Unknown,Transcriptomics,Genomics,Proteomics

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The molecular basis of the renal and vascular consequences of Uremia

ABSTRACT: Background. Chronic renal failure is characterized by progressive renal scarring and accelerated cardiovascular disease. In animal models, this is thought to be due to non-dialyzable uremic toxins M-bM-^@M-^S small, protein-bound molecules normally secreted via Organic Anion Transporters (OATs) in the proximal renal tubule,rather than filtered at the glomerulus. The best studied of these is indoxyl sulfate (IS). Methods. We examined global gene expression responses in cultured normal human renal tubular cells incubated with control plasma (n=5) or pre- and post-dialysis uremic plasma (n=10). Results. GeneSpring analysis of microarrays revealed significantly altered expression of 2016 genes. The expression of 537 genes M-bM-^@M-^\normalizedM-bM-^@M-^] in post-dialysis plasma, suggesting removal of M-bM-^@M-^\low molecular weight uremic toxinsM-bM-^@M-^] by dialysis. The expression of the majority of dysregulated genes (1479) was not normalized in post-dialysis plasma. These likely represent the effects of substances not effectively removed by dialysis (M-bM-^@M-^\protein-bound uremic toxinsM-bM-^@M-^]). Addition of indoxyl sulfateto control plasma simulated most effects (81.1%) of uremic plasma, while the addition of probenecid, an OAT inhibitor, to uremic plasma reversed most changes in gene expression. Analysis of molecular programs with the Gene Set Enrichment Analysis and the DAVID database revealed patterns common to indoxyl sulfate-treated control plasma, pre-dialysis, and post-dialysis uremic plasma. These included increased cell cycle, pro-inflammatory, and pro-fibrotic molecular programs, particularly genes in the TGF-M-NM-2 pathway. Conclusion: These findings provide insight into the role of non-dialyzable, protein-bound uremic toxins in the pathogenesis of renal scarring and uremic vasculopathy. The GSEA patterns confirm that inflammatory and fibrotic programs are active. Transcriptomic remodeling in response to external stimulus RNA from non-immortalized cultured renal cortical cells incubated with plasma samples from 5 controls, 10 uremics pre-dialysis, 10 uremics post-dialysis, 5 controls with indoxyl sulfate added, 5 uremics pre-dialysis with probenecid added, 5 uremics post-dialysis with indoxyl sulfate added

ORGANISM(S): Homo sapiens

SUBMITTER: Jiri Zavadil

PROVIDER: E-GEOD-45709 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Expression data from peritoneal biopsies of patients with encapsulating peritoneal sclerosis (EPS), patients undergoing first implantation of a peritoneal dialysis catheter (PD), and patients undergoing abdominal surgery for non-peritoneal conditions (controls) We used microarrays to determine the transcriptional profiles of peritoneal membrane in patients with encapsulating peritoneal sclerosis (EPS), patients undergoing first insertion of a peritoneal dialysis cathetier (PD), and uremic patients without history of PD or EPS, undergoing abdominal surgery for non-peritoneal problems (CON) Encapsulating peritoneal sclerosis (EPS) is a devastating complication of peritoneal dialysis (PD), characterized by marked inflammation and severe fibrosis of the peritoneum, and associated with high morbidity and mortality. EPS can occur years after termination of PD and, in severe cases, leads to intestinal obstruction and ileus requiring surgical intervention. Despite ongoing research, the pathogenesis of EPS remains unclear. We performed a global transcriptome analysis of peritoneal tissue specimens from EPS patients, PD patients without EPS, and uremic patients without history of PD or EPS (Uremic). Unsupervised and supervised bioinformatics analysis revealed distinct transcriptional patterns that discriminated these three clinical groups. The analysis identified a signature of 219 genes expressed differentially in EPS as compared to PD and Uremic groups. Canonical pathway analysis of differentially expressed genes showed enrichment in several pathways, including antigen presentation, dendritic cell maturation, B cell development, chemokine signaling and humoral and cellular immunity (P value <0.05). Further interactive network analysis depicted effects of EPS-associated genes on networks linked to inflammation, immunological response, and cell proliferation. Gene expression changes were confirmed by qRT-PCR for a subset of the differentially expressed genes. EPS patient tissues exhibited elevated expression of genes encoding sulfatase1, thrombospondin 1, fibronectin 1 and alpha smooth muscle actin, among many others, while in EPS and PD tissues mRNAs encoding leptin and retinol-binding protein 4 were markedly down-regulated, compared to Uremic group patients. Immunolocalization of Collagen 1 alpha 1 revealed that Col1a1 protein was predominantly expressed in the submesothelial compact zone of EPS patient peritoneal samples, whereas PD patient peritoneal samples exhibited homogenous Col1a1 staining throughout the tissue samples. The results are compatible with the hypothesis that encapsulating peritoneal sclerosis is a distinct pathological process from the simple peritoneal fibrosis that accompanies all PD treatment. Total RNA was isolated from frozen peritoneal biopsy specimens obtained at time of surgery. RNA was hybridized to Affymetrix arrays, and analyzed. Select transcripts were subjected to validation by rt-pcr and by immunodetection.

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The molecular basis of the renal and vascular consequences of Uremia

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