In deceased donor kidney transplantation, acute kidney injury (AKI) prioir to surgery is a major determinant of delayed graft function (DGF), but AKI is histologically silent and difficult to assess. We hypothesized that a molecular measurement of AKI would add power to conventional risk assessments to predict the early poor allograft function at first week post transplantation.
Comparing molecular assessment of implantation biopsies with histologic and demographic risk assessment.
Specimen part
View SamplesTissue inhibitors of metalloproteinases (TIMP) are endogenous inhibitors of matrix metalloproteinases (MMP). While TIMP2 and TIMP3 inhibit MMPs, TIMP3 also inhibits activation of pro-MMP2 whereas TIMP2 promotes it. Here we assessed the differential role of TIMP2 and TIMP3 in renal injury using the unilateral ureteral obstruction model. Gene microarray assay showed that post-obstruction, the lack of TIMP3 had a greater impact on gene expression of intermediate, late injury- and repair-induced transcripts, kidney selective transcripts and solute carriers. Renal injury in TIMP3-/-, but not in TIMP2-/- mice increased expression of collagen type I/III, connective tissue growth factor, transforming growth factor- and the downstream Smad2/3 pathway. Interestingly, ureteral obstruction markedly increased MMP2 activation in the kidneys of TIMP3-/- mice which was completely blocked in the kidneys of TIMP2-/- mice. These changes are consistent with enhanced renal tubulointerstitial fibrosis in TIMP3-/- and its reduction in TIMP2-/- mice. The activity of tumor necrosis factor- converting enzyme, caspase-3 and mitogen activated kinases were elevated in the kidneys of TIMP3-/- but not TIMP2-/- mice, suggesting enhanced activation of apoptotic and pathological signaling pathways only in the obstructed kidney of TIMP3-/- mice. Thus, TIMP2 and TIMP3 play differential and contrasting roles in renal injury, TIMP3 protects from damage whereas TIMP2 promotes injury through MMP2 activation.
TIMP2 and TIMP3 have divergent roles in early renal tubulointerstitial injury.
Specimen part, Treatment
View SamplesHistologic diagnosis of T cell-mediated rejection in kidney transplant biopsies has limited reproducibility because it is based on non-specific lesions using arbitrary rules that are subject to differing interpretations. We used microarray results from 403 indication biopsies previously given histologic diagnoses to develop a molecular classifier that assigned a molecular T cell-mediated rejection score to each biopsy. Independent assessment of the biopsies by multiple pathologists confirmed considerable disagreement on the presence of TCMR features: 79-88% accuracy and 35-69% sensitivity. The agreement of the molecular T cell-mediated rejection score with the histology diagnosis was similar to agreement among individual pathologists: accuracy 89%, sensitivity 51%. However, the score also predicted the consensus among pathologists, being highest when all agreed. Many discrepancies between the scores and the histologic diagnoses were in situations where histology is unreliable e.g. scarred biopsies. The score correlated with histologic lesions and gene sets associated with T cell-mediated rejection. The transcripts most often selected by the classifier were expressed in effector T cells, dendritic cells, or macrophages or inducible by interferon-gamma. Thus the T cell-mediated rejection score offers an objective assessment of kidney transplant biopsies, predicting the consensus opinion among multiple pathologists, and offering insights into underlying disease mechanisms.
Molecular diagnosis of T cell-mediated rejection in human kidney transplant biopsies.
Disease
View SamplesKidney transplants that develop dysfunction or proteinuria after one year post transplant are at considerable risk for progression to renal failure. Identifying the molecules associated with graft failure could potentially lead to interventions that would slow the progression of organ failure.
A molecular classifier for predicting future graft loss in late kidney transplant biopsies.
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View SamplesMicroarray analysis of human kidneys with acute kidney injury (AKI) has been limited because such kidneys are seldom biopsied. However, all kidney transplants experience AKI, and early kidney transplants without rejection are an excellent model for human AKI: they are screened to exclude chronic kidney disease, frequently biopsied, and have extensive follow-up. We used histopathology and microarrays to compare indication biopsies from 28 transplants with AKI to 11 pristine protocol biopsies of stable transplants. Kidneys with AKI showed increased expression of 394 injury-repair response associated transcripts, including many known epithelial injury molecules (e.g. ITGB6, LCN2), tissue remodeling molecules (e.g. VCAN), and inflammation molecules (S100A8, ITGB3). Many other genes also predict the phenotype, depending on statistical filtering rules, including AKI biomarkers as HAVCR1 and IL18. Most mouse orthologs of the top injury-repair transcripts were increased in published mouse AKI models. Pathway analysis of the injury-repair transcripts revealed similarities to cancer, development, and cell movement. The injury-repair transcript score AKI kidneys correlated with reduced function, future recovery, brain death, and need for dialysis, but not future graft loss. In contrast, histologic features of "acute tubular injury" did not correlate with function or with the molecular changes. Thus the injury-repair associated transcripts represent a massive coordinate injury-repair response of kidney parenchyma to AKI, similar to mouse AKI models, and provide an objective measure for assessing the severity of AKI in kidney biopsies and validation for the use of many AKI biomarkers.
Molecular phenotypes of acute kidney injury in kidney transplants.
Specimen part, Disease
View SamplesNon-tumor-reactive T cells are characterized by the inabilitzy to lyse autologous tumor cells, low to intermediate avidity TCRs and lack of NY-ESO-1 peptide tetramer binding. However most strikingly, non-tumor-reactive T cells are characterized by a molecular program associated with division arrest anergy with elevated expression of the inhibitory molecule p27kip1. This is accompanied by elevated expression of inhibitory molecules and reduced levels of transcription factors involved in T cell activation. Frequency analysis of the inhibited T cell population using the established molecular fingerprint as a novel biomarker might be applied for cancer vaccine development and optimization.
Cancer vaccine enhanced, non-tumor-reactive CD8(+) T cells exhibit a distinct molecular program associated with "division arrest anergy".
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View SamplesAnalysis of musashi2 contribution towards maintaing myelodysplastic phenotype in stem cells. We find that musashi2 plays an integral role in maintaining the myelodysplastic phenotype Overall design: Control, NUP98-HOXD13; NHD13, NHD13/MSI2 bone marrow was transplated allowed to engraft into lethally irradiated congenic CD45.1 animals. Mice were then fed doxycycline to induce MSI2 overexpression. Mice were induced for 3 months and then CD45.2 Lineage lo Sca1+ and Kit+ cells were sorted and then assessed for gene expression.
MSI2 is required for maintaining activated myelodysplastic syndrome stem cells.
Age, Specimen part, Cell line, Subject
View SamplesRegulatory T (Treg) cells are involved in self tolerance, immune homeostasis, prevention of autoimmunity, and suppression of immunity to pathogens or tumours. The forkhead transcription factor FOXP3 is essential for Treg cell development and function as mutations in FOXP3 cause severe autoimmunity in mice and humans. However, the FOXP3-dependent molecular mechanisms leading to this severe phenotype are not well understood. Here we introduce the chromatin remodelling enzyme SATB1 (special AT-rich sequence-binding protein-1) as an important target gene of FOXP3. So far, SATB1 has been associated with normal thymic T-cell development, peripheral T-cell homeostasis, TH1/TH2 polarization, and reprogramming of gene expression. In natural and induced murine and human FOXP3+ Treg cells SATB1 expression is significantly reduced. While there is no differential epigenetic regulation of the SATB1 locus between Treg and Teffector cells, FOXP3 reduces SATB1 expression directly as a transcriptional repressor at the SATB1 locus and indirectly via miR-155 induction, which specifically binds to the 3UTR of the SATB1 mRNA. Reduced SATB1 expression in FOXP3+ cells achieved either by overexpression or induction of FOXP3 is linked to significant reduction in TH1 and TH2 cytokines, while loss of FOXP3 function either by knock down or genetic mutation leads to significant upregulation of SATB1 and subsequent cytokine production. Alltogether, these findings demonstrate that reduced SATB1 expression in Treg cells is necessary for maintenance of a Treg-cell phenotype in vitro and in vivo and places SATB1-mediated T cell-specific modulation of global chromatin remodelling central during the decision process between effector and regulatory T-cell function.
Repression of the genome organizer SATB1 in regulatory T cells is required for suppressive function and inhibition of effector differentiation.
Specimen part, Disease, Disease stage, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Functional screen of MSI2 interactors identifies an essential role for SYNCRIP in myeloid leukemia stem cells.
Specimen part, Cell line
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Novel subtype-specific genes identify distinct subpopulations of callosal projection neurons.
Specimen part
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