title: Tacrolimus pharmacodynamics and pharmacogenetics along the calcineurin pathway in human lymphocytes.
abstract: BACKGROUND
  Although therapeutic drug monitoring has improved the clinical use of immunosuppressive drugs, there is still interpatient variability in efficacy and toxicity that pharmacodynamic monitoring may help to reduce. To select the best biomarkers of tacrolimus pharmacodynamics, we explored the strength and variability of signal transduction and the influence of polymorphisms along the calcineurin pathway.
  
  
  METHODS
  Peripheral blood mononuclear cells from 35 healthy volunteers were incubated with tacrolimus (0.1-50 ng/mL) and stimulated ex vivo. Inhibition of NFAT1 (nuclear factor of activated T cells 1) translocation to the nucleus and intracellular expression of interleukin-2 in CD4(+) and CD8(+) T cells and the surface activation marker CD25 in CD3(+) cells were measured by flow cytometry. We sequenced the promoter regions of immunophilins and calcineurin subunits and characterized selected single nucleotide polymorphisms in the genes of the calcineurin pathway with allelic discrimination assays.
  
  
  RESULTS
  All responses closely fitted an I/Imax sigmoid model. Large interindividual variability (n = 30) in I0 and IC50 was found for all biomarkers. Moreover, strong and statistically significant associations were found between tacrolimus pharmacodynamic parameters and polymorphisms in the genes coding cyclophilin A, the calcineurin catalytic subunit α isoenzyme, and CD25.
  
  
  CONCLUSIONS
  This study demonstrates the consistency and large interindividual variability of signal transduction along the calcineurin pathway, as well as the strong influence of pharmacogenetic polymorphisms in the calcineurin cascade on both the physiological activity of this route and tacrolimus pharmacodynamics.
authors.affiliation: INSERM U850 and Liver Diseases Department, National Center for Liver Transplantation, Hospital Central de las Fuerzas Armadas, Montevideo, Uruguay; Molecular Biology Unit, Clinical Biochemistry Department, School of Chemistry, and.
authors.forename: Ofelia M
authors.initials: OM
authors.lastname: Noceti
authors.affiliation: INSERM U850 and.
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Woillard
authors.affiliation: CNRS UMR 7276, Université Limoges, Limoges, France;
authors.forename: Ahmed
authors.initials: A
authors.lastname: Boumediene
authors.affiliation: Molecular Biology Unit, Clinical Biochemistry Department, School of Chemistry, and.
authors.forename: Patricia
authors.initials: P
authors.lastname: Esperón
authors.affiliation: CNRS UMR 5164, Université Bordeaux Segalen, Bordeaux, France.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Taupin
authors.affiliation: Liver Diseases Department, National Center for Liver Transplantation, Hospital Central de las Fuerzas Armadas, Montevideo, Uruguay;
authors.forename: Solange
authors.initials: S
authors.lastname: Gerona
authors.affiliation: Liver Diseases Department, National Center for Liver Transplantation, Hospital Central de las Fuerzas Armadas, Montevideo, Uruguay;
authors.forename: Marcelo
authors.initials: M
authors.lastname: Valverde
authors.affiliation: Department of Fundamental Medicine, School of Medicine, Universidad de la República, Montevideo, Uruguay;
authors.forename: Cristina
authors.initials: C
authors.lastname: Touriño
authors.affiliation: INSERM U850 and pierre.marquet@unilim.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Marquet
mesh_terms: D000328:Adult; D000483:Alleles; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D019703:Calcineurin / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004247:DNA / Q000235:genetics; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007166:Immunosuppressive Agents / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000633:toxicity; D007376:Interleukin-2 / Q000235:genetics; D008297:Male; D050778:NFATC Transcription Factors / Q000378:metabolism; D010597:Pharmacogenetics; D020641:Polymorphism, Single Nucleotide; D021381:Protein Transport; D015398:Signal Transduction / Q000235:genetics; D016559:Tacrolimus / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000633:toxicity
chemical_list: C508594:IL2 protein, human; D007166:Immunosuppressive Agents; D007376:Interleukin-2; D050778:NFATC Transcription Factors; C494006:NFATC2 protein, human; D004247:DNA; D019703:Calcineurin; D016559:Tacrolimus