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Intra-graft expression of genes involved in iron homeostasis predicts the development of operational tolerance in human liver transplantation.

ABSTRACT: Following organ transplantation, lifelong immunosuppressive therapy is required to prevent the host immune system from destroying the allograft. This can cause severe side effects and increased recipient morbidity and mortality. Complete cessation of immunosuppressive drugs has been successfully accomplished in selected transplant recipients, providing proof of principle that operational allograft tolerance is attainable in clinical transplantation. The intra-graft molecular pathways associated with successful drug withdrawal, however, are not well defined. In this study, we analyzed sequential blood and liver tissue samples collected from liver transplant recipients enrolled in a prospective multicenter immunosuppressive drug withdrawal clinical trial. Before initiation of drug withdrawal, operationally tolerant and non-tolerant recipients differed in the intra-graft expression of genes involved in the regulation of iron homeostasis. Furthermore, as compared with non-tolerant recipients, operationally tolerant patients exhibited higher serum levels of hepcidin and ferritin and increased hepatocyte iron deposition. Finally, liver tissue gene expression measurements accurately predicted the outcome of immunosuppressive withdrawal in an independent set of patients. These results point to a critical role for iron metabolism in the regulation of intra-graft alloimmune responses in humans and provide a set of biomarkers to conduct drug-weaning trials in liver transplantation.

SUBMITTER: Bohne F

PROVIDER: S-EPMC3248302 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Intra-graft expression of genes involved in iron homeostasis predicts the development of operational tolerance in human liver transplantation.

Bohne Felix F Martínez-Llordella Marc M Lozano Juan-José JJ Miquel Rosa R Benítez Carlos C Londoño María-Carlota MC Manzia Tommaso-María TM Angelico Roberta R Swinkels Dorine W DW Tjalsma Harold H López Marta M Abraldes Juan G JG Bonaccorsi-Riani Eliano E Jaeckel Elmar E Taubert Richard R Pirenne Jacques J Rimola Antoni A Tisone Giuseppe G Sánchez-Fueyo Alberto A

The Journal of clinical investigation 20111212 1

Following organ transplantation, lifelong immunosuppressive therapy is required to prevent the host immune system from destroying the allograft. This can cause severe side effects and increased recipient morbidity and mortality. Complete cessation of immunosuppressive drugs has been successfully accomplished in selected transplant recipients, providing proof of principle that operational allograft tolerance is attainable in clinical transplantation. The intra-graft molecular pathways associated ...[more]

PMID: 22156196

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Project description:Immune responses induced by ongoing and/or past infections prevent the establishment of transplantation tolerance in experimental animal models. How host-pathogen interactions influence allograft tolerance in humans has not been investigated before. The spontaneous development of operational tolerance in liver transplant recipients with chronic hepatitis C virus (HCV) infection constitutes a unique setting to address this question. We conducted a clinical trial of immunosuppression withdrawal in stable HCV-infected liver recipients to elucidate: i) the mechanisms through which allograft tolerance is established in the presence of an ongoing inflammatory response; and ii) how is influenced by anti-HCV heterologous immune responses. Enrolled patients gradually discontinued their immunosuppressive drugs over 6-9 months, and those who maintained normal allograft status 12 months after drug withdrawal were considered operationally tolerant. Successful drug withdrawal was associated with intra-hepatic over-expression of type I interferon and immune-regulatory genes, and correlated with an expansion of exhausted PD1/CTLA4/2B4-positive HCV-specific circulating CD8+ T cells. These findings were already present before immunosuppression was discontinued and were specific for HCV infection. In contrast, the magnitude of HCV-induced inflammatory gene expression and the scope of anti-HCV effector T cell responses did not influence drug withdrawal outcome. Our data indicate that in humans persistent viral infections do not necessarily preclude the development of transplantation tolerance. At least in HCV-infected liver allografts, mechanisms associated with the capacity of the virus to evade adaptive immunity could contribute to the restraining of alloimmune responses and the establishment of transplantation tolerance. Transcriptomic study from the following liver tissue samples: 12 tolerant before immunosuppression (IS), 13 non-tolerant before IS, 4 from non-tolerant at the time of rejection, 13 from tolerant patients 12 months after IS discontinuation. Additionally, 8 liver tissue samples obtained from healthy living liver donors undergoing partial hepatectomy were included as non-transplanted controls.

Project description:The ability to identify a robust means for both pediatric and adult liver transplant recipients for minimization and weaning of immunosuppression is greatly needed. We analyzed 298 samples from pediatric (n=83) and published adult (n=57) liver transplant recipients, and the public available cell or tissue specific samples (n=158). Biomarkers were first identified from the integration of the cross-platform analysis of Stanford pediatric and adult studies and validated in independent samples from UCLA on microarray. Furthermore, Q-PCR was performed for targets validation and delivers a robust diagnostic assay of predicting potential liver tolerance after liver transplantation. Thirteen unique genes were identified (FDR<5%) using nearest shrunken centroid classification methods as a minimum gene set to cross-validate and predict Stanford pediatric tolerance samples with 1misclassification, 5 misclassification for adult samples, and 100% sensitivity and 83% specificity for an independent UCLA pediatric samples in microarray platform. These subset of tolerant specific genes are highly expressed CD56+ natural killer cells (p=0.03). Furthermore, the subset can be narrowed down to 3 key genes with combined ROC=0.988 for the liver tolerance prediction from Q-PCR verification and 64% MIS and STA were predicted as tolerance with the >90% prediction probability. Specific peripheral transcriptional programs can be identified in operational tolerance in pediatric recipients of liver allografts, distinct from those previously identified in adult operationally tolerant liver recipients, and may provide a means to non-invasively monitor patients in a serial manner for immunosuppression minimization. These genes are highly expressed in specific peripheral blood lymphocyte subsets, and their coordinated may support the maintenance of operational tolerance in children, following liver transplantation. Two centers data was included, which are 41 samples from Stanford as the training set and 44 samples from UCLA as the test set. 26 samples from Stanford and 15 samples from UCLA were used in microarray Agilent whole human genome microarray

Dataset Information

Intra-graft expression of genes involved in iron homeostasis predicts the development of operational tolerance in human liver transplantation.

Publications

Intra-graft expression of genes involved in iron homeostasis predicts the development of operational tolerance in human liver transplantation.

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