Hesselink, D.A.

Prevalence of renal dysfunction in tacrolimus-treated pediatric transplant recipients: A systematic review (Article)

2013-05-01T00:00:00Z

Renal dysfunction after non-renal transplantation in adult tacrolimus-treated transplant patients is well documented. Little is known about its prevalence in children. Age-related changes in both disposition and effect of tacrolimus as well as renal function may preclude extrapolation of adult data to children. To systematically review the literature on renal dysfunction in non-renal pediatric transplant recipients treated with tacrolimus. PubMed/Medline, Embase, and Google were searched from their inception until April 19, 2012, with the search terms "tacrolimus," "renal function," "transplantation," and "children." Eighteen of 385 retrieved papers were considered relevant. Twelve dealt with liver, four with heart transplant, one with heart and lung transplant, and one with intestinal recipients. Reported prevalences of mild and severe chronic kidney disease ranged from 0% to 39% and 0% to 71.4%, respectively, for liver, and from 22.7% to 40% and 6.8% to 46%, respectively, for heart and/or lung transplant recipients. Ranges remained wide after adjusting for follow-up time and disease severity. Possible explanations are inclusion bias and definitions used for renal dysfunction. A considerable proportion of pediatric non-renal transplant patients who receive tacrolimus-based immunosuppression, appear to suffer from chronic kidney disease. This conclusion warrants further research into the real risk, its risk factors, and individualization of immunosuppressant therapy.

Inhibitory effect of tacrolimus on p38 mitogen-activated protein kinase signaling in kidney transplant recipients measured by whole-blood phosphospecific flow cytometry. (Article)

2012-06-27T00:00:00Z

Tacrolimus (TAC), the cornerstone of immunosuppressive therapy after solid organ transplantation, inhibits calcineurin activation. Despite pharmacokinetic monitoring, patients frequently experience toxicity or lack of efficacy, which could be prevented by pharmacodynamic monitoring. In Jurkat T-cell lines, it has been shown that TAC, in addition to calcineurin, inhibits the p38 mitogen-activated protein kinase (MAPK) pathway, which is important in T-cell activation and is therefore a potential drug-specific biomarker. We studied whether TAC inhibits p38 MAPK signaling in primary human T cells and ex vivo in healthy volunteers and kidney transplant recipients. Phorbol-12-myristate-13-acetate/ionomycin-induced MAPK signaling was measured by whole-blood phosphospecific flow cytometry. In vitro, 10-ng/mL TAC inhibited p38 MAPK phosphorylation by a mean of 27% in CD3, 26% in CD4, and 34% in CD8 T cells (P<0.01 compared with baseline). In healthy adults (n=4), 2 hr after a single oral dose of 10-mg TAC, the p38 MAPK activation was inhibited by 35% in CD3, CD4, and CD8 T cells (P<0.05 compared with baseline). In kidney transplant recipients (n=24), TAC predose concentrations (range, 3.2-10.5 ng/mL) were inversely correlated with p38 MAPK activation in CD3, CD4, and CD8 T cells (r=0.51, 0.34, and 0.37, respectively; P<0.01). TAC inhibits activation of the MAPK pathway in a dose-dependent manner in kidney transplant patients and may be a potential marker for immune monitoring.

Copeptin does not accurately predict disease severity in imported malaria (Article)

2012-01-06T00:00:00Z

Background: Copeptin has recently been identified to be a stable surrogate marker for the unstable hormone arginine vasopressin (AVP). Copeptin has been shown to correlate with disease severity in leptospirosis and bacterial sepsis. Hyponatraemia is common in severe imported malaria and dysregulation of AVP release has been hypothesized as an underlying pathophysiological mechanism. The aim of the present study was to evaluate the performance of copeptin as a predictor of disease severity in imported malaria. Methods. Copeptin was measured in stored serum samples of 204 patients with imported malaria that were admitted to our Institute for Tropical Diseases in Rotterdam in the period 1999-2010. The occurrence of WHO defined severe malaria was the primary end-point. The diagnostic performance of copeptin was compared to that of previously evaluated biomarkers C-reactive protein, procalcitonin, lactate and sodium. Results: Of the 204 patients (141 Plasmodium falciparum, 63 non-falciparum infection), 25 had severe malaria. The Area Under the ROC curve of copeptin for severe disease (0.66 [95% confidence interval 0.59-0.72]) was comparable to that of lactate, sodium and procalcitonin. C-reactive protein (0.84 [95% CI 0.79-0.89]) had a significantly better performance as a biomarker for severe malaria than the other biomarkers. Conclusions: C-reactive protein but not copeptin was found to be an accurate predictor for disease severity in imported malaria. The applicability of copeptin as a marker for severe malaria in clinical practice is limited to exclusion of severe malaria.

Measurement of cyclosporine A in rat tissues and human kidney transplant biopsies - A method suitable for small (<1 mg) samples (Article)

2011-12-01T00:00:00Z

Therapeutic drug monitoring is used to individualize cyclosporine A (CsA) dosing after transplantation. However, immunosuppressant concentrations within the graft may better predict clinical outcomes, including toxicity. This study aimed to develop a method suitable for CsA measurement using routine fineneedle biopsy samples. CsA was quantified retrospectively in kidney and liver tissues from 10 rats administered CsA, and 21 core needle kidney biopsies taken from renal transplant patients with suspected graft dysfunction. Dried biopsies were weighed (mean ± SD weights of 0.22 ± 0.18 mg), enzymatically solubilized, and then CsA was extracted and quantified using online 2-dimensional liquid chromatography-tandem mass spectrometry. The method was linear (r2> 0.997, n = 10), accurate, and precise (quality control and calibrator coefficient of variation and bias <15%), with minimal matrix effects (coefficient of variation and bias < 15%). Reproducibility of tissue weight measurements was confirmed by retrospective DNA quantitation, with a significant linear correlation between weight and total DNA concentration (r2= 0.988). In rats, there was a significant linear correlation between CsA concentrations in liver and kidney tissues (r2= 0.996) but there was no correlation between blood (C0) and tissue CsA concentrations (Spearman r = 0.430 and 0.503, P > 0.05). Similarly, in 16 transplant patients, for whom blood CsA concentrations (C2) were available within 1 day of the renal biopsy being performed, there was no significant correlation between CsA concentrations in blood and kidney tissue (Spearman r = 0.168, P > 0.05). In situ CsA measurements acquired using this method could make an easy transition into clinical use due to their retrospective nature and minimal disruption to current clinical protocols and could provide an additional tool for optimizing clinical outcomes in the future. Copyright

ATP-binding cassette transporters as pharmacogenetic biomarkers for kidney transplantation (Article)

2011-10-27T00:00:00Z

Immunosuppressive drugs used in organ transplantation are highly effective in preventing acute rejection. However, the clinical use of these drugs is complicated by the fact that they display highly variable pharmacokinetics and pharmacodynamics between individual patients. The influence of genetic variation on the interindividual variability in immunosuppressive drug disposition, efficacy, and toxicity has been explored in recent years. The polymorphically-expressed ATP-binding cassette (ABC) transporter proteins, in particular ABCB1 and ABCC2, have been investigated extensively because they play an important role in the absorption, distribution and elimination of many immunosuppressive drugs in use today. From these studies it can be concluded that polymorphisms in ABCB1 and ABCC2 have no consistent effect on immunosuppressant pharmacokinetics and toxicity although polymorphisms in ABCB1 appear to be related to the risk of developing calcineurin inhibitor-related nephrotoxicity. However, the latter needs to be replicated before an individual's ABCB1 genotype can become a useful marker that is applied in clinical practice. Future studies evaluating the influence of ABC transporter gene polymorphisms should explore the relationship with intracellular rather than systemic drug concentrations further in well-designed clinical studies. Until then, single-nucleotide polymorphisms in ABC transporter genes are not suitable to act as biomarkers for solid organ transplantation.

High cut-off haemodialysis induces remission of recurrent idiopathic focal segmental glomerulosclerosis after renal transplantation but is no alternative to plasmapheresis (Article)

2011-10-01T00:00:00Z

A 26-year-old male experienced a recurrence of idiopathic focal segmental glomerulosclerosis (iFSGS) after his second renal transplant. Reduction of proteinuria was rapidly induced by plasmapheresis (PP) and the patient has remained in remission with a once-weekly PP regimen, which has now been continued for >3 years. We were also able to induce remission of iFSGS in this patient by treatment with high cut-off haemodialysis using the Theralite™ dialyser. This observation lends support for the pathophysiological role of an as yet unknown, circulating glomerular filtration barrier permeability factor with an estimated weight of between 30 and 50 kDa.

CYP3A5 genotype is not related to the intrapatient variability of tacrolimus clearance (Article)

2011-06-01T00:00:00Z

Background: The risk of long-term chronic allograft nephropathy and graft loss after kidney transplantation is increased in patients with a high intrapatient variability of tacrolimus (Tac) clearance. Methods: To test whether this intrapatient variability is associated with an individual's CYP3A5 genotype, we measured the intrapatient variability in Tac clearance in a cohort of 208 kidney transplant recipients treated with Tac and mycophenolate mofetil. Results: Tac dose requirement was significantly higher in patients expressing CYP3A5. However, intraindividual variability of Tac clearance was not related to CYP3A5 genotype. Conclusions: Intraindividual variability in Tac clearance is not related to CYP3A5 genotype. Other factors, including patient adherence, may explain the variability in Tac clearance within an individual patient over time. Copyright

A case of primary aldosteronism revealed after renal transplantation (Article)

2010-11-23T00:00:00Z

Background. A 57-year-old woman was referred to a nephrology clinic because of chronic hypokalemia. She had a history of polycystic kidney disease, resistant hypertension, atrial fibrillation, type 2 diabetes, stroke, and end-stage renal disease, and had received a kidney transplant from a deceased donor at the age of 48 years. At presentation, the patient described symptoms of chronic fatigue and muscle aches, but she did not report pareses. Her medications included four antihypertensive agents, glucose-lowering drugs, immunosuppressants, digoxin, a coumarin derivative, and potassium chloride.Investigations. Full history, physical examination, laboratory testing of blood and urine, including aldosterone-torenin ratio, and a saline infusion test.Diagnosis. Primary aldosteronism.Management. Treatment with spironolactone resulted in prompt control of hypertension and hypokalemia, allowing discontinuation of potassium chloride and reduction in antihypertensive medication.

The pharmacogenetics of calcineurin inhibitor-related nephrotoxicity (Article)

2010-08-01T00:00:00Z

Chronic calcineurin inhibitor (CNI)-induced nephrotoxicity is associated with prolonged use of cyclosporine and tacrolimus and has been observed after all types of transplantation, as well as during treatment of autoimmune disease. Extensive alterations in the renal architecture including glomerular sclerosis, tubular atrophy and interstitial fibrosis may lead to end-stage renal failure. Increasing evidence shows that pharmacogenetic factors explain part of the between-patient differences in susceptibility to developing CNI-induced nephrotoxicity. In this paper this evidence is reviewed, with special emphasis on the role of genetic factors influencing metabolism and transportation of CNIs in both acceptor and donor.

Dosing tacrolimus based on CYP3A5 genotype: Will it improve clinical outcome? (Article)

2010-06-01T00:00:00Z

Tacrolimus, widely used to prevent acute rejection following solid-organ transplantation, has become the cornerstone of immunosuppressive therapy after kidney transplantation. More than 70% of all renal transplant recipients receive this remarkably effective agent. 1 But tacrolimus is also highly toxic, and there is great between-patient variability in its pharmacokinetics. This, combined with a low therapeutic index, mandates routine therapeutic drug monitoring in clinical practice. 2 Typically, predose concentrations are monitored and the dose is adjusted to aim for target values that depend on immunological risk, comedication, and time since transplantation.

Efficacy and safety of exchange transfusion as an adjunct therapy for severe Plasmodium falciparum malaria in nonimmune travelers: A 10-year single-center experience with a standardized treatment protocol (Article)

2010-04-01T00:00:00Z

Background: Even in circumstances where optimal antimalarial and supportive treatment is available, severe Plasmodium falciparum malaria is still associated with a significant case fatality. Although exchange transfusion (ET) has been considered as a controversial adjunct therapy, we have not encountered any case fatality since ET was introduced as a standard adjunct therapy for patients with severe malaria. Study design and methods: In this retrospective cohort study of 25 patients with severe malaria, the efficacy and safety of ET as an adjunct to parenteral antimalarial treatment (which was implemented in our hospital starting in 1998) were evaluated and compared with 31 historical control patients who were treated with conventional parenteral antimalarial treatment in the period before ET was added to the standard of care for severe malaria (generally before 1997). Results: The parasite clearance times (PCT)25%, PCT50%, PCT75%and PCT90%were all significantly shorter for patients treated with ET than for patients treated with parenteral quinine only. The shorter PCTs in the ET group were the result of a more rapid parasite clearance in the early phases after initiation of ET. Conclusion: No case fatalities were observed in the ET group. The complications that were observed with ET were more likely related either to the multiorgan dysfunction associated with severe malaria or to side effects of parenteral quinine rather than to the ET procedure. ET may be safely executed in a setting with intensive care facilities and availability of safe blood products and should be considered as a beneficial adjunct treatment to parenteral antimalarial therapy.

Procalcitonin as a biomarker for severe Plasmodium falciparum disease: A critical appraisal of a semi-quantitative point-of-care test in a cohort of travellers with imported malaria (Article)

2009-09-21T00:00:00Z

Background. Imported malaria occurs as a relatively rare event in developed countries. As a consequence, most clinicians have little experience in making clinical assessments of disease severity and decisions regarding the need for parenteral therapy or high-level monitoring. In this study, the diagnostic accuracy of procalcitonin (PCT) for severe Plasmodium falciparum disease was assessed in a cohort of 100 consecutive travellers with various species of imported malaria. Methods and results. In all patients, PCT was measured on admission with a semi-quantitative 'point-of-care' test. Patients with severe P. falciparum malaria had significantly higher median PCT levels on admission as compared with patients with uncomplicated P. falciparum disease. In addition, PCT levels in patients with non-falciparum malaria were also higher compared with patients with non-severe falciparum malaria but lower compared with severe P. falciparum malaria. At a cut-off point of 10 ng/mL, PCT had a sensitivity of 0,67 and a specificity of 0,94 for severe falciparum disease. However, at lower cut-off points the specificity and positive predictive value were rather poor although the sensitivity and negative predictive value remained high. Discussion. Potential drawbacks in the interpretation of elevated PCT levels on admission may be caused by infections with non-falciparum species and by concomitant bacterial infections. Conclusion. Semi-quantitative determination of PCT on admission is of limited use in the initial clinical assessment of disease severity in travellers with imported malaria, especially in settings with limited experience with the treatment of malaria.

A drug transporter for all ages? ABCB1 and the developmental pharmacogenetics of cyclosporine (Article)

2008-09-01T00:00:00Z

The clinical use of the immunosuppressive agent cyclosporine is complicated by its toxicity, narrow therapeutic window and highly variable pharmacokinetics between individuals. In adults, genetic polymorphisms in the genes encoding the cyclosporine-metabolizing enzymes CYP3A4 and CYP3A5, as well as the ABCB1 gene, which encodes the efflux-pump P-glycoprotein, seem to have a limited effect, if any, on cyclosporine pharmacokinetics. However, the authors have now reported for the first time an association between cyclosporine oral bioavailability and the ABCB1 c.1236C>T and c.2677G>T polymorphisms, as well as the related haplotype c.1199G-c.1236C-c.2677G-c.3435C, in children with end-stage renal disease older than 8 years of age. Carriers of the variant alleles had a cyclosporine oral bioavailability that was around 1.5-times higher compared with noncarriers. This association was not observed in children younger than 8 years of age. In addition, no relation between cyclosporine disposition and genetic variation in the CYP3A4, CYP3A5, ABCC2, SLCO1B1 and NR1I2 genes was observed. These data suggest that the effect of ABCB1 polymorphisms on cyclosporine pharmacokinetics is related to age, and thus developmental stage. Although further study is necessary to establish the predictive value of ABCB1 genotyping for individualization of cyclosporine therapy in children older than 8 years, an important step towards further personalized immunosuppressive drug therapy has been made.

CYP3A5 genotype is not associated with a higher risk of acute rejection in tacrolimus-treated renal transplant recipients (Article)

2008-04-01T00:00:00Z

OBJECTIVE: Patients expressing the tacrolimus-metabolizing enzyme, cytochrome P450 (CYP) 3A5, require more tacrolimus to reach target concentrations. We studied the influence of the CYP3A5*3 allele, which results in the absence of CYP3A5 protein, on tacrolimus dose and exposure, as well as the incidence of biopsy-proven acute rejection (BPAR) after renal transplantation. METHODS: A total of 136 patients participating in a prospective, randomized-controlled clinical trial with the primary aim of comparing the efficacy of a fixed-dose versus a concentration-controlled mycophenolate mofetil immunosuppressive regimen, were genotyped for CYP3A5*3. The patients described herein, participated in a pharmacogenetic substudy and were all treated with mycophenolate mofetil, corticosteroids and tacrolimus. Tacrolimus predose concentrations (C0) were measured on day 3 and 10, and month 1, 3, 6 and 12. RESULTS: Compared with CYP3A5*3/*3 individuals (n=110), patients carrying at least one CYP3A5*1 (wild-type) allele (CYP3A5 expressers; n=26) had a lower tacrolimus C0 on day 3 only (16.6 versus 12.3 ng/ml, respectively), whereas dose-corrected tacrolimus C0 were significantly lower in the latter group at all time points. After day 3, the overall daily tacrolimus dose was 68% higher in CYP3A5 expressers (P<0.001). The incidence of BPAR was comparable between CYP3A5 expressers and nonexpressers (8 versus 16%, respectively; P=0.36). CONCLUSION: We conclude that patients expressing CYP3A5 need more tacrolimus to reach target concentrations and have a lower tacrolimus exposure shortly after transplantation. This delay in reaching target concentrations, however, did not result in an increased incidence of early BPAR and therefore, genotyping for CYP3A5 is unlikely to improve short-term transplantation outcome.

Kinetic analysis reveals potency of CD4+ CD25bright+ regulatory T-cells in kidney transplant patients (Article)

2007-11-01T00:00:00Z

Donor-specific hyporesponsiveness as occurs after allogeneic kidney transplantation may be mediated by repression of effector cells by a specific subset of T-cells: the CD4+CD25bright+FoxP3+regulatory T-cells (Tregs). Here, we examined the suppressive capacity of Tregs isolated from the leukafereses product of 6 kidney transplant recipients, by reconstituting Tregs to responder T-cells at several time-points after initiation of proliferation. We show that Tregs derived from kidney transplant patients potently restrain proliferation to donor-antigens and 3rd party-antigens in classic reconstitution assays (i.e. addition of Tregs at the start of the co-incubation). However, when Tregs were added 5 days after initiation of proliferation, they were still capable of suppressing proliferation to donor-antigens (by 38%) but no longer to 3rd party-antigens. Thus, we conclude that the potency of Tregs to suppress reactivity to specific antigens should be determined by reconstitution to ongoing reactions.

Optimization of Calcineurin Inhibitor Treatment after Solid Organ Transplantation (Doctoral Thesis)

2007-09-19T00:00:00Z

On December 23, 1954, Ronald Herrick donated a kidney to his identical twin brother Richard who was dying of renal failure. The kidney transplant produced urine immediately and in February 1955, Richard Herrick was discharged from hospital. He survived for another nine years (at which time his kidney allograft failed from recurrent glomerulonephritis), married the nurse who attended him, became father of two children and returned to work as a radio and television engineer. His brother Ronald lived on for more than 50 years after donating his kidney.1-3 In the years following this first successful human kidney transplantation, several more kidney transplants were performed between identical twins. Most of these patients had a return of normal kidney function and survived for a considerable period of time.4 However, it was clear from previous experience that if kidney transplantation was to be extended successfully to genetically non-identical individuals, suppressing the recipient’s immune system was necessary in order to prevent acute rejection. Early after World War II, a small number of human kidney transplantations had been performed in Europe and the United States. The recipients had received no immunosuppression except for a few cases in which short courses of ACTH or cortisone had been given. Although some of these kidney allografts did function for a limited period of time -most likely as a result of profound uremia5- most of the transplanted kidneys were acutely rejected or destroyed as a result of thrombosis or infection, and none of the recipients survived for a long period of time.

Functional impairment of monocyte-derived dendritic cells in patients with severe chronic kidney disease (Article)

2007-01-01T00:00:00Z

Background. Dendritic cells (DCs) are antigen-presenting cells that are pivotal for the initiation of the primary immune response. Patients with chronic kidney disease (CKD) with or without chronic intermittent haemodialysis (CIHD) show an impaired immune response. Dysfunction of DCs may underlie this phenomenon. Methods. In this study, several different functions of monocyte-derived DCs (moDC) of patients with CKD class IV-V (glomerular filtration rate <30 ml/min) and patients on CIHD were studied in vitro and compared with age- and sex-matched healthy volunteers. Results. We demonstrate that, independent of the maturation stimulus used, mature moDC from both groups of patients did not acquire the same level of terminal differentiation as moDC from controls, as shown by analysis of cell surface markers and the relative high macropinocytosis activity of moDC. The stimulation of allogeneic T-cells by immature moDC and mature moDC did not differ between patients and controls. However, in the presence of immature moDC or antigen-loaded maturated moDC from patients, less proliferation of autologous T-cells was observed in response to recall antigens. There was no difference between moDC from controls and patients in their ability to activate naive T-cells and to differentiate them into Th1 and Th2 cells. Conclusions. These results show that the terminal differentiation of moDC in patients with severe CKD is impaired. This impairment is not restricted to one maturation stimulus and is independent of treatment with haemodialysis.

A high prevalence of culture-positive extrapulmonary tuberculosis in a large Dutch teaching hospital (Article)

2003-01-01T00:00:00Z

BACKGROUND: In the Netherlands the incidence of tuberculosis (TB) has increased during the last decade. Growing immigration and international travel were important determining factors. To determine if this has resulted in altered clinical manifestations of the disease, we assessed the clinical spectrum of all TB cases diagnosed at our hospital in the period 1994 to 2000. METHODS: All culture-proven TB cases during the study period were retrospectively reviewed for clinical and demographic data. RESULTS: Sixty-five patients were identified. Solitary pulmonary TB was diagnosed in 33.9%, extrapulmonary TB in 51.8% and combined pulmonary and extrapulmonary TB in 14.3% of all cases. Patients were of foreign descent in 78.6% of all cases. Incidence peaked between 15 to 45 years. Decreased immunity was an important determining factor in the older patients. Presenting symptoms were mostly aspecific causing an important doctor's delay in establishing the diagnosis in 25%. Mortality was 3.6% and isoniazid resistance 3.6% CONCLUSIONS: Our data suggest an increase in the percentage of extrapulmonary TB concomitantly with an increasing percentage of patients of foreign descent. Because of aspecific presenting symptoms, TB was often diagnosed late. Treatment is mainly hindered by non-compliance and a high index of suspicion is necessary in making the diagnosis.

New rat model that phenotypically resembles autosomal recessive polycystic kidney disease (Article)

2000-01-01T00:00:00Z

Numerous murine models of polycystic kidney disease (PKD) have been described. While mouse models are particularly well suited for investigating the molecular pathogenesis of PKD, rats are well established as an experimental model of renal physiologic processes. Han:SPRD-CY: rats have been proposed as a model for human autosomal dominant PKD. A new spontaneous rat mutation, designated wpk, has now been identified. In the mutants, the renal cystic phenotype resembles human autosomal recessive PKD (ARPKD). This study was designed to characterize the clinical and histopathologic features of wpk/wpk mutants and to map the wpk locus. Homozygous mutants developed nephromegaly, hypertension, proteinuria, impaired urine-concentrating capacity, and uremia, resulting in death at 4 wk of age. Early cysts were present in the nephrogenic zone at embryonic day 19. These were localized, by specific staining and electron microscopy, to differentiated proximal tubules, thick limbs, distal tubules, and collecting ducts. In later stages, the cysts were largely confined to collecting ducts. Although the renal histopathologic features are strikingly similar to those of human ARPKD, wpk/wpk mutants exhibited no evidence of biliary tract abnormalities. The wpk locus maps just proximal to the CY: locus on rat chromosome 5, and complementation studies demonstrated that these loci are not allelic. It is concluded that the clinical and renal histopathologic features of this new rat model strongly resemble those of human ARPKD. Although homology mapping indicates that rat wpk and human ARPKD involve distinct genes, this new rat mutation provides an excellent experimental model to study the molecular pathogenesis and renal pathophysiologic features of recessive PKD.