Graft function 5-7 years after renal transplantation in early childhood

Is mild dehydration a risk for progression of childhood chronic kidney disease?

Children with chronic kidney disease (CKD) can have an inherent vulnerability to dehydration. Younger children are unable to freely access water, and CKD aetiology and stage can associate with reduced kidney concentrating capacity, which can also impact risk. This article aims to review the risk factors and consequences of mild dehydration and underhydration in CKD, with a particular focus on evidence for risk of CKD progression. We discuss that assessment of dehydration in the CKD population is more challenging than in the healthy population, thus complicating the definition of adequate hydration and clinical research in this field. We review pathophysiologic studies that suggest mild dehydration and underhydration may cause hyperfiltration injury and impact renal function, with arginine vasopressin as a key mediator. Randomised controlled trials in adults have not shown an impact of improved hydration in CKD outcomes, but more vulnerable populations with baseline low fluid intake or poor kidney concentrating capacity need to be studied. There is little published data on the frequency of dehydration, and risk of complications, acute or chronic, in children with CKD. Despite conflicting evidence and the need for more research, we propose that paediatric CKD management should routinely include an assessment of individual dehydration risk along with a treatment plan, and we provide a framework that could be used in outpatient settings.

Hospital admissions associated with dehydration in childhood kidney transplantation

BACKGROUND

Paediatric kidney transplant recipients may be at a particular risk of dehydration due to poor kidney concentrating capacity and illness associated with poor fluid intake or losses. In this population, creatinine rise may be more likely with relatively mild dehydration, which may trigger hospital admission. This study describes hospital admissions in the first 12 months after transplantation with diagnosis of graft dysfunction associated with dehydration due to illness or poor fluid intake. We assess risk factors for these admissions.

METHODS

Data was extracted from medical records of patients transplanted in two tertiary children hospitals. Following descriptive analysis, multiple failure regression analyses were used to identify factors associated with admission for acute kidney allograft dysfunction associated with dehydration.

RESULTS

Of 92 children, 42% had at least 1 dehydration admission in the 12 months following transplantation. Almost half of the dehydration admissions were due to poor fluid intake, which accounted for 1/5 of all unplanned hospital admissions. Target fluid intake at first discharge of > 100 ml/kg/day was associated with dehydration admissions of all types (hazard ratio (HR) 2.04 (95% CI 1.13-3.68)). Teen age was associated with poor fluid intake dehydration admissions (HR 4.87 (95% CI 1.19-19.86)), which were more frequent in mid-summer. Use of enteric feeding tube, which correlated with age under 4, associated with contributing illness dehydration admissions (HR 2.18 (95% CI 1.08-4.41)).

CONCLUSIONS

Dehydration admissions in the 12 months following childhood kidney transplantation are common. Highlighted admission risk factors should prompt further study into optimal fluid intake prescription and hydration advice given to children, teenagers, and their carers following kidney transplantation. Use of an enteric feeding tube may not protect patients from admission with dehydration associated with contributing illness. A highger resolution version of the Graphical abstract is available as Supplementary information.

Congenital nephrotic syndrome: is early aggressive treatment needed? Yes

Congenital nephrotic syndrome (CNS) was primarily considered one disease entity. Hence, one treatment protocol was proposed in the beginning to all CNS patients. Today, with the help of gene diagnostics, we know that CNS is a heterogeneous group of disorders and therefore, different treatment protocols are needed. The most important gene defects causing CNS are NPHS1, NPHS2, WT1, LAMB2, and PLCE1. Before active treatment, all infants with CNS died. It was stated already in the mid-1980s that intensive medical therapy followed by kidney transplantation (KTx) should be the choice of treatment for infants with severe CNS. In Finland, early aggressive treatment protocol was adopted from the USA and further developed for treatment of children with the Finnish type of CNS. The aim of this review is to state reasons for "early aggressive treatment" including daily albumin infusions, intensified nutrition, and timely bilateral nephrectomy followed by KTx at the age of 1-2 years.

NPHS1 gene mutations confirm congenital nephrotic syndrome in four Brazilian cases: A novel mutation is described

AIM

Autosomal recessive mutations in NPHS1 gene are a common cause of congenital nephrotic syndrome (CNS). The disorder is characterized by massive proteinuria that manifests in utero or in the neonatal period during the first 3 months of life. NPHS1 encodes nephrin, a member of the immunoglobulin family of cell adhesion molecules and the main protein expressed at the renal slit diaphragm. Currently, there are approximately 250 mutations described in the NPHS1 gene distributed among all nephrin domains. The main objective of this study was to perform the analysis of the NPHS1 gene in patients with congenital nephrotic syndrome in order to determine the molecular cause of the disease.

METHODS

Direct sequencing of NPHS1 gene in four children was performed.

RESULTS

Each patient was heterozygous for two pathogenic mutations disclosing the molecular cause of the disease in 100% of the cases. We identified six different mutations, consisting of one in-frame deletion, one frameshift, and four missense substitutions. The p.Val736Met mutation that is described here for the first time was considered pathogenic by different mutation predictive algorithms. Regardless of the type of mutation, three patients had a bad outcome and died

CONCLUSIONS

Despite the small size of the cohort, this study contributed to the increasing number of deleterious mutations in the NPHS1 gene by describing a new mutation. Also, since we identified NPHS1 pathogenic mutations as the cause of the disease in all cases analyzed, it might be a frequent cause of CNS in the South Eastern region of Brazil, although the analysis of a larger sample is required to obtain more indicative epidemiological data.

Pathology of Podocytopathies Causing Nephrotic Syndrome in Children

Nephrotic syndrome (NS) in children includes a diverse group of diseases that range from genetic diseases without any immunological defects to causes that are primarily due to immunological effects. Recent advances in molecular and genomic studies have resulted in a plethora of genetic defects that have been localized to the podocyte, the basic structure that is instrumental in normal filtration process. Although the disease can manifest from birth and into adulthood, the primary focus of this review would be to describe the novel genes and pathology of primary podocyte defects that cause NS in children. This review will restrict itself to the pathology of congenital NS, minimal change disease (MCD), and its variants and focal segmental glomerulosclerosis (FSGS). The two major types of congenital NS are Finnish type characterized by dilated sausage shaped tubules morphologically and diffuse mesangial sclerosis characterized by glomerulosclerosis. MCD has usually normal appearing biopsy features on light microscopy and needs electron microscopy for diagnosis, whereas FSGS in contrast has classic segmental sclerosing lesions identified in different portions of the glomeruli and tubular atrophy. This review summarizes the pathological characteristics of these conditions and also delves into the various genetic defects that have been described as the cause of these primary podocytopathies. Other secondary causes of NS in children, such as membranoproliferative and membranous glomerulonephritis, will not be covered in this review.

Renal transplantation in children with nephrotic syndrome in the first year of life

OBJECTIVE

The aim of this work was to analyze the evolution of the 1st renal transplantation in children with nephrotic syndrome in the 1st year of life (NSFL).

METHODS

In this retrospective study of 15 patients (8 women and 7 men) with NSFL receiving transplants from 1989 to 2013, 9 had NS of Finnish type, 4 diffuse mesangial sclerosis, 1 minimal changes, and 1 collapsing glomerulopathy. We analyzed the clinical and analytic situation at 4 time points: before dialysis, before transplantation, 3 months after transplantation, and long-term evolution.

RESULTS

Mean follow-up was 72.8 months (range, 1 month to 16.9 years); mean age at diagnosis was 2.21 months (range, 0-8.2 months); mean age at onset of replacement therapy was 22.9 ± 16.4 months (range, 3.8-55.4 months); and mean time on dialysis was 14.9 months (range, 2-44 months). Age at transplantation was 3.1 years (range, 1.8 to 7.7 years), with 6 living-donor transplantations (LDTs) and 9 cadaveric (CDTs). Ten patients required nephrectomy before transplantation (9 bilateral) to control proteinuria after 3.1 ± 3.8 months on dialysis, 1 during transplantation, and 3 after transplantation (2 persistent proteinuria, 1 hypertension). Mean time on dialysis for LDTs was 5.4 ± 2.7 months versus 13.2 ± 6.9 months for CDTs (P < .005). Mean age of cadaveric donors was 6.2 ± 2.4 years and that of living donors 35.5 ± 7.9 years. As complications, there was 1 bleeding from venous anastomosis and 1 urinary leakage after surgery. After 6 ± 5.2 years of evolution, actuarial survival at both 1 and 7 years was 92.9%. One graft was lost owing to acute rejection 1 month after transplantation and 2 others owing to chronic rejection >9 years after transplantation. None had disease recurrence.

CONCLUSIONS

Short-term complications did not differ from the rest of population if transplantation occurred with standard albumin levels, for which most required pre-transplantation nephrectomy because dialysis failed to reduce proteinuria.

Metabolic risk factors and long-term graft function after paediatric renal transplantation

The aim of this study was to evaluate metabolic risk factors and their impact on long-term allograft function in paediatric renal transplant (RTx) patients. We reviewed the medical records of 210 RTx patients who underwent transplantation at a median age of 4.5 years (range 0.7-18.2) and a median follow-up of 7.0 years (range 1.5-18.0). Data on lipid and glucose metabolism, uric acid levels, weight and blood pressure were collected up to 13 years post-RTx, and the findings were correlated with the measured glomerular filtration rate (GFR). Beyond the first year, GFR showed gradual deterioration with a mean decline of 2.4 ml/min/1.73 m(2)/year. Metabolic syndrome, overweight, hypertension and type 2 diabetes were diagnosed in 14-19%, 20-23%, 62-87% and 3-5% of the patients, respectively. These entities showed only mild association with the concomitant or long-term GFR values. Dyslipidaemia was common and hypertriglyceridaemia associated with a lower GFR at 1.5 and 5 years post-RTx (P = 0.008 and P = 0.017, respectively). Similarly, hyperuricaemia was frequent and associated significantly with GFR (P < 0.001). Except for hyperuricaemia and hypertriglyceridaemia, metabolic risk factors beyond the first postoperative year associated modestly with the long-term kidney graft function in paediatric RTx patients.

Nineteen novel NPHS1 mutations in a worldwide cohort of patients with congenital nephrotic syndrome (CNS)

BACKGROUND

Recessive mutations in the NPHS1 gene encoding nephrin account for approximately 40% of infants with congenital nephrotic syndrome (CNS). CNS is defined as steroid-resistant nephrotic syndrome (SRNS) within the first 90 days of life. Currently, more than 119 different mutations of NPHS1 have been published affecting most exons.

METHODS

We here performed mutational analysis of NPHS1 in a worldwide cohort of 67 children from 62 different families with CNS.

RESULTS

We found bi-allelic mutations in 36 of the 62 families (58%) confirming in a worldwide cohort that about one-half of CNS is caused by NPHS1 mutations. In 26 families, mutations were homozygous, and in 10, they were compound heterozygous. In an additional nine patients from eight families, only one heterozygous mutation was detected. We detected 37 different mutations. Nineteen of the 37 were novel mutations (approximately 51.4%), including 11 missense mutations, 4 splice-site mutations, 3 nonsense mutations and 1 small deletion. In an additional patient with later manifestation, we discovered two further novel mutations, including the first one affecting a glycosylation site of nephrin.

CONCLUSIONS

Our data hereby expand the spectrum of known mutations by 17.6%. Surprisingly, out of the two siblings with the homozygous novel mutation L587R in NPHS1, only one developed nephrotic syndrome before the age of 90 days, while the other one did not manifest until the age of 2 years. Both siblings also unexpectedly experienced an episode of partial remission upon steroid treatment.

The effect of donor/recipient body surface area ratio on outcomes in pediatric kidney transplantation

In pediatric kidney transplantation, the effect of inadequate nephron dosing on graft survival remains undetermined. The aim of this study was to assess the use of D/R BSA, as a reliable indicator of adequate nephron dosing, and eventually a tool to optimize pediatric graft allocation. Following Institutional Review Board approval, we reviewed deceased donor pediatric kidney transplantation (N = 156). We divided patients into three groups, based on D/R BSA: A < or =0.8; B 0.81-1.19; C > or =1.2. Five-yr graft survival rates in the groups were: A 82.0%; B 94.9%; C 97.1% (p = 0.01). Group C had the lowest rate of acute rejection, suggesting a protective effect of increased D/R BSA (group A = 35.7%, group B = 38.9%, group C = 18.8%; p = 0.029). The logistic regression analysis showed that decreased D/R BSA ratio is a risk factor for loss of graft function, at one and five yr [i.e., group A OR 6 (95% CI 1.14-39.30, p = 0.015) and OR 4.49 (95% CI 1.46-13.79, p = 0.009), respectively]. We conclude that for pediatric recipients, D/R BSA is a valuable adjunct when determining long-term graft survival. Its utility may avoid an alloimmune-independent risk factor, increasing the long-term protective value of a good matching policy.

Congenital nephrotic syndrome

Congenital nephrotic syndrome (CNS) is a rare kidney disorder characterized by heavy proteinuria, hypoproteinemia, and edema starting soon after birth. The majority of cases are caused by genetic defects in the components of the glomerular filtration barrier, especially nephrin and podocin. CNS may also be a part of a more generalized syndrome or caused by a perinatal infection. Immunosuppressive medication is not helpful in the genetic forms of CNS, and kidney transplantation is the only curative therapy. Before the operation, management of these infants largely depends on the magnitude of proteinuria. In severe cases, daily albumin infusions are required to prevent life-threatening edema. The therapy also includes hypercaloric diet, thyroxin and mineral substitution, prevention of thrombotic episodes, and prompt management of infectious complications. The outcome of CNS patients without major extrarenal manifestations is comparable with other patient groups after kidney transplantation.

Thirteen novel NPHS1 mutations in a large cohort of children with congenital nephrotic syndrome

BACKGROUND

Congenital nephrotic syndrome (CNS) is de- fined as nephrotic syndrome that manifests at birth or within the first 3 months of life. Most patients develop end-stage renal disease (ESRD) within 2 to 3 years of life. CNS of the Finnish-type (CNF) features a rather specific renal histology and is caused by recessive mutations in the NPHS1 gene encoding nephrin, a major structural protein of the glomerular slit-diaphragm. So far, more than 80 different mutations of NPHS1 causing CNF have been published.

METHODS

Here, we performed mutation analysis of NPHS1 by exon sequencing in a worldwide cohort of 32 children with CNS from 29 different families.

RESULTS

Sixteen of the 29 families (55%) were found to have two disease-causing alleles in NPHS1. Two additional patients had a single heterozygous mutation in NPHS1. Thirteen of a total of 20 different mutations detected were novel (65%). These were five missense mutations, one nonsense mutation, three deletions, one insertion and three splice-site mutations.

CONCLUSION

Our data expand the spectrum of known NPHS1 mutations by >15% in a worldwide cohort. Surprisingly, two patients with disease-causing mutations showed a relatively mild phenotype, as one patient had a partial remission with steroid treatment and one patient had normal renal function 1 year after the onset of disease. The increased number of known mutations will facilitate future studies into genotype/phenotype correlations.

Early treatment of acute rejections gives favorable long-term function after renal transplantation in small children

AR is considered as a risk factor for CAN after kidney TX. We combined data on AR with long-term graft function and histopathology to assess whether early treatment of AR is beneficial for long-term graft outcome in small children. Seventy-seven children with a mean age of 4.7 yr were studied. Early AR were diagnosed with FNAB and treated with methylprednisolone already before clinical signs occurred. The children were grouped into three groups (clinical, subclinical, and no AR) and then followed prospectively up to seven yr after TX with measured GFR and core needle biopsies to assess histopathological findings with the CADI score. Early AR, whether clinical or subclinical, did not affect long-term graft survival (80% with AR vs. 83% without AR, at 10 yr). Late AR, more than one yr after TX, had an inferior graft survival 50% vs. 84% (p = 0.02). GFR declined and the CADI scores increased with time, but there were no significant differences between the three groups. Prompt and early treatment of post-operative AR gives favorable long-term graft function compared with children without AR. Late AR is a risk factor for inferior long-term graft function.

Tracking of blood pressure and its impact on graft function in pediatric renal transplant patients

We studied tracking of BP and its impact on GFR in 44 PRTP followed for 56 months. Three months PT 77% had elevated SBP percentile. First year SBP and DBP correlated positively with final values (p < 0.0001, 0.0002, respectively). Pretransplant and three month PT SBP correlated positively (p = 0.02). At one yr, SBP and DBP were inversely associated with GFR (p = 0.002, p < 0.0001, respectively). SBP and BMI were positively associated at all time points. DBP was significantly higher in deceased recipients throughout the study period. Final DBP was higher (p = 0.03) and GFR lower (p = 0.04) in African-American patients. Patients with end-stage renal disease caused by glomerular disease had higher SBP (p = 0.03) and DBP (p = 0.04) than those with congenital malformations. GFR at one-yr PT (p = 0.02) and end of study (p = 0.003) was significantly lower in patients with high BP. Moreover, patients who maintained a normal systolic BP throughout the study had a significantly higher final GFR than those who were hypertensive at both time points [84 (normal BP throughout) vs. 52 mL/min/1.73 m(2) (high BP throughout), p = 0.02]. We conclude that PT hypertension is common in PRTP and predicts lower GFR.

25 years of live related renal transplantation in children: The Buenos Aires experience

The number of pediatric patients with end stage renal disease (ESRD) has been steadily growing during the last 10 years all over the world, because of the improvement of medical and surgical treatment of severe urologic malformations and congenital and acquired nephrological disorders. Kidney transplantation (Tx) with a live related donor continues to be the gold standard therapy to treat ESRD in children because of the best final results, the chronic lack of cadaveric donors and the frequent possibility of young patients to have parents or relatives as a source of a potential graft donor.Nowadays almost every pediatric patient can be dialyzed and transplanted, even early in life, if he or she has the possibility of a live related donor. Improvements in pediatric anesthesiology and intensive care have also been very important, in reducing the morbidity and mortality related to Tx procedures.Here we report our experience with Tx for the last 25 years, specially our long experience of live related donor transplantation in children and adolescents with emphasis on technical issues in small children and pediatric patients with severe urologic malformations and bladder dysfunction. We'll make special considerations on the improvement in short and long follow-up with the actual prevention and treatment of graft rejection, due to the new immunosuppressive agents and protocols.

Plasma exchange and retransplantation in recurrent nephrosis of patients with congenital nephrotic syndrome of the Finnish type (NPHS1)

BACKGROUND

Recurrent nephrotic syndrome (NS) is a severe problem after renal transplantation in patients with congenital nephrotic syndrome of the Finnish type (NPHS1). The NPHS1 kidneys do not express nephrin, and antibodies against this major glomerular filter protein have been observed in NPHS1 children with recurrent NS. We evaluated here the use of plasma exchange (PE) therapy and kidney retransplantation in NPHS1 patients with recurrent NS and extended our studies on the pathogenesis of the recurrence.

METHODS

Clinical data on 65 NPHS1 patients who received 77 kidney transplants between the years 1986 and 2006 was collected. Serum anti-nephrin antibodies were assayed with an enzyme-linked immunosorbent assay method, and the kidney biopsy samples were evaluated by light microscopy and immunohistochemistry.

RESULTS

Twenty-three episodes of recurrent NS occurred in 19 grafts of 13 NPSH1 patients homozygous for Fin-major mutation. Six retransplantations were performed to four NPHS1 patients, who lost their graft because of recurrent NS, and heavy proteinuria developed immediately in all cases. Although 73% of the patients had detectable serum anti-nephrin antibodies, the kidney biopsy findings were minimal. Introduction of PE alongside cyclophosphamide proved effective in the treatment of the proteinuric episodes (one graft loss out of nine). If remission was achieved, recurrent NS did not significantly deteriorate the long term graft function.

CONCLUSIONS

The clinical and pathological data suggest that anti-nephrin antibodies effectively impair the glomerular function in kidney grafts of NPHS1 patients homozygous for Fin-major mutation. Plasma exchange is a useful adjunct to the treatment of the recurrent NS.

Better renal function with enhanced immunosuppression and protocol biopsies after kidney transplantation in children

Subclinical rejection may be associated with decreased graft function after renal transplantation (Tx). Detection by protocol biopsies and treatment could thus be important for the long-term prognosis. We have earlier discovered that glomerular filtration rate (GFR) declined in young children during the first 18 months. Consequently, we slightly enhanced and individualized each patient's immunosuppression. This was a retrospective study of 59 pediatric renal Tx patients between 1995 and 2001. The 35 historical controls received triple-therapy of azathioprine, methylprednisolone and cyclosporine. GFR was measured by protocol at discharge, 6 and 18 months, and a core biopsy was obtained at 18 months. The 24 study patients in addition received basiliximab, had GFR measured at 3 and 12 months, and a biopsy taken at 3 months. Based on histology and function, immunosuppression was individually adjusted. The groups were compared for GFR and histology at 18 months after Tx. There were less acute rejection episodes in the study group (0.38 vs. 1.23 per patient) and serum creatinine concentrations were lower. Subclinical rejection was detected and treated in 39% at 3 months. There were more chronic changes in the control (47%) than in the study group (29%) at 18 months. GFR was significantly higher in the study group at 18 months (87 vs. 68 mL/min/1.73 m(2)), most remarkably in patients < or =2 yr of age (99 vs. 68 mL/min/1.73 m(2)). Detection of subclinical rejection and slightly enhanced and individualized immunosuppression improved GFR 18 months after renal Tx, especially in the youngest patients.

Tubular and glomerular function in children after renal transplantation

Glomerular and tubular function of transplanted kidneys were assessed in 46 children aged 15.7 +/- 4.6 yr, 4.2 +/- 2.8 yr after renal transplantation. There were 34 cadaveric, and 12 living-related donors. Twelve patients (26%) had acute episodes (acute tubular necrosis, rejection, or urinary tract infection) during follow-up. All patients were on triple immunosuppression. The mean serum creatinine was 1.5 +/- 0.6 mg/dL. Creatinine clearance (Ccreat) calculated from a 24-h urine collection was 48.0 +/- 19.7 mL/min/1.73 m(2), and that estimated from the Schwartz formula, 61.0 +/- 22.5 mL/min/1.73 m(2). A positive correlation was found between the calculated and estimated clearances. Mean urine concentrating ability was 487 +/- 184 mOsmol/kg, with a value lower than 400 mOsmol/kg in 35% of patients. There was a positive correlation between urine osmolality and estimated Ccreat. Metabolic acidosis (bicarbonate <22 mmol/L) was found in 41% of patients, with relatively alkaline urine and high chloride level. Fractional excretion (FE) of sodium was above 1% in 68% of patients (mean 1.66 +/- 1.06%), and FE(Mg) was above 3% (mean 10.9 +/- 5.2%) in 93% of patients. Tubular reabsorption of phosphate (TP)/glomerular filtration rate (GFR) was 3.2 +/- 0.8 mg/dL glomerular filtrate (GF). FE(K), FE(UA), and Ca/creatinine in urine were normal. There were no functional group differences between the cadaveric and living-related kidneys. Significant group differences were found in those with acute episodes and those with a normal course. Estimated Ccreat was 54 +/- 20 vs. 67 +/- 20 mL/min/1.73 m(2) in the acute episodes and the normal course groups, respectively. Also, the FE(NA), FE(UA), and FE(Mg) were higher in the acute episodes group -2.3 +/- 1.6, 10.6 +/- 4.4, and 14.8 +/- 6.5%, respectively, compared with the normal course group -1.4 +/- 0.6, 8.2 +/- 2.8, and 9.6 +/- 4.0%, respectively. There were no between-group differences in plasma bicarbonate, FE(K), TP/GFR, and urine osmolality. We believe that most, if not all tubular dysfunctions in the transplanted kidney are secondary to renal failure and interstitial damage from acute episodes and nephrotoxic drugs. These dysfunctions are similar to those in chronic renal failure, where interstitial fibrosis plays a role in kidney function deterioration.

Cyclosporine A monitoring--how to account for twice and three times daily dosing

Cyclosporine A (CsA) dose-interval pharmacokinetic profiles, performed 1-4 years post-transplantation, were collected from 74 renal transplanted children. Forty patients were on three times daily dosing (t.i.d.) and 34 on twice daily dosing (b.i.d.). Regression models for prediction of area under the curve (AUC) using 1-3 concentration time points as independent variables were developed. With similar weight-adjusted single doses (mg kg(-1)) of CsA, t.i.d. dosing resulted in a trough-concentration (C0) similar to that from b.i.d. dosing, but a 30% lower 2 h post-dose concentration (C2). For b.i.d. dosing the relationship between C0 and AUC was poor (r2=0.23) and the prediction error was large (5.8+/-33.5%). For t.i.d. dosing the relationship was better (r2=0.79), but prediction error was still large (4.5+/-24.9%). For C2 relationships were similar to those for the b.i.d. (r2=0.59) and t.i.d. (r2=0.63) groups, but explained modestly the variations of AUC (prediction error=2.6+/-16.8% b.i.d., 4.8+/-23.2% t.i.d.). Both C0 and C2 are useful monitoring methods when CsA is administered t.i.d. If the aim is similar specified daily drug exposure, the target C2 should be roughly 30% smaller in t.i.d. dosing than in b.i.d. dosing and the target C0 could be similar. The prediction error of AUC can be large in individual patients when using single time-point determinations, however. The use of multiple time points reduces the variation, but is less feasible.

A longitudinal study of children who received renal transplants 10-20 years ago

BACKGROUND

We have previously reported on our 10-year experience of renal transplantation in children in the cyclosporine era, that is, from December 1981 until December 1991. In this paper, we report on the same children observed for another 10 years.

METHODS

Of 53 children who received a renal transplant between 1981 and 1991, 47 survived and were observed for 10 to 20 years. Immunosuppression consisted of cyclosporine, prednisolone, and azathioprine. Yearly clinical examinations were performed.

RESULTS

Overall, actual patient survival is 91%, 89%, and 89%, and actual graft survival 85%, 77%, and 66% at 1, 5, and 10 years, respectively. No patients have died during the last 10 years. Twenty-six grafts were lost over 20 years. Thirteen of those were lost during the present follow-up (10-20 years): 11 in chronic rejection and 2 because of development of renal cell carcinoma. No other malignancies were noted. Mean glomerular filtration rate decreased from 58+/-19 at 1 year (n=42) to 44+/-16 mL/min/1.73 m2 body surface area at 10 (n=33) years. Hypertension was treated in 46%, 40%, and 66% of the children at 1, 5, and 10 years, respectively; two of them showed left ventricular hypertrophy 10 years after transplant. Minor cataracts without visual disturbance were found in 45% of patients. All children except three with mental retardation are, or have been, attending normal day care or normal school.

CONCLUSION

Social integration is good, and severe complications are scarce, even when renal transplantation occurred at a very young age.

Differential early posttransplant cytokine responses in living and cadaver donor renal allografts

BACKGROUND

Differences in early posttransplant immunologic responses between living donor (LDT) and cadaver donor transplant (CDT) recipients have not been thoroughly studied. This is the first study comparing lymphocyte subpopulations and plasma levels of different cytokines, soluble cytokine receptors, cytokine receptor antagonists, and neopterin during the first 2 posttransplant weeks.

PATIENTS AND METHODS

Lymphocyte subpopulations (CD3, CD4, CD8, CD16, CD19, and CD25) and plasma levels of soluble (s) interleukin(IL)-1 receptor antagonist (RA), IL-2, sIL-2R, IL-3, IL-4, IL-6, sIL-6R, IL-8, IL-10, transforming growth factor-beta(2), tumor necrosis factor-alpha, interferon-gamma, and neopterin were studied in 52 CDT and 33 LDT recipients 1 to 2, 4 to 6, and 8 to 10 days after transplantation.

RESULTS

The most impressive finding was a consistently higher neopterin plasma level in CDT than LDT recipients. Although plasma neopterin decreased during the second posttransplant week in both groups (CDT, P = 0.0001; LDT, P = 0.001), the difference in plasma neopterin levels 8-10 days after transplantation was highly significant (P = 0.005). In contrast, LDT had consistently higher sIL-1RA plasma levels during the first 2 posttransplant weeks. Whereas sIL-1RA plasma levels decreased in both groups during the first posttransplant week (CDT, P = 0.001; LDT, P = 0.005), they increased during the second posttransplant week in LDT (P = 0.02) but remained stable and low in CDT recipients. Eight to ten days after transplantation, the difference was highly significant (P = 0.002).

CONCLUSION

These data suggest that transplantation of CDT is associated with strong monocyte-macrophage activation with consistently high neopterin plasma levels, whereas the effect of inflammatory cytokines seems to be down-regulated in LDT recipients by an increased release of antiinflammatory sIL-1RA.

Predictive value of pretransplantation cyclosporine pharmacokinetic studies on initial post-transplantation dosing in pediatric kidney allograft recipients

Despite the introduction of a variety of new immunosuppressive agents, cyclosporine A (CsA) has maintained a strong position in pediatric transplantation (Tx). Post-Tx dosing with CsA is a challenging task because of the narrow therapeutic window of the drug, the great individual variability of metabolism and the lack of consensus about the optimal dosage and targeted blood concentration. Sufficient administration of CsA may be protective against acute rejections and other early complications after Tx, which is crucial for the long-term survival of the graft. Individual doses based on pre-Tx pharmacokinetic studies might be helpful in achieving optimal early concentrations of CsA. To asses the usefulness of pharmacokinetic studies, we retrospectively compared the post-Tx doses administered with the individually predicted doses between 1988 and 1998. Multiple regression of data on 65 de novo renal transplant recipients, 1.1-15.5 yr old, was used to analyze the significance of the predicted dose, trough blood concentration of CsA (B-CsA), serum creatinine and age at the time of Tx in explaining the doses used during the first three post-Tx weeks. Patients were grouped according to age (<2, 2-8 and >8 yr), according to the predicted dose (within or outside +/-25% of age-group average), and according to the oral formulation of CsA. Standard dosing scheme was simulated by using age-specific average doses in the place of the individual predicted doses. Administered doses of CsA were high [averaging 22.6 (504), 20.7 (484), and 12.4 mg/kg/d (329 mg/m2/d) for patients <2, 2-8, and >8 yr old] but the average B-CsA remained in the target range of 250-450 microg/L. The predicted dose and age were significant parameters in explaining the administered doses during the first 3 wk after Tx. B-CsA and S-creatinine were non-significant. The predicted doses were used to initiate the dosing of CsA after Tx (R2 = 0.70) and adjustments to dosing were made during the next weeks (R2 = 0.59, 0.52). Multiple regression model showed better fit for 60% of our patients, who had atypical predicted doses (R2 = 0.74, 0.60, 0.64 for first, second and third post-Tx weeks, respectively), most remarkably in patients <2 yr of age, than for the study population as a whole. A simulated standard dose was not able to explain the administered doses of CsA. In conclusion, pre-Tx pharmacokinetic studies are valuable for determining individual post-Tx starting doses, especially for those patients who need high or low doses of CsA. Individual dosing led to relatively high initial CsA doses, which could be significant for the long-term survival of the graft.

Better long-term functional adaptation to the child's size with pediatric compared to adult kidney donors

BACKGROUND

Pros and cons for pediatric kidney donors have been debated, especially with respect to survival rates. However, the effect of donor age on kidney function remains conflicting. The aim of this study was to compare short and long-term renal function according to the age of the donor, in grafts from adult living related (LRD), adult cadaveric and pediatric cadaveric donors (PedCD) following pediatric transplantation (Tx).

METHODS

One hundred and thirty-four children were repeatedly followed for four years, and 44 were followed for eight years. Absolute and relative glomerular filtration rate (GFR; inulin clearance, mL/min and mL/min/1.73 m(2), respectively) were determined within 6 months, and yearly thereafter.

RESULTS

Absolute GFR increased along with body growth in the PedCD group (P < 0.001) during the 4 years following Tx, leading to stable relative GFR, whereas absolute GFR of the LRD group did not change, with a progressive decrease of relative GFR (P < 0.001). Relative GFR did not differ between PedCD and LRD recipients by the sixth month but became higher in PedCD 4 years post-Tx (70 +/- 25 vs 52 +/- 19 mL/min/1.73 m(2), P < 0.001). Among those followed for 8 years, relative GFR showed a slow decrease in both recipient groups from 6 years post-Tx. At 8 years post-Tx, relative GFR was still significantly higher in PedCD than in LRD (57 +/- 19 vs. 45 +/- 19; P < 0.05).

CONCLUSIONS

Adult-sized grafts may adapt to pediatric recipients during the first months post-Tx, but graft function cannot improve thereafter along with the increase in body size of the recipient. Interestingly, the absolute GFR of children receiving pediatric grafts increased along with body growth, leading to a stable relative GFR up to 6 years post-Tx.

Recurrence of nephrotic syndrome in kidney grafts of patients with congenital nephrotic syndrome of the Finnish type: role of nephrin

BACKGROUND

Congenital nephrotic syndrome of the Finnish type (CNF, NPHS1) is caused by mutations in the NPHS1 gene. NPHS1 codes for nephrin, a cell adhesion protein located at the glomerular slit diaphragm. Renal transplantation is the only treatment option for most patients with NPHS1. We have previously described recurrence of severe proteinuria in grafts transplanted to children with NPHS1. Here we studied the pathophysiology of this proteinuria.

METHODS

Clinical data, light and electron microscopic findings as well as the expression of nephrin in the proteinuric grafts were studied. The patients' sera were screened for antibodies against kidney glomerulus and nephrin molecule using indirect immunofluorescence and ELISA.

RESULTS

Fifteen episodes of recurrent nephrotic syndrome occurred in 13 (25%) of 51 grafts transplanted to 45 Finnish children with NPHS1. All nine patients with recurrence had a Fin-major/Fin-major genotype, which leads to absence of nephrin in the native kidney. Rescue therapy (cyclophosphamide) was successful in seven episodes, but six kidneys were lost due to this process. Antibodies reacting against glomerulus were found in eight, and high anti-nephrin antibody levels were detected in four of the nine patients. In electron microscopy, the fusion of the foot process and decreases in the detectable slit diaphragms in the podocyte pores were observed. The expression of nephrin mRNA was markedly reduced in two, and granular staining for nephrin was seen in three of five grafts.

CONCLUSIONS

Circulating anti-nephrin antibodies seem to have a pathogenic role in the development of heavy proteinuria in kidney grafts of NPHS1 patients with Fin-major/Fin-major genotype.

Neurodevelopmental outcome in high-risk patients after renal transplantation in early childhood

Patient and graft survival rates of pediatric renal transplant recipients are currently excellent, but there are few reports regarding the long-term neurodevelopmental outcome after renal transplantation (Tx) in early childhood. Children with renal failure from infancy would be expected to have a less favorable developmental prognosis. We report the neurodevelopmental outcome in 33 school-age children transplanted between 1987 and 1995 when < 5 yr of age. We prospectively performed a neurological examination, magnetic resonance imaging (MRI) of the brain, electroencephalograms (EEGs), audiometry, and neuropsychological tests (NEPSY), and measured cognitive performance (WISC-R); we related these results to school performance and to retrospective risk factors prior to Tx. Twenty-six (79%) children attended normal school and 76% had normal motor performance. Six of the seven children attending a special school had brain infarcts on MRI. The EEG was abnormal in 11 (35%), and five (15%) received anti-convulsive treatment after Tx. Sensorineural hearing loss was documented in six patients. The mean intelligence quotient (IQ) was 87, and 6-24% showed impairment in neuropsychological tests. The children attending a special school had been more premature, but had not had a greater number of pre- or neonatal complications. They had experienced a greater number of hypertensive crises (p = 0.002) and seizures (p = 0.03), mainly during dialysis, but the number of septic infections and the mean serum aluminum levels were not significantly greater than in the children with normal school performance. In these previously lethal diseases, the overall neurodevelopmental outcome is reassuring. However, it is of crucial importance to further minimize the risk factors prior to Tx.

Fine-needle aspiration biopsy allows early detection of acute rejection in children after renal transplantation

analysis detected rejections often before clinical signs. Half of the patients had increased serum creatinine concentration and 38% had fever at the time of rejection diagnosis. Both signs were present in only 19% of the episodes. A decrease in urine output (>20%) was seen in a third of the episodes. The rejections responded well to oral methylprednisolone (3 mg/kg/day), and lymphoglobulins were needed in only 12% of the episodes. More than 90% of the rejections were completely reversible and no transplant was lost because of acute rejection.

CONCLUSION

The results indicate that FNAB is a safe and sensitive method for the diagnosis and follow-up of acute cellular rejection in pediatric recipients of different ages.

Congenital nephrotic syndrome (NPHS1): features resulting from different mutations in Finnish patients

BACKGROUND

Congenital nephrotic syndrome (NPHS1) is a rare disease inherited as an autosomally recessive trait. The NPHS1 gene mutated in NPHS1 children has recently been identified. The gene codes for nephrin, a cell-surface protein of podocytes. Two mutations, named Fin-major and Fin-minor, have been found in over 90% of the Finnish patients. In this study, we correlated the NPHS1 gene mutations to the clinical features and renal findings in 46 Finnish NPHS1 children.

METHODS

Clinical data were collected from patient files, and kidney histology and electron microscopy samples were re-evaluated. The expression of nephrin was studied using immunohistochemistry, Western blotting, and in situ hybridization.

RESULTS

Nephrotic syndrome was detected in most patients within days after birth regardless of the genotype detected. No difference could be found in neonatal, renal, cardiac, or neurological features in patients with different mutations. Nephrin was not expressed in kidneys with Fin-major or Fin-minor mutations, while another slit diaphragm-associated protein, ZO-1, stained normally. In electron microscopy, podocyte fusion and podocyte filtration slits of various sizes were detected. The slit diaphragms, however, were missing. In contrast to this, a nephrotic infant with Fin-major/R743C genotype expressed nephrin in kidney had normal slit diaphragms and responded to therapy with an angiotensin-converting enzyme inhibitor and indomethacin.

CONCLUSIONS

The most common NPHS1 gene mutations, Fin-major and Fin-minor, both lead to an absence of nephrin and podocyte slit diaphragms, as well as a clinically severe form of NPHS1, the Finnish type of congenital nephrotic syndrome.

Course of renal allograft histopathology after transplantation in early childhood

BACKGROUND

We report a long-term prospective follow-up of renal allograft histology in children <5 years of age at transplantation (Tx).

METHODS

Fifty-one kidney allograft recipients were prospectively followed for renal allograft histology and function up to 7 years after Tx. Twenty patients were recipients of kidneys from living related donors, and 31 were cadaveric kidney recipients. All patients received triple immunosuppression. Biopsies were analyzed according to the Banff classification and scored semiquantitatively. The "chronic allograft damage index" (CADI) was calculated.

RESULTS

Five of seven grafts were lost because of nephrosis in patients with congenital nephrotic syndrome of the Finnish type. Most of the biopsies (52-69%) were considered normal (Banff classification), and the proportion with chronic allograft nephropathy did not increase with time. The median CADI score was 2.5 (scale: 0-36) at 1.5 years and 3.5 at 7 years. Recipients with an acute rejection episode had higher CADI scores than recipients without acute rejection episode. Patients with a high CADI score at 3 years had inferior graft function at 5 years. Recipients <2 years of age had CADI scores and numbers of acute rejection episode similar to recipients between 2 and 5 years of age. However, in contrast to the older recipients, the younger recipients did not improve their absolute glomerular filtration rate with time.

CONCLUSIONS

The long-term histopathological findings were mostly mild and stable with time. Acute rejection episode had an impact on these changes and CADI predicted later graft function. Nonimmunological risk factors seem to be more important in the youngest recipients.

Primary structure of mouse and rat nephrin cDNA and structure and expression of the mouse gene

Nephrin is a central component of the glomerular podocyte slit diaphragm and is essential for the normal renal filtration process. This study describes the complete structure of the mouse nephrin gene, which was shown to be homologous to the human gene, the major difference being 30 exons in the mouse gene as opposed to 29 in human. The complete primary structure of mouse and rat nephrins was also determined. The sequence identity between the mouse and rat proteins was shown to be 93%, while both rodent proteins have only about 83% sequence identity with human nephrin. The availability of the three mammalian sequences is significant for the interpretation of sequence variants and mutations in the nephrin gene in patients with congenital nephrotic syndrome. In situ hybridization analyses of whole mouse embryos and tissues revealed high expression of nephrin in kidney glomeruli and, surprisingly, an intense and highly restricted expression in a set of cells in hindbrain and spinal cord. No expression was observed elsewhere. This expression pattern may explain occasionally occurring neural symptoms caused by inactivating mutations in the nephrin gene in patients with congenital nephrotic syndrome.