Serum lipids in children 3 to 5 years after kidney, liver, and heart transplantation

Children Are Not Small Adults: Similarities and Differences in Renal Transplantation Between Adults and Pediatrics

Kidney transplantation is the treatment of choice for all patients with end-stage kidney disease, including pediatric patients. Graft survival in pediatrics was lagging behind adults, but now is comparable with the adult cohort. Although many of the protocols have been adopted from adults, there are issues unique to pediatrics that one should be aware of to take care of this population. These issues include recipient size consideration, increased incidence of viral infections, problems related to growth, common occurrence of underlying urological issues, and psychosocial issues. This article addresses the similarities and differences in renal transplantation, from preparing a patient for transplant, the transplant process, to post-transplant complications.

Long-term mortality in pediatric solid organ recipients-A nationwide study

BACKGROUND

The present study aimed at investigating long-term mortality of patients who underwent solid organ transplantation during childhood and at identifying their causes of death.

METHODS

A cohort of 233 pediatric solid organ transplant recipients who had a kidney, liver, or heart transplantation between 1982 and 2015 in Finland were studied. Year of birth-, sex-, and hometown-matched controls (n = 1157) were identified using the Population Register Center registry. The Causes of Death Registry was utilized to identify the causes of death.

RESULTS

Among the transplant recipients, there were 60 (25.8%) deaths (median follow-up 18.0 years, interquartile range of 11.0-23.0 years). Transplant recipients' risk of death was nearly 130-fold higher than that of the controls (95% CI 51.9-1784.6). The 20-year survival rates for kidney, liver, and heart recipients were 86.1% (95% CI 79.9%-92.3%), 58.5% (95% CI 46.2%-74.1%), and 61.4% (95% CI 48.1%-78.4%), respectively. The most common causes of death were cardiovascular diseases (23%), infections (22%), and malignancies (17%). There were no significant differences in survival based on sex or transplantation era.

CONCLUSION

The late mortality is still significantly higher among pediatric solid organ recipients in comparison with controls. Cardiovascular complications, infections, and cancers are the main causes of late mortality for all studied transplant groups. These findings emphasize the cruciality of careful monitoring of pediatric transplant recipients in order to reduce long-term mortality.

Pediatric vascularized composite allotransplantation: What is the landscape for obtaining appropriate donors in the United States?

Listing the world's first pediatric bilateral hand transplant patient for a donor posed many challenges including matching the appropriate donor age, bone size, skin tone, and growth potential in an already limited donor population. This study describes the prevalence and distribution of potential pediatric VCA donors in the United States. We assessed the UNOS database from 2008 to 2015 to identify the prevalence of potential pediatric VCA donors. Standard VCA inclusion and exclusion criteria were applied to the dataset for all pediatric solid organ donors. Frequency analyses were performed of characteristics important for VCA matching. The dataset began with 57 300 brain-dead donors and after applying the inclusion and exclusion criteria including age <18, decreased to 4663 (8.1%). The number of pediatric potential VCA donors per UNOS region ranged from 11 to 112/year. The majority of pediatric potential VCA donors were blood type O Whites, with the least common profile being blood type AB of "other" ethnicity. The present study confirmed that pediatric VCA donors are rare and may require longer travel times for procurement and listing at multiple centers in order to find a suitable donor. This will be a limiting factor for the expansion of pediatric VCA.

Dyslipidemia after pediatric renal transplantation-The impact of immunosuppressive regimens

Dyslipidemia contributes to cardiovascular morbidity and mortality in pediatric transplant recipients. Data on prevalence and risk factors in pediatric cohorts are, however, scarce. We therefore determined the prevalence of dyslipidemia in 386 pediatric renal transplant recipients enrolled in the CERTAIN registry. Data were obtained before and during the first year after RTx to analyze possible non-modifiable and modifiable risk factors. The prevalence of dyslipidemia was 95% before engraftment and 88% at 1 year post-transplant. Low estimated glomerular filtration rate at 1 year post-transplant was associated with elevated serum triglyceride levels. The use of TAC and of MPA was associated with significantly lower concentrations of all lipid parameters compared to regimens containing CsA and mTORi. Immunosuppressive regimens consisting of CsA, MPA, and steroids as well as of CsA, mTORi, and steroids were associated with a three- and 25-fold (P<.001) increased risk of having more than one pathologic lipid parameter as compared to the use of TAC, MPA, and steroids. Thus, amelioration of the cardiovascular risk profile after pediatric RTx may be attained by adaption of the immunosuppressive regimen according to the individual risk profile.

Lipid profile and cardiovascular risk factors in pediatric liver transplant recipients

Cardiovascular diseases induce long-term morbidity and mortality of adult LT recipients. The aim of this retrospective study was to assess CVRF, lipid abnormalities, and atherosclerosis (appraised by c-IMT), more than 10 yr after pediatric LT. Thirty-one children who underwent LT between December 1990 and December 2000 were included. Median age at LT was 14 months (range 4-64), and median follow-up after LT was 11.9 yr (range 9.0-17.3). In our cohort, obesity (9.7%) and treated hypertension (9.7%) were rare. None of the patients was smoker or diabetic. High TC and TG were both observed in 6.5% of the patients. The mean c-IMT for male patients was 1.22 ± 1.55 and 1.58 ± 1.23 mm in female patients. Seven patients (22%) had a mean c-IMT above +2 s.d. Values below the 5th percentile were noted for LDL-cholesterol (58.1%), HDL-cholesterol (25.8%), apolipoprotein B (40%), and apolipoprotein A1 (20%). LDL-cholesterol and apolipoprotein B levels were significantly lower in patients treated by tacrolimus in comparison with CsA (p < 0.05). In conclusion, our results suggest that pediatric LT patients do not present significant CVRF; moreover, instead of hyperlipidemia, hypocholesterolemia (LDL-C) is frequent and immunosuppressive therapy is probably the cause.

Long-term effects of paediatric kidney transplantation

Renal transplantation in paediatric patients usually provides excellent short-term and medium-term results. Early diagnosis of chronic kidney disease and active therapy of end-stage renal disease before and after transplantation enables the majority of children to grow and develop normally. The adverse effects of immunosuppressive medication and reduced graft function might, however, hamper long-term outcomes in these patients and can lead to metabolic complications, cardiovascular disease, reduced bone health, and malignancies. The neurocognitive development and quality of life of paediatric transplant recipients largely depend on the primary diagnosis and on graft function. Poor adherence to immunosuppression is an important risk factor for graft loss in adolescents, and controlled transition to adult care is of utmost importance to ensure a continued normal life. In this Review, we discuss the outcomes and long-term effects of renal transplantation in paediatric recipients, including consequences on growth, development, bone, metabolic, and cardiovascular disorders. We discuss the key problems in the care of paediatric renal transplant recipients and the remaining challenges that should be the focus of future research.

Pediatric post-transplant metabolic syndrome: new clouds on the horizon

Liver transplantation (LT) is a standard treatment for children with end-stage liver disease, standing at more than 90% survival rate after one yr, and at over a 70% survival rate after five yr. The majority of transplanted children enjoy an excellent quality of life but complications can occur in the long term, and can develop subclinically in otherwise well children; there are various underestimated nutritional and metabolic aspects, including the so-called post-transplant metabolic syndrome (PTMS). During the post-transplant period, the use of immunosuppressants, corticosteroids, calcineurin inhibitors, and the presence of risk factors, including non-alcoholic fatty liver disease (NAFLD), and kidney and bone complications have been largely implicated in PTMS development. Strategies to reduce the progression of PMTS should include careful screening of patients for diabetes, dyslipidemia, and obesity, and to support weight reduction with a carefully constructed program, particularly based on diet modification and exercise. With early identification and appropriate and aggressive management, excellent long-term health outcomes and acceptable graft survival can be achieved.

Cholesterol metabolism altered and FGF21 levels high after pediatric liver transplantation despite normal serum lipids

Liver transplantation (LT) predisposes to metabolic derangements and increases the risk for cardiovascular disease. We conducted a national cross-sectional study of all pediatric recipients who underwent LT between 1987 and 2007. We measured serum levels of noncholesterol sterols (surrogate markers of cholesterol synthesis and intestinal absorption) and fibroblast growth factor 21 (FGF21) in 49 patients (74% of survivors) at a median of 10 years posttransplant and in 93 controls matched for age and gender. Although serum cholesterol levels were similar in patients and controls, patients displayed increased whole-body synthesis and decreased intestinal absorption of cholesterol compared with controls (lathosterol to cholesterol ratio 129 ± 55 vs. 96 ± 41, respectively, p < 0.001; campesterol to cholesterol ratio 233 ± 91 vs. 316 ± 107, respectively; p < 0.001). Azathioprine (r =-0.383, p = 0.007) and low-dose methylpredisolone (r =-0.492, p < 0.001) were negatively associated with lathosterol/sitosterol ratio reflecting a favorable effect on cholesterol metabolism. FGF21 levels were higher in patients than in controls (248 pg/mL vs. 77 pg/mL, p < 0.001). In healthy controls, FGF21 was associated with cholesterol metabolism, an association missing in LT recipients. Normal serum lipids are achievable in long-term survivors of pediatric LT, but changes in cholesterol metabolism and increased FGF21 levels may explicate later cardiovascular risk.

Posttransplant metabolic syndrome in children and adolescents after liver transplantation: a systematic review

During long-term follow-up, 18% to 67% of pediatric liver transplant recipients are overweight or obese, with rates varying by age and pretransplant weight status. A similar prevalence of posttransplant obesity has been seen in adults. Adults also develop posttransplant metabolic syndrome and, consequently, cardiovascular disease at rates that exceed the rates in age- and sex-matched populations. Posttransplant metabolic syndrome has never been studied in pediatric liver transplant recipients, and this population is growing as transplant outcomes continue to improve. Here we systematically review the literature for each component of metabolic syndrome-obesity, hypertension, dyslipidemia, and glucose intolerance-in pediatric liver transplant recipients. Their rates of obesity are similar to the rates in children in the general U.S. population. However, hypertension, dyslipidemia, and diabetes are more common than would be expected in transplant recipients according to age, sex, and obesity severity. Immunosuppressive medications are major contributors. The limitations of previous studies, including heterogeneous methods of diagnosis, follow-up times, and immunosuppressive regimens, hinder the analysis of risk factors. Importantly, no studies have reported graft or patient outcomes associated with components of metabolic syndrome after pediatric liver transplantation. However, if the trends in children are similar to the trends seen in adults, these conditions may lead to significant long-term morbidity. Further research on the prevalence, causes, and consequences of posttransplant metabolic syndrome in pediatric liver transplant recipients is needed and will ultimately help to improve long-term outcomes.

Characteristics of low-density and high-density lipoprotein subclasses in pediatric renal transplant recipients

Renal transplant recipients often suffer from dyslipidemia which is one of the principal risk factors for cardiovascular disease. This study sought to determine characteristics of high-density lipoprotein (HDL) and low-density lipoprotein (LDL) particles and their associations with carotid intima-media thickness (cIMT) in a group of pediatric renal transplant recipients. We also examined the influence of immunosuppressive therapy on measured LDL and HDL particle characteristics. HDL size and subclass distribution were determined using gradient gel electrophoresis, while concentrations of small, dense LDL (sdLDL)-cholesterol (sdLDL-C) and sdLDL-apolipoprotein B (sdLDL-apoB) using heparin-magnesium precipitation method in 21 renal transplant recipients and 32 controls. Renal transplant recipients had less HDL 2b (P < 0.001), but more HDL 3a (P < 0.01) and 3b (P < 0.001) subclasses. They also had increased sdLDL-C (P < 0.01) and sdLDL-apoB (P < 0.05) levels. The proportion of the HDL 3b subclasses was a significant predictor of increased cIMT (P < 0.05). Patients treated with cyclosporine had significantly higher sdLDL-C and sdLDL-apoB concentrations (P < 0.05) when compared with those on tacrolimus therapy. Pediatric renal transplant recipients have impaired distribution of HDL and LDL particles. Changes in the proportion of small-sized HDL particles are significantly associated with cIMT. Advanced lipid testing might be useful in evaluating the effects of immunosuppressive therapy.

Cardiorespiratory fitness is a marker of cardiovascular health in renal transplanted children

Children with renal transplants (TX) are at increased risk of cardiovascular (CV) disease. Study objectives were to assess the level of cardiorespiratory fitness (CR fitness) and daily physical activity (PA) in renal TX children and adolescents in relation to traditional cardiovascular risk factors. Laboratory testing included assessment of CR fitness by treadmill exercise testing (VO(2peak)), 24-h ambulatory blood-pressure (ABPM) measurement, oral glucose tolerance test (OGTT), anthropometrics and measurement of lipid levels. PA was self-reported by questionnaire. Twenty-two TX patients with a median (range) age 14.5 (9-18) years were tested. Median V0(2peak) was 66% (36-97) of the expected values compared with controls. Nineteen (86%) children reported <60 min of daily moderate to vigorous physical activity (MVPA). Sixteen (73%) were hypertensive and 8 (34%) were overweight or obese. Four children fulfilled the criteria for a metabolic syndrome. Children with at least 2 of the 3 metabolic risk factors (hypertension, overweight, and glucose intolerance, n=7) achieved significantly lower VO(2peak) compared with those with one or none of these factors (median V0(2peak) 45% and 73% of the expected values respectively, p=0.003). Renal TX children and adolescents have severely impaired CR fitness and PA. Reduced CR fitness was associated with the clustering of CV risk factors. Routine counseling for increased PA is strongly recommended.

Carotid intima-media thickness after pediatric renal or liver transplantation at high-resolution B-mode ultrasonography

In a previous study, we observed a higher incidence of dyslipidemia in pediatric renal recipients compared with liver recipients. In the present study, we measured common carotid artery intima-media thickness (IMT) in 13 pediatric renal recipients, 9 liver recipients, and 26 control individuals with median age of 11.4, 10.8, and 12.0 years, respectively. The patients were studied from 0.2 to 10.8 years after renal transplantation (RTx) or liver transplantation (LTx). An experienced radiologist (T.K.) blinded to the status of the children measured the IMT using a high-resolution B-mode ultrasonography method. In patients who underwent RTx or LTx, serum fasting lipid profile, estimates of renal and liver function, and glucose metabolism were determined. Children undergoing RTx or LTx more often had hypertension compared with the control individuals (P = .004). Before transplantation, dyslipidemia was greater in patients undergoing RTx compared with those undergoing LTx (P < .05). Children who underwent RTx, compared with those who underwent LTx or control individuals, had thicker mean IMT at the 6 sites measured (mean [SD], 0.57 [0.07], 0.51 [0.05], and 0.53 [0.06] mm, respectively; P = .02]. As a result of linear regression in renal recipients, variability of glomerular filtration rate (<60 mL/min/1.73 m(2) vs normal) accounted for 43.3% of variability of the mean of maximal IMT (B = 8.9; SE = 3.1; P = .01). Variability of pre-RTx serum triglyceride concentration (B = 1.6; SE = 0.6; P = .03) and actual triglyceride concentration (B = 10.3; SE = 2.2; P = .002) accounted for 82.2% of variability of maximal IMT. Our findings support previous data on the importance of maintenance of good graft function with sufficient but not overly efficient immunosuppression after transplantation in prevention of future cardiovascular disease.

Cure of multifocal panhepatic hepatoblastoma: is liver transplantation always necessary?

PURPOSE

Multifocal panhepatic hepatoblastoma (HB) without extrahepatic disease is generally considered as an indication for total hepatectomy and liver transplantation. However, after initial chemotherapy, downstaging of the tumor sometimes allows complete macroscopic resection by partial hepatectomy. This procedure is no longer recommended because of the risk of persistent viable tumor cells in the hepatic remnant. We report our experience with conservative surgery in such cases.

METHOD

Between 2000 and 2005, 4 children were consecutively referred to our unit with multinodular pan-hepatic HBs (classification PRETEXT IV of the International Society of Pediatric Oncology Liver Tumor Study Group SIOPEL). Three of them had extrahepatic disease at diagnosis. All patients were treated according to SIOPEL 3 and 4 protocols.

RESULTS

Extrahepatic metastases were still viable in 2 of 3 patients after initial chemotherapy. These patients eventually died of tumor recurrence. In the 2 patients without residual extrahepatic disease, liver tumors had regressed, and complete macroscopic excision of hepatic tumor remnants could be achieved by conservative surgery. These 2 children are alive and well and free of tumor 7 years after diagnosis.

CONCLUSIONS

Conservative surgery may be curative in some multinodular PRETEXT IV HB patients, with a good response to preoperative chemotherapy and complete excision of all macroscopic tumor remnants. However, because of the lack of reliable predictors of sterilization of the microscopic disease in the residual liver, with subsequent poor prognosis, total hepatectomy and liver transplantation remain currently recommended in patients with multinodular PRETEXT IV HB without extrahepatic disease, even though some of these children are probably overtreated.

Adverse effects of immunosuppression in pediatric solid organ transplantation

Solid organ transplantation is a life-saving treatment for end-stage organ failure in children. Immunosuppressant medications are used to prevent rejection of the organ transplant. However, these medications are associated with significant adverse effects that impact growth and development, quality of life (QOL), and sometimes long-term survival after transplantation. Adverse effects can differ between the immunosuppressants, but many result from the overall state of immunosuppression. Strategies to manage immunosuppressant adverse effects often involve minimizing exposure to the drugs while balancing the risk for rejection. Early recognition of immunosuppressant adverse effects may help to reduce morbidities associated with solid organ transplantation, improve QOL, and possibly increase overall patient survival.

Calcineurin inhibitor sparing in paediatric solid organ transplantation : managing the efficacy/toxicity conundrum

Despite their efficacy, the calcineurin inhibitors (CNIs) ciclosporin and tacrolimus carry a risk of debilitating adverse effects, especially nephrotoxicity, that affect the long-term outcome and survival of children who are given organ transplants. Simple reduction in dosage of CNI has little or no long-term benefit on their adverse effects, and complete withdrawal without threatening graft outcome may only be possible after liver transplantation. Until the last decade, the only option was to increase corticosteroid and/or azathioprine doses, which imposed additional long-term hazards. Considered here are the emerging generation of new agents offering an opportunity for improving long-term graft survival, minimizing CNI-related adverse events and ensuring patient well-being.A holistic, multifaceted strategy may need to be considered - initial selection and optimized use and monitoring of immunosuppressant regimens, early recognition of indicators of patient and graft dysfunction, and, where applicable, early introduction of CNI-sparing regimens facilitating CNI withdrawal. The evidence reviewed here supports these approaches but remains far from definitive in paediatric solid organ transplantation. Because de novo immunosuppression uses CNI in more than 93% of patients, reduction of CNI-related adverse effects has focused on CNI sparing or withdrawal.A recurring theme where sirolimus and mycophenolate mofetil have been used for this purpose is the importance of their early introduction to limit CNI damage and provide long-term benefit: for example, long-term renal function critically reflects that at 1 year post-transplant. While mycophenolic acid shows advantages over sirolimus in preserving renal function because the latter is associated with proteinuria, sirolimus appears the more potent immunosuppressant but also impairs early wound healing. The use of CNI-free immunosuppressant regimens with depleting or non-depleting antibodies plus sirolimus and mycophenolic acid needs much wider investigation to achieve acceptable rejection rates and conserve renal function. The adverse effects of the alternative immunosuppressants, particularly the dyslipidaemia associated with sirolimus, needs to be minimized to avoid replacing one set of adverse effects (from CNIs) with another. While we can only conjecture that judicious combinations with the second generation of novel immunosuppressants currently in development will provide these solutions, a rationale of low-dose therapy with multiple immunosuppressants acting by complementary mechanisms seems to hold the promise for efficacy with minimal toxicity until the vision of tolerance achieves reality.

Genetic polymorphisms of the RAS-cytokine pathway and chronic kidney disease

Chronic kidney disease (CKD) in children is irreversible. It is associated with renal failure progression and atherosclerotic cardiovascular (CV) abnormalities. Nearly 60% of children with CKD are affected since birth with congenital or inherited kidney disorders. Preliminary evidence primarily from adult CKD studies indicates common genetic risk factors for CKD and atherosclerotic CV disease. Although multiple physiologic pathways share common genes for CKD and CV disease, substantial evidence supports our attention to the renin angiotensin system (RAS) and the interlinked inflammatory cascade because they modulate the progressions of renal and CV disease. Gene polymorphisms in the RAS-cytokine pathway, through altered gene expression of inflammatory cytokines, are potential factors that modulate the rate of CKD progression and CV abnormalities in patients with CKD. For studying such hypotheses, the cooperative efforts among scientific groups and the availability of robust and affordable technologies to genotype thousands of single nucleotide polymorphisms (SNPs) across the genome make genome-wide association studies an attractive paradigm for studying polygenic diseases such as CKD. Although attractive, such studies should be interpreted carefully, with a fundamental understanding of their potential weaknesses. Nevertheless, whole-genome association studies for diabetic nephropathy and future studies pertaining to other types of CKD will offer further insight for the development of targeted interventions to treat CKD and associated atherosclerotic CV abnormalities in the pediatric CKD population.

Low HDL-C predicts the onset of transplant vasculopathy in pediatric cardiac recipients on pravastatin therapy

The levels and protein/lipid compositions of major lipoprotein particles of 19 pediatric cardiac transplant recipients (4-18 yr of age) were studied in this prospective, open clinical follow-up study before and at one yr of pravastatin therapy (10 mg/day). The recipients were grouped into those with (n = 6; group A) and those without (n = 13; group B) angiographically detectable vasculopathy. Twenty-one pediatric non-transplant controls were studied at baseline. At baseline, the group A recipients had 29% lower HDL-C concentrations (p = 0.031) and 29% higher apoB-100/apoA-I ratios (p = 0.034) than the group B recipients. At one yr of pravastatin, the respective figures were 29% (p = 0.013) and 33% (p = 0.005). Compared with the healthy pediatric controls, the transplant recipients had significantly higher serum TG before pravastatin [median (range): 1.3 mmol/L (0.6-3.2) vs. 0.7 mmol/L (0.3-2.4), p = 0.0002] and at one yr [1.3 mmol/L (0.5-3.5) vs. 0.7 mmol/L (0.3-2.4), p = 0.0004]. The baseline apoB-100/apoA1 ratios of the recipients were 33% higher (p = 0.005). In conclusion, low HDL-C and high apoB-100/apoA-I ratio were associated with angiographically detectable vasculopathy. Even though pravastatin effectively lowered the TC and LDL-C and improved compositional properties of LDL and HDL(2) particles, it failed to normalize the elevated TG and, in some patients, to prevent the progression of transplant vasculopathy.

Calcineurin inhibitors in pediatric renal transplant recipients

The calcineurin inhibitors, cyclosporine (ciclosporin) [microemulsion] and tacrolimus, are the principal immunosuppressants prescribed for adult and pediatric renal transplantation. For pediatric patients, both drugs should be dosed per body surface area, and pharmacokinetic monitoring is mandatory. While monitoring of the trough levels may suffice for tacrolimus, cyclosporine therapy that utilizes the microemulsion formulation requires additional monitoring (e.g. determination of 2-hour post-dose levels). In a well designed randomized study in children, as in studies in adults, there was no difference in short-term patient and graft survival with cyclosporine microemulsion and tacrolimus. However, tacrolimus was significantly more effective than cyclosporine microemulsion in preventing acute rejection after renal transplantation when used in conjunction with azathioprine and corticosteroids. With regard to long-term outcome, the difference in acute rejection episodes resulted in a better glomerular filtration rate at 1 year after transplantation and eventually in better graft survival 4 years after renal transplantation. Whether this difference persists when calcineurin inhibitors are used in combination with mycophenolate mofetil has not been determined. The prevalence of hypomagnesemia was higher in the tacrolimus group whereas hypertrichosis and gingival hyperplasia occurred more frequently in the cyclosporine group. In contrast with adults, the incidence of post-transplantation diabetes mellitus was not significantly different between tacrolimus- and cyclosporine-treated patients. There was also no difference with regard to post-transplantation lymphoproliferative disorder. Medication costs were similar, but in view of the lower rejection episodes and better long-term graft survival as well as the more favorable cosmetic side effect profile, tacrolimus may be preferable. The recommendation drawn from the available data is that both cyclosporine and tacrolimus can be used safely and effectively in children. We recommend that cyclosporine should be chosen when patients experience tacrolimus-related adverse events.

Lipid, Carbohydrate Metabolism, and Antioxidant Status in Children After Liver Transplantation

Organ transplantation is a risk factor for atherogenesis that may be related to immunosuppressive therapy. Increased free radical generation may even aggravate atherogenesis. The aim of the study was to assess lipid metabolism in relation to risk factors for atherogenesis as well as carbohydrate metabolism and antioxidant status among children after liver transplantation. We studied 35 children at 3 to 5 years after liver transplant in whom the following parameters were assessed: total cholesterol; triglyceride; high-density lipoprotein cholesterol; low-density lipoprotein cholesterol (LDL-C); very low-density lipoprotein cholesterol; apolipoproteins B, AI, E, lipoprotein (a); vitamin E; glutathione; glucose; insulin; and glutathione peroxidase activity. Three subgroups of patients were assessed according to the immunosuppressive therapy: cyclosporine (CsA), tacrolimus (Tac), or mycophenolate mofetil (MMF) in combination with low-dose CsA or Tac. We observed differences among the subgroups only in total cholesterol (CsA: 131.6 to 285.6; Tac: 144.0 to 181.61; MMF: 132.1 to 181.2) and LDL-C (CsA: 79.4 to 126.9; Tac: 42.2 to 118.8; MMF: 74.2 to 117.3). Lipid metabolism was not significantly disturbed among children after liver transplantation, an observation that does not point to a high risk of atherogenesis. CsA seems to have the strongest untoward effect on cholesterol metabolism. Decreased GSH concentration after liver transplantation may be related to slightly impaired liver function, but GPx activity and vitamin E concentrations remained normal.

Immunosuppression in pediatric solid organ transplantation: opportunities, risks, and management

The pediatric transplant community stands at a time of unprecedented choice of immunosuppressive agents - and with a legacy of morbidity from those agents used in the previous two decades. This review considers the clinical utility and side-effect profiles of immunosuppressants used widely in current practice (e.g., glucocorticoids, azathioprine, ciclosporin, tacrolimus, mycophenolate, and sirolimus) and those agents which are in increasing use or in evaluation (e.g., IL-2 receptor antibodies, everolimus, FTY720, LEA29Y, and deoxyspergualin). Further consideration is given to the wider drug interactions likely during the use of new immunosuppressant regimens and to our growing awareness of the influences of genetic heterogeneity on drug efficacy and handling. Finally, we consider the new demands being placed on the use of drug monitoring to regulate dosage of this new repertoire of immunosuppressants.

Methylprednisolone exposure in pediatric renal transplant patients

Glucocorticoid (GC) dosing is commonly based on body mass or surface area in children, although the drug effects appear to correlate with steroid exposure, rather than dose. We compared the area under the serum concentration-time curve (AUC) of methylprednisolone (MP) with a recombinant cell bioassay measuring serum glucocorticoid bioactivity (GBA), in prediction of side effects in 16 pediatric patients (5.4-18.4 years of age) 2.0-14.9 years after renal transplantation (TX). They received 0.3 mg/kg of MP orally and timed blood samples were drawn up to 8 h postdose. Serum MP concentrations correlated moderately with GBA (r= 0.65, p < 0.0001) with best linear fit at 6 and 8 h (r= 0.72, 0.79, respectively, p < 0.001). MP-AUC(t = 0-8) and GBA(t = 6) were significantly greater in patients who gained excessive weight soon after TX. Change in growth after TX was inversely correlated with MP-AUC (r= 0.73, p < 0.05) and GBA(t = 6) (r= 0.62, p < 0.05). No correlation of MP-AUC or GBA was found with blood glucose or serum lipid concentrations, glomerular filtration rate, bone mineral density or graft histology. In conclusion, GC exposure varies individually and dosing should be adjusted accordingly to control the adverse effects. GBA might provide a complementary tool for monitoring GC exposure but further studies are needed.

Cholesterol Absorption and Synthesis in Pediatric Kidney, Liver, and Heart Transplant Recipients

BACKGROUND

Hypercholesterolemia after organ transplantation is common. Previously, we observed higher serum total cholesterol (TC) concentrations in our pediatric kidney than liver or heart transplant recipients. To find an explanation to the observed difference, our kidney recipients' cholesterol synthesis and absorption efficiency was compared to those of liver and heart recipients.

METHODS

Serum noncholesterol sterol ratios (10 x mmol to the mol of TC, surrogate estimates of hepatic cholesterol synthesis and intestinal absorption) were studied in 50 pediatric kidney, 25 liver and 12 heart transplant recipients without diabetes or cholestasis, and in 29 controls.

RESULTS

The kidney recipients had lower Delta-cholesterol (P=0.031), similar lathosterol and higher desmosterol ratios (markers of cholesterol synthesis) (P=0.020), and similar campesterol and sitosterol ratios (markers of cholesterol absorption) when compared to the controls. The liver recipients had lower campesterol ratios than the kidney recipients and controls (P=0.002). Glomerular filtration rates were not associated with the ratios of noncholesterol sterols. Multivariate analysis showed markers of cholesterol synthesis to be lower and absorption to be higher in the kidney than the liver or the heart transplant recipients. Weight-adjusted dosages of immunosuppressive agents were associated with some ratios of noncholesterol sterols and cholestanol though these varied between the transplant recipient groups.

CONCLUSIONS

Serum TC concentration in kidney recipients was not significantly associated with absorption efficiency or synthesis of cholesterol, though kidney transplantation was associated with low synthesis and high absorption efficiency of cholesterol. Immunosuppressive therapy with cyclosporine and methylprednisolone may modulate absorption efficiency and synthesis of cholesterol.

Insulin resistance, LDL particle size, and LDL susceptibility to oxidation in pediatric kidney and liver recipients

BACKGROUND

Dyslipidemia is common after solid organ transplantation. We have described hypertriglyceridemia in about 50% of our pediatric kidney, and in about 30% of our liver recipients. The aim of the present study was to find out whether this post-transplantation hypertriglyceridemia after pediatric solid organ transplantation is associated with insulin resistance and the occurrence of small, dense low-density lipoprotein (LDL).

METHODS

Fifty kidney and 25 liver recipients (aged 4 to 18 years) on triple immunosuppression, and 181 control children participated in the study for an average of 5.3 and 6.4 years after kidney and liver transplantation (range 1 to 11 years), respectively. Homeostasis model assessments for insulin resistance (HOMA) were calculated and fasting lipoprotein lipid profile, apolipoprotein A-I and B concentrations, LDL particle diameter, and indices of LDL susceptibility to copper-induced oxidation determined.

RESULTS

Kidney patients had significantly higher serum total, high-density, and low-density lipoprotein cholesterol, triglyceride, apolipoprotein A-I and B concentrations than liver patients or control subjects (P < 0.003 for all). HOMA indices higher than the 95th percentile of Canadian normal children were seen in 50.0% of kidney (of liver 41.2%) recipients younger than 11 years, and in 27.3% of older recipients (of liver 37.5%). Smaller sized LDL or LDL of increased oxidizability was not more frequent in patients than in control children.

CONCLUSION

Pediatric kidney recipients had significantly higher lipid and insulin concentrations than healthy control children. Combined hyperlipidemia and features of the dysmetabolic syndrome were common in children after kidney and liver transplantation. However, no small, dense LDL, or LDL prone to oxidation was seen in either group.