Intragraft iNOS induction during human liver allograft rejection depresses cytochrome p450 activity.
Allograft function may become impaired during rejection after human liver transplantation. Cytokines induce nitric oxide (NO) production in hepatocytes, Kupffer cells and infiltrating mononuclear cells. NO inhibits cytoplasmatic cytochrome p450 (CYP) enzyme activity in vitro. It is not known whether this mechanism plays a role in vivo. In order to characterize the role of locally produced cytokines in the pathogenesis of liver dysfunction, we analysed human liver transplant biopsy material for the expression of proinflammatory cytokines as well as for NO synthase and we compared these results to the microsomal liver function in vivo [aminopyrine breath test (ABT)] and in vitro (enzymatic analysis of CYP). Microsomal liver function decreased in vivo during rejection while ABT levels decreased by 40% and increased again by 59% after the acute rejection episode. Similarly, CYP 1A2 and 2E1 activity dropped 42% and 24% in rejecting samples, respectively. Competitive reverse transcriptase polymerase chain reaction (RT-PCR) showed a fivefold upregulation of interferon gamma (IFN-gamma) gene expression. Inducible, but not constitutive NO-synthase gene expression was upregulated fivefold in samples from rejecting patients suggesting a local induction of NO in response to immune events. Our data show a marked impairment of CYP enzyme activity during allograft rejection which is presumably secondary to an increased intragraft production of proinflammatory cytokines and NO.
Westerholt
Alexandra
A
Department of Surgery, Ernst Moritz Arndt Universität Greifswald, Friedrich-Loeffler-Strasse 23b, 17487 Greifswald, Germany.
Himpel
Sigrid
S
Hager-Gensch
Birgit
B
Maier
Stefan
S
Werner
Martin
M
Stadler
Josef
J
Doehmer
Johannes
J
Heidecke
Claus-Dieter
CD
D000632:Aminopyrine / Q000378:metabolism; D001944:Breath Tests; D019388:Cytochrome P-450 CYP1A2 / Q000378:metabolism*; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism*; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D006084:Graft Rejection / Q000378:metabolism*; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics; D016031:Liver Transplantation; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014184:Transplantation, Homologous; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D014409:Tumor Necrosis Factor-alpha; D000632:Aminopyrine; D009569:Nitric Oxide; D007371:Interferon-gamma; D003577:Cytochrome P-450 Enzyme System; D019392:Cytochrome P-450 CYP2E1; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C104464:CYP3A protein, human; D019388:Cytochrome P-450 CYP1A2; D051544:Cytochrome P-450 CYP3A