Renal transplantation in children with emphasis on young patients

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.

Timing of renal replacement therapy does not influence survival and growth in children with congenital nephrotic syndrome caused by mutations in NPHS1: data from the ESPN/ERA-EDTA Registry

BACKGROUND

Congenital nephrotic syndrome (CNS) of the Finnish type, NPHS1, is the most severe form of CNS. Outcomes of renal replacement therapy (RRT) in NPHS1 patients in Europe were analysed using data from the ESPN/ERA-EDTA Registry. As NPHS1 is most prevalent in Finland and the therapeutic approach differs from that in many other countries, we compared outcomes in Finnish and other European patients.

METHODS

NPHS1 mutations were confirmed in 170 children with CNS who initiated RRT (dialysis or renal transplantation) between 1991 and 2012. Finnish (n = 66) and non-Finnish NPHS1 patients (n = 104) were compared with respect to treatment policy, age at first RRT and renal transplantation (RTX), patient and graft survival, estimated glomerular filtration rate (eGFR) and growth. Age-matched patients with congenital anomalies of the kidney and urinary tract (CAKUT) served as controls.

RESULTS

Finnish NPHS1 patients were significantly younger than non-Finnish patients, both at the start of RRT and at the time of RTX. We found similar overall 5-year patient survival on RRT (91 %) and graft survival (89 %) in both NPHS1 groups and CAKUT controls. At the start of RRT, height standard deviation score (SDS) was higher in Finnish patients than in non-Finnish patients (mean [95 % CI]: -1.31 [-2.13 to -0.49] and -3.0 [-4.22 to -1.91], p < 0.01 respectively), but not at 5 years of age. At 5 years of age height and body mass index (BMI) SDS were similar to those of CAKUT controls.

CONCLUSIONS

Overall, 5-year patient and graft survival of both Finnish and non-Finnish NPHS1 patients on RRT were excellent and comparable with CAKUT patients with equally early RRT onset and was independent of the timing of RRT initiation and RTX.

Serum C-reactive protein in pediatric kidney and liver transplant patients

The clinical manifestations of different complications after organ transplantation (Tx) are often vague, and simple laboratory tests for early diagnosis would be valuable. In this work we retrospectively analyzed our data on the daily measurements of serum C-reactive protein (CRP) in 132 children after 63 liver and 83 kidney Txs. A total of 3,886 CRP measurements were performed and 353 episodes of elevated CRP were recorded. One-third of these were regarded as a response to surgery. The CRP level normalized within 5-10 days post-operatively in patients who had a favorable outcome, but in patients with a poor outcome CRP tended to remain elevated. Half of the CRP elevations were associated with complications such as acute rejection, infection or thrombotic events. An elevated serum CRP level was found in 68% of the rejection episodes, in 88% of the bacterial infections, and in 73% of the viral infections. The most significant elevations were associated with bacterial infection. In nine of 11 vascular complications, an elevation of CRP was also recorded. Serum CRP responded to rejection therapy in 86% of the episodes. The initial CRP level did not predict steroid-resistant rejection. CRP seemed to be a more sensitive marker than fever or white blood cell (WBC) count in all complications. We conclude that the daily measurement of serum CRP is a simple and fairly sensitive, but non-specific, method for detecting rejection and infectious complications after pediatric liver and kidney Tx.

Differences in anthropometric parameters and the IFG-I-IGFBP3 axis between liver and renal transplant children

BACKGROUND

Growth can be differently altered after liver and renal transplantation (Tx) in childhood.

METHODS

We compared graft function, linear growth, immunosuppression and serum IGF-I (RIA) and IGFBP3 (IRMA) concentrations in 15 liver (5.6+/-1.1 years old) and 17 renal (7.4+/-0.1 years old) Tx patients who were followed for 4-6 years.

RESULTS

Graft function was normal post-liver Tx, although in renal recipients creatinine clearance decreased significantly during follow-up. Liver Tx children presented an increase in mean height of 0.92+/-0.2 SDS (P<0.01) beyond the 2nd year post-Tx, although in renal Tx patients height SDS did not improve. Immunosuppressive corticoid dosage could be decreased and discontinued in liver Tx patients, while in renal recipients it was maintained between 0.18+/-0.01 and 0.16+/-0.02 mg/kg/day. At 3.7+/-0.4 years post Tx, liver Tx patients presented higher mean serum IGF-I level, lower mean serum IGFBP3 value, leading to a higher mean IGF-I/IGFBP3 molar ratio, P<0.001.

CONCLUSIONS

We found that while catch up growth coud be achieved after liver Tx, height SDS did not improve after renal Tx. This may be related to a reduced renal graft function and/or to differences in immunosuppressive corticoid dosage. In children with renal transplants a challenge for the future will reside in making it possible to substitute steroid therapy without altering graft function.

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.

Paediatric kidney transplantation

Renal transplantation is the optimal form of renal replacement therapy leading to substantial improvement in the quality of life. It has rapidly become the standard treatment for end-stage renal disease in children. However, despite impressive short-term results significant long-term problems remain unsolved. Because of the lack of effective treatment for chronic rejection and common recipient noncompliance, allograft half-life has not improved significantly during the last decade. A paediatric recipient is likely to need several retransplantations in adulthood. Moreover, the immunosuppressive drugs used today have potentially serious side-effects including nephrotoxicity and de novo malignancy. These are especially relevant for paediatric recipients who will continue to receive therapy for several decades. Most therapeutic protocols used for children are derived from those used for adults. However, the metabolic differences between an adult and a growing and developing paediatric transplant recipient are not always adequately appreciated before these new therapies are initiated. In the near future, we are likely to see new and more efficient drugs become available. It is important that we try to understand their properties in children and use them and our current arsenal on an individual basis aiming at optimal graft survival but also at avoiding unnecessary adverse effects.

Renal transplantation in children less than two years old

Twenty-one infants, 2 years old or younger, received 21 renal transplants between 1983 and 1995. Six of the transplantations were performed from 1983 to 1989, and the remaining 15 were performed from 1990 to 1995. The median age at transplantation was 16.0 months and the median body weight was 9.0 kg. Living-related donor kidneys were used in 15 cases, an adult cadaveric donor kidney was used in one case, and pediatric cadaveric donor kidneys were used in five cases. All grafts were placed intra-abdominally. The immunosuppressive therapy consisted of cyclosporine, azathioprine, and prednisolone. No prophylactic antithymocyte globulins were used. Five infants have died, one with a functioning graft and four after loss of graft function. All graft losses and deaths occurred during the first 6 months after transplantation. The 5-year patient survival and graft survival rates were 87% for recipients of living donor grafts and 44% for recipients of cadaveric grafts. The median height SD score increased from -3.7 before operation to -1.9 at 1 year, -0.7 at 3 years, and -1.1 at 5 years. The glomerular filtration rate in absolute values remained stable in all infants, whereas a reduction in glomerular filtration rate related to body surface area was seen at follow-up, 5 years after transplantation. We conclude that renal transplantation can be performed with good long-term results in children less than 2 years old.

Apoptotic cell death in human chronic renal allograft rejection

Chronic renal allograft rejection is characterized by gradual progression suggesting persistent low-grade injury. Apoptotic cell death may be initiated by low-grade injury secondary to external factors, making apoptosis a potential pathway of chronic rejection. In the present investigation, protocol kidney biopsies of 20 pediatric renal allograft recipients (12 with chronic rejection and 8 with normal histology), 9 pediatric liver allograft recipients, and 7 children with minimal change nephrotic syndrome were evaluated. The presence of apoptotic cell death was studied by determining apoptosis-induced oligonucleosomal DNA fragmentation in the biopsy specimens using 3' end labeling with terminal transferase, gel fractionation, and Southern blotting. The specific cell types with increased DNA fragmentation were determined by in situ 3' end labeling performed on sections of the biopsies. Significant DNA fragmentation was found only in the specimens from patients with chronic rejection. In situ investigation revealed increased apoptosis of both proximal and distal tubular epithelial cells, but not in the glomeruli or interstitium. The mean number of apoptotic tubular epithelial cells per 400x magnified field was higher in the renal allografts than in kidneys of liver transplant recipients or patients with minimal change nephrotic syndrome (2.3 vs. 0.8, P<0.05, in both cases). Our data provide biochemical evidence of increased apoptotic cell death of renal tubular epithelial cells in patients undergoing chronic renal allograft rejection.

Chronic rejection and late renal allograft dysfunction

Renal transplantation is currently standard therapy for end-stage kidney disease for children. Despite the considerable improvement in short-term results, the expected allograft half-life has remained the same. This is due to chronic rejection/late graft dysfunction which has proved resistant to therapeutic attempts. During the last few years the multifactorial pathogenesis of chronic renal allograft rejection has been clarified to some extent. Early injury by immunological and non-immunological mechanisms is followed by vascular remodelling due to repetitive cycles of cytokine release, upregulation of growth factors, and vascular smooth muscle cell proliferation. This leads to typical concentric arteriosclerosis and ischemia. Secondary kidney-specific mechanisms are initiated by the reduction in functioning renal mass and lead to gradual progression of chronic rejection. There is no single optimal therapy. Several attempts to influence the pathophysiological cascade have been promising. Attention should be focused on minimizing early immunological/non-immunological injury in order to attenuate future progression of chronic rejection. A significant prolongation of allograft half-life may be achieved during the next decade with the introduction of new therapeutic agents and comprehensive approach to treatment. This would be especially beneficial for pediatric recipients, reducing the need for retransplantation in adulthood.

Recombinant human growth hormone treatment. Its effect on renal allograft function and histology

Our objective was to investigate the effects of recombinant human growth hormone (rhGH) treatment on long-term renal allograft function and histopathology. RhGH is a potent therapy for poor growth after renal transplantation. However, rhGH has proinflammatory properties and may induce acute rejection or accelerate chronic rejection. Nine prepubertal rhGH-treated renal transplanted children and nine pair-matched controls were studied 18 (before the start of rhGH) and 36 months after transplantation (mean duration of rhGH-treatment 14 months). 51Cr-EDTA- and PAH-clearances were performed. A protocol renal biopsy was done at 36 months. Growth showed significant improvement during rhGH (P<0.01). One graft loss occurred in both groups. One acute rejection was seen in the control group. There was no difference in the rate pf change in 51Cr-EDTA-or PAH-clearance between the two groups. Histopathological findings were mostly mild. One new onset chronic rejection developed in both groups. Proximal tubular atrophy was more extensive in the rhGH-treated patients (P<0.05), but there was no uniform trend toward more severe findings. RhGH improved growth, and no significant differences were seen in allograft function or histopathology; however, larger trials controlled for pretreatment renal function and immunosuppression are needed.

Renal and adrenal mechanisms in cyclosporine-induced hyperkalaemia after renal transplantation

CsA associated hyperkalaemia was investigated in 24 renal transplant recipients 6 months after transplantation. 51Cr-EDTA-, PAH-, lithium and sodium clearances, 24 h urinary creatinine and potassium excretions, plasma renin activity and aldosterone concentrations were measured. Transtubular potassium concentration gradient (TTKG) was calculated. An ACTH test was performed to document adrenal function. Eleven patients had hyperkalaemia. The TTKGs were low normal or reduced in both normo- and hyperkalaemic patients implying inhibition of K+ secretion. The hyperkalaemic patients received more CsA (mean dose 21.3 vs. 9.7 mg kg-1d-1, P = 0.01), and had lower lithium clearances (mean 9.9 vs. 17.0 mL min-1 1.73 m-2, P < 0.05). Adrenal function had no clear effect. Serum potassium concentration correlated with CsA dose (r = 0.773, P < 0.001) and inversely with lithium clearance (r = -0.568, P < 0.01) suggesting that CsA induced decrease in distal tubular flow rate reduced K+ excretion. Hyperkalaemia was not fully explained by renal mechanisms.

Management of congenital nephrotic syndrome of the Finnish type

Congenital nephrotic syndrome of the Finnish type (CNF) is a rare autosomal recessively inherited disease characterised by intrauterine onset of massive urinary loss of proteins, 90% of which is albumin. The CNF gene has been localised to the long arm of chromosome 19, but the pathogenesis remains unclear. Historically, all CNF patients died, usually within the first 6 months of life. Today, a normal life can be achieved for a child with CNF by correcting the protein deficiency and normalising nutrition. This is accomplished by early intravenous albumin supplementation, nutritional support, aggressive treatment of complications and early renal transplantation, after bilateral nephrectomy and peritoneal dialysis. In the present article current treatment strategies are reviewed, and our own experience with 43 CNF patients during the last 10 years is presented.