Long-term side effects of treatment with mTOR inhibitors in children after renal transplantation.

BACKGROUND: mTOR inhibitors (mTORI) have emerged as alternative and additive immunosuppressive agents in pediatric renal transplantation (pRTx). Their immunosuppressive, anti-proliferative, and anti-neoplastic mechanisms have been described to be effective, whereas some side effects are alarming. In particular, growth and pubertal development are of concern. The aim of this study was to look for long-term side effects of mTORI therapy in pRTx. PATIENTS AND METHODS: The retrospective analysis focused on side effects, growth, and pubertal development under mTORI therapy in 31 children. Eighteen children were routinely monitored for estradiol, testosterone, LH, and FSH levels. RESULTS: The occurrence of bacterial infections, lymphoceles, myelosuppression, and the course of overall linear growth was comparable with other pediatric renal transplant cohorts. According to the clinical puberty status, all but one patient showed normal age-related development in parallel to normal serum hormone levels. Only one patient experienced cytomegaly virus infection under mTORI, no post-transplant lymphoproliferative disorders (PTLD) occurred. CONCLUSIONS: Long-term mTORI therapy is safe in pRTx. No negative impact on growth and pubertal development was observed.

Comprehensive analysis of glomerular mRNA expression of pro- and antithrombotic genes in atypical haemolytic-uremic syndrome (aHUS).

Atypical haemolytic-uremic syndrome (aHUS) is, in most cases, due to hereditary or acquired defects in complement regulation and a life-threatening disease. Despite the rapidly grown knowledge about the primary defects in aHUS, the pathogenesis that links complement dysregulation with microthrombus formation in aHUS is still unknown. Thus, we examined the glomerular microvascular expression of pro- and antithrombotic genes. Glomeruli were microdissected from 12 archival paraffin-embedded biopsies with aHUS and from seven control biopsies. Glomerular mRNA expression was quantified by single real-time PCR reactions after preamplification. In addition immunostains were performed for plasminogen activator inhibitor 1 (PAI-1) and for tissue plasminogen activator (tPA). Results were compared between cases and controls and with clinical data. Glomeruli in aHUS had increased mRNA expression of antifibrinolytic, prothrombotic PAI-1, antithrombotic thrombomodulin (THBD) and CD73 and decreased expression of profibrinolytic, antithrombotic tPA compared to controls. Impaired fibrinolysis due to increased microvascular expression of the antifibrinolytic PAI-1 in combination with the decreased expression of the profibrinolytic tPA seems to be a final common pathway in renal thrombotic microangiopathy that is also effective in aHUS. The concomitant induction of antithrombotic transcripts likely indicates counterregulatory efforts, demonstrating that the capillary bed is not a passive victim of complement attack. Future research should investigate if and how complement activation could induce the reported shift in the expression of PAI-1 and tPA.

EBV-specific T-cell immunity in pediatric solid organ graft recipients with posttransplantation lymphoproliferative disease.

BACKGROUND: Posttransplantation lymphoproliferative disease (PTLD) is an often Epstein-Barr virus (EBV)-associated mainly malignant complication after transplantation. We present data on EBV-specific T cells in children treated with rituximab with or without chemotherapy on the pediatric PTLD Pilot 2005 protocol. METHODS: Peripheral blood mononuclear cells were isolated from 16 pediatric patients with PTLD, 4 transplanted children with EBV reactivation, and 18 healthy controls. EBV-specific T cells were quantified by flow cytometric detection of intracellular interferon-γ after stimulation with autologous EBV-transformed lymphoblastoid cell lines and correlated with EBV load in peripheral blood. RESULTS: At diagnosis, PTLD patients had similar numbers of EBV-specific CD4 and CD8 T cells as healthy EBV-positive controls. EBV-specific T cells tended to be lower in early PTLD compared with late PTLD. During treatment with rituximab, CD4 and/or CD8 EBV-specific T cells increased in most patients, possibly reflecting restored immunocompetence due to a reduction of immunosuppression as well as antigenic stimulation by cross-presentation of EBV antigen from destroyed B cells. However, this increase did not predict response to rituximab or chemotherapy. EBV load and circulating B cells became undetectable in most patients during rituximab therapy. B-cell recovery after treatment was accompanied by redetection of EBV in peripheral blood, which was controlled by T-cell responses in 11 of 11 evaluable cases. CONCLUSIONS: In pediatric PTLD patients, pretreatment EBV-specific T-cell numbers are in the range of healthy controls. These cells increased on reduction of immunosuppression and treatment with rituximab. Recurrence of EBV viremia during complete remission is matched by strong T-cell responses.

Characteristics of early and late PTLD development in pediatric solid organ transplant recipients.

BACKGROUND: Posttransplantation lymphoproliferative disorders (PTLD) present a major cause of mortality and morbidity after solid organ transplantation. The purpose of this study was to identify the factors associated with the development of early- and late-onset PTLD in pediatric solid organ transplant recipients. METHODS: We examined the medical history, laboratory parameters, and pathology of 127 children with PTLD who were registered in the German multicenter pediatric PTLD registry. Data were collected retrospectively from 1991 to 2003 and prospectively from 2004 onward. We compared early (<1 year) and late (>1 year) PTLD using survival analysis. RESULTS: The median time to PTLD was 3.00 (95% confidence interval, 2.12-3.26) years. Forty-two patients developed PTLD within the first year after transplantation (early PTLD) and 85 patients developed PTLD after 1 year (late PTLD). Early PTLD development was associated with younger age (P=0.0016), extranodal disease (P=0.019), graft organ involvement (P=0.0065), and immunosuppressive regimens including tacrolimus (P=0.001) or mycophenolate (P=0.0025). Most early PTLD patients experienced graft rejection before PTLD diagnosis (P=0.0081). Early PTLD was often of B-cell lymphoma histology (P=0.024) and tended to be Epstein-Barr virus positive (P=0.052). In contrast, Burkitt's lymphoma (P=0.0047) and Hodgkin's disease (P=0.016) were only observed in late PTLDs, which are more likely to present with nodal disease (P=0.019). Overall survival and event-free survival were not significantly different between early and late PTLD. CONCLUSION: Early and late childhood PTLD have distinct characteristics. Whereas early PTLD appears mainly as an Epstein-Barr virus-driven disease especially favored by insufficient immunosurveillance, late PTLD often resembles tumors with distinct pathogenetic alterations and nodal appearance.

Obesity in patients with Bardet-Biedl syndrome: influence of appetite-regulating hormones.

BACKGROUND: Bardet-Biedl syndrome (BBS) is a genetic disorder with obesity as one of the major phenotypic criterion, which is proposed to be of neuroendocrine origin. Therefore, disturbances in appetite-regulating hormones have been considered as causative factors. Acyl ghrelin is an orexigenic hormone, whereas its desacylated form, obestatin, and leptin have the opposite functions. Ghrelin is negatively regulated in relation to nutritional status. The aim of this study was to evaluate the impact of hormone alterations on obesity development in BBS patients. METHODS: Total and acylated ghrelin, obestatin, leptin and adiponectin were measured in eight children with BBS. The results were analyzed in relation to auxological parameters [body mass index (BMI), height]. RESULTS: The mean BMI was significantly increased in BBS patients compared to the controls. Plasma levels of acylated ghrelin, total ghrelin and obestatin were slightly elevated in BBS patients compared to controls, as was the acyl/total ghrelin ratio. Leptin levels were significantly elevated in BBS patients. CONCLUSION: BBS patients lack the negative regulatory mechanisms of appetite-regulating hormones with respect to nutritional status and exhibit resistance to anorexigenic leptin. This results in a shift towards the orexigenic effects of this self-regulating system. These alterations may in part be responsible for the disturbed appetite regulation in BBS patients.

Prevalence of hepatitis E virus infection in pediatric solid organ transplant recipients--a single-center experience.

HEV infection appears to be an emerging disease in industrialized countries. The aim of this study was to evaluate the prevalence of HEV infection in pediatric solid organ transplant recipients. One hundred and twenty-four pediatric recipients of liver (n = 41) or kidney (n = 83) transplants aged between one and 18 yr were screened for anti-HEV IgG antibodies. Patients were tested for fecal HEV RNA excretion if they showed anti-HEV seropositivity. As a control group, 108 immunocompetent pediatric patients without liver disease aged between three and 18 yr were screened for anti-HEV IgG. HEV seroprevalence was 2.4% in renal Tx (2/83), 4.9% in liver Tx patients (2/41), and 3.2% overall (4/124). Three of these four patients were HEV RNA-negative. In one renal transplant patient, HEV genotype 3 RNA excretion persisted and liver enzymes were elevated, indicating chronic hepatitis. In the control group, eight patients (7.4%) were HEV IgG-positive without biochemical evidence of hepatitis. The prevalence of HEV infection in pediatric renal or liver transplant recipients is not higher compared with immunocompetent children. Chronic HEV infection with long-term carriage of the virus may develop in pediatric transplant recipients. Autochthonous HEV infection needs to be considered in uncertain cases of hepatitis in immunosuppressed as well as immunocompetent children.

Association of nephrotic syndrome with immune reconstitution inflammatory syndrome.

BACKGROUND: Up to 50% of patients with severe immune deficiency experience an excessive inflammatory response called immune reconstitution inflammatory syndrome (IRIS) after the initiation of antiretroviral therapy (ART). IRIS has been observed after various opportunistic infections with pathogens such as mycobacteria, including Bacille Calmette-Guérin, cryptococci, human herpesvirus-8, non-Hodgkin's lymphoma, and progressive multifocal leukoencephalopathy. Non-acquired immune deficiency-defining illnesses can also deteriorate after commencement of ART. Renal IRIS has been reported in a few patients with mycobacterial infections, but to the best of our knowledge no cases of nephrotic syndrome and IRIS have been described. CASE-DIAGNOSIS/TREATMENT: We report the case of an infant with human immunodeficiency virus-1 (HIV-1) infection, Pneumocystis pneumonia, and encephalopathy. During immune reconstitution the patient developed nephrotic syndrome. Treatment of nephrotic syndrome was initiated with prednisone, an angiotensin-converting enzyme inhibitor (lisinopril), and low-molecular-weight heparin. ART was continued, but only a low level of lopinavir/ritonavir could be achieved. There was no relapse of nephrotic syndrome during 10 months of follow-up. CONCLUSIONS: Nephrotic syndrome may occur in infants during immune reconstitution and should not be overlooked.

Donor and recipient ACE I/D genotype are associated with loss of renal function in children following renal transplantation.

Genetic polymorphisms of the RAS correlate with allograft function. We therefore analyzed common RAS polymorphisms in kidney donors and in children following RTx to determine the relationship between genotype and decline in GFR, blood pressure, and LVM. A total of 107 children who underwent RTx were included: 70 male, 37 female, mean age 8.8±4.9 yr, mean follow up 5.4 yr. The following RAS polymorphisms were studied in all 107 recipients, 48 donors, and 120 healthy controls: Renin (Renin Mbol 18G/A), ACE I/D; angiotensinogen (AGT M235T), and angiotensin II receptor type-1 (AT1R A1166C). Only patients homozygous for the ACE D allele had a significantly steeper decline in GFR compared with homozygous carriers of the ACE I allele (slope DD: -4.3±0.8 vs. II: -1.3±1.1 mL/min/1.73 m2 per yr; p=0.035). In four cases, a DD recipient received a kidney from a DD donor, and these patients showed a more pronounced decline in GFR (-5.2±0.5 mL/min/1.73 m2 per yr; p=0.002). MABP was not different before vs. after RTx and was independent of ACE I/D genotype. LVMI increased significantly in the majority of patients (36.6±13.9 g/m2.7 six months before RTx vs. 46.4±15.3 g/m2.7 12 months after RTx, p=0.015). However, this difference disappeared after stratification by ACE I/D genotype. The ACE DD genotype is a potential marker for identifying patients at high risk of poor allograft outcome.

Immunosuppression and renal outcome in congenital and pediatric steroid-resistant nephrotic syndrome.

BACKGROUND AND OBJECTIVES: Mutations in podocyte genes are associated with steroid-resistant nephrotic syndrome (SRNS), mostly affecting younger age groups. To date, it is unclear whether these patients benefit from intensified immunosuppression with cyclosporine A (CsA). The aim of this study was to evaluate the influence of podocyte gene defects in congenital nephrotic syndrome (CNS) and pediatric SRNS on the efficacy of CsA therapy and preservation of renal function. DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS: Genotyping was performed in 91 CNS/SRNS patients, irrespective of age at manifestation or response to CsA. RESULTS: Mutations were identified in 52% of families (11 NPHS1, 17 NPHS2, 11 WT1, 1 LAMB2, 3 TRPC6). Sixty-eight percent of patients with nongenetic SRNS responded to CsA, most of them achieved complete remission. In contrast, none of the patients with genetic CNS/SRNS experienced a complete remission and only two (17%) achieved a partial response, both affected by a WT1 mutation. Preservation of renal function was significantly better in children with nongenetic disease after a mean follow-up time of 8.6 years (ESRD in 29% versus 71%). CONCLUSIONS: The mutation detection rate in our population was high (52%). Most patients with genetic CNS/SRNS did not benefit from CsA with significantly lower response rates compared with nongenetic patients and showed rapid progression to end-stage renal failure. These data strongly support the idea not to expose CNS/SRNS patients with inherited defects related to podocyte function to intensified immunosuppression with CsA.

Continuous venovenous haemodialysis (CVVHD) and continuous peritoneal dialysis (CPD) in the acute management of 21 children with inborn errors of metabolism.

BACKGROUND: Newborns with inborn errors of metabolism often present with hyperammonaemic coma, requiring prompt diagnosis and specific medical therapy, nutritional support and efficient toxin removal. Little information regarding the efficacy and safety of continuous venovenous haemodialysis (CVVHD) as an option for extracorporal ammonia detoxification in children is available. METHODS: Twenty-one patients with hyperammonaemia [19 neonates (mean age 4.1 +/- 2.4 days) and two children 1 and 7 years of age, respectively] were admitted to our hospital for dialysis between 1996 and 2008. Seventeen children (15 neonates), received CVVHD. Four neonates received continuous peritoneal dialysis (CPD). All started medical treatment with sodium benzoate, l-arginine hydrochloride and carnitine as well as protein-restricted parenteral diets with high caloric intake before dialysis. RESULTS: Plasma ammonia levels (range 464-7267 microg/dl before dialysis and 27-3317 microg/dl after dialysis) were significantly reduced by 50% within 4.7 +/- 2.5 h with CVVHD compared with 13.5 +/- 6.2 h with CPD (P < 0.0001). Plasma ammonia levels <200 microg/dl critical range were achieved within 22.4 +/- 18.1 h in CVVHD patients compared with 35.0 +/- 24.1 h with CPD. Depending on the weight and blood pressure stability of the patients, mean blood flow velocities of 9.8 +/- 3.4 ml/kg/min and mean dialysate flow rates of 3925 +/- 2398 ml/min/1.73 m(2) were employed. Blood and dialysate flows significantly correlated with ammonia clearance and decay of ammonia in vivo. Because of the severe underlying disease, 18% of CVVHD patients died compared with 50% undergoing CPD. In total, 82% of CVVHD patients survived the first 6 months after dialysis. Among these, 43% were without sequelae, 43% developed moderate mental retardation, and two (14%) developed severe mental retardation. CONCLUSION: CVVHD effectively and quickly eliminates plasma ammonia. To optimize long-term mental outcome, rapid identification and appropriate treatment of the underlying disease as well as starting dialysis early are of enormous therapeutic value.

Acute rejection episodes in pediatric renal transplant recipients with cytomegalovirus infection.

CMV infection is the most important opportunistic virus infection after renal transplantation leading to increased patient mortality, graft loss, risk for acute rejection episodes and impaired renal function. The potential impact of prophylactic anti-viral therapy on long-term graft outcome is relevant. The aim of this study was to evaluate the incidence of CMV infection, its risk factors and long-term outcome in children after renal transplantation. 103 children (mean age 10.6 +/- 5.3, range 1.6-22.0 yr) were monitored weekly for pp65 for the first 6-8 wk after renal transplantation, followed by a monthly monitoring for the first year. CMV infection occurred in 23/103 children (21.1%) with 10 patients (9.7%) developing CMV disease characterized by positive pp65 in the presence of organ involvement. The CMV R-/D+ and R+/D+ serostatus was significantly associated with an increased risk of CMV infection (p < 0.0001 and p = 0.009). 14/28 R-/D+ patients developed CMV infection despite prophylactic treatment with CMV hyperimmune globulin. The incidence of acute rejection episodes after or during CMV infection was significantly increased (p = 0.003) and the D+ serostatus was significantly associated with acute rejection episodes within the first year after transplantation (p = 0.006). In summary the overall incidence of CMV infection in this single center experience is 21.1%. The D+ serostatus represents a serious risk factor for both CMV infection and acute rejection episodes. In future the potential impact of different modalities of prophylactic anti-viral therapy on the prevention of acute rejection should be considered.

Cyclosporine-A-induced nephrotoxicity in children with minimal-change nephrotic syndrome: long-term treatment up to 10 years.

The impact of cyclosporine A (CsA) therapy in patients with steroid-dependent nephrotic-syndrome (SDNS) on long-term renal function is controversial. Data beyond 5 years are rare. Long-term renal function was evaluated in children with SDNS with and without CsA therapy, especially beyond 5 years. Twenty children were treated with CsA (study group) for a mean of 5.4 +/- 2.2 years (ten patients for 5-11 years). Glomerular filtration rate (GFR) was calculated before and after 3 and 12 months and at latest follow-up of therapy. Fifteen children with cyclophosphamide-treated SDNS without CsA served as controls. In the study group, GFR decreased within 12 months from 136 +/- 19 to 120 +/- 31, to 114 +/- 14 ml/min per 1.73 m(2) at latest follow-up (p < 0.0001). Patients with CsA > 5 years had a GFR of 111 +/- 14 ml/min per 1.73 m(2) at latest follow-up without a GFR below 90 ml/min per 1.73 m(2). No CsA toxicity was found in biopsies. In the control group, GFR dropped within 3 months, from 137 +/- 27 to 130 +/- 24, to 126 +/- 19 ml/min per 1.73 m(2) at latest follow-up (p = 0.1). Patients with and without nephrotoxic CsA therapy showed a drop in GFR. In CsA-treated patients, GFR was about 12% lower at latest follow-up compared with patients without nephrotoxic therapy but always remained within normal range. CsA seems to be safe, even in long-term treatment for more than 5 years.

Development of growth and body mass index after pediatric renal transplantation.

Suboptimal final height and marked weight gain after renal transplantation (RTx) are common and may result in obesity. Steroid free immunosuppression has been advocated to improve growth and limit weight gain. We evaluated retrospectively the evolution of growth and body mass index (BMI) after renal transplantation to study risk factors for weight gain under steroid based treatment. Sixty-four pediatric patients (age 9.9 +/- 5.0 yr) were included in the study. To allow comparison between different age groups, standard deviation scores (SDS) for height and BMI for height age were calculated at time of transplantation and 3, 6, 9, 12, 24, 36, 48 and 60 months later. Induction immunosuppression consisted of basiliximab, cyclosporine and prednisone. Growth retardation at time of RTx was obvious with a SDS for height of -2.20 +/- 1.34. Height during the first year improved to an SDS of -2.0 +/- 1.27 (p < 0.01) but did further not increase in year 2 and 3. More than 40% of all patients remained 2 SDS below normal mean. SDS BMI for height age at transplantation was -0.19 +/- 0.98 and increased significantly during the first 3 months after transplantation to +0.64 +/- 1.07 (p < 0.01). Thereafter, BMI remained stable but did not decline to pretransplant values. A SDS BMI for height age of more than 2 SDS was observed in 2, 6, 9 and 11% of children at RTx and 1, 2 and 3 yr later respectively. BMI gain over 3 yr was significantly enhanced in children whose parents (especially the mother) were overweight. No influence of gender, BMI at RTx, dialysis modality prior to RTx or rejection episodes could be detected. We conclude that after RTx children exhibit some improvement in growth but height remains suboptimal. The BMI does increase significantly during the first months after RTx and does not return to baseline values under steroid-based immunosuppression. Obesity (>2 SDS above normal) does not occur more often than in the normal population. The most predictive parameter of inappropriate weight gain during 3 yr is the BMI of the mother. We would speculate that steroids may play a major role in weight gain in the early phase after RTx. However, genetic or environmental factors predict the long-term weight development.

Autoimmune thyroiditis in association with membranous nephropathy.

Hashimoto's thyroiditis and membranous nephropathy are believed to be mediated by immune mechanisms. A 12 year-old patient is reported who presented with fatigue, dislike of cold, pallor and growth retardation. Initial laboratory assessment showed moderate proteinuria and impaired renal function (serum creatinine 2.3 mg/dl), and hypothyroidism due to autoimmune thyroiditis. Light, immunofluorescence and electron microscopy of the renal biopsy showed membranous nephropathy. The patient recovered from nephropathy after substitution of thyroid hormone and therapy with prednisone. Megalin can be envisaged as a potential pathogenetic link between the two disease entities. The glycoprotein megalin is expressed on thyroid cells in a TSH-dependent manner and may have a crucial role in the immunopathogenesis of glomerular injury in membranous nephropathy. For similar cases, we want to encourage colleagues to consider this hypothesis and to examine blood and renal biopsy specimens for the presence of megalin and antibodies against it.

Nutrition in children with preterminal chronic renal failure. Myth or important therapeutic aid?

Nutrition has been believed to be an important therapeutic instrument in children with chronic renal failure (i) for improving growth, and (ii) for slowing down the deterioration of renal function. The therapeutic strategies for both targets may be conflicting, at least in part, since a high calorie intake is needed for optimal growth, whereas a low protein diet, which was believed to protect renal function, places patients at risk of low calorie intake. Dietary manipulations for optimal growth are mainly effective in infants with chronic renal failure. However, growth remains suboptimal even with an energy intake above 80% of RDA. Although a low protein diet is able to slow down the rate of deterioration in renal function in rodent studies, the results of prospective clinical studies were disappointing at least for an observation period up to three years. The conclusions out of meta-analyses of these clinical studies in adults are contradictory. The progression rate was not significantly influenced by protein restriction, whereas renal replacement therapy could be postponed. However, the latter seems to be the effect of weakening uremic symptoms during the phase of end-stage renal failure. According to our present knowledge it is not justified to prescribe special diets to children early in the course of chronic renal failure, but the composition of their nutrition should follow the general concept of an optimal mixed diet.