CYP3A4 activity shows considerable interindividual variability. Although studies indicate 60%–80% is heritable, common single nucleotide variants (SNVs) in CYP3A4 together only explain ~10%.... Show moreCYP3A4 activity shows considerable interindividual variability. Although studies indicate 60%–80% is heritable, common single nucleotide variants (SNVs) in CYP3A4 together only explain ~10%. Transcriptional factors, such as the testis-specific Y-encoded-like proteins (TSPYLs) family, have been reported to regulate the expression of CYP enzymes including CYP3A4 in vitro. Here, we investigated the effect of genetic variants in TSPYL on CYP3A4 activity using data from a clinical study and a human liver bank. Five SNVs (rs3828743, rs10223646, rs6909133, rs1204807, and rs1204811) in TSPYL were selected because of a reported effect on CYP3A4 expression in vitro or suggested clinical effect. For the clinical study, whole blood concentrations, clinical data, and DNA were available from 295 kidney transplant recipients participating in the prospective MECANO study. A multivariate pharmacokinetic model adjusted for body weight, steroid treatment, and CYP3A4 genotype was used to assess the effect of the genetic variants on cyclosporine clearance. In multivariate analysis, homozygous carriers of rs3828743 had a 18% lower cyclosporin clearance compared to the wild-type and heterozygous patients (28.72 vs. 35.03 L/h, p = 0.018) indicating a lower CYP3A4 activity and an opposite direction of effect compared to the previously reported increased CYP3A4 expression. To validate, we tested associations between rs3828743 and CYP3A4 mRNA and protein expression as well as enzyme activity with data from a liver bank (n = 150). No association with any of these end points was observed. In conclusion, the totality of evidence is not in support of a significant role for TSPYL SNV rs3828743 in explaining variability in CYP3A4 activity. Show less
Background. Evidence on the optimal maintenance of immunosuppressive regimen in kidney transplantation recipients is limited. Methods. The Amsterdam, LEiden, GROningen trial is a randomized,... Show moreBackground. Evidence on the optimal maintenance of immunosuppressive regimen in kidney transplantation recipients is limited. Methods. The Amsterdam, LEiden, GROningen trial is a randomized, multicenter, investigator-driven, noninferiority, open-label trial in de novo kidney transplant recipients, in which 2 immunosuppression minimization strategies were compared with standard immunosuppression with basiliximab, corticosteroids, tacrolimus, and mycophenolic acid. In the minimization groups, either steroids were withdrawn from day 3, or tacrolimus exposure was reduced from 6 mo after transplantation. The primary endpoint was kidney transplant function at 24 mo. Results. A total of 295 participants were included in the intention-to-treat analysis. Noninferiority was shown for the primary endpoint; estimated glomerular filtration rate at 24 mo was 45.3 mL/min/1.73 m(2) in the early steroid withdrawal group, 49.0 mL/ min/1.73 m2 in the standard immunosuppression group, and 44.7 mL/min/1.73 m2 in the tacrolimus minimization group. Participants in the early steroid withdrawal group were significantly more often treated for rejection (P = 0.04). However, in this group, the number of participants with diabetes mellitus during follow-up and total cholesterol at 24 mo were significantly lower. Conclusions. Tacrolimus minimization can be considered in kidney transplant recipients who do not have an increased immunological risk. Before withdrawing steroids the risk of rejection should be weighed against the potential metabolic advantages. Show less
In kidney transplantation, survival rates are still partly impaired due to the deleterious effects of donor specific HLA antibodies (DSA). However, not all luminex-defined DSA appear to be... Show moreIn kidney transplantation, survival rates are still partly impaired due to the deleterious effects of donor specific HLA antibodies (DSA). However, not all luminex-defined DSA appear to be clinically relevant. Further analysis of DSA recognizing polymorphic amino acid configurations, called eplets or functional epitopes, might improve the discrimination between clinically relevant vs. irrelevant HLA antibodies. To evaluate which donor epitope-specific HLA antibodies (DESAs) are clinically important in kidney graft survival, relevant and irrelevant DESAs were discerned in a Dutch cohort of 4690 patients using Kaplan-Meier analysis and tested in a cox proportional hazard (CPH) model including nonimmunological variables. Pre-transplant DESAs were detected in 439 patients (9.4%). The presence of certain clinically relevant DESAs was significantly associated with increased risk on graft loss in deceased donor transplantations (p < 0.0001). The antibodies recognized six epitopes of HLA Class I, 3 of HLA-DR, and 1 of HLA-DQ, and most antibodies were directed to HLA-B (47%). Fifty-three patients (69.7%) had DESA against one donor epitope (range 1-5). Long-term graft survival rate in patients with clinically relevant DESA was 32%, rendering DESA a superior parameter to classical DSA (60%). In the CPH model, the hazard ratio (95% CI) of clinically relevant DESAs was 2.45 (1.84-3.25) in deceased donation, and 2.22 (1.25-3.95) in living donation. In conclusion, the developed model shows the deleterious effect of clinically relevant DESAs on graft outcome which outperformed traditional DSA-based risk analysis on antigen level. Show less
In kidney transplantation, donor HLA antibodies are a risk factor for graft loss. Accessibility of donor eplets for HLA antibodies is predicted by the ElliPro score. The clinical usefulness of... Show moreIn kidney transplantation, donor HLA antibodies are a risk factor for graft loss. Accessibility of donor eplets for HLA antibodies is predicted by the ElliPro score. The clinical usefulness of those scores in relation to transplant outcome is unknown. In a large Dutch kidney transplant cohort, Ellipro scores of pretransplant donor antibodies that can be assigned to known eplets (donor epitope specific HLA antibodies [DESAs]) were compared between early graft failure and long surviving deceased donor transplants. We did not observe a significant Ellipro score difference between the two cohorts, nor significant differences in graft survival between transplants with DESAs having high versus low total Ellipro scores. We conclude that Ellipro scores cannot be used to identify DESAs associated with early versus late kidney graft loss in deceased donor transplants. Show less
Background We explored the potential of emerging and conventional urinary kidney injury biomarkers in recipients of living donor (LD) or donation after circulatory death (DCD) kidney... Show moreBackground We explored the potential of emerging and conventional urinary kidney injury biomarkers in recipients of living donor (LD) or donation after circulatory death (DCD) kidney transplantation, patients with chronic kidney disease (CKD), and individuals from the general population. Methods Urine samples from kidney allograft recipients with mild (LD; n = 199) or severe (DCD; n = 71) ischemia-reperfusion injury (IRI) were analyzed for neutrophil gelatinase-associated lipocalin (NGAL), insulin-like growth factor-binding protein 7 (IGFBP7), tissue inhibitor of metalloproteinases 2 (TIMP2), kidney injury molecule-1 (KIM-1), chemokine C-X-C motif (CXCL9), solute carrier family 22 member 2 (SLC22A2), nephrin, and uromodulin (UMOD) by quantitative multiplex LC-MS/MS analysis. The fold-change in biomarker levels was determined in mild and severe IRI and in patients with CKD stage 1-2 (n = 127) or stage & GE;3 (n = 132) in comparison to the general population (n = 1438). Relationships between the biomarkers and total protein, & beta;2-microglobulin (B2M), creatinine, and osmolality were assessed. Results NGAL, IGFBP7, TIMP2, KIM-1, CXCL9, and UMOD were quantifiable, whereas nephrin and SLC22A2 were below the limit of detection. Kidney injury biomarkers were increased up to 6.2-fold in allograft recipients with mild IRI and 8.3-fold in recipients with severe IRI, compared to the reference population, with the strongest response observed for NGAL and B2M. In CKD stage 1-2, B2M, NGAL, IGFBP7, TIMP2, KIM-1, UMOD, and CXCL9 were not altered, but in individuals with CKD stage & GE;3, B2M, NGAL, and KIM-1 were increased up to 1.3-fold. IGFBP7, TIMP2, NGAL, and CXCL9 were strongly correlated (all r & GE; 0.8); correlations with B2M and TP were smaller (all r & LE; 0.6). Conclusions IRI, but not stable CKD, was associated with increased urinary levels of kidney injury biomarkers determined by LC-MS/MS. Absolute and multiplexed protein quantitation by LC-MS/MS is an effective strategy for biomarker panel evaluation for translation toward the clinical laboratory. Show less
Hendriks, S.H.; Heidt, S.; Schulz, A.R.; Fijter, J.W. de; Reinders, M.E.J.; Koning, F.; Kooten, C. van 2023
Tacrolimus is the backbone of immunosuppressive agents to prevent transplant rejection. Paradoxically, tacrolimus is nephrotoxic, causing irreversible tubulointerstitial damage. Therefore, infusion... Show moreTacrolimus is the backbone of immunosuppressive agents to prevent transplant rejection. Paradoxically, tacrolimus is nephrotoxic, causing irreversible tubulointerstitial damage. Therefore, infusion of mesenchymal stromal cells (MSC) 6 and 7 weeks post-transplantation was assessed to facilitate withdrawal of tacrolimus in the randomized phase II TRITON trial. Here, we performed detailed analysis of the peripheral blood immune composition using mass cytometry to assess potential effects of MSC therapy on the immune system. We developed two metal-conjugated antibody panels containing 40 antibodies each. PBMC samples from 21 MSC-treated patients and 13 controls, obtained pre-transplant and at 24 and 52 weeks post-transplantation, were analyzed. In the MSC group at 24 weeks, 17 CD4(+) T cell clusters were increased of which 14 Th2-like clusters and three Th1/Th2-like clusters, as well as CD4+FoxP3+ Tregs. Additionally, five B cell clusters were increased, representing either class switched memory B cells or proliferating B cells. At 52 weeks, CCR7(+)CD38(+) mature B cells were decreased. Finally, eight Tc1 (effector) memory cytotoxic T cell clusters were increased. Our work provides a comprehensive account of the peripheral blood immune cell composition in kidney transplant recipients after MSC therapy and tacrolimus withdrawal. These results may help improving therapeutic strategies using MSCs with the aim to reduce the use of calcineurin inhibitors. Show less
Meziyerh, S.; Gelder, T. van; Kers, J.; Helm, D. van der; Boog, P.J.M. van der; Fijter, J.W. de; ... ; Vries, A.P.J. de 2023
Evidence to define target ranges for tacrolimus (Tac) and mycophenolic acid (MPA) exposure after the first year of kidney transplantation is limited. We investigated the association of measurements... Show moreEvidence to define target ranges for tacrolimus (Tac) and mycophenolic acid (MPA) exposure after the first year of kidney transplantation is limited. We investigated the association of measurements at 1 year and repeated measurements of real-world Tac-trough levels (C-0) and abbreviated area under the curve from zero to 12 hours (AUC(0-12h)) of Tac and MPA with biopsy-proven acute rejection (BPAR) between years 1 and 3 post-transplant in 968 kidney transplant recipients (KTRs). Thirty-five (3.6%) out of 968 KTRs experienced BPAR. Both Tac-AUC(0-12h) (hazard ratio (HR): 0.39, 95% confidence interval (CI): 0.30-0.50, P < 0.001), Tac-C-0 (HR: 0.46, 95% CI: 0.38-0.57, P < 0.001) and MPA-AUC(0-12h) at 1 year (HR: 0.80, 95% CI: 0.68-0.94, P = 0.006), as well as repeated measurements of Tac-C-0 (HR: 0.70, 95% credibility interval (CrI): 0.61-0.82, P < 0.001), and of MPA-AUC(0-12h) (HR: 0.75, 95% CrI: 0.62-0.93, P < 0.001) were associated with BPAR. In our population, the recommended target range for Tac-AUC(0-12h) at 1 year would be 75-95 ng*hour/mL and a Tac-C-0 5-7 ng/mL. The Tac-AUC(0-12h) predicted BPAR better than Tac-C-0 and identified KTRs with over- or underexposure despite supposedly adequate Tac-C-0. We did not find evidence to recommend another target than the consensus range of 30-60 mg*hour/L for MPA-AUC(0-12h) after the first year of transplantation. To our knowledge, this is a first study on the simultaneous exposure of Tac and MPA at year 1 and subsequent BPAR up to year 3, which may help define the therapeutic target window for the longer term. Show less
Meziyerh, S.; Bouwmans, P.; Gelder, T. van; Helm, D. van der; Messchendorp, L.; Boog, P.J.M. van der; ... ; RECOVAC Collaborators 2023
Despite (repeated) boosting, kidney transplant recipients (KTRs) may remain at increased risk of severe COVID-19 since a substantial number of individuals remain seronegative or with low antibody... Show moreDespite (repeated) boosting, kidney transplant recipients (KTRs) may remain at increased risk of severe COVID-19 since a substantial number of individuals remain seronegative or with low antibody titers. In particular, mycophenolic acid use has been shown to affect antibody formation negatively and may be an important modifiable risk factor. We investigated the exposure-response relationship between mycophenolic acid 12-hour area under the curve (AUC(0-12h)) exposure and seroconversion including antibody titers after vaccination using mRNA-1273 SARS-CoV-2 vaccine (Moderna) in 316 KTRs from our center that participated in the national Dutch renal patients COVID-19 vaccination - long term efficacy and safety of SARS-CoV-2 vaccination in kidney disease patients vaccination study. After two vaccination doses, 162 (51%) KTRs seroconverted. KTRs treated with mycophenolic acid showed less seroconversion and lower antibody titers compared with KTRs without mycophenolic acid (44% vs. 77%, and 36 binding antibody units (BAU)/mL vs. 340 BAU/mL; P < 0.001). The mean mycophenolic acid AUC(0-12h) exposure was significantly lower in KTRs who seroconverted compared with KTRs who did not (39 vs. 29 mg.h/L; P < 0.001). High mycophenolic acid exposure (+/- 90 mg.h/L) and no exposure to mycophenolic acid resulted in a seroconversion rate ranging from 10% to 80%. Every 10 mg.h/L increase in mycophenolic acid AUC(0-12h) gave an adjusted odds ratio for seroconversion of 0.87 (95% confidence interval (CI), 0.79-0.97; P = 0.010) and 0.89 (95% CI, 0.85-0.93; P < 0.001) for KTRs on dual and triple maintenance immunosuppressive therapy, respectively. Higher mycophenolic acid AUC(0-12h) correlated with lower antibody titers (R = 0.44, P < 0.001). This study demonstrates the exposure-response relationship between gold standard mycophenolic acid exposure and antibody formation to support interventional studies investigating mycophenolic acid adjustment to improve antibody formation after further boosting. Show less
Recently, the randomized phase-II Triton study demonstrated that mesenchymal stromal cell (MSC) therapy facilitated early tacrolimus withdrawal in living donor kidney transplant recipients. The... Show moreRecently, the randomized phase-II Triton study demonstrated that mesenchymal stromal cell (MSC) therapy facilitated early tacrolimus withdrawal in living donor kidney transplant recipients. The current sub-study analyzed formation of de novo donor-specific HLA antibodies (dnDSA) in the context of the degree of HLA eplet mismatches. At the time of protocol biopsy at 6 months, 7/29 patients (24%) in the MSC group and 1/27 patient (3.7%) in the control group had developed dnDSA. In the MSC group, all dnDSA were antiHLA-DQ; two patients had anti-DQ alone and five patients combined with anti-class I, HLA-DR or-DP. Despite excess dnDSA formation in the MSC-arm of the study, the evolution of eGFR (CKD-EPI) and proteinuria were comparable 2 years posttransplant. All dnDSA were complement-binding and three patients had antibody-mediated rejection in the protocol biopsy, but overall rejection episodes were not increased. Everolimus had to be discontinued in nine patients because of toxicity, and tacrolimus was reintroduced in six patients because of dnDSA formation. The HLA-DQ eplet mismatch load independently associated with dnDSA (adjusted hazard ratio = 1.07 per eplet mismatch, p = 0.008). A threshold of >= 11 HLA-DQ eplet mismatches predicted subsequent dnDSA in all 11 patients in the MSC group, but specificity was low (44%). Further research is warranted to explore HLA molecular mismatch load as a biomarker to guide personalized maintenance immunosuppression in kidney transplantation. Show less
BackgroundAutologous bone marrow–derived mesenchymal stromal cell (MSC) therapy and withdrawal of calcineurin inhibitors (CNIs) has been shown to improve systemic blood pressure control and left ve...Show moreBackgroundAutologous bone marrow–derived mesenchymal stromal cell (MSC) therapy and withdrawal of calcineurin inhibitors (CNIs) has been shown to improve systemic blood pressure control and left ventricular hypertrophy regression in kidney transplant recipients. In the current subanalysis, we aimed to evaluate the impact of this novel immunosuppressive regimen on the longitudinal changes of left atrial (LA) structure and function after kidney transplantation.MethodsKidney transplant recipients randomized to MSC therapy—infused at weeks 6 and 7 after transplantation, with complete discontinuation at week 8 of tacrolimus (MSC group)—or standard tacrolimus dose (control group) were evaluated with transthoracic echocardiography at weeks 4 and 24 after kidney transplantation. The changes in echocardiographic parameters were compared between the randomization arms using an analysis of covariance model adjusted for baseline variable.ResultsFifty-four participants (MSC therapy = 27; tacrolimus therapy = 27) were included. There was no significant interaction between the allocated treatment and the changes of indexed maximal LA volume (LAVImax) over the study period. Conversely, between 4 and 24 weeks post-transplantation, an increase in indexed minimal LA volume (LAVImin) was observed in control subjects, while it remained unchanged in the MSC group, leading to a significant difference between groups (P = .021). Additionally, patients treated with MSC therapy showed a benefit in LA function, assessed by a significant interaction between changes in LA emptying fraction and LA reservoir strain and the randomization arm (P = .012 and P = .027, respectively).ConclusionsThe combination of MSC therapy and CNIs withdrawal prevents progressive LA dilation and dysfunction in the first 6 months after kidney transplantation. LAVImin and LA reservoir strain may be more sensitive markers of LA reverse remodeling, compared with LAVImax. Show less
AimAlemtuzumab is a monoclonal antibody used as induction immunosuppressive therapy in kidney transplantation. It targets CD52 on lymphocytes, inducing profound immune cell depletion upon... Show moreAimAlemtuzumab is a monoclonal antibody used as induction immunosuppressive therapy in kidney transplantation. It targets CD52 on lymphocytes, inducing profound immune cell depletion upon administration. Owing to its off-label status in kidney transplantation, its pharmacokinetic characteristics are largely unknown in this setting, and its current fixed dosing algorithm originates from other populations. We developed a population pharmacokinetic model for alemtuzumab in kidney transplant recipients and investigated the potential of personalized alemtuzumab therapy. MethodsIn total, 362 pharmacokinetic observations drawn 0-165 days after transplantation were available from 61 adult kidney transplant recipients who received two consecutive doses of 15 mg alemtuzumab subcutaneously. A population pharmacokinetic model was developed using nonlinear mixed-effects modelling and applied to simulate various dosing regimens. ResultsThe alemtuzumab concentration-time data were best described by a two-compartmental model with first-order absorption and parallel first-order and time-varying concentration-dependent elimination, with between-subject variability on the first-order elimination (39.6%) and central distribution volume (39.6%). Alemtuzumab pharmacokinetics varied with body size, rendering lighter individuals exposed to lympholytic alemtuzumab concentrations (>0.1 mg/L) for prolonged durations as compared to their heavier peers. This between-subject variability could be reduced through lean bodyweight-adjusted dosing, showing a twofold to threefold reduction in the slope of the median alemtuzumab exposure over the bodyweight range. ConclusionAlemtuzumab displays substantial pharmacokinetic variability in kidney transplant recipients, which may warrant a personalized treatment strategy. Lean bodyweight-adjusted dosing poses an option for individualized dosing, but further evaluation of its potential clinical benefit is warranted. Show less
Rooij, E.N.M. de; Meuleman, Y.; Fijter, J.W. de; Jager, K.J.; Chesnaye, N.C.; Evans, M.; ... ; EQUAL Study Investigators 2022
Background and objectives For older patients with kidney failure, lowering symptom burden may be more important than prolonging life. Dialysis initiation may affect individual kidney failure... Show moreBackground and objectives For older patients with kidney failure, lowering symptom burden may be more important than prolonging life. Dialysis initiation may affect individual kidney failure-related symptoms differently, but the change in symptoms before and after start of dialysis has not been studied. Therefore, we investigated the course of total and individual symptom number and burden before and after starting dialysis in older patients.Design, setting, participants, & measurements The European Quality (EQUAL) study is an ongoing, prospective, multicenter study in patients >= 65 years with an incident eGFR <= 20 ml/min per 1.73 m(2) . Using the dialysis symptom index (DSI), 30 symptoms were assessed every 3-6 months between 2012 and 2021. Scores for symptom number range from zero to 30 and, for burden, from zero to 150, with higher scores indicating more severity. Using mixed effects models, we studied symptoms during the year preceding and the year after dialysis initiation.Results We included 456 incident patients on dialysis who filled out at least one DSI during the year before or after dialysis. At dialysis initiation, mean (SD) participant age was 76 (6) years, 75% were men, mean (SD) eGFR was 8 (3) ml/min per 1.73 m(2), 44% had diabetes, and 46% had cardiovascular disease. In the year before dialysis initiation, symptom number increased +3.6 (95% confidence interval [95% CI], +2.5 to +4.6) and symptom burden increased +13.3 (95% CI, +9.5 to +17.0). In the year after, symptom number changed -0.9 (95% CI, -3.4 to +1.5) and burden decreased -5.9 (95% CI, -14.9 to -3.0). At dialysis initiation, "fatigue," "decreased interest in sex," and "difficulty becoming sexually aroused" had the highest prevalence of 81%, 69%, and 68%, respectively, with a burden of 2.7, 2.4, and 2.3, respectively. "Fatigue" somewhat improved after dialysis initiation, whereas the prevalence and burden of sexual symptoms further increased.Conclusions Symptom burden worsened considerably before and stabilized after dialysis initiation. "Fatigue," "decreased interest in sex," and "difficulty becoming sexually aroused" were considered most burdensome, of which only "fatigue" somewhat improved after dialysis initiation. Show less
Alem, C.M.A. van; Bank, J.R.; Vries, D.K. de; Bajema, I.M.; Mallat, M.J.K.; Fijter, J.W. de; ... ; Kooten, C. van 2022
Acute cellular rejection (ACR) occurs in 10% of renal allograft recipients and is characterized by leukocyte infiltration as observed in needle biopsies. ACR onset is subject to several risk... Show moreAcute cellular rejection (ACR) occurs in 10% of renal allograft recipients and is characterized by leukocyte infiltration as observed in needle biopsies. ACR onset is subject to several risk factors, including delayed graft function (DGF). As the impact of DGF on the etiology of ACR remains unclear, this study analyzed the association between presence of leukocyte subsets and ACR onset, in DCD kidney biopsies with extensive DGF following transplantation. Immunohistochemical analysis of protocol biopsies taken 10 days after kidney transplantation revealed that patients with high levels of renal CD163+ macrophages have a decreased risk (OR = 0.021, P = 0.008) for ACR in the first 6 months after transplantation. In pre-transplant biopsies of a comparable DCD cohort, with >80% DGF, presence of donor CD163+ macrophages showed no effect on ACR risk. Therefore, leukocyte infiltrate present during the inflammatory response at the time of DGF may contain anti-inflammatory macrophages that exert a protective effect against ACR development. Show less
Background and objectives In older people with kidney failure, improving health-related quality of life is often more important than solely prolonging life. However, little is known about the... Show moreBackground and objectives In older people with kidney failure, improving health-related quality of life is often more important than solely prolonging life. However, little is known about the effect of dialysis initiation on health-related quality of life in older patients. Therefore, we investigated the evolution of health-related quality of life before and after starting dialysis in older patients with kidney failure. Design, setting, participants, & measurements The European Quality study is an ongoing prospective, multicenter study in patients aged >_65 years with an incident eGFR <_20 ml/min per 1.73 m2. Between April 2012 and December 2021, health-related quality of life was assessed every 3-6 months using the 36-item Short-Form Health Survey (SF-36), providing a mental component summary (MCS) and a physical component summary (PCS). Scores range from zero to 100, with higher scores indicating better health-related quality of life. With linear mixed models, we explored the course of health-related quality of life during the year preceding and following dialysis initiation. Results In total, 457 patients starting dialysis were included who filled out at least one SF-36 during follow-up. At dialysis initiation, mean +/- SD age was 76 +/- 6 years, eGFR was 8 +/- 3 ml/min per 1.73 m2, 75% were men, 9% smoked, 45% had diabetes, and 46% had cardiovascular disease. Median (interquartile range) MCS was 53 (38-73), and median PCS was 39 (27-58). During the year preceding dialysis, estimated mean change in MCS was -13 (95% confidence interval, -17 to -9), and in PCS, it was -11 (95% confidence interval, -15 to -7). In the year following dialysis, estimated mean change in MCS was +2 (95% confidence interval, -7 to +11), and in PCS, it was -2 (95% confidence interval, -11 to +7). Health-related quality-of-life patterns were similar for most mental (mental health, role emotional, social functioning, vitality) and physical domains (physical functioning, bodily pain, role physical). Conclusions Patients experienced a clinically relevant decline of both mental and physical health-related quality of life before dialysis initiation, which stabilized thereafter. These results may help inform older patients with kidney failure who decided to start dialysis. Show less
Aims Immunosuppressant and kidney function monitoring are crucial for kidney transplant recipient follow-up. Microsamples enable remote sampling and minimise patient burden as compared to... Show moreAims Immunosuppressant and kidney function monitoring are crucial for kidney transplant recipient follow-up. Microsamples enable remote sampling and minimise patient burden as compared to conventional venous sampling at the clinic. We developed a liquid chromatography-tandem mass spectrometry assay to quantify tacrolimus, mycophenolic acid (MPA), creatinine and iohexol in dried blood spot (DBS), and volumetric absorptive microsample (VAMS) samples. Methods The assay was successfully validated analytically for all analytes. Clinical validation was conducted by direct comparison of paired DBS, VAMS and venous reference samples from 25 kidney transplant recipients. Patients received iohexol 5-15 minutes before immunosuppressant intake and were sampled 0, 1, 2 and 3 hours thereafter, enabling tacrolimus and MPA area under the concentration-time curve (AUC) and creatinine-based and iohexol-based glomerular filtration rate (GFR) estimation. Method agreement was evaluated using Passing-Bablok regression, Bland-Altman analysis and the percentages of values within 15-30% of the reference (P-15-P-30) with a P-20 acceptance threshold of 80%. Results For DBS samples, method agreement was excellent for tacrolimus trough concentrations (n = 25, P-15 = 92.0%) and AUCs (n = 25; P-20 = 95.8%) and adequate for creatinine-based GFR trend monitoring (n = 25; P-20 = 80%). DBS-based MPA AUC assessment showed suboptimal agreement (n = 16; P-20 = 68.8%), but was considered acceptable given its P-30 of 100%. The assay performed inadequately for DBS-based iohexol GFR determination (n = 24; P-20 = 75%). The VAMS technique generally showed inferior performance, but can be considered for certain situations. Conclusion The assay was successfully validated for tacrolimus, MPA and creatinine quantification in DBS samples, enabling simultaneous remote kidney function trend monitoring and immunosuppressant therapeutic drug monitoring in kidney transplant recipients. Show less
Duijl, T.T. van; Ruhaak, L.R.; Kooten, C. van; Fijter, J.W. de; Cobbaert, C.M. 2022
Background: LC-MS/MS has enabled the translation of many novel biomarkers to the clinical laboratory, but its potential for measurement of urinary proteins is still unexplored. In this study we... Show moreBackground: LC-MS/MS has enabled the translation of many novel biomarkers to the clinical laboratory, but its potential for measurement of urinary proteins is still unexplored. In this study we examined the correlation and agreement between immunoassay and LC-MS/MS in the quantitation of kidney injury biomarkers and evaluated the application of technical LC-MS/MS meta-data assessment to ensure test result validity. Methods: NGAL, IGFBP7, TIMP2, and KIM-1 were quantified in 345 urine samples with one multiplex labdeveloped test that combines immunocapture with mass spectrometry read-out and 4 singleplex sandwich-type immunoassays. Assay performance and imprecision were monitored by 2 urine-based quality controls. Ion ratios, signal intensity, and retention time were monitored over all study samples. Results: The LC-MS/MS retention time drift was <= 1.2%, ion ratios were within 20% of the target values at concentrations of >100 pmol/L, and peptides originating from the same protein were in agreement (slopes between 1.03 and 1.41). The interassay CV was between 9.3% and 19.1% for LC-MS/MS analysis and between 4.2% and 10.9% for immunoassay. Direct LC-MS/MS analysis was correlated with immunoassay in the quantitation of NGAL (r = 0.93; range: 0.01-37 nmol/L), IGFBP7 (r = 0.80; range: 0.01-2.6 nmol/L), TIMP2 (r = 0.85; range: 0.01-6.3 nmol/L), and KIM-1 (r = 0.70; range 0.01-0.4 nmol/L), but the analytical methodologies differed in measurands and calibration strategies. Conclusions: LC-MS/MS is explored as a next-generation technology for multiplex urinary protein measurement. It has great potential to overcome nonselectivity and lack of standardization because of its capability of directly measuring well-defined molecular proteins. Show less
Duijl, T.T. van; Ruhaak, L.R.; Kooten, C. van; Fijter, J.W. de; Cobbaert, C.M. 2022
BackgroundLC-MS/MS has enabled the translation of many novel biomarkers to the clinical laboratory, but its potential for measurement of urinary proteins is still unexplored. In this study we... Show moreBackgroundLC-MS/MS has enabled the translation of many novel biomarkers to the clinical laboratory, but its potential for measurement of urinary proteins is still unexplored. In this study we examined the correlation and agreement between immunoassay and LC-MS/MS in the quantitation of kidney injury biomarkers and evaluated the application of technical LC-MS/MS meta-data assessment to ensure test result validity.MethodsNGAL, IGFBP7, TIMP2, and KIM-1 were quantified in 345 urine samples with one multiplex lab-developed test that combines immunocapture with mass spectrometry read-out and 4 singleplex sandwich-type immunoassays. Assay performance and imprecision were monitored by 2 urine-based quality controls. Ion ratios, signal intensity, and retention time were monitored over all study samples.ResultsThe LC-MS/MS retention time drift was ≤1.2%, ion ratios were within 20% of the target values at concentrations of >100 pmol/L, and peptides originating from the same protein were in agreement (slopes between 1.03 and 1.41). The interassay CV was between 9.3% and 19.1% for LC-MS/MS analysis and between 4.2% and 10.9% for immunoassay. Direct LC-MS/MS analysis was correlated with immunoassay in the quantitation of NGAL (r = 0.93; range: 0.01–37 nmol/L), IGFBP7 (r = 0.80; range: 0.01–2.6 nmol/L), TIMP2 (r = 0.85; range: 0.01–6.3 nmol/L), and KIM-1 (r = 0.70; range 0.01–0.4 nmol/L), but the analytical methodologies differed in measurands and calibration strategies.ConclusionsLC-MS/MS is explored as a next-generation technology for multiplex urinary protein measurement. It has great potential to overcome nonselectivity and lack of standardization because of its capability of directly measuring well-defined molecular proteins. Show less
Introduction: In autosomal dominant polycystic kidney disease (ADPKD) patients, predicting renal disease progression is important to make a prognosis and to support the clinical decision whether to... Show moreIntroduction: In autosomal dominant polycystic kidney disease (ADPKD) patients, predicting renal disease progression is important to make a prognosis and to support the clinical decision whether to initiate renoprotective therapy. Conventional markers all have their limitations. Metabolic profiling is a promising strategy for risk stratification. We determined the prognostic performance to identify patients with a fast progressive disease course and evaluated time-dependent changes in urinary metabolites. Methods: Targeted, quantitative metabolomics analysis (H-1 NMR-spectroscopy) was performed on spot urinary samples at two time points, baseline (n = 324, 61% female; mean age 45 years, SD 11; median eGFR 61 mL/min/1.73 m(2), IQR 42-88; mean years of creatinine follow-up 3.7, SD 1.3) and a sample obtained after 3 years of follow-up (n = 112). Patients were stratified by their eGFR slope into fast and slow progressors based on an annualized change of > -3.0 or <= -3.0 mL/min/1.73 m(2)/year, respectively. Fifty-five urinary metabolites and ratios were quantified, and the significant ones were selected. Logistic regression was used to determine prognostic performance in identifying those with a fast progressive course using baseline urine samples. Repeated-measures ANOVA was used to analyze whether changes in urinary metabolites over a 3-year follow-up period differed between fast and slow progressors. Results: In a single urinary sample, the prognostic performance of urinary metabolites was comparable to that of a model including height-adjusted total kidney volume (htTKV, AUC = 0.67). Combined with htTKV, the predictive value of the metabolite model increased (AUC = 0.75). Longitudinal analyses showed an increase in the myoinositol/citrate ratio (p < 0.001) in fast progressors, while no significant change was found in those with slow progression, which is in-line with an overall increase in the myoinositol/citrate ratio as GFR declines. Conclusion: A metabolic profile, measured at a single time point, showed at least equivalent prognostic performance to an imaging-based risk marker in ADPKD. Changes in urinary metabolites over a 3-year follow-up period were associated with a fast progressive disease course. Show less
Over the past decade, high HLA epitope mismatch scores have been associated with inferior transplant outcomes using several tools, of which HLAMatchmaker is most well-known. This software uses... Show moreOver the past decade, high HLA epitope mismatch scores have been associated with inferior transplant outcomes using several tools, of which HLAMatchmaker is most well-known. This software uses theoretically defined polymorphic amino acid configurations, called eplets, for HLA compatibility analysis. Although consideration of eplet mismatch loads has potential for immunological risk stratification of transplant patients, the use of eplet matching in organ allocation algorithms is hindered by lacking knowledge of the immunogenicity of individual eplets, and the possibility that single mismatched amino acids, rather than complete eplets, are responsible for HLA antibody induction.There are several approaches to define eplet immunogenicity, such as antibody verification of individual eplets, and data-driven approaches using large datasets that correlate specific eplet mismatches to donor specific antibody formation or inferior transplant outcomes. Data-driven approaches can also be used to define whether single amino acid mismatches may be more informative than eplet mismatches for predicting HLA antibody induction.When using epitope knowledge for the assignment of unacceptable antigens, it important to realize that alleles sharing an eplet to which antibodies have formed are not automatically all unacceptable since multiple contact sites determine the binding strength and thus biological function and pathogenicity of an antibody, which may differ between reactive alleles.While the future looks bright for using HLA epitopes in clinical decision making, major steps need to be taken to make this a clinical reality.(c) 2021 The Author(s). Published by Elsevier Inc. on behalf of American Society for Histocompatibility and Immunogenetics. This is an open access article under the CC BY-NC-ND license (http://creativecommons. org/licenses/by-nc-nd/4.0/). Show less
