Kristine Kloster-Jensen1,2, Nils Tore Vethe3, Sara Bremer4, Shadab Abadpour1,2, Olle Korsgren5, Aksel Foss1,2,6, Stein Bergan3,7, Hanne Scholz1,2. 1. Department of Transplantation Medicine, Oslo University Hospital, Norway. 2. Institute for Surgical Research, University of Oslo, Norway. 3. Department of Pharmacology, Oslo University Hospital, Norway. 4. Department of Medical Biochemistry, Oslo University Hospital, Norway. 5. Department of Immunology Genetics and Pathology, Science for Life Laboratory, Uppsala University, Sweden. 6. Faculty of Medicine, University of Oslo, Norway. 7. School of Pharmacy, University of Oslo, Norway.
Abstract
MAIN PROBLEM: Islet transplantation has become a promising treatment for type 1 diabetes. However, immunosuppressive drugs used today cause islet deterioration and modification strategies are necessary. But little is known about pharmacokinetics interactions and intracellular concentrations of immunosuppressive drugs in human islets. METHODS: We determined the pharmacokinetics of tacrolimus and sirolimus in islets by measuring intracellular concentration after exposure alone or in combination at two different doses up to 48 h. A quantification technique established in our laboratory using a Micromass Quattro micro API MS/MS-instrument with electrospray ionization was used. Islets function was measured by oxygen consumption rates. Presence of drug transporters OATP1B1 and ABCB1 and metabolizing enzyme CYP3A4 in islets were quantified using real-time quantitative PCR. RESULTS: Islets incubated with tacrolimus and sirolimus had a significant decrease in intracellular concentration of sirolimus compared to sirolimus alone. Reduced intracellular sirolimus concentration was followed by increased p70S6k phosphorylation suggesting preservation of the mTOR-signaling pathway. Drug transporters OATP1B1 and ABCB1 and enzyme CYP3A4 were expressed in human islets, but were not involved in the reduced sirolimus concentration by tacrolimus. CONCLUSION: These findings provide new knowledge of the drug interaction between tacrolimus and sirolimus, suggesting that tacrolimus has an inhibitory effect on the intracellular concentration of sirolimus in human islets.
MAIN PROBLEM: Islet transplantation has become a promising treatment for type 1 diabetes. However, immunosuppressive drugs used today cause islet deterioration and modification strategies are necessary. But little is known about pharmacokinetics interactions and intracellular concentrations of immunosuppressive drugs in human islets. METHODS: We determined the pharmacokinetics of tacrolimus and sirolimus in islets by measuring intracellular concentration after exposure alone or in combination at two different doses up to 48 h. A quantification technique established in our laboratory using a Micromass Quattro micro API MS/MS-instrument with electrospray ionization was used. Islets function was measured by oxygen consumption rates. Presence of drug transporters OATP1B1 and ABCB1 and metabolizing enzyme CYP3A4 in islets were quantified using real-time quantitative PCR. RESULTS: Islets incubated with tacrolimus and sirolimus had a significant decrease in intracellular concentration of sirolimus compared to sirolimus alone. Reduced intracellular sirolimus concentration was followed by increased p70S6k phosphorylation suggesting preservation of the mTOR-signaling pathway. Drug transporters OATP1B1 and ABCB1 and enzyme CYP3A4 were expressed in human islets, but were not involved in the reduced sirolimus concentration by tacrolimus. CONCLUSION: These findings provide new knowledge of the drug interaction between tacrolimus and sirolimus, suggesting that tacrolimus has an inhibitory effect on the intracellular concentration of sirolimus in human islets.
Authors: Michelle Kim; Perri Deacon; Rommel G Tirona; Richard B Kim; Christopher L Pin; Henriette E Meyer Zu Schwabedissen; Rennian Wang; Ute I Schwarz Journal: Histochem Cell Biol Date: 2017-05-10 Impact factor: 4.304