Blood gene expression at 3 months post-transplantation predicts 1-year histologic features in renal transplantation
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ABSTRACT: Histological analysis of biopsy is the gold standard to assess renal allograft status. Furthermore, 1-year protocol biopsy is often performed to evaluated graft outcome. However, since biopsy cannot be performed in a time serial basis, we decided to investigate whether blood can be a good compartment to predict allograft outcome. Gene expression microarrays and a large phenotype have been performed in peripheral blood mononuclear cells from 79 renal transplanted patients taken 3 months after transplantation. We evaluated the association of biological parameters with 4 histological groups defined on renal biopsy taken at 1-year post-transplantation: patients which display normal biopsy (n=45), patients with signs of tubular atrophy and interstitial fibrosis (IFTA) (n=14), with IFTA with inflammation (i-IFTA) (n=14) and patients with alloimmune lesions (n=6) Transcriptomic profile using PBMC from patients showing normal biopsy (n=45), patients with signs of tubular atrophy and interstitial fibrosis (IFTA) (n=14), with IFTA with inflammation (i-IFTA) (n=14) and patients with alloimmune lesions (n=6).
Project description:Histological analysis of biopsy is the gold standard to assess renal allograft status. Furthermore, 1-year protocol biopsy is often performed to evaluated graft outcome. However, since biopsy cannot be performed in a time serial basis, we decided to investigate whether blood can be a good compartment to predict allograft outcome. Gene expression microarrays and a large phenotype have been performed in peripheral blood mononuclear cells from 79 renal transplanted patients taken 3 months after transplantation. We evaluated the association of biological parameters with 4 histological groups defined on renal biopsy taken at 1-year post-transplantation: patients which display normal biopsy (n=45), patients with signs of tubular atrophy and interstitial fibrosis (IFTA) (n=14), with IFTA with inflammation (i-IFTA) (n=14) and patients with alloimmune lesions (n=6)
Project description:The aim of this study was to investigate the role of infiltrating macrophages in renal allograft fibrosis. Forty-six protocol renal allograft biopsies obtained one-year after transplantation were stained with Sirius Red to quantify fibrosis and double stained with CD68 and CD206 to identify the proportion of alternately activated (M2) macrophages. 23 protocol biopsies obtained 12 months post transplant were analyzed for gene expression by microarray, which was correlated with macrophage infiltration and the severity of fibrosis. Phenotypic analysis showed 92% of infiltrating macrophages exhibited an M2 phenotype with CD68+CD206+ dual staining. Gene microarrays demonstrated a distinct alloimmune response despite the lack of rejection and inflammatory infiltrate with upregulation of interferon-γ-response genes. This suggests that following initiation of Th1 driven macrophage proliferation or infiltration, M2 macrophages contribute to tubular injury and progression of fibrosis. 23 protocol renal biopsies were obtained from patients at 12 month post transplant. The study population was divided into two groups according to the number of infiltrating macrophages (CD68 positive cells) (Group I: Recipients with a low number of infiltrating macrophages, CD68 positive cells < 400/mm2; Group II: Recipients with a high number of infiltrating macrophages, CD68 positive cells ≥ 400/mm2). Additional analyses were undertaken by dividing the group into those with fibrosis (ci score >1) and those without. To correlate gene expression with kidney fibrosis, or intensity of CD68 infiltrate, Spearman correlations analysis of the gene expression data with 12 month IFTA was performed and the correlation co-efficiency and its p value calculated. Gene Ontology enrichment and IPA pathway and network analysis (Ingenuity System Inc.) were performed on the associated genes. All p-values were two-sided, and p < 0.05 was considered significant.
Project description:In this proof-of-concept study, spatial transcriptomics combined with public single-cell RNA sequencing data were used to explore the potential of this technology to study kidney allograft rejection. We aimed to map gene expression patterns within diverse pathological states by examining biopsies classified across non-rejection, T cell-mediated acute rejection, and interstitial fibrosis and tubular atrophy (IFTA). Our results revealed distinct immune cell signatures, including those of T and B lymphocytes, monocytes, mast cells, and plasma cells, and their spatial organization within the renal interstitium. We also mapped chemokine receptors and ligands to study immune-cell migration and recruitment. Finally, our analysis demonstrated differential spatial enrichment of transcription signatures associated with kidney allograft rejection across various biopsy regions. Interstitium regions displayed higher enrichment scores for rejection-associated gene expression patterns than did tubular areas, which had negative scores. This implies that these signatures are primarily driven by processes unfolding in the renal interstitium. Overall, this study highlights the value of spatial transcriptomics for revealing cellular heterogeneity and immune signatures in renal transplant biopsies, and demonstrates its potential for studying the molecular and cellular mechanisms associated with rejection. However, certain limitations must be borne in mind regarding the development and future applications of this technology.
Project description:The aim of this study was to investigate the role of infiltrating macrophages in renal allograft fibrosis. Forty-six protocol renal allograft biopsies obtained one-year after transplantation were stained with Sirius Red to quantify fibrosis and double stained with CD68 and CD206 to identify the proportion of alternately activated (M2) macrophages. 23 protocol biopsies obtained 12 months post transplant were analyzed for gene expression by microarray, which was correlated with macrophage infiltration and the severity of fibrosis. Phenotypic analysis showed 92% of infiltrating macrophages exhibited an M2 phenotype with CD68+CD206+ dual staining. Gene microarrays demonstrated a distinct alloimmune response despite the lack of rejection and inflammatory infiltrate with upregulation of interferon-γ-response genes. This suggests that following initiation of Th1 driven macrophage proliferation or infiltration, M2 macrophages contribute to tubular injury and progression of fibrosis.
Project description:The study comprises various components: Samples TD: We aims to screen out different gene expression profile in donor biopsies after revascularization , We aims to predict renal allograft dysfunction early after transplantation. Samples AR, ATN, Tx: We aim to screen out different gene expression profile in acute rejection on the kidney. We aim to screen out different gene expression profile in acute tubular necrosis on the kidney. Results from the various study components can help to diagnose renal allograft dysfunction with different causes by distinct gene expression profile. Keywords: acute rejection, acute tubular necrosis, donor biopsies, renal allograft dysfunction Samples AR1-AR17: This study has been accomplished with 17 patients of acute rejection on the kidney.Technical replicates: 2 replicates Samples ATN1-ATN5: This study has been accomplished with 5 patients of acute tubular necrosis on the kidney. Technical replicates: 2 replicates Samples Tx1-Tx14: This study has been accomplished with 14 patients of stable renal function on the kidney.Tecnical replicates:2 replicates(except Tx12) Samples TD1-TD12: This study has been accomplished with 12 patients of donor tissue with stable function early after transplantation on the kidney.Technical replicates: 2 replicates Samples TD13-TD21: This study has been accomplished with 9 patients of donor tissue with renal dysfunction early after transplantation on the kidney.Technical replicates: 2 replicates
Project description:The presence of Donor-Specific anti-HLA Antibodies (DSA) is associated with an increased risk of both acute and chronic antibody-mediated rejection (AMR) in kidney allografts. AMR has remained challenging in kidney transplantation and is the major cause of late allograft loss. However, not all patients with DSA develop AMR, leading to the question of whether this represents accommodation, if other protective mechanisms exist or if this is actually a state of pre-rejection. Clinical and histological features, and gene expression profiles of kidney biopsy and blood samples of donor-specific antibody (DSA)+ patients without rejection were compared to antibody-mediated rejection (AMR) patients to elucidate the mechanisms involved in prevention of AMR. Of the 71 DSA+ patients, 46 had diagnosis of AMR and 25 did not show rejection. 50 DSA- patients without rejection were used as control. A subgroup of patients with available biopsy (n=61) and blood samples (n=54) were analyzed by microarrays. Both, DSA+/AMR+ and DSA+/AMR- biopsies showed increased expression of gene transcripts associated with cytotoxic T, natural killer cells, macrophages, interferon-gamma and rejection compared to DSA- biopsies. Regulatory T cell transcripts were up-regulated in DSA+/AMR+ and B cell transcripts in DSA+/AMR- biopsies. Whole blood gene expression analysis showed increased immune activity in only DSA+/AMR+ patients. There were no differentially expressed tolerant genes studied (n=14) in the blood or biopsy specimens of DSA+/AMR- patients. During a median 36 months follow-up, 4 DSA+/AMR- patients developed AMR, 12 continued to have DSAs but 9 lost DSAs. Gene expression profiles did not predict the development of AMR or persistence of DSAs. These results indicate increased immune activity in DSA+/AMR- biopsies despite lack of histologic findings of rejection. All clinically indicated kidney transplant biopsies performed at our institution after January 2009 were reviewed and 263 patients with anti-HLA antibody testing at the time of biopsy were identified. There were 71 DSA+ and 192 DSA- patients (Figure 1). Of the 71 DSA+ patients, 46 had biopsy diagnosis of acute AMR (n=9) or chronic AMR (n=37), and 25 had normal histopathology or minimal non-specific interstitial fibrosis/tubular atrophy (IFTA). Of the 192 DSA- patients, 50 patients with normal histology and/or mild non-specific IFTA were used as a control group. Clinical and histopathological findings of these 3 groups (DSA+/AMR+, DSA+/AMR- and DSA-) were analyzed. A subgroup of patients who were enrolled in the Institutional Review Board-approved âImmune Monitoring Studyâ who had clinically indicated biopsy (n=61) and whole blood samples (n=54) stored were used for genomic analysis. Twenty-eight biopsy and blood samples from DSA+/AMR+ patients, 13 biopsy and 14 blood samples from DSA+/AMR- patients, and 20 biopsy and 12 blood samples from DSA- patients, were available for microarray analysis.
Project description:We hypothesized that T cell-mediated immune mechanisms play a role in two conditions; 1: donor-specific antibody (DSA) negative transplant glomerulopathy (TGP) and 2: interstitial fibrosis and tubular atrophy (IFTA) with inflammation (i>0). We investigated gene expression profiles of those biopsies compared to biopsies with antibody-mediated rejection(ABMR) and to biopsies with non-specific IFTA and no inflammation. DSA negative TGP and IFTA with inflammation biopsies have a unique molecular signature distinct to that seen in biopsies with ABMR and IFTA without inflammation with significant expression of cytotoxic and regulatory T cells.
Project description:Renal transplantation is the preferred treatment of end stage renal disease, but allograft survival is limited by development of interstitial fibrosis and tubular atrophy in response to various stimuli. Much effort has been put into identifying new protein markers of fibrosis to support the diagnosis. In present work, we performed an in-depth quantitative proteomics analysis of allograft biopsies from 31 prevalent renal transplant patients and identified correlated the quantified proteins with the volume fraction of fibrosis as determined by a morphometric method. Linear regression analysis identified four proteins that were highly associated with the degree of interstitial fibrosis, namely Coagulation Factor XIII A chain (estimate 18.7, adjusted p<0.03), Uridine Phosphorylase 1 (estimate 19.4, adjusted p<0.001), Actin-related protein 2/3 subunit 2 (estimate 34.2, adjusted p<0.05) and Cytochrome C Oxidase Assembly Factor 6 homolog (estimate -44.9, adjusted p<0.002) even after multiple testing. Proteins that were negatively associated with fibrosis (p < 0.005) were primarily related to normal metabolic processes and respiration, whereas proteins that were positively associated with fibrosis (p < 0.005) were involved in catabolic processes, cytoskeleton organization and immune response. The identified proteins may be candidates for further validation with regards to renal fibrosis. The results support the notion that cytoskeleton organization and immune responses are prevalent processes in renal allograft fibrosis.
Project description: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.
Project description:Rationale: Interstitial fibrosis and tubular atrophy (IFTA) is found in ~25% of 1-year biopsies post-transplant(1, 2). It correlates with decreased graft survival when histological evidence of inflammation is present¬.(3-5) Identifying the etiology of IFTA is important because longterm graft survival has not changed as expected given improved therapies and a dramatically reduced incidence of acute rejection.(6-8) Methods: Gene expression profiles of 234 samples were obtained with matching clinical and outcome data (7 transplant centers). 81 IFTA samples were divided into subphenotypes by the degree of inflammation on histology: IFTA with acute rejection (AR), IFTA with inflammation and IFTA without inflammation. Samples with AR (n=54) and normally functioning transplants (TX; n=99) were used in comparisons. Conclusions: Gene expression profiling of all IFTA phenotypes were strongly enriched for cAR gene dysregulation pathways, including IFTA samples without histological evidence of inflammation. Thus, by molecular profiling we demonstrate that most IFTA samples have ongoing immune-mediated injury or chronic rejection that is more sensitively detected by gene expression profiling. We also found that the relative expression of AR-affiliated genes correlated with future graft loss in IFTA samples without inflammation. We conclude that undetected and/or undertreated immune rejection is leading to IFTA and graft failure. RNA was extracted from biopsy samples using the RNEasy kit (Qiagen), biotinylated cRNA prepared using Ambion MessageAmp Biotin II and hybridized to Affymetrix HG U133 Plus PM peg arrays (http://affymetrix.com/index.affx). Probe intensity data were log2–transformed and normalized using a custom-designed frozen Robust Multichip Average (fRMA). Low-variance and low signal probes were filtered according to industry standards, resulting in a filtered gene list with 17,564 transcripts. This dataset is part of the TransQST collection.