Inhibitory effect of tacrolimus on p38 mitogen-activated protein kinase signaling in kidney transplant recipients measured by whole-blood phosphospecific flow cytometry.
BACKGROUND
Tacrolimus (TAC), the cornerstone of immunosuppressive therapy after solid organ transplantation, inhibits calcineurin activation. Despite pharmacokinetic monitoring, patients frequently experience toxicity or lack of efficacy, which could be prevented by pharmacodynamic monitoring. In Jurkat T-cell lines, it has been shown that TAC, in addition to calcineurin, inhibits the p38 mitogen-activated protein kinase (MAPK) pathway, which is important in T-cell activation and is therefore a potential drug-specific biomarker. We studied whether TAC inhibits p38 MAPK signaling in primary human T cells and ex vivo in healthy volunteers and kidney transplant recipients.


METHODS
Phorbol-12-myristate-13-acetate/ionomycin-induced MAPK signaling was measured by whole-blood phosphospecific flow cytometry.


RESULTS
In vitro, 10-ng/mL TAC inhibited p38 MAPK phosphorylation by a mean of 27% in CD3, 26% in CD4, and 34% in CD8 T cells (P<0.01 compared with baseline). In healthy adults (n=4), 2 hr after a single oral dose of 10-mg TAC, the p38 MAPK activation was inhibited by 35% in CD3, CD4, and CD8 T cells (P<0.05 compared with baseline). In kidney transplant recipients (n=24), TAC predose concentrations (range, 3.2-10.5 ng/mL) were inversely correlated with p38 MAPK activation in CD3, CD4, and CD8 T cells (r=0.51, 0.34, and 0.37, respectively; P<0.01).


CONCLUSIONS
TAC inhibits activation of the MAPK pathway in a dose-dependent manner in kidney transplant patients and may be a potential marker for immune monitoring.
Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands. r.vafadari@erasmusmc.nl
Ramin
R
Vafadari
Dennis A
DA
Hesselink
Monique M
MM
Cadogan
Willem
W
Weimar
Carla C
CC
Baan
D000328:Adult; D002273:Carcinogens / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006084:Graft Rejection / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage; D019169:Jurkat Cells; D016030:Kidney Transplantation; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010750:Phosphoproteins / Q000097:blood; D010766:Phosphorylation / Q000187:drug effects; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D016559:Tacrolimus / Q000008:administration & dosage*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D002273:Carcinogens; D007166:Immunosuppressive Agents; D010750:Phosphoproteins; D048051:p38 Mitogen-Activated Protein Kinases; D013755:Tetradecanoylphorbol Acetate; D016559:Tacrolimus