Project description:Transplant glomerulopathy (TGP) is frequently found in the setting of chronic antibody mediated rejection along with microvascular inflammation (MVI) (peritubular capillaritis+glomerulitis score > 1) and/or positive c4d staining. We assessed the molecular profiles of TGP in the absence of microvascular inflammation and C4d staining as compared to TGP with positive MVI and/or C4d. Gene expression profiles of TGP in the absence of microvascular inflammation and C4d lack molecular features of antibody-mediated rejection but suggest chronic cellular rejection.
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:We investigated the clinical, histopathologic and genomic features of donor-specific antibody (DSA) +/C4d- and DSA-/C4d- transplant glomerulopathy (TGP) using microarrays. Comparison of the gene expression profiles of DSA-/C4d- TGP biopsies with ptc+g score > 1 to normal and IFTA (Interstitial Fibrosis and Tubular Atrophy) biopsies by microarrays revealed increased expression of quantitative cytotoxic T cell--associated transcripts (QCAT). However, CAMR (chronic antibody-mediated rejection) and DSA+/C4d- TGP had increased expression of QCAT, interferon-gamma and rejection induced, constitutive macrophage-associated, natural killer cell-associated, and DSA selective transcripts. B cell and endothelial cell associated transcripts expression were upregulated only in CAMR biopsies. Our results suggest that while DSA+/C4d- TGP should be classified under CAMR, DSA-/C4d- TGP with ptc+g score > 1 probably develops through a chronic cellular immune response. Total of 57 arrays included in this study. G1. Normal transplant kidney biopsies (N= 12); G2. Non-specific IFTA (N= 17); G3. TGP DSA-/C4d- (N=8); G4. TGP DSA+/C4d- (N= 9); G5. CAMR/TGP C4d+/DSA+ (N= 11)
Project description:We studied intragraft gene expression profiles of positive crossmatch (+XM) kidney transplant recipients who develop transplant glomerulopathy (TG) and those who do not. Whole genome microarray analysis and quantitative rt-PCR for 30 transcripts were performed on RNA from protocol renal allograft biopsies in 3 groups: 1) +XM/TG+ biopsies before and after TG; 2) +XM/NoTG; and 3) negative crossmatch kidney transplants (control). Microarray comparisons showed few differentially expressed genes between paired biopsies from +XM/TG+ recipients before and after the diagnosis of TG. Comparing +XM/TG+ and control groups, significantly altered expression was seen for 2,447 genes (18%) and 3,200 genes (24%) at early and late time points, respectively. Canonical pathway analyses of differentially expressed genes showed inflammatory genes associated with innate and adaptive immune responses. Comparing +XM/TG+ and +XM/NoTG groups, 3,718 probe sets were differentially expressed but these were over-represented in only 4 pathways. A classic accommodation phenotype was not identified. Using rt-PCR, the expression of inflammatory genes was significantly increased in +XM/TG+ recipients compared to control biopsies and to +XM/NoTG biopsies. In conclusion, pre-transplant DSA results in a gene expression profile characterized by inflammation and cellular infiltration and the majority of XM+ grafts are exposed to chronic injury. We analyzed gene expression from 2 groups of positive crossmatch kidney transplant recipients (+XM/TG+ and +XM/TG-). Patients in the +XM/TG+ group had 2 biopsies - prior to the development of transplant glomerulopathy on biopsy (Biopsy 1; cg=0; n=10) and after development of transplant glomerulopathy (Biopsy 2; cg>0; n=10). The +XM/TG- patients had only a Biopsy 2 (cg=0; n=11). A third patient group served as controls (n=10) and were from -XM recipients. 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 ‘chronic glomerulopathy [cg]’ 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.
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.
Project description:We investigated the clinical, histopathologic and genomic features of donor-specific antibody (DSA) +/C4d- and DSA-/C4d- transplant glomerulopathy (TGP) using microarrays. Comparison of the gene expression profiles of DSA-/C4d- TGP biopsies with ptc+g score > 1 to normal and IFTA (Interstitial Fibrosis and Tubular Atrophy) biopsies by microarrays revealed increased expression of quantitative cytotoxic T cell--associated transcripts (QCAT). However, CAMR (chronic antibody-mediated rejection) and DSA+/C4d- TGP had increased expression of QCAT, interferon-gamma and rejection induced, constitutive macrophage-associated, natural killer cell-associated, and DSA selective transcripts. B cell and endothelial cell associated transcripts expression were upregulated only in CAMR biopsies. Our results suggest that while DSA+/C4d- TGP should be classified under CAMR, DSA-/C4d- TGP with ptc+g score > 1 probably develops through a chronic cellular immune response.
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.
Project description:The aim of this study was to investigate correlations between early subclinical findings (10 and 90 day histology and gene expression data) and late outcomes (transplant glomerulopathy and graft loss) in positive crossmatch kidney transplants (+XMKTx). Our goal was threefold: first, to confirm that intragraft molecular changes at 12m post-transplant are associated with the observed histologic changes in SLK transplant recipients, compared with KTA transplant recipients; second, to ascertain whether specific molecular pathways/markers that are not accounted for by routine histology are differentially expressed in the kidney allografts of the SLK transplant recipients; and third, to determine whether a molecular signature that is uniquely associated with simultaneous liver transplantation can be identified in kidney allografts. Biopsy samples were from positive and negative crossmatch simultaneous liver-kidney transplant recipients (12 month protocol biopsies) were compared to control patient (positive and negative crossmatch) biopsies obtained at 12 months. This dataset is part of the TransQST collection.
Project description:Acute cellular rejection occurs frequently during the first few weeks following liver transplantation. During this period its molecular phenotype is confounded by pro-inflammatory events elicited by surgery, ischemia-reperfusion injury and early post-transplant complications. To unambiguously define the molecular profile associated with rejection we collected sequential biological specimens from liver transplant patients at least 3 years after transplantation who developed rejection while enrolled in trials of intentional immunosuppression withdrawal Transcriptomic RISET 2.0 chips were employed using portal blood vein from 37 liver trasplant patients.Two timepoints were selected: before immunosupressive weaning and rejection time point.