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
Wang, Y.M.; Veltkamp, D.M.J.; Boog, P.J.M. van der; Hemmelder, M.H.; Dekker, F.W.; Vries, A.P.J. de; Meuleman, Y. 2022
Background: Medication nonadherence to immunosuppressants is a well-known risk factor for suboptimal health outcomes in kidney transplant recipients (KTRs). This study examined the relationship... Show moreBackground: Medication nonadherence to immunosuppressants is a well-known risk factor for suboptimal health outcomes in kidney transplant recipients (KTRs). This study examined the relationship between illness perceptions and medication nonadherence in prevalent Dutch KTRs and whether this relationship depended on post-transplant time.Methods: Eligible KTRs transplanted in Leiden University Medical Center were invited for this cross-sectional study. The illness perceptions and medication nonadherence were measured via validated questionnaires. Associations between illness perceptions and medication nonadherence were investigated using multivariable logistic regression models.Results: For the study, 627 participating KTRs were analyzed. 203 (32.4%) KTRs were considered nonadherent to their immunosuppressants with "taking medication more than 2 h from the prescribed dosing time" as the most prevalent nonadherent behaviour (n = 171; 27.3%). Three illness perceptions were significantly associated with medication nonadherence: illness identity (adjusted odds ratio [ORadj] = 1.07; 95% confidence interval [CI], 1.00-1.14), concern (ORadj = 1.07; 95%CI,1.00-1.14), and illness coherence (ORadj = 1.11; 95%CI,1.01-1.22). The relationships between illness perceptions and medication nonadherence did not differ depending on post-transplant time (p-values ranged from 0.48 to 0.96).Conclusion: Stronger negative illness perceptions are associated with medication nonadherence to immunosuppressants. Targeting negative illness perceptions by means of psychoeducational interventions could optimize medication adherence and consequently improve health outcomes in KTRs. Show less
Saghari, M.; Gal, P.; Ziagkos, D.; Burggraaf, J.; Powell, J.F.; Brennan, N.; ... ; Moerland, M. 2020
Aims Keyhole limpet haemocyanin (KLH) immunization is a clinical model for the evaluation of human antibody responses. The current study evaluated the anti-KLH antibody response after KLH... Show moreAims Keyhole limpet haemocyanin (KLH) immunization is a clinical model for the evaluation of human antibody responses. The current study evaluated the anti-KLH antibody response after KLH immunization and the delayed-type hypersensitivity response following intradermal KLH administration, using objective imaging techniques.Methods Healthy male subjects aged 24.5 +/- 5.4 years were randomized to intramuscular immunization with 100 mu g KLH (n = 12) or placebo (n = 3). Anti-KLH antibody (Ig) M and IgG titres were determined before and every 7 days after KLH immunization for a total of 28 days. Twenty-one days after the immunization, all subjects received 1 mu g KLH intradermally. Prior to and 2 days after intradermal KLH administration, skin blood perfusion, erythema and oedema were quantified using noninvasive imaging tools. Repeated measures ANCOVAs were used to analyse data.Results Anti-KLH IgM and IgG titres increased after KLH immunization compared to placebo (estimated difference [ED]: 37%, 95% confidence interval [CI]: 19-51% and ED: 68%, 95% CI: 56-76% respectively). Upon intradermal KLH administration an increase in skin blood perfusion (ED: 10.9 arbitrary units (AU), 95% CI: 1.4-20.4 AU) and erythema (ED: 0.3 AU, 95% CI: 0.1-0.5 AU) was observed in KLH-immunized subjects compared to placebo.Conclusion KLH immunization followed by intradermal KLH administration resulted in increased anti-KLH IgM and IgG titres and a delayed-type hypersensitivity response quantified by an increase in skin blood perfusion and erythema. Using noninvasive imaging tools the KLH model has the potential to serve as an objective tool to study the pharmacodynamics of T-cell-directed immunomodulatory drugs. Show less
Calcineurin (protein phosphatase 3, Cn) is best known for its central position in Ca(2+)-dependent T-cell signaling. Interest in calcineurin has, however, conserved its momentum as new Ca(2+)... Show moreCalcineurin (protein phosphatase 3, Cn) is best known for its central position in Ca(2+)-dependent T-cell signaling. Interest in calcineurin has, however, conserved its momentum as new Ca(2+)-dependent pathways have been steadily surfacing in several other cell types, such as brain, heart, skin cells and beta pancreatic cells, and Cn appears to serve as a central controller of stress, immune response, and cellular proliferation and differentiation. Calcineurin is the principal target of the immunosuppressive drugs cyclosporin A (CsA) and tacrolimus (TRL). Therapy based on these immunosuppressants has markedly reduced the incidence of transplant rejection in allograft recipients. In addition, these drugs have proven very useful for patients suffering from chronic inflammatory skin conditions. Unfortunately, their application is somewhat limited by a broad spectrum of toxic side-effects, affecting several organ systems. This calls for enhancements in the design of this class of immunosuppressants. An intricate constellation of regulatory systems allows for precise modulation and adaptation of calcineurin activity in vivo. The last few years have been very fruitful in elucidating several long-standing issues regarding the binding patterns of substrates and inhibitors to Cn. This new knowledge may enable more precise manipulation of the Ca(2+)-calcineurin pathway in the near future, preferably targeted towards one specific substrate or cell system. In this review, we will discuss the factors and mechanisms underlying calcineurin activity regulation and their exploitation in recent approaches towards better immunosuppressants. Show less
