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Sousa IS, Tavares LFS, Silva BA, Moreno DSA, Alviano CS, Santos ALS, Kneipp LF. Calcineurin activity in Fonsecaea pedrosoi: tacrolimus and cyclosporine A inhibited conidia growth, filamentation and showed synergism with itraconazole. Braz J Microbiol 2024:10.1007/s42770-024-01463-2. [PMID: 39044105 DOI: 10.1007/s42770-024-01463-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 07/11/2024] [Indexed: 07/25/2024] Open
Abstract
Fonsecaea pedrosoi is a melanized fungus that causes chromoblastomycosis (CBM), a tropical neglected disease responsible for chronic and disability-related subcutaneous mycosis. Given the challenging nature of CBM treatment, the study of new targets and novel bioactive drugs capable of improving patient life quality is urgent. In the present work, we detected a calcineurin activity in F. pedrosoi conidial form, employing primarily colorimetric, immunoblotting and flow cytometry assays. Our findings reveal that the calcineurin activity of F. pedrosoi was stimulated by Ca2+/calmodulin, inhibited by EGTA and specific inhibitors, such as tacrolimus (FK506) and cyclosporine A (CsA), and proved to be insensitive to okadaic acid. In addition, FK506 and CsA were able to affect the cellular viability and the fungal proliferation. This effect was corroborated by transmission electron microscopy that showed both calcineurin inhibitors promoted profound changes in the ultrastructure of conidia, causing mainly cytoplasm condensation and intense vacuolization that are clear indication of cell death. Our data indicated that FK506 exhibited the highest effectiveness, with a minimum inhibitory concentration (MIC) of 3.12 mg/L, whereas CsA required 15.6 mg/L to inhibit 100% of conidial growth. Interestingly, when both were combined with itraconazole, they demonstrated anti-F. pedrosoi activity, exhibiting a synergistic effect. Moreover, the fungal filamentation was affected after treatment with both calcineurin inhibitors. These data corroborate with other calcineurin studies in fungal cells and open up further discussions aiming to establish the role of this enzyme as a potential target for antifungal therapy against CBM infections.
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Affiliation(s)
- Ingrid S Sousa
- Laboratório de Taxonomia, Bioquímica e Bioprospecção de Fungos (LTBBF), Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, 21040-900, Brazil
| | - Lucilene F S Tavares
- Laboratório de Taxonomia, Bioquímica e Bioprospecção de Fungos (LTBBF), Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, 21040-900, Brazil
| | - Bianca A Silva
- Laboratório de Estudos Avançados de Microrganismos Emergentes e Resistentes (LEAMER), Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, 21941-901, Brazil
| | - Daniela S A Moreno
- Laboratório de Estrutura de Microrganismos, IMPG, UFRJ, Rio de Janeiro, 21941-902, Brazil
| | - Celuta S Alviano
- Laboratório de Estrutura de Microrganismos, IMPG, UFRJ, Rio de Janeiro, 21941-902, Brazil
| | - André L S Santos
- Laboratório de Estudos Avançados de Microrganismos Emergentes e Resistentes (LEAMER), Instituto de Microbiologia Paulo de Góes (IMPG), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, 21941-901, Brazil
- Rede Micologia RJ, Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), Rio de Janeiro, 21941-901, Brazil
| | - Lucimar F Kneipp
- Laboratório de Taxonomia, Bioquímica e Bioprospecção de Fungos (LTBBF), Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, 21040-900, Brazil.
- Rede Micologia RJ, Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), Rio de Janeiro, 21941-901, Brazil.
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in ’t Veld AE, Jansen MAA, Huisman BW, Schoonakker M, de Kam ML, Moes DJAR, van Poelgeest MIE, Burggraaf J, Moerland M. Monitoring of Ex Vivo Cyclosporin a Activity in Healthy Volunteers Using T Cell Function Assays in Relation to Whole Blood and Cellular Pharmacokinetics. Pharmaceutics 2022; 14:pharmaceutics14091958. [PMID: 36145707 PMCID: PMC9503885 DOI: 10.3390/pharmaceutics14091958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 09/12/2022] [Accepted: 09/13/2022] [Indexed: 11/16/2022] Open
Abstract
Therapeutic drug monitoring (TDM) of calcineurin inhibitors (i.e., tacrolimus and cyclosporin A) is standard of care after solid organ transplantation. Although the incidence of acute rejection has strongly decreased, there are still many patients who experience severe side effects or rejection after long-term treatment. In this healthy volunteer study we therefore aimed to identify biomarkers to move from a pharmacokinetic-based towards a pharmacodynamic-based monitoring approach for calcineurin inhibitor treatment. Healthy volunteers received a single dose of cyclosporine A (CsA) or placebo, after which whole blood samples were stimulated to measure ex vivo T cell functionality, including proliferation, cytokine production, and activation marker expression. The highest whole blood concentration of CsA was found at 2 h post-dose, which resulted in a strong inhibition of interferon gamma (IFNy) and interleukin-2 (IL-2) production and expression of CD154 and CD71 on T cells. Moreover, the in vitro effect of CsA was studied by incubation of pre-dose whole blood samples with a concentration range of CsA. The average in vitro and ex vivo CsA activity overlapped, making the in vitro dose–effect relationship an interesting method for prediction of post-dose drug effect. The clinical relevance of the results is to be explored in transplantation patients on calcineurin inhibitor treatment.
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Affiliation(s)
- Aliede E. in ’t Veld
- Centre for Human Drug Research, 2333 CL Leiden, The Netherlands
- Department of Surgery, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | | | - Bertine W. Huisman
- Centre for Human Drug Research, 2333 CL Leiden, The Netherlands
- Department of Gynaecology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | | | | | - Dirk Jan A. R. Moes
- Department of Clinical Pharmacy & Toxicology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Mariëtte I. E. van Poelgeest
- Centre for Human Drug Research, 2333 CL Leiden, The Netherlands
- Department of Gynaecology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Jacobus Burggraaf
- Centre for Human Drug Research, 2333 CL Leiden, The Netherlands
- Department of Surgery, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
- Leiden Academic Centre of Drug Research, 2333 AL Leiden, The Netherlands
| | - Matthijs Moerland
- Centre for Human Drug Research, 2333 CL Leiden, The Netherlands
- Department of Clinical Pharmacy & Toxicology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
- Correspondence:
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Immunomonitoring of Tacrolimus in Healthy Volunteers: The First Step from PK- to PD-Based Therapeutic Drug Monitoring? Int J Mol Sci 2019; 20:ijms20194710. [PMID: 31547590 PMCID: PMC6801784 DOI: 10.3390/ijms20194710] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/05/2019] [Accepted: 09/20/2019] [Indexed: 12/20/2022] Open
Abstract
Therapeutic drug monitoring is routinely performed to maintain optimal tacrolimus concentrations in kidney transplant recipients. Nonetheless, toxicity and rejection still occur within an acceptable concentration-range. To have a better understanding of the relationship between tacrolimus dose, tacrolimus concentration, and its effect on the target cell, we developed functional immune tests for the quantification of the tacrolimus effect. Twelve healthy volunteers received a single dose of tacrolimus, after which intracellular and whole blood tacrolimus concentrations were measured and were related to T cell functionality. A significant correlation was found between tacrolimus concentrations in T cells and whole blood concentrations (r = 0.71, p = 0.009), while no correlation was found between tacrolimus concentrations in peripheral blood mononuclear cells (PBMCs) and whole blood (r = 0.35, p = 0.27). Phytohemagglutinin (PHA) induced the production of IL-2 and IFNγ, as well as the inhibition of CD71 and CD154 expression on T cells at 1.5 h post-dose, when maximum tacrolimus levels were observed. Moreover, the in vitro tacrolimus effect of the mentioned markers corresponded with the ex vivo effect after dosing. In conclusion, our results showed that intracellular tacrolimus concentrations mimic whole blood concentrations, and that PHA-induced cytokine production (IL-2 and IFNγ) and activation marker expression (CD71 and CD154) are suitable readout measures to measure the immunosuppressive effect of tacrolimus on the T cell.
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Measurement of calcineurin activity in peripheral blood mononuclear cells by ultra-high performance liquid chromatography-tandem mass spectrometry. Renal transplant recipients application (pharmacodynamic monitoring). Clin Chim Acta 2019; 495:287-293. [DOI: 10.1016/j.cca.2019.04.079] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 04/26/2019] [Indexed: 11/24/2022]
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Bulbule SR, Aravind P, Hemalatha N, Devaraju KS. Modeling, Synthesis and Characterization of Phospho–Penta–Peptide derived from PKA RII Sub Unit: A Candidate Substrate for CaN Assay. Int J Pept Res Ther 2018. [DOI: 10.1007/s10989-018-9770-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Kahlert V, Prell E, Ohlenschläger O, Melesina J, Schumann M, Lücke C, Fischer G, Malešević M. Synthesis and biochemical evaluation of two novel N-hydroxyalkylated cyclosporin A analogs. Org Biomol Chem 2018; 16:4338-4349. [DOI: 10.1039/c8ob00980e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
N-Hydroxyalkylation of cyclosporine A residues Val5 and d-Ala8 significantly influenced their conformation behavior and pharmacological properties.
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Affiliation(s)
- Viktoria Kahlert
- Max Planck Research Unit for Enzymology of Protein Folding
- 06120 Halle/Saale
- Germany
| | - Erik Prell
- Max Planck Research Unit for Enzymology of Protein Folding
- 06120 Halle/Saale
- Germany
- Max-Planck Institute for Biophysical Chemistry
- Göttingen
| | | | - Jelena Melesina
- Martin-Luther-University Halle-Wittenberg
- Institute of Pharmacy
- Medicinal Chemistry department
- 06120 Halle
- Germany
| | - Michael Schumann
- Max Planck Research Unit for Enzymology of Protein Folding
- 06120 Halle/Saale
- Germany
- Martin-Luther-University Halle-Wittenberg
- Institute of Biochemistry and Biotechnology
| | - Christian Lücke
- Max Planck Research Unit for Enzymology of Protein Folding
- 06120 Halle/Saale
- Germany
| | - Gunter Fischer
- Max Planck Research Unit for Enzymology of Protein Folding
- 06120 Halle/Saale
- Germany
- Max-Planck Institute for Biophysical Chemistry
- Göttingen
| | - Miroslav Malešević
- Max Planck Research Unit for Enzymology of Protein Folding
- 06120 Halle/Saale
- Germany
- Martin-Luther-University Halle-Wittenberg
- Institute of Biochemistry and Biotechnology
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Figueiredo SA, de Moraes DC, Vilela FMP, de Faria AN, Dos Santos MH, Fonseca MJV. A novel research model for evaluating sunscreen protection in the UV-A1. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2017; 178:61-68. [PMID: 29112891 DOI: 10.1016/j.jphotobiol.2017.10.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 09/18/2017] [Accepted: 10/26/2017] [Indexed: 12/01/2022]
Abstract
The use of a broad spectrum sunscreen is considered one of the main and most popular measures for preventing the damaging effects of ultraviolet radiation (UVR) on the skin. In this study we have developed a novel in vitro method to assess sunscreens efficacy to protect calcineurin enzyme activity, a skin cell marker. The photoprotective efficacy of sunscreen products was assessed by measuring the UV-A1 radiation-induced depletion of calcineurin (Cn) enzyme activity in primary neonatal human dermal fibroblast (HDFn) cell lysates. After exposure to 24J/cm2 UV-A1 radiation, the sunscreens containing larger amounts of UV-A1 filters (brand B), the astaxanthin (UV-A1 absorber) and the Tinosorb® M (UV-A1 absorber) were capable of preventing loss of Cn activity when compared to the sunscreens formulations of brand A (low concentration of UV-A1 filters), with the Garcinia brasiliensis extract (UV-B absorber) and with the unprotected cell lysate and exposed to irradiation (Irradiated Control - IC). The Cn activity assay is a reproducible, accurate and selective technique for evaluating the effectiveness of sunscreens against the effects of UV-A1 radiation. The developed method showed that calcineurin activity have the potential to act as a biological indicator of UV-A1 radiation-induced damages in skin and the assay might be used to assess the efficacy of sunscreens agents and plant extracts prior to in vivo tests.
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Affiliation(s)
- Sônia Aparecida Figueiredo
- Quality Control and Photochemoprevention Laboratory, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Avenida do Café, s/n, Ribeirão Preto, SP 14040-903, Brazil
| | - Dayane Cristina de Moraes
- Quality Control and Photochemoprevention Laboratory, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Avenida do Café, s/n, Ribeirão Preto, SP 14040-903, Brazil
| | - Fernanda Maria Pinto Vilela
- Faculty of Pharmacy, Federal University of Juiz de Fora, Rua José Lourenço Kelmer, s/n, Juiz de Fora, Minas Gerais 36036-900, Brazil
| | - Amanda Natalina de Faria
- Department of Biochemistry, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Avenida Bandeirantes, 3900, Ribeirão Preto, SP 14049-900, Brazil
| | - Marcelo Henrique Dos Santos
- Department of Chemistry, Federal University of Viçosa, Avenida Peter Henry Rolfs, s/n, Viçosa, MG 36570-000, Brazil
| | - Maria José Vieira Fonseca
- Quality Control and Photochemoprevention Laboratory, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Avenida do Café, s/n, Ribeirão Preto, SP 14040-903, Brazil.
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Andrews LM, Li Y, De Winter BCM, Shi YY, Baan CC, Van Gelder T, Hesselink DA. Pharmacokinetic considerations related to therapeutic drug monitoring of tacrolimus in kidney transplant patients. Expert Opin Drug Metab Toxicol 2017; 13:1225-1236. [PMID: 29084469 DOI: 10.1080/17425255.2017.1395413] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
INTRODUCTION Tacrolimus (Tac) is the cornerstone of immunosuppressive therapy after solid organ transplantation and will probably remain so. Excluding belatacept, no new immunosuppressive drugs were registered for the prevention of acute rejection during the last decade. For several immunosuppressive drugs, clinical development halted because they weren't sufficiently effective or more toxic. Areas covered: Current methods of monitoring Tac treatment, focusing on traditional therapeutic drug monitoring (TDM), controversies surrounding TDM, novel matrices, pharmacogenetic and pharmacodynamic monitoring are discussed. Expert opinion: Due to a narrow therapeutic index and large interpatient pharmacokinetic variability, TDM has been implemented for individualization of Tac dose to maintain drug efficacy and minimize the consequences of overexposure. The relationship between predose concentrations and the occurrence of rejection or toxicity is controversial. Acute cellular rejection also occurs when the Tac concentration is within the target range, suggesting that Tac whole blood concentrations don't necessarily correlate with pharmacological effect. Intracellular Tac, the unbound fraction of Tac or pharmacodynamic monitoring could be better biomarkers/tools for adequate Tac exposure - research into this has been promising. Traditional TDM, perhaps following pre-emptive genotyping for Tac-metabolizing enzymes, must suffice for a few years before these strategies can be implemented in clinical practice.
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Affiliation(s)
- Louise M Andrews
- a Department of Hospital Pharmacy , Erasmus MC, University Medical Center Rotterdam , Rotterdam , The Netherlands
| | - Yi Li
- a Department of Hospital Pharmacy , Erasmus MC, University Medical Center Rotterdam , Rotterdam , The Netherlands.,b Department of Laboratory Medicine , West China Hospital of Sichuan University , Chengdu , China
| | - Brenda C M De Winter
- a Department of Hospital Pharmacy , Erasmus MC, University Medical Center Rotterdam , Rotterdam , The Netherlands
| | - Yun-Ying Shi
- c Department of Nephrology , West China Hospital of Sichuan University , Chengdu , China
| | - Carla C Baan
- d Department of Internal Medicine , Erasmus MC, University Medical Center Rotterdam , Rotterdam , The Netherlands
| | - Teun Van Gelder
- a Department of Hospital Pharmacy , Erasmus MC, University Medical Center Rotterdam , Rotterdam , The Netherlands.,d Department of Internal Medicine , Erasmus MC, University Medical Center Rotterdam , Rotterdam , The Netherlands
| | - Dennis A Hesselink
- d Department of Internal Medicine , Erasmus MC, University Medical Center Rotterdam , Rotterdam , The Netherlands
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Analytical Aspects of the Implementation of Biomarkers in Clinical Transplantation. Ther Drug Monit 2016; 38 Suppl 1:S80-92. [PMID: 26418704 DOI: 10.1097/ftd.0000000000000230] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In response to the urgent need for new reliable biomarkers to complement the guidance of the immunosuppressive therapy, a huge number of biomarker candidates to be implemented in clinical practice have been introduced to the transplant community. This includes a diverse range of molecules with very different molecular weights, chemical and physical properties, ex vivo stabilities, in vivo kinetic behaviors, and levels of similarity to other molecules, etc. In addition, a large body of different analytical techniques and assay protocols can be used to measure biomarkers. Sometimes, a complex software-based data evaluation is a prerequisite for appropriate interpretation of the results and for their reporting. Although some analytical procedures are of great value for research purposes, they may be too complex for implementation in a clinical setting. Whereas the proof of "fitness for purpose" is appropriate for validation of biomarker assays used in exploratory drug development studies, a higher level of analytical validation must be achieved and eventually advanced analytical performance might be necessary before diagnostic application in transplantation medicine. A high level of consistency of results between laboratories and between methods (if applicable) should be obtained and maintained to make biomarkers effective instruments in support of therapeutic decisions. This overview focuses on preanalytical and analytical aspects to be considered for the implementation of new biomarkers for adjusting immunosuppression in a clinical setting and highlights critical points to be addressed on the way to make them suitable as diagnostic tools. These include but are not limited to appropriate method validation, standardization, education, automation, and commercialization.
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Development of a Fluorescent Quenching Based High Throughput Assay to Screen for Calcineurin Inhibitors. PLoS One 2015; 10:e0131297. [PMID: 26176772 PMCID: PMC4503349 DOI: 10.1371/journal.pone.0131297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 05/11/2015] [Indexed: 01/11/2023] Open
Abstract
Currently there is no effective treatment available for major neurodegenerative disorders associated to protein misfolding, including Alzheimer's and Parkinson's disease. One of most promising therapeutic approaches under development focuses on inhibiting the misfolding and aggregation pathway. However, it is likely that by the time clinical symptoms appear, there is a large accumulation of misfolded aggregates and a very substantial damage to the brain. Thus, it seems that at the clinical stage of the disease it is necessary also to develop strategies aiming to prevent the neuronal damage produced by already formed misfolded aggregates. Chronic activation of calcineurin (CaN), a type IIB phosphatase, has been implicated as a pivotal molecule connecting synaptic loss and neuronal damage to protein misfolding. The fact that the crystal structure of CaN is also well established makes it an ideal target for drug discovery. CaN activity assays for High Throughput Screening (HTS) reported so far are based on absorbance. In this article we report the development of a fluorescent quenching based CaN activity assay suitable for robotic screening of large chemical libraries to find novel inhibitors. The assay yielded a Z score of 0.84 with coefficient of variance ≤ 15%. Our results also show that this assay can be used to identify CaN inhibitors with a wide range of potencies.
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Carr L, Gagez AL, Essig M, Sauvage FL, Marquet P, Gastinel LN. Calcineurin Activity Assay Measurement by Liquid Chromatography–Tandem Mass Spectrometry in the Multiple Reaction Monitoring Mode. Clin Chem 2014; 60:353-60. [DOI: 10.1373/clinchem.2013.213264] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Abstract
BACKGROUND
Blood concentrations of the calcineurin inhibitors (CNIs) cyclosporine and tacrolimus are currently measured to monitor immunosuppression in transplant patients. The measurement of calcineurin (CN) phosphatase activity has been proposed as a complementary pharmacodynamic approach. However, determining CN activity with current methods is not practical. We developed a new method amenable to routine use.
METHODS
Using liquid chromatography–multiple reaction monitoring mass spectrometry (LC-MRM-MS), we quantified CN activity by measuring the dephosphorylation of a synthetic phosphopeptide substrate. A stable isotope analog of the product peptide served as internal standard, and a novel inhibitor cocktail minimized dephosphorylation by other major serine/threonine phosphatases. The assay was used to determine CN activity in peripheral blood mononuclear cells (PBMCs) isolated from 20 CNI-treated kidney transplant patients and 9 healthy volunteers.
RESULTS
Linearity was observed from 0.16 to 2.5 μmol/L of product peptide, with accuracy in the 15% tolerance range. Intraassay and interassay recoveries were 100.6 (9.6) and 100 (7.5), respectively. Michaelis–Menten kinetics for purified CN were Km = 10.7 (1.6) μmol/L, Vmax = 2.8 (0.3) μmol/min · mg, and for Jurkat lysate, Km = 182.2 (118.0) μmol/L, Vmax = 0.013 (0.006) μmol/min · mg. PBMC CN activity was successfully measured in a single tube with an inhibitor cocktail.
CONCLUSIONS
Because LC-MRM-MS is commonly used in routine clinical dosage of drugs, this CN activity assay could be applied, with parallel blood drug concentration monitoring, to a large panel of patients to reevaluate the validity of PBMC CN activity monitoring.
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Affiliation(s)
| | | | - Marie Essig
- INSERM U850, Limoges, France
- Department of Nephrology, Dialysis and Transplantation and
| | | | - Pierre Marquet
- INSERM U850, Limoges, France
- Department of Pharmacology-Toxicology, CHU Limoges, Limoges, France
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Vafadari R, Kraaijeveld R, Weimar W, Baan CC. Tacrolimus inhibits NF-κB activation in peripheral human T cells. PLoS One 2013; 8:e60784. [PMID: 23573283 PMCID: PMC3613409 DOI: 10.1371/journal.pone.0060784] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 03/02/2013] [Indexed: 12/31/2022] Open
Abstract
The calcineurin inhibitor, tacrolimus (TAC), inhibits the protein phosphatase activity of calcineurin, leading to suppression of the nuclear translocation of NFAT and inhibition of T cell activation. Apart from NFAT also the transcription factor NF-κB plays a key functional role in T cell activation. Therefore, blockade of the NF-κB activation cascade by immunosuppressive drugs prevents immune activation. Here we studied whether TAC blocks NF-κB activation in peripheral human T cells. After anti-CD3/CD28-activation of T cells from healthy volunteers, NF-κB (p65) phosphorylation was measured by flow cytometry in CD3+ T cells, CD4+ helper T cells and CD8+ cytotoxic T cells in the absence and presence of TAC 10 ng/mL, sotrastaurin 500 nM (positive control) and mycophenolic acid 10 µg/mL (negative control; n = 6). NF-κB transcriptional activity was measured by ELISA and intracellular TNFα protein, a downstream target, was measured by flow cytometry to assess the functional consequences of NF-κB blockade. Anti-CD3/28-activation induced NF-κB phosphorylation in CD3+ T cells, CD4+ T cells and CD8+ T cells by 34% (mean), 38% and 30% resp. (p<0.01). Sotrastaurin inhibited NF-κB activation in the respective T cell subsets by 93%, 95% and 86% (p<0.01 vs. no drug), while mycophenolic acid did not affect this activation pathway. Surprisingly, TAC also inhibited NF-κB phosphorylation, by 55% (p<0.01) in CD3+ T cells, by 56% (p<0.01) in CD4+ T cells and by 51% in CD8+ T cells (p<0.01). In addition, TAC suppressed NF-κB DNA binding capacity by 55% (p<0.05) in CD3+ T cells and TNFα protein expression was inhibited in CD3+ T cells, CD4+ T cells and CD8+ T cells by 76%, 71% and 93% resp. (p<0.01 vs. no drug), confirming impaired NF-κB signaling. This study shows the suppressive effect of TAC on NF-κB signaling in peripheral human T cell subsets, measured at three specific positions in the NF-κB activation cascade.
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Affiliation(s)
- Ramin Vafadari
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Rens Kraaijeveld
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Willem Weimar
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Carla C. Baan
- Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Prell E, Kahlert V, Rücknagel KP, Malešević M, Fischer G. Fine tuning the inhibition profile of cyclosporine A by derivatization of the MeBmt residue. Chembiochem 2012; 14:63-5. [PMID: 23225707 DOI: 10.1002/cbic.201200621] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Indexed: 12/28/2022]
Abstract
Unique respect: The biological properties of four CsA derivatives were fine-tuned by tractable modifications of the MeBmt residue. The new CsA derivatives share strong inhibitory activity toward cyclophilins (Cyps), but each is unique with respect to immunosuppressive action and cellular localization. These CsA analogues can be used to study the physiological roles of extracellular Cyps.
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Affiliation(s)
- Erik Prell
- Max Planck Research Unit for Enzymology of Protein Folding, Weinbergweg 22, 06120 Halle/Saale, Germany
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14
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Calcineurin inhibitors and NFAT-regulated gene expression. Clin Chim Acta 2012; 413:1379-86. [DOI: 10.1016/j.cca.2011.09.041] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 09/21/2011] [Accepted: 09/27/2011] [Indexed: 12/20/2022]
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Musson REA, Mullenders LHF, Smit NPM. Effects of arsenite and UVA-1 radiation on calcineurin signaling. Mutat Res 2012; 735:32-38. [PMID: 22564430 DOI: 10.1016/j.mrfmmm.2012.04.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 04/16/2012] [Accepted: 04/26/2012] [Indexed: 05/31/2023]
Abstract
Calcineurin is a Ca(2+)-dependent serine/threonine phosphatase and the target of the immunosuppressive drugs cyclosporin and tacrolimus, which are used in transplant recipients to prevent rejection. Unfortunately, the therapeutic use of this drugs is complicated by a high incidence of skin malignancy, which has set off a number of studies into the role of calcineurin signaling in skin, particularly with respect to cell cycle control and DNA repair. Both UVA1 radiation and arsenic species are known to promote skin cancer development via production of reactive oxygen species. In light of the well-documented sensitivity of calcineurin to oxidative stress, we examined and compared the effects of UVA1 and arsenite on calcineurin signaling. In this paper, we show that physiologically relevant doses of UVA1 radiation and low micromolar concentrations of arsenite strongly inhibit calcineurin phosphatase activity in Jurkat and skin cells and decrease NFAT nuclear translocation in Jurkat cells. The effects on calcineurin signaling could be partly prevented by inhibition of NADPH oxidase in Jurkat cells or increased dismutation of superoxide in Jurkat and skin cells. In addition, both UVA1 and arsenite decreased NF-κB activity, although at lower concentrations, arsenite enhanced NF-κB activity. These data indicate that UVA1 and arsenite affect a signal transduction route of growingly acknowledged importance in skin and that calcineurin may serve as a potential link between ROS exposure and impaired tumor suppression.
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Affiliation(s)
- Ruben E A Musson
- Department of Clinical Chemistry, Leiden University Medical Center, The Netherlands.
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Distinct dendritic spine and nuclear phases of calcineurin activation after exposure to amyloid-β revealed by a novel fluorescence resonance energy transfer assay. J Neurosci 2012; 32:5298-309. [PMID: 22496575 DOI: 10.1523/jneurosci.0227-12.2012] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Calcineurin (CaN) activation is critically involved in the regulation of spine morphology in response to oligomeric amyloid-β (Aβ) as well as in synaptic plasticity in normal memory, but no existing techniques can monitor the spatiotemporal pattern of CaN activity. Here, we use a spectral fluorescence resonance energy transfer approach to monitor CaN activation dynamics in real time with subcellular resolution. When oligomeric Aβ derived from Tg2576 murine transgenic neurons or human AD brains were applied to wild-type murine primary cortical neurons, we observe a dynamic progression of CaN activation within minutes, first in dendritic spines, and then in the cytoplasm and, in hours, in the nucleus. CaN activation in spines leads to rapid but reversible morphological changes in spines and in postsynaptic proteins; longer exposure leads to NFAT (nuclear factor of activated T-cells) translocation to the nucleus and frank spine loss. These results provide a framework for understanding the role of calcineurin in synaptic alterations associated with AD pathogenesis.
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Abstract
Abstract
BACKGROUND
The Ca2+-dependent protein phosphatase enzyme calcineurin (Cn) (protein phosphatase 3) is best known for its role as director of the adaptive immune response. One of its principal substrates is the nuclear factor of activated T cells (NFAT), which translocates to the nucleus after dephosphorylation to mediate gene transcription. Drugs targeting Cn (the Cn inhibitors tacrolimus and cyclosporin A) have revolutionized posttransplantation therapy in allograft recipients by considerably reducing rejection rates.
CONTENT
Owing primarily to intensive study of the side effects of the Cn inhibitors, the unique importance of Cn and Cn/NFAT signaling in the normal physiological processes of many other cell and tissue types is becoming more evident. During the last decade, it has become clear that an extensive and diverse array of clinical conditions can be traced back, at least in part, to a disturbed Cn-signaling axis. Hence, both diagnostics and therapeutic monitoring could benefit from a technique that conveniently reads out Cn/NFAT operative status.
SUMMARY
This review outlines the current knowledge on the pathologic conditions that have calcineurin as a common denominator and reports on the progress that has been made toward successfully applying Cn and Cn/NFAT activity markers in molecular diagnostics.
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Affiliation(s)
- Ruben E A Musson
- Departments of Clinical Chemistry and
- Toxicogenetics, Leiden University Medical Center, Leiden, the Netherlands
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Margassery LM, Kennedy J, O'Gara F, Dobson AD, Morrissey JP. A high-throughput screen to identify novel calcineurin inhibitors. J Microbiol Methods 2011; 88:63-6. [PMID: 22056231 DOI: 10.1016/j.mimet.2011.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 10/19/2011] [Accepted: 10/19/2011] [Indexed: 01/26/2023]
Abstract
Calcineurin is a eukaryotic protein phosphatase important for many signalling and developmental processes in cells. Inhibitors of this enzyme are used clinically and there is interest in identifying novel inhibitors for therapeutic applications. This report describes a high-throughput assay that can be used to screen natural or chemical libraries of compounds to identify new calcineurin inhibitors. The microtitre plate assay is based on a yeast reporter strain and was validated with known inhibitors and tested in a pilot screen of bacterial extracts.
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Affiliation(s)
- Lekha Menon Margassery
- Marine Biotechnology Centre, Environmental Research Institute, Microbiology Department, University College Cork, Ireland
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Musson REA, Hensbergen PJ, Westphal AH, Temmink WPM, Deelder AM, van Pelt J, Mullenders LHF, Smit NPM. UVA1 radiation inhibits calcineurin through oxidative damage mediated by photosensitization. Free Radic Biol Med 2011; 50:1392-9. [PMID: 21354304 DOI: 10.1016/j.freeradbiomed.2011.02.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 02/14/2011] [Accepted: 02/15/2011] [Indexed: 12/21/2022]
Abstract
The protein phosphatase calcineurin has been gradually revealing itself as the central controller of our immune response, although it is involved in a wide array of signaling pathways related to cellular development and cell cycle progression. As such, calcineurin is an attractive, yet delicate, therapeutic target for the prevention of allograft rejection and treatment of several inflammatory skin conditions. However, calcineurin activity is not only sensitive to immunosuppressants such as cyclosporin A and tacrolimus, but also subject to modulation by reactive oxygen species. We have recently shown, both in vivo and in vitro, that UVA1 radiation suppresses calcineurin activity. In this paper, we present evidence that this activity loss is due to singlet oxygen and superoxide generated by photosensitization and show that a closely related phosphatase, PP2A, is not affected. Furthermore, a survey of this damage reveals oxidation of several Met and Cys residues as well as an overall conformational change. These findings provide a mechanistic basis for the hypothesis that UVA1 and calcineurin inhibitors both affect the same signal transduction pathway in skin.
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Affiliation(s)
- Ruben E A Musson
- Department of Clinical Chemistry, Leiden University Medical Center, Leiden, The Netherlands.
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Dekter HE, Romijn FP, Temmink WP, van Pelt J, de Fijter JW, Smit NP. A spectrophotometric assay for routine measurement of mammalian target of rapamycin activity in cell lysates. Anal Biochem 2010; 403:79-87. [DOI: 10.1016/j.ab.2010.04.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 04/16/2010] [Accepted: 04/20/2010] [Indexed: 10/19/2022]
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Pharmacodynamic monitoring of calcineurin inhibition therapy: principles, performance, and perspectives. Ther Drug Monit 2010; 32:3-10. [PMID: 20009796 DOI: 10.1097/ftd.0b013e3181c0eecb] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The calcineurin inhibitors (CNIs) cyclosporin A and tacrolimus are immunosuppressive drugs used extensively in allograft recipients. These drugs show large interindividual pharmacokinetic variation and are associated with severe adverse affects, including nephrotoxicity and cardiovascular disease. In current practice, CNIs are combined with other immunosuppressive drugs such as steroids and mycophenolate mofetil. Dosage is titrated based on blood concentration measurement. For further optimization of calcineurin (CN) inhibition therapy, new monitoring strategies are required. Pharmacodynamic-monitoring strategies constitute novel approaches for optimization of CNIs therapy. This review focuses on the general aspects of immunosuppressive drug pharmacodynamic monitoring and describes the methodologies used for monitoring CN inhibition therapy. Two different types of pharmacodynamic-monitoring strategies can be distinguished: (1) enzymatic strategies, which monitor inhibition of drug-target enzyme activity, and (2) immunologic strategies, which measure cellular responsiveness after in vitro simulated immunologic responses. Enzymatic tests are drug type-specific markers in which CN activity is directly determined. Immunologic strategies measure immune responsiveness at several levels, such as mRNA transcripts (intracellular) concentrations/excretion of cytokines, expression of surface activation markers, and cell proliferation. This review also discusses analytical issues and clinical experience with these techniques. The call for new methodologies to evaluate immunosuppressive therapy has led to the development of a large variety of pharmacodynamic-monitoring strategies. The first reports of their clinical relevance are available, but further understanding of the analytical and clinical variables involved are required for the development of accurate, reproducible, and clinically relevant markers.
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Smit N, Musson R, Romijn F, van Rossum H, van Pelt J. Effects of Ultraviolet A-1 Radiation on Calcineurin Activity and Cytokine Production in (Skin) Cell Cultures. Photochem Photobiol 2010; 86:360-6. [DOI: 10.1111/j.1751-1097.2009.00650.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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van Rossum HH, Romijn FP, Smit NP, de Fijter JW, van Pelt J. Everolimus and sirolimus antagonize tacrolimus based calcineurin inhibition via competition for FK-binding protein 12. Biochem Pharmacol 2009; 77:1206-12. [DOI: 10.1016/j.bcp.2008.12.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Revised: 12/15/2008] [Accepted: 12/16/2008] [Indexed: 12/16/2022]
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Sommerer C, Giese T, Meuer S, Zeier M. Pharmacodynamic monitoring of calcineurin inhibitor therapy: is there a clinical benefit? Nephrol Dial Transplant 2008; 24:21-7. [PMID: 18842676 DOI: 10.1093/ndt/gfn556] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Blanchet B. [Therapeutic monitoring of immunosuppressive drugs: interest of calcineurin activity assessment in liver transplantation]. ANNALES PHARMACEUTIQUES FRANÇAISES 2008; 66:96-101. [PMID: 18570908 DOI: 10.1016/j.pharma.2008.03.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Accepted: 03/26/2008] [Indexed: 11/26/2022]
Abstract
Therapeutic monitoring of calcineurin inhibitors (ciclosporin and tacrolimus) consists in pharmacokinetic monitoring. Pharmacodynamics based on calcineurin activity may be particularly interesting in liver transplantation due to the large intra- and interindividual variability of pharmacokinetics of ciclosporin and tacrolimus. A recent investigation on the pharmacokinetic-pharmacodynamic relationship of tacrolimus showed that monitoring of calcineurin activity in PBMC may be particularly relevant within the first three post-transplantation months. Thereafter, the monitoring of trough blood concentrations of tacrolimus remains adequate. Moreover, two clinical investigations carried out within the early and late post-transplantation periods reported a promising result which is a positive correlation between calcineurin activity and incidence of graft rejection, whatever graft type and calcineurin inhibitors. In each study, transplanted recipients with a graft rejection exhibited a greater trough calcineurin activity compared to patients without graft rejection. However, prospective investigations are required because of the small cohorts of patients enrolled in both studies. The aim of these investigations will be to confirm the interest of calcineurin activity monitoring as a marker of cellular immunity and its positive link with pharmacokinetic monitoring.
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Affiliation(s)
- B Blanchet
- Laboratoire de pharmacologie et toxicologie, CHU Henri-Mondor, 51, avenue du Maréchal-de-Lattre-de-Tassigny, 94000 Créteil, France.
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Ciclosporin A tapering monitored by NFAT-regulated gene expression: a new concept of individual immunosuppression. Transplantation 2008; 85:15-21. [PMID: 18192906 DOI: 10.1097/01.tp.0000296824.58884.55] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND The impact of long-term immunosuppression in renal transplant recipients with respect to safety and efficacy remains undetermined. Pharmacodynamic monitoring of the relative reduction of T-cell-specific gene expression in renal transplant recipients treated with cyclosporine A (CsA) was applied in this study. METHODS During the study, 20 stable renal transplant recipients with tapered CsA dose and 20 patients with stable CsA dose (matched for age, gender, CsA dose, time after transplantation) were compared for a median period of 18 months (range 6-44). CsA dose was tapered in two stages of 15% each, and the expression of the nuclear factor of activated T cells (NFAT)-regulated genes was determined by reverse-transcription polymerase chain reaction method at CsA trough level and 2 hr after oral uptake. RESULTS The initial residual gene expression at 2 hr after CsA intake increased from 6.31% (range 1.30-16.6) to 21.3% (range 6.58-31.8) in patients with CsA dosage reduction. In one patient, the residual gene expression increased more than 40% and resulted in a reversible Banff 1A rejection episode. Blood pressure was significantly lower after CsA dosage reduction (P<0.05). In the pair-matched control group NFAT-regulated gene expression was comparable before and after the follow-up period (7.45% [range 0.21-18.3] vs. 5.87% [range 0.66-13.2]; P=NS). Estimated glomerular filtration rate was significantly worse in the control group (P<0.05). CONCLUSION Our observation suggests that the measurement of the relative gene expression in CsA-treated patients is a promising tool to monitor the CsA dosage reduction in long-term renal transplant patients. An increase in residual expression of NFAT-regulated gene expression may result in an acute rejection episode.
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van Rossum HH, Romijn FPHTM, Sellar KJ, Smit NPM, van der Boog PJM, de Fijter JW, van Pelt J. Variation in Leukocyte Subset Concentrations Affects Calcineurin Activity Measurement: Implications for Pharmacodynamic Monitoring Strategies. Clin Chem 2008; 54:517-24. [DOI: 10.1373/clinchem.2007.097253] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
AbstractBackground: In renal transplantation patients, therapeutic drug monitoring of the calcineurin (CN) inhibitor cyclosporin A (CsA) is mandatory because of the drug’s narrow therapeutic index. Pharmacodynamic monitoring of CN inhibition therapy could provide a tool to define and maintain the therapeutic efficacy of CsA therapy. We investigated the effect of variation in cell counts of leukocyte subsets on leukocyte CN activity measurement in renal transplant recipients.Methods: We measured leukocyte CN activity, whole blood CsA concentrations, and leukocyte subset cell counts in 25 renal transplant recipients. Blood was collected before graft implantation and CsA therapy, 1 day before transplantation when CsA therapy was already started, and 5 days after transplantation. Monocyte, granulocyte, CD4+ T-cell, CD8+ T-cell, B-cell, and natural killer–cell CN activities and CsA inhibition sensitivities were determined in vitro by a spectrophotometric CN assay.Results: Leukocyte CN activity was inhibited after drug intake. Inter- and intrapatient variation in leukocyte subset cell counts resulted in variation of sample composition. The mean (SD) CN activity varied among leukocyte cell subsets, ranging from 650 (230) to 166 (26) pmol/min/106 cells for monocytes and CD4+ T cells, respectively. CsA half maximal inhibitory concentration (IC50) values ranged from 15 to 78 μg/L for monocytes and B cells, respectively.Conclusion: Inter- and intraindividual leukocyte subset cell count variation can affect measured CN activity independent of CsA concentration. Cell-specific activity and drug sensitivity should be considered for sample validation to optimize method specificity when pharmacodynamic monitoring strategies are applied in a clinical setting.
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Affiliation(s)
| | | | | | | | | | - Johan W de Fijter
- Nephrology, Leiden University Medical Center, Leiden, the Netherlands
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Smit NPM, Van Rossum HH, Romijn FP, Sellar KJ, Breetveld M, Gibbs S, Van Pelt J. Calcineurin activity and inhibition in skin and (epi)dermal cell cultures. J Invest Dermatol 2008; 128:1686-90. [PMID: 18200052 DOI: 10.1038/sj.jid.5701244] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Calcineurin (Cn) is the target of the immunosuppressive drugs cyclosporine A (CsA), tacrolimus (Trl), and pimecrolimus (Prl). Trl and Prl are often used topically for treatment of various skin diseases. The Cn inhibitors CsA and Trl are mostly used for maintenance therapy of transplant patients. Their long-term use, however, causes a dramatic increase in skin cancer risk. By using a newly developed assay for Cn measurement in blood, we were able to demonstrate Cn activity in total skin homogenates. A significantly higher activity was found in epidermis compared to dermis. In skin cell cultures, fibroblasts showed the highest activity as compared to keratinocytes and melanocytes. Of the Cn inhibitors, Trl showed stronger inhibition than CsA and Prl (57 and 55% in fibroblast and keratinocyte cultures, respectively). Also, the lowest IC(50) (the half maximal inhibitory concentration) values were found for Trl (0.5 and 1.3 nM in two different fibroblast cultures). Cn activity and its inhibition can thus be studied in dermatological samples. The effects of Cn inhibition in fibroblasts and keratinocytes may be of influence on the overall functioning of the skin immune system.
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Affiliation(s)
- N P M Smit
- Department of Clinical Chemistry, Leiden University Medical Center, Leiden, The Netherlands.
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