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Global gene expression profiling on renal scarring in rat model of pyelonephritis

ABSTRACT: Renal scarring is a serious complication of chronic pyelonephritis due to vesicoureteral reflux, and requires specific biomarker for indication of early intervention. We investigated global expression profile of kidney during renal scarring formation using rat pyelonephritis model. An inoculum of the DS-17 strain Escherchia coli was injected directly into renal cortex of Wister rat. Histologically, renal scarring developed during 3 and 4 weeks after injection. The time course expression profile of approximately 20,500 genes was analyzed using high density oligonucleotide microarray followed by validation using real time RT-PCR. Most of up-regulated genes during this experimental renal scarring were associated with immune and defense response, including cytokines, chemokines, their receptors, complements, and adhesion molecules as well as proteins related to extra cellular matrix. These genes were up-regulated as early as 1 week after injection when histological examination did not show fibrotic change yet, peaked at 2 weeks and gradually decreased thereafter. However, a subset of cytokine genes is persistently activated even in 6 weeks after the injection, which are involved in TGF-β related tissue regeneration pathway or IL-1β related pathway. The products of these genes may potentially be the source of novel non-invasive diagnostic or prognostic biomarkers for renal scarring. Keywords: renal scarring, TGF-β , IL-1β

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE7087 | GEO | 2007/02/22

SECONDARY ACCESSION(S): PRJNA98451

REPOSITORIES: GEO

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Project description:Renal scarring is a serious complication of chronic pyelonephritis due to vesicoureteral reflux, and requires specific biomarker for indication of early intervention. We investigated global expression profile of kidney during renal scarring formation using rat pyelonephritis model. An inoculum of the DS-17 strain Escherchia coli was injected directly into renal cortex of Wister rat. Histologically, renal scarring developed during 3 and 4 weeks after injection. The time course expression profile of approximately 20,500 genes was analyzed using high density oligonucleotide microarray followed by validation using real time RT-PCR. Most of up-regulated genes during this experimental renal scarring were associated with immune and defense response, including cytokines, chemokines, their receptors, complements, and adhesion molecules as well as proteins related to extra cellular matrix. These genes were up-regulated as early as 1 week after injection when histological examination did not show fibrotic change yet, peaked at 2 weeks and gradually decreased thereafter. However, a subset of cytokine genes is persistently activated even in 6 weeks after the injection, which are involved in TGF-Î² related tissue regeneration pathway or IL-1Î² related pathway. The products of these genes may potentially be the source of novel non-invasive diagnostic or prognostic biomarkers for renal scarring. Experiment Overall Design: Experimental pyelonephritis was produced by standard method of direct infection of rat kidney. In brief, animals were anesthetized with pentobarbital intraperitoneally. The kidneys were exposed through a midline abdominal incision. An inoculum of 1x109 colony-forming units / 0.1 ml of Escherchia coli was injected directly into bilateral renal cortex of Wister rat using 26-gauge needle. We used DS-17 or NU-14 strains, both of which has type 1 and P pili, and SEC strain, which has only type 1 pili. Control rats received isotonic saline instead of bacterial solution. Both test and control kidneys were harvested at 1, 2, 4 and 6 weeks after injection. The kidney samples (1x1x2 mm each) were obtained including the injection site, which was easily identified by surface color change. Then we cut the kidney into half; one was used for microscopic examination and the other half was immediately frozen in liquid nitrogen for later RNA extraction.

Project description:<p>Primary vesicoureteric reflux (PVUR), or non-syndromic VUR, is the most common type of congenital anomaly of the kidney and the urinary tract (CAKUT). PVUR is the single most important risk factor for pyelonephritis and renal parenchymal scarring in the pediatric age group. Renal parenchymal scarring due to PVUR is referred to as reflux nephropathy and is a major cause of end stage kidney disease requiring dialysis and kidney transplantation in children. PVUR shows familial aggregation; however, the specific genetic cause(s) of PVUR is unknown despite a number of linkage studies. Reasons for this include: variable expression of the disease, difficulty with case ascertainment, genetic heterogeneity and lack of large pedigrees that can facilitate locus identification. We have ascertained a large 97 member PVUR kindred spanning five generations. We performed a genome-wide linkage study (GWLS) on this family and obtained a significant genome-wide LOD score of 3.3 on chromosome 6p. We performed exome sequencing on affected individuals in the family and identified mutations in tenascin XB (TNXB) as a cause of familial VUR. The proposed studies have the following specific objectives: a) to define the role of tenascin genes in the etiology of PVUR, and b) to identify new PVUR causative genes. Our specific aims are (1) To perform mutation analysis in TNXB and other tenascins in a cohort of 200 individuals with familial and sporadic PVUR and define genotype/phenotype correlations. (2) To perform sequential genome wide linkage studies (GWLS) and whole exome/targeted sequencing in families with PVUR. Impact on public health: Identification of PVUR genes may provide a novel non-invasive diagnostic tool for a subset of children with PVUR. Furthermore, this research will provide insights into the pathogenesis of PVUR and further elucidate the pathways involved in the development of the kidney and genitourinary tract. Future studies will define the role of the genes in the etiology of other malformations of the kidney and urinary tract and also seek to unravel the mechanisms by which the identified gene causes PVUR and other malformations of the kidney and the urinary tract.</p>

Project description: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

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Global gene expression profiling on renal scarring in rat model of pyelonephritis

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