Unknown,Transcriptomics,Genomics,Proteomics

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Borderline Changes in Renal Allografts: Molecular Diagnostics Identifies Risks for Graft Dysfunction

ABSTRACT: The significance of borderline changes (BL) in kidney allograft biopsies is widely debated. We examined differences in gene expression patterns between early clinical biopsy tissue and 3-month protocol biopsy tissue, all of which had histological BL changes and identified specific molecular BL patterns associated with poor graft outcome. The expression profiles were analyzed in training set of patients and next data were validated in validation cohort using RT-qPCR. Using the Illumina microarray technology, we observed greater expression of immunity- and inflammation-related genes in tissues from early clinical biopsies compared to 3-month protocol biopsies with BL findings. In tissues with early clinically manifested BL changes, graft deterioration within 24 months due to chronic rejection was associated with increased activation of immune, defense, and inflammatory processes, specifically with higher donor age and expression of macrophage receptor CLEC5A. In the 3-month protocol biopsies with BL changes, graft dysfunction was associated with increased expression of fibrinogen complex transcripts. This study highlights the molecular differences between clinical and subclinical biopsies with similar histological findings. The data also support a recommendation for frequent patient monitoring, especially in those who received grafts from expanded criteria donors (ECDs). The experiments were performed with total RNA derived from the renal graft biopsy samples of 28 different patients who had undergone a kidney transplantation. Only the patients with diagnosis of borderline changes early (M-bM-^IM-$2 months) or protocolar (3 months) were included in the study. RNA profiles of patients with stable and deteriorated graft function during 2 years after transplantation were compared. As microarray platform, Illumina HumanHT-12 v4.0 Expression BeadChips (Illumina) was used. The chip scanning was performed with a BeadStation 500 instrument (Illumina Inc), and the raw data were extracted with the BeadStudio Data Analysis Software (Illumina). The R software lumi package was used to further process the raw data. The quantile method was used for normalization.

ORGANISM(S): Homo sapiens

SUBMITTER: Petra Hruba

PROVIDER: E-GEOD-52694 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:We previously observed reduced graft survival for kidney transplants having interstitial fibrosis with subclinical inflammation, but not fibrosis alone, on 1-year protocol biopsy. The current study aimed to determine whether fibrosis with inflammation at 1 year is associated with renal functional decline in a low-risk transplant cohort and to characterize the nature of the inflammation. Subjects were living-donor, tacrolimus/mycophenolate-treated transplant recipients without overt risk factors for reduced graft survival (n=151). Transplants with normal histology (n=86) or fibrosis alone (n=45) on 1-year protocol biopsy had stable renal function between 1 and 5 years, while those having fibrosis with inflammation (n=20) had declining glomerular filtration rate and reduced graft survival. Immunohistochemistry confirmed increased interstitial T-cells and macrophages/dendritic cells in the fibrosis with inflammation group. Gene expression was performed on a subset of biopsies in each group and demonstrated increased expression of transcripts related to innate and cognate immunity in transplants having fibrosis with inflammation. Pathway- and pathological process-specific analyses of microarray profiles revealed that, in fibrosis with inflammation, over-expressed transcripts were enriched for potentially damaging immunological activities including Toll-like receptor signaling, antigen presentation/dendritic cell maturation, interferon gamma-inducible response, cytotoxic T lymphocyte-associated and acute rejection-associated genes. Thus, fibrosis with inflammation in 1-year protocol biopsies is associated with reduced graft survival and function and with a rejection-like gene expression signature even in recipients with no clinical risk for inferior outcome. Early interventions aimed at altering rejection-like inflammation may favor improved long-term KTx survival. We analyzed gene expression from a group of 65 renal transplant recipients. Patient groups were carefully selected to include patients on the same immunosuppression (Prograf-MMF-Pred), transplant type (LD), absence of over post-transplant complications (AR, BK, DGF). For each patient a 1 year protocol biopsy was examined by conventional histology and gene expression. By histology the patients were categorized as histologically normal (n=25, i/cg/ci=0), IF/TA (n=24, i/cg=0, ci>0) and IFTA+i (n=16, cg=0, i/ci>0). This dataset is part of the TransQST collection.

Project description:Chronic injury in kidney transplants remains a major cause of graft loss. The aim of this study was to identify a predictive gene set capable of classifying renal grafts at risk for progressive injury due to fibrosis.The Genomics of Chronic Allograft Rejection (GoCAR) study is a prospective, multicenter study. Biopsies obtained prospectively 3 months after transplantation from renal allograft recipients (n=159) with stable renal function were analyzed for gene expression by microarray. Genes were sought which correlated with subsequent 12-month Chronic Allograft Damage Index (CADI) but neither CADI in the 3 month biopsy nor other histological or clinical parameters. We identified a set of 13 genes that was independently predictive for the development of fi brosis at 1 year (ie, CADI-12 >=2). The gene set had high predictive capacity (area under the curve [AUC] 0·967), which was superior to that of baseline clinical variables (AUC 0·706) and clinical and pathological variables (AUC 0·806). Furthermore routine pathological variables were unable to identify which histologically normal allografts would progress to fi brosis (AUC 0·754), whereas the predictive gene set accurately discriminated between transplants at high and low risk of progression (AUC 0·916). The 13 genes also accurately predicted early allograft loss (AUC 0·842 at 2 years and 0·844 at 3 years). We validated the predictive value of this gene set in an independent cohort from the GoCAR study (n=45, AUC 0·866) and two independent, publically available expression datasets (n=282, AUC 0·831 and n=24, AUC 0·972). Biopsies obtained prospectively 3 months after transplantation from renal allograft recipients (n=159) with stable renal function were analyzed for gene expression by Affymetrix exon arrays. Genes that were specifically correlated with 12-month Chronic Allograft Damage Index (CADI) but neither CADI in the 3 month biopsy nor other histological or clinical parameters were identified by correlation analysis. The minimal geneset was further identified to predict the progressors/non progressors and validated by qPCR in an independent cohort and two public datasets. This dataset is part of the TransQST collection.

Project description:We study the global gene expression profiles of TGP patients with or without graft loss to determine if a clinical and/or gene expression profile can predict allograft survival. Transplant glomerulopathy (TGP) carries a poor prognosis and is associated with decreased allograft survival. In a large series of kidney transplant recipients, graft loss was observed in 38% of TGP patients at 5 years compared to 5% in patients without TGP. Among patients with TGP, predictors of poor outcome included C4d deposition in the peritubular capillaries, higher serum creatinine and proteinuria at diagnosis, the severity of interstitial fibrosis, and GBM duplication (higher Banff M-bM-^@M-^Xchronic glomerulopathy [cg]M-bM-^@M-^Y score), and the presence of DSA. However, the importance of microvascular inflammation determined by peritubular capillaritis (ptc) and glomerulitis (g) scores and the strength of DSA has not been explored thoroughly. We have recently reported the intragraft gene expression profiles of TGP patients, with or without DSA. However, the association between gene expression profiles of biopsies and the allograft survival has not been investigated. In this study, in addition to known clinical and demographic factors associated with poor outcomes in TGP, we specifically aimed to investigate if intragraft gene expression profiles by microarrays, microvascular inflammation scores, and the strength of DSA determined by mean fluorescence intensity (MFI) values could predict allograft loss in TGP patients. The study population was derived from renal allograft biopsies diagnosed with TGP at Montefiore Medical Center, Bronx, NY from January 2009 to December 2012. All biopsies were clinically indicated for elevated creatinine or proteinuria. A retrospective chart review was conducted to record clinical, demographic, immunological, and histopathological parameters and graft outcomes. Graft loss was defined as requiring dialysis and/or retransplantation during follow-up. Of the 525 patients who underwent clinically indicated transplant kidney biopsies, 52 patients (10%) had diagnosis of TGP. Median follow up time after the biopsy was 23 months (range, 1-46). Seventeen patients (32%) lost their allografts (defined by return to dialysis or re-transplantation) at a median time of 16 months (range, 1-44). A subgroup of patients who were enrolled in the IRB-approved M-bM-^@M-^\Immune Monitoring StudyM-bM-^@M-^] and had clinically indicated biopsy samples were included in the analysis. A total of 28 biopsy samples (8 graft loss and 20 functioning allograft) were used for gene expression profiling.

Project description:Steroid-refractory acute rejection is a risk factor for inferior renal allograft outcome. We aimed to gain insight into the mechanisms underlying steroid resistance by identifying novel molecular markers of steroid-refractory acute rejection. Eighty-three kidney transplant recipients (1995-2005), who were treated with methylprednisolone during a first acute rejection episode, were included in this study. Gene expression patterns were investigated in a discovery cohort of 36 acute rejection biopsies, and verified in a validation cohort of 47 acute rejection biopsies. In the discovery set, expression of metallothioneins (MT) was significantly (P<0.000001) associated with decreased response to steroid treatment. Multivariate analysis resulted in a predictive model containing MT-1 as an independent covariate (AUC=0.88, P<0.0000001). In the validation set, MT-1 expression was also significantly associated with steroid resistance (P=0.029). Metallothionein expression was detected in macrophages and tubular epithelial cells. Parallel to the findings in patients, in vitro experiments of peripheral blood mononuclear cells from 11 donors showed that non-response to methylprednisolone treatment is related to highly elevated MT levels. High expression of metallothioneins in renal allografts is associated with resistance to steroid treatment. Metallothioneins regulate intracellular concentrations of zinc, through which they may diminish the zinc-requiring anti-inflammatory effect of the glucocorticoid receptor. Transcriptional profiles of 40 renal allograft biopsy samples were analyzed using Illumina HumanRef-8 v3.0 BeadChips (Illumina, San Diego, CA). Expression profiles were investigated in total RNA isolated from biopsy samples of 18 patients with steroid responsive acute rejection and 18 patients with steroid resistant acute rejection. Four biopsies, taken during acute decrease of graft function but with no histomorphologic indication of rejection, were included as controls.

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Borderline Changes in Renal Allografts: Molecular Diagnostics Identifies Risks for Graft Dysfunction

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