Is indoleamine 2,3-dioxygenase important for graft acceptance in highly sensitized patients after combined auxiliary liver-kidney transplantation?
BACKGROUND
In the clinical setting, transplanted liver seems to protect other grafts from the same donor from rejection. Our previous findings suggest that an auxiliary liver transplantation a few hours before a renal transplantation not only inhibits hyperacute antibody-mediated rejection but also improves long-term kidney graft survival in sensitized recipients. Here, we investigated indoleamine 2,3-dioxygenase (IDO) activity, as one potential mechanism for liver-induced long-term acceptance of kidney grafts.


METHODS
Tryptophan degradation was measured to estimate IDO activity in patient sera and cell culture supernatants with high performance liquid chromatography. Gene expression in the grafted organs and cell lysates was studied using real time polymerase chain reaction analysis.


RESULTS
Tryptophan degradation increased in peripheral blood from patients undergoing combined auxiliary liver-kidney transplantation, whereas it decreased in patients after regular renal transplantation. A 100-fold increase in IDO mRNA, preceded by upregulation of the IDO-inducing cytokines tumor necrosis factor-alpha, interleukin-1beta, and interferon-gamma, was observed in the transplanted organs after graft reperfusion in patients undergoing combined graft transplantation. Subsequent studies in vitro revealed that immature dendritic cells, but not hepatocytes, strongly activated IDO on maturation with tumor necrosis factor-alpha, interleukin-1beta, and interferon-gamma. Finally, serum from liver-transplanted patients elicited an even stronger IDO-activity in such cytokine-stimulated dendritic cells.


CONCLUSIONS
Taken together these findings suggest that the liver-induced long-term acceptance seen in human combined auxiliary liver and kidney transplantation is at least partly mediated by IDO activity.
Ingelsten
Madeleine
M
Department of Molecular and Clinical Medicine (Nephrology), University of Gothenburg, Gothenburg, Sweden. Madeleine.ingelsten@wlab.gu.se
Gustafsson
Karin
K
Oltean
Mihai
M
Karlsson-Parra
Alex
A
Olausson
Michael
M
Haraldsson
Börje
B
Nyström
Jenny
J
D000328:Adult; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology; D005260:Female; D006084:Graft Rejection / Q000517:prevention & control; D022781:Hepatocytes / Q000187:drug effects / Q000276:immunology; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000235:genetics / Q000378:metabolism*; D007371:Interferon-gamma / Q000235:genetics / Q000494:pharmacology; D053583:Interleukin-1beta / Q000235:genetics / Q000494:pharmacology; D016030:Kidney Transplantation / Q000276:immunology*; D016031:Liver Transplantation / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000494:pharmacology
D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma