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Genomic biomarkers correlate with HLA-identical renal transplant tolerance.

ABSTRACT: The ability to achieve immunologic tolerance after transplantation is a therapeutic goal. Here, we report interim results from an ongoing trial of tolerance in HLA-identical sibling renal transplantation. The immunosuppressive regimen included alemtuzumab induction, donor hematopoietic stem cells, tacrolimus/mycophenolate immunosuppression converted to sirolimus, and complete drug withdrawal by 24 months post-transplantation. Recipients were considered tolerant if they had normal biopsies and renal function after an additional 12 months without immunosuppression. Of the 20 recipients enrolled, 10 had at least 36 months of follow-up after transplantation. Five of these 10 recipients had immunosuppression successfully withdrawn for 16-36 months (tolerant), 2 had disease recurrence, and 3 had subclinical rejection in protocol biopsies (nontolerant). Microchimerism disappeared after 1 year, and CD4(+)CD25(high)CD127(-)FOXP3(+) regulatory T cells and CD19(+)IgD/M(+)CD27(-) B cells were increased through 5 years post-transplantation in both tolerant and nontolerant recipients. Immune/inflammatory gene expression pathways in the peripheral blood and urine, however, were differentially downregulated between tolerant and nontolerant recipients. In summary, interim results from this trial of tolerance in HLA-identical renal transplantation suggest that predictive genomic biomarkers, but not immunoregulatory phenotyping, may be able to discriminate tolerant from nontolerant patients.

SUBMITTER: Leventhal JR

PROVIDER: S-EPMC3752953 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Immunosuppression is needed in HLA identical sibling renal transplantation. We conducted a tolerance trial in this patient cohort using Alemtuzumab induction, donor hematopoietic stem cells, tacrolimus/mycophenolate immunosuppression converted to sirolimus, planning complete drug withdrawal by 24 months post-transplantation. After an additional 12 months with no immunosuppression, normal biopsies and renal function, recipients were considered tolerant. Twenty recipients were enrolled. Of the first 10 (>36 months post-transplantation), 5 had immunosuppression successfully withdrawn for 16-36 months (tolerant), 2 had disease recurrence and 3 had subclinical rejection in protocol biopsies (non-tolerant). Microchimerism disappeared after 1 year, and CD4+CD25highCD127-FOXP3+ T cells and CD19+IgD/M+CD27- B cells increased to 5 years post-transplantation in both groups, whereas immune/inflammatory gene expression pathways in the peripheral blood and urine were differentially downregulated in tolerant compared to non-tolerant recipients. Therefore, in this HLA identical renal transplant tolerance trial, absent chimerism, Treg and Breg immunophenotypes were indistinguishable between tolerant and non-tolerant recipients, but global genomic changes indicating immunomodulation were observed only in tolerant recipients. A total of 46 PBMC samples representing blood draws from four time points in the first 9 recipients were processed for microarray analysis (The Scripps Research Institute, La Jolla, CA). The analyzed time points were: immediately pre-operatively in the absence of immunosuppression (n=9); post-operatively at 1 year (n=8, range 11-13 months); at 2 years (n=12, range 18-25 months); >3 years (n=17, range 32-48 months). (At year 2 and at > 3 years, repeated samples were obtained from individual subjects, and at one year, one subject had a technically unsatisfactory sample.) To discount the effects of immunosuppression on gene expression, microarray data were included on whole blood from 18 healthy human subjects (controls: GSE40586; NCBI Gene Expression Omnibus [GEO] repository).

Project description:Being able to identify patients in whom immunological tolerance has been established or is developing would allow an individually tailored approach to post-transplant management of kidney allograft recipients. Ex vivo immunological monitoring was performed on samples from five groups of European renal transplant recipients (“IOT samples”): ten drug-free tolerant recipients who were functionally stable despite remaining immunosuppression-free for more than one year (Tol-DF); also functionally stable patients on minimal immunosuppression (<10 mg/day prednisone, s-LP); stable patients maintained with calcineurin inhibitors (s-CNI); stable patients maintained on CNI-free immunosuppression regimen (s-nCNI); patients showing signs of chronic rejection (CR) and healthy controls (HC). Among the investigation of other biomarkers and bioassays, gene expression profiles were generated on custom Agilent 8x15K 60mer oligonucleotide microarrays (“RISET 2.0”) on the IOT cohort (training set) and on an independent cohort of patients from the ITN (USA) that contained similar groups of patients and included 23 tolerant recipients (“ITN samples”, test set). Set of genes were identified, whose expression on whole blood allowed the identification of 100% of the tolerant recipients in the training set and 84% in the test set. Keywords: classification of clinical samples, tolerance prediction IOT samples: 13 samples from 10 Tol-DF patients, 16 samples from 11 s-LP patients, 8 samples from 8 s-nCNI patients, 40 samples from 28 s-CNI patients, 10 samples from 9 CR patients, and 8 samples from 8 HC donors were analysed on a custom Agilent 8x15K 60mer oligonucleotide microarray encomprising 5069 probes in triplicates. The microarray is dedicated to transplantation research and was designed based on current literature and published and unpublished data provided by the RISET consortium. For the probe selection procedure we specially focused on the detection of multiple transcript variants of a gene, on optimized hybridization properties of the probes, and on the avoidance of crosshybridization. The sampling dates of replicate samples from the same patient range from one day to 1.5 years. ITN samples: 31 samples from 23 Tol-DF patients, 14 samples from 11 s-LP patients, 52 samples from 34 s-CNI patients, 25 samples from 18 CR patients, and 20 samples from 20 HC donors were analysed on the same microarray platform and served as test set. The samples of the two cohorts differ in the protocol of RNA preparation.

Project description:Operational tolerance after solid organ transplantation is defined as stable graft acceptance without immunosuppression while maintaining normal immunocompetence against immunological insults. However, it is not clear yet which cellular and molecular pathways are driving tolerance in these patients and how this state can be induced in order to improve graft survival. Several transcriptomic analysis have shown that transcription signatures in blood can reflect the immunological state associated with operational tolerance in kidney transplant. Nonetheless, epigenetic dynamics orchestrating these transcription signatures have not yet been studied. Here, we performed genome-wide analysis of DNA methylation of kidney transplant recipients with chronic rejection and operational tolerance. Our data showed that chronic rejection and operational tolerance recipients have differential DNA methylation in 2737 genes, indicating that each patient group has a specific epigenetic signature associated with transplant outcome. In addition, we observed that operational tolerance is associated with DNA demethylation in genes involved in immune function, including B cell activation (e.g. ST6GAL1, MS4A1 and MEF2C) and the Th17 differentiation program (e.g. LY9 and BATF), while in CR patients is mostly associated intracellular signaling and ubiquitination pathways. Finally, we used weighted gene co-expression network analysis (WGCNA) to select the more defining epigenetic changes associated with operational tolerance. By this method, we select 12 genomic regions specifically hypomethylated (HIVEP2, HOMER1, UTRN, PTPRO, SP100 and JAZF1) or hypermethylated (EMZ8, EZR-AS, WDR20, NADSYN1, TBCD and MED17) in tolerant patients. Analysis of these genes in stable transplant recipients with immunosuppression showed that these patients have a similar methylation signature to operational tolerance recipients. Overall, these results demonstrate that DNA methylation in blood can mirror the immune status associated with kidney transplant outcome and provides a starting point for understanding the epigenetic mechanisms associated with operational tolerance.

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Genomic biomarkers correlate with HLA-identical renal transplant tolerance.

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