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Molecular profiling of anemia in acute renal allograft rejection

ABSTRACT: Compromised renal function after renal allograft transplantation often results in anemia in the recipient. Molecular mechanisms leading to anemia during acute rejection are not fully understood; inadequate erythropoietin production and iron deficiency have been reported to be the main contributors. To increase our understanding of the molecular events underlying anemia in acute rejection, we analyzed the gene expression profiles of peripheral blood lymphocytes (PBL) from four pediatric renal allograft recipients with acute rejection and concurrent anemia, using DNA microarrays containing 9000 human cDNA clones (representing 7469 unique genes). In these anemic rejecting patients, an 'erythropoiesis cluster' of 11 down-regulated genes was identified, involved in hemoglobin transcription and synthesis, iron and folate binding and transport. Additionally, some alloimmune response genes were simultaneously down-regulated. An independent data set of 36 PBL samples, some with acute rejection and some with concurrence of acute rejection and anemia, were analyzed to support a possible association between acute rejection and anemia. In conclusion, analysis using DNA microarrays has identified a cluster of genes related to hemoglobin synthesis and/or erythropoeisis that was altered in kidneys with renal allograft rejection compared with normal kidneys. The possible relationship between alterations in the expression of this cluster, reduced renal function, the alloimmune process itself, and other influences on the renal transplant awaits further analysis. A disease state experiment design type is where the state of some disease such as infection, pathology, syndrome, etc is studied. Keywords: disease_state_design

ORGANISM(S): Homo sapiens

PROVIDER: GSE3976 | GEO | 2006/01/06

SECONDARY ACCESSION(S): PRJNA94239

REPOSITORIES: GEO

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Project description:Objective: Apolipoprotein E (Apo E) is a multifunctional protein, originally described in the context of lipoprotein metabolism and cardiovascular disease. More recently, anti-inflammatory functions of ApoE have been documented. ApoE was studied in the context of several inflammatory disorders, but its role in the pathogenesis of acute organ rejection is unknown. In this study, we test the hypothesis that ApoE attenuates acute renal allograft rejection. Materials and methods: The Dark Agouti (DA) to Lewis (Lew) and the Brown Norway (BN) to Lew rat strain combinations were used to investigate fatal acute rejection. In addition, Fischer 344 (F344) kidneys were transplanted to Lew rats to study reversible acute rejection. Isograft recipients and untreated Lew rats were used as controls. ApoE mRNA expression was quantified in intravascular leukocytes accumulating in the blood vessels of renal grafts and in graft tissue. Apo E protein levels were assessed in blood plasma. To test the protective potential of ApoE, recipients of BN kidneys were treated with ApoE-mimetic peptide. Results: Intravascular graft leukocytes and renal tissue obtained from animals undergoing reversible acute rejection expressed increased levels of ApoE mRNA, whereas during fatal rejection, ApoE expression remained unchanged in the BN to Lew rat strain combination or was significantly reduced when DA rats were used as donors of the kidney. On the protein level, no changes in ApoE were seen in plasma. However, we do not know if local leukocytic ApoE expression results in increased ApoE concentrations inside graft blood vessels. Peptide treatment of allograft recipients reversed fatal rejection and significantly improved animal survival. Conclusions: ApoE plays a protective role in acute organ rejection. Further studies are needed to understand the exact mechanism how ApoE reverses acute rejection. dual-color balanced dye-swap design with 4 biological replicates, hybridized on 4 arrays

Project description:The data set contains 67 array (lymphochip cDNA array), published in N Engl J Med 2003 Jul 10;349(2):125-38. PMID: 12853585. TITLE: Molecular heterogeneity in acute renal allograft rejection identified by DNA microarray profiling. BACKGROUND: The causes and clinical course of acute rejection vary, and it is not possible to predict graft outcome reliably on the basis of available clinical, pathological, and genetic markers. We hypothesized that previously unrecognized molecular heterogeneity might underlie some of the variability in the clinical course of acute renal allograft rejection and in its response to treatment. METHODS: We used DNA microarrays in a systematic study of gene-expression patterns in biopsy samples from normal and dysfunctional renal allografts. A combination of exploratory and supervised bioinformatic methods was used to analyze these profiles. : We found consistent differences among the gene-expression patterns associated with acute rejection, nephrotoxic effects of drugs, chronic allograft nephropathy, and normal kidneys. The gene-expression patterns associated with acute rejection suggested at least three possible distinct subtypes of acute rejection that, although indistinguishable by light microscopy, were marked by differences in immune activation and cellular proliferation. Since the gene-expression patterns pointed to substantial variation in the composition of immune infiltrates, we used immunohistochemical staining to define these subtypes further. This analysis revealed a striking association between dense CD20+ B-cell infiltrates and both clinical glucocorticoid resistance (P=0.01) and graft loss (P<0.001). CONCLUSIONS: Systematic analysis of gene-expression patterns provides a window on the biology and pathogenesis of renal allograft rejection. Biopsy samples from patients with acute rejection that are indistinguishable on conventional histologic analysis reveal extensive differences in gene expression, which are associated with differences in immunologic and cellular features and clinical course. The presence of dense clusters of B cells in a biopsy sample was strongly associated with severe graft rejection, suggesting a pivotal role of infiltrating B cells in acute rejection. A disease state experiment design type is where the state of some disease such as infection, pathology, syndrome, etc is studied. Disease State: normal vs disease Keywords: disease_state_design Using regression correlation

Project description:CONTEXT Slowly progressive chronic tubulo-interstitial damage jeopardizes long-term renal allograft survival. Both immune and non-immune mechanisms are thought to contribute, but the most promising targets for timely intervention have not been identified. OBJECTIVE In the current study we seek to determine the driving force behind progressive histological damage of renal allografts, without the interference of donor pathology, delayed graft function and acute graft rejection. DESIGN We used microarrays to examine whole genome expression profiles in renal allograft protocol biopsies, and analyzed the correlation between gene expression and the histological appearance over time. The gene expression profiles in these protocol biopsies were then compared with gene expression of biopsies with acute T-cell mediated rejection. PATIENTS Human renal allograft biopsies (N=120) were included: 96 rejection-free protocol biopsies and 24 biopsies with T-cell mediated acute rejection. RESULTS In this highly cross-validated study, we demonstrate the significant association of established, ongoing and future chronic histological damage with regulation of adaptive immune gene expression (T-cell and B-cell transcript sets) and innate immune response gene expression (dendritic cell, NK-cell, mast cell and granulocyte transcripts). We demonstrate the ability of gene expression analysis to perform as a quantitative marker for ongoing inflammation with a wide dynamic range: from subtle subhistological inflammation prior to development of chronic damage, over moderate subclinical inflammation associated with chronic histological damage, to marked inflammation of Banff-grade acute T-cell mediated rejection. CONCLUSION Progressive chronic histological damage after kidney transplantation is associated with significant regulation of both innate and adaptive immune responses, months before the histological lesions appear. This study therefore corroborates the hypothesis that quantitative inflammation below the diagnostic threshold of classic T-cell or antibody-mediated rejection is associated with early subclinical stages of progressive renal allograft damage. We used microarrays to examine whole genome expression profiles in renal allograft protocol biopsies, and analyzed the correlation between gene expression and the histological appearance over time. The gene expression profiles in these protocol biopsies were then compared with gene expression of biopsies with acute T-cell mediated rejection. Human renal allograft biopsies (N=120) were included: 96 rejection-free protocol biopsies and 24 biopsies with T-cell mediated acute rejection.

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Molecular profiling of anemia in acute renal allograft rejection

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