Author:
Bremer Sara,Vethe Nils T,Rootwelt Helge,Jørgensen Pål F,Stenstrøm Jean,Holdaas Hallvard,Midtvedt Karsten,Bergan Stein
Abstract
Abstract
Background
Mycophenolic acid (MPA) is widely used as part of immunosuppressive regimens following allograft transplantation. The large pharmacokinetic (PK) and pharmacodynamic (PD) variability and narrow therapeutic range of MPA provide a potential for therapeutic drug monitoring. The objective of this pilot study was to investigate the MPA PK and PD relation in combination with belatacept (2nd generation CTLA4-Ig) or cyclosporine (CsA).
Methods
Seven renal allograft recipients were randomized to either belatacept (n = 4) or cyclosporine (n = 3) based immunosuppression. Samples for MPA PK and PD evaluations were collected predose and at 1, 2 and 13 weeks posttransplant. Plasma concentrations of MPA were determined by HPLC-UV. Activity of inosine monophosphate dehydrogenase (IMPDH) and the expressions of two IMPDH isoforms were measured in CD4+ cells by HPLC-UV and real-time reverse-transcription PCR, respectively. Subsets of T cells were characterized by flow cytometry.
Results
The MPA exposure tended to be higher among belatacept patients than in CsA patients at week 1 (P = 0.057). Further, MPA concentrations (AUC0–9 h and C0) increased with time in both groups and were higher at week 13 than at week 2 (P = 0.031, n = 6). In contrast to the postdose reductions of IMPDH activity observed early posttransplant, IMPDH activity within both treatment groups was elevated throughout the dosing interval at week 13. Transient postdose increments were also observed for IMPDH1 expression, starting at week 1. Higher MPA exposure was associated with larger elevations of IMPDH1 (r = 0.81, P = 0.023, n = 7 for MPA and IMPDH1 AUC0–9 h at week 1). The maximum IMPDH1 expression was 52 (13–177)% higher at week 13 compared to week 1 (P = 0.031, n = 6). One patient showed lower MPA exposure with time and did neither display elevations of IMPDH activity nor IMPDH1 expression. No difference was observed in T cell subsets between treatment groups.
Conclusion
The significant influence of MPA on IMPDH1 expression, possibly mediated through reduced guanine nucleotide levels, could explain the elevations of IMPDH activity within dosing intervals at week 13. The present regulation of IMPDH in CD4+ cells should be considered when interpreting measurements of IMPDH inhibition.
Publisher
Springer Science and Business Media LLC
Subject
General Biochemistry, Genetics and Molecular Biology,General Medicine
Reference44 articles.
1. Natsumeda Y, Ohno S, Kawasaki H, Konno Y, Weber G, Suzuki K: Two distinct cDNAs for human IMP dehydrogenase. J Biol Chem. 1990, 265: 5292-5295.
2. Gu JJ, Tolin AK, Jain J, Huang H, Santiago L, Mitchell BS: Targeted disruption of the inosine 5'-monophosphate dehydrogenase type I gene in mice. Mol Cell Biol. 2003, 23: 6702-6712. 10.1128/MCB.23.18.6702-6712.2003.
3. Gu JJ, Stegmann S, Gathy K, Murray R, Laliberte J, Ayscue L, Mitchell BS: Inhibition of T lymphocyte activation in mice heterozygous for loss of the IMPDH II gene. J Clin Invest. 2000, 106: 599-606. 10.1172/JCI8669.
4. Dayton JS, Lindsten T, Thompson CB, Mitchell BS: Effects of human T lymphocyte activation on inosine monophosphate dehydrogenase expression. J Immunol. 1994, 152: 984-991.
5. Nagai M, Natsumeda Y, Konno Y, Hoffman R, Irino S, Weber G: Selective up-regulation of type II inosine 5'-monophosphate dehydrogenase messenger RNA expression in human leukemias. Cancer Res. 1991, 51: 3886-3890.
Cited by
11 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献