritoneal protein loss but not to protein intake. Plasma free amino acid concentrations were not significantly modified. No changes occurred in the oral glucose tolerance test during the course of CAPD. Plasma cholesterol and triglycerides were abnormally high for age, with a correlation seen between cholesterolemia and peritoneal protein loss.

Comparison of three low-nitrogen diets containing essential amino acids and their alpha analogues for severely uremic children.

Six infants, 4.5 to 19 months old, whose creatinine clearance was less than 6 ml/min/1.73 m2 received, successively, three low-nitrogen diets. Diet A contained 9.3 g of human milk protein; and diet B, 4.2 g of human milk protein plus synthetic essential amino acids. Diet C was the same as B except that five essential amino acids were replaced by alpha-keto and hydroxy analogs. Serum urea decreased as the infants were transferred from diet A to diets B and C, and the serum urea/creatinine ratio decreased from diet A to diet B and from diet B to diet C. Urea appearance was 14.8 +/- 4.5, 9.1 +/- 4.3, and 6.9 +/- 1.7 mmoles/day, with diets A, B, and C, respectively. Weight gain was also lowest with diet C, as was the difference between nitrogen intake and urea nitrogen appearance, an indicator of nitrogen balance. Plasma free amino acids were not modified by diets A and B, but valine, leucine, and the plasma free essential amino acid pool decreased significantly with diet C.

A specific glomerular lesion of the graft: allograft glomerulopathy.

During the period from January 1973 to December 1970, 774 renal transplantations in 698 children have been performed in our Renal Unit. A total of 540 grafts have been examined both by light and immunofluorescence microscopy at least once. Recurrent glomerulonephritis was diagnosed in 62 grafts, de novo glomerulonephritis in 68 and allograft glomerulopathy (AGP) in 38. AGP was defined as a lesion affecting all glomeruli and characterized by widespread reduplication of the GBM with widening of the subendothelial space and interposition of mesangial matrix and without significant deposits by immunofluorescence. The aim of the current study is to describe the natural history of AGP and to delinate its clinical significance. At time of biopsy, an increase in serum creatinine was present in 30 patients associated with a proteinuria > or = 1 g/day in 21. During the post-transplantation course, proteinuria was present in 29 patients and associated with a nephrotic syndrome in 10 of them. With a mean follow-up of eight years seven months, two patients died, 23 lost their grafts and 13 have a functioning graft. The lesions of AGP recurred in three of the nine children who received a second graft. Thirteen of the 33 patients in whom earlier biopsies were performed showed a different pattern of involvement characterized by a prominent swelling of active endothelial and mesangial cells and a hypercellularity related to the presence of mononuclear cells both in the lumens and in the mesangial areas.(ABSTRACT TRUNCATED AT 250 WORDS)