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Peripheral blood transcriptomic profiles of rejection and polyomavirus-associated nephropathy after kidney transplantation

ABSTRACT: Kidney transplant injury processes are associated with molecular changes in renal tissue, primarily related to immune cell activation and infiltration. How these processes are reflected by molecular alterations in circulating immune cells is poorly understood. We performed RNA-sequencing on 384 biobanked blood samples from four transplant centers, taken at time of a kidney allograft biopsy, selected for their phenotype (acute T cell- and antibody-mediated rejection, polyomavirus-associated nephropathy, and control). We performed differential expression analysis and pathway analysis per phenotype. In peripheral blood, differentially expressed genes in rejection vs. no rejection samples demonstrated upregulation of glucocorticoid receptor and NOD-like receptor signaling pathways. Pathways enriched in antibody-mediated rejection were strongly immune-specific, whereas pathways enriched in T cell-mediated rejection were less immune related. Differentially expressed genes in polyoma viremia and polyomavirus-associated nephropathy were similar and demonstrated upregulation of mitochondrial dysfunction and interferon signaling pathways. Our results highlight the immune activation pathways in peripheral blood leukocytes at time of antibody-mediated rejection and polyomavirus nephropathy and provide a framework for future therapeutic interventions.

ORGANISM(S): Homo sapiens

PROVIDER: GSE175718 | GEO | 2022/05/06

REPOSITORIES: GEO

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Project description:Histologic 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. Antibody-mediated rejection is a major cause of kidney transplant failure, but the current diagnostic system misses most cases due to dependency on subjective non-standardized tests. We hypothesized that molecular features could provide a test to address this problem. We classified 403 biopsies by a reference standard based on microcirculation lesions and donor-specific HLA antibody, and used microarray analysis to develop a classifier that assigned each biopsy a score reflecting the probability of antibody-mediated rejection. The scores correlated with donor-specific antibody and histologic lesions: 42/45 biopsies with antibody-mediated rejection scores >0.5 had both donor-specific antibody and microcirculation lesions. Intermediate scores (0.2-0.5) were more ambiguous, but became more specific combined with donor-specific antibody. Compared to diagnoses based on histology-plus-donor-specific antibody, the scores had sensitivity 0.67; specificity 0.90. Donor-specific antibody improved the specificity to 0.97. The score correlated not only with diagnoses of individual pathologists but with the consensus among multiple pathologists. The classifier used transcripts expressed in endothelial cells (e.g. CDH13, DARC, ROBO4) and NK cells (e.g. CX3CR1, FGFBP2), as well as IFNG-inducible transcripts e.g. CXCL11. Thus the molecular phenotype of antibody-mediated rejection provides not only an objective test that predicts microcirculation lesions and donor-specific HLA antibody, but also offers mechanistic insights. All consenting renal transplant patients undergoing biopsies for cause as standard of care. 403 samples and 8 controls (nephrectomies). This dataset is part of the TransQST collection.

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.

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Peripheral blood transcriptomic profiles of rejection and polyomavirus-associated nephropathy after kidney transplantation

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