Thymic antigen-presenting cells (APCs), including thymic dendritic cells (t-DCs) and medullary thymic epithelial cells (mTECs) have been described to play a critical role in thymic Treg generation. Our findings could show that both these thymic APCs can induce a more pronounced demethylation of Foxp3 and other Treg-specific epigenetic signature genes in developing Tregs when compared to splenic DCs. In order to elucidate the unique properties of thymic APCs, gene expression profiling was performed in comparison to splenic DCs. Transcriptome analysis of thymic APCs revealed differential expression of costimulatory molecules that could be involved in stable Treg generation. Importantly, both mTEC- and t-DC- induced alloantigen-specific Tregs displayed significantly higher efficacy in prolonging skin allograft acceptance when compared to alloantigen-specific Tregs generated by splenic DCs. Overall design: Thymic APCs, including mTECs and t-DCs and splenic DCs were isolated ex vivo from thymus as CD45-EpCAM+Ly51- (mTECs) and CD45+EpCAM-CD11chiLin- (t-DCs) and from spleen as CD11chiLin- (splenic DCs) (Lin is defined as CD90, CD49b, F4/80 and CD19), respectively.
Unique properties of thymic antigen-presenting cells promote epigenetic imprinting of alloantigen-specific regulatory T cells.
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Intra-graft expression of genes involved in iron homeostasis predicts the development of operational tolerance in human liver transplantation.
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View SamplesComplications due to long-term administration of immunosuppressive therapy increase the morbidity and mortality of liver transplant recipients. Discontinuation of immunosuppressive drugs in recipients spontaneously developing operational tolerance could substantially lessen this burden. However, this strategy results in the development of rejection in a high proportion of recipients who require lifelong immunosuppression. Thus, there is a need to identify predictive factors of successful drug withdrawal and to define the clinical and histological outcomes of operationally tolerant liver recipients. Methods. We enrolled 102 stable liver transplant recipients in an immunosuppression withdrawal trial in which drugs were gradually discontinued over a 6-9 month period. Patients with stable graft function and no signs of rejection in a liver biopsy conducted 12 months after cessation of immunosuppressive therapy were considered operationally tolerant. Results. Out of the 98 recipients who completed the study, immunosuppression discontinuation was successful in 41 recipients and rejection occurred in 57. Rejection episodes were mild and were resolved in all cases. Development of tolerance was independently associated with time elapsed since transplantation, recipient age, and male gender. No histological damage was apparent in protocol biopsies performed after successful drug withdrawal.
Intra-graft expression of genes involved in iron homeostasis predicts the development of operational tolerance in human liver transplantation.
Age, Specimen part
View SamplesIn clinical organ transplantation complete cessation of immunosuppressive therapy can be successfully accomplished in selected recipients providing a proof-of-principle that allograft tolerance is attainable in humans. The intra-graft molecular pathways associated with human allograft tolerance, however, have not been comprehensively studied before. In this study we analyzed sequential liver tissue samples collected from liver recipients enrolled in a prospective multicenter immunosuppressive withdrawal clinical trial. Tolerant and non-tolerant recipients differed in the intra-graft expression of genes involved in the regulation of iron homeostasis.These results point to a critical role of iron homeostasis in the regulation of intra-graft alloimmune responses in humans and provide a set of novel biomarkers to conduct drug-weaning trials in liver transplantation.
Intra-graft expression of genes involved in iron homeostasis predicts the development of operational tolerance in human liver transplantation.
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View SamplesIntrauterine growth restriction is a common complication of pregnancy. We induce IUGR in rats by bilateral uterine artery ligation at e18 of a 23 day gestation.
Neutralizing Th2 inflammation in neonatal islets prevents β-cell failure in adult IUGR rats.
Specimen part, Treatment
View SamplesA mouse embryonic stem cell line was generated which stably expressed the ngn3 transcription factor under the control of the Tet-On inducible system using knock-ins in the ROSA26 and the HPRT loci. The undifferentiated mouse embryonic stem cells were then differentiated into Embryoid Bodies in suspension culture and were either treated with Doxycycline to induce NGN3 expression or left untreated as a contol. Cells were harvested at 12 hours, 24 hours and 48 hours.
A shift from reversible to irreversible X inactivation is triggered during ES cell differentiation.
Sex, Specimen part, Cell line, Treatment, Time
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Chromatin structure and gene expression programs of human embryonic and induced pluripotent stem cells.
Cell line
View SamplesKnowledge of both the global chromatin structure and the gene expression programs of human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells should provide a robust means to assess whether the genomes of these cells have similar pluripotent states. Recent studies have suggested that ES and iPS cells represent different pluripotent states with substantially different gene expression profiles. We describe here a comparison of global chromatin structure and gene expression data for a panel of human ES and iPS cells. Genome-wide maps of nucleosomes with histone H3K4me3 and H3K27me3 modifications indicate that there is little difference between ES and iPS cells with respect to these marks. Gene expression profiles confirm that the transcriptional programs of ES and iPS cells show very few consistent differences. Although some variation in chromatin structure and gene expression was observed in these cell lines, these variations did not serve to distinguish ES from iPS cells.
Chromatin structure and gene expression programs of human embryonic and induced pluripotent stem cells.
Cell line
View SamplesGene expression heterogeneity in the pluripotent state of mouse embryonic stem cells (mESCs) has been increasingly well-characterized. In contrast, exit from pluripotency and lineage commitment have not been studied systematically at the single-cell level. Here we measured the gene expression dynamics of retinoic acid driven mESC differentiation using an unbiased single-cell transcriptomics approach. We found that the exit from pluripotency marks the start of a lineage bifurcation as well as a transient phase of susceptibility to lineage specifying signals. Our study revealed several transcriptional signatures of this phase, including a sharp increase of gene expression variability and a handover between two classes of transcription factors. In summary, we provide a comprehensive analysis of lineage commitment at the single cell level, a potential stepping stone to improved lineage control through timing of differentiation cues. Overall design: Bulk and single-cell RNA-seq (SCRB-seq and SMART-seq) of mouse embryonic stem cells after different periods of continuous exposure to retinoic acid. Bulk RNA-seq of cell lines derived after retinoic exposure and after differentiation with retinoic acid and MEK inhibitor combined.
Dynamics of lineage commitment revealed by single-cell transcriptomics of differentiating embryonic stem cells.
Cell line, Subject
View SamplesResponse to photoperiod in Arabidopsis wildtype, co, and ft mutant plants.
Integration of spatial and temporal information during floral induction in Arabidopsis.
Specimen part
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