Unknown,Transcriptomics,Genomics,Proteomics

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Expression data from peripheral blood - blood draws at Pre and Post time points of Allergen inhalation challenge (PAX.GR)

ABSTRACT: Detecting differential changes in the peripheral whole-blood transcriptome, post-challenge compared to pre-challenge; using globin reduced PAXgene (PAX.GR) tubes Blood was collected immediately prior to, and two hours after challenge Blood samples from 4 subjects were used to study the effects of globin reduction on differential gene expression Preprocessing and filtering were applied to the PAX.GR dataset using the Factor Analysis for Robust MicroArray Summarization (farms) package in R The Linear Models for MicroArrays (limma) package in R was used to determine differential gene expression using a Benjamini Hochberg FDR of 5%.

ORGANISM(S): Homo sapiens

SUBMITTER: Scott Tebbutt

PROVIDER: E-GEOD-34158 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: COPD is currently the fourth leading cause of death worldwide and predicted to rank third by 2020. Statins are commonly used lipid lowering agents with documented benefits on cardiovascular morbidity and mortality, and have also been shown to have pleiotropic effects including anti-inflammatory and anti-oxidant activity. Objective: Identify a gene signature associated with statin use in the blood of COPD patients, and identify molecular mechanisms and pathways underpinning this signature that could explain any potential benefits in COPD. Methods: Whole blood gene expression was measured on 168 statin users and 452 non-users from the ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) study. Gene expression was measured using the Affymetrix Human Gene 1.1 ST microarray chips. Factor Analysis for Robust Microarray Summarization (FARMS) was used to process the expression data and to filter out non-informative probe sets. Differential gene expression analysis was undertaken using the Linear Models for Microarray data (Limma) package adjusting for propensity score and employing a surrogate variable analysis. Similarity of the expression signal with published gene expression profiles was performed in ProfileChaser. Results: 18 genes were differentially expressed between statin users and non-users at a false discovery rate of 10%. Top genes included LDLR, ABCA1, ABCG1, MYLIP, SC4MOL, and DHCR24. The 18 genes were significantly enriched in pathways and biological processes related to cholesterol homeostasis and metabolism, and were enriched for transcription factor binding sites for sterol regulatory element binding protein 2 (SREBP-2). The resulting gene signature showed correlation with Huntington disease, Parkinson’s disease and acute myeloid leukemia. Conclusion: Statins gene signature was not enriched in any pathways related to respiratory diseases, beyond the drug’s effect on cholesterol homeostasis. Study subjects were a subset of those with COPD from the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) study (Vestbo et al.), funded by GlaxoSmithKline (GSK Study No. SCO104960, NCT00292552). ECLIPSE is a non-interventional, observational, multicentre, three-year study in people with COPD. Blood was collected in PAXGene tubes and frozen at -80oC. In this work we have looked at the effect of statins on gene expression in 620 subjects of whom 168 were statin users. ECLIPSE study was described in: Vestbo J, Anderson W, Coxson HO, et al.: Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points (ECLIPSE). Eur Respir J. 2008;31(4):869-73

Project description:Microarray-based gene expression analysis of peripheral whole blood is a common strategy in the development of clinically relevant biomarker panels for a variety of human diseases. However, the results of such an analysis are often plagued by decreased sensitivity and reliability due to the effects of relatively high levels of globin mRNA in whole blood. Globin reduction assays have been shown to overcome such effects, but they require large amounts of total RNA and may induce distinct gene expression profiles. The Illumina whole-genome DASL (WG-DASL) assay can detect gene expression levels using partially degraded RNA samples and has the potential to detect rare transcripts present in highly heterogeneous whole blood samples without the need for globin reduction. We therefore assessed the utility of the WG-DASL assay in the analysis of peripheral whole blood gene expression profiles. We find that gene expression detection is significantly increased with the use of WG-DASL compared to the standard in vitro transcription-based direct hybridization (IVT), while globin-probe-negative WG-DASL did not exhibit significant improvements over globin-probe-positive WG-DASL. Globin reduction increases the detection sensitivity and reliability of both WG-DASL and IVT with little effect on raw intensity correlations: raw intensity correlations between total RNA and globin-reduced RNA were 0.970 for IVT and 0.981 for WG-DASL. Overall, the detection sensitivity of the WG-DASL assay is higher than the IVT-based direct hybridization assay, with or without globin reduction, and should be considered in conjunction with globin reduction methods for future blood-based gene expression studies. Peripheral whole blood samples were collected from eight human donors in PAXGene tubes. RNA was isolated after freezing and storage, and then prepared for gene expression analysis using the Illumina Human-Ref8 v3.0 BeadChip. Alpha and beta globin were reduced from a portion of the total RNA using the GLOBINclear assay (Ambion, Austin, TX, USA). Two methods of microarray target preparation were examined: Illumina IVT-based direct hybridization (IVT) and Illumina Whole-Genome DASL (WG-DASL). Two DASL Assay Oligo pools (DAP) were utilized for DASL target preparation: the DASL Assay Oligo Pool with globin probes (DAP +) and the DASL Asssay Oligo Pool without globin probes (DAP-).

Project description:Background: Allergen inhalation challenge in mild asthmatics induces airflow obstruction, airway hyperresponsiveness and inflammation, providing a model for hypothesis-generating experiments to understand regulation of these responses. We have sought to evaluate the peripheral whole blood transcriptome, post-challenge compared to pre-challenge, and to determine the effect of globin mRNA reduction methodology. Methods: Asthmatic subjects (20-60 years of age, with stable, mild allergic asthma, n=17) underwent allergen inhalation challenges. All subjects had an early asthmatic response of ≥ 20% fall in FEV1; most had a late phase response of ≥ 15% fall in FEV1. Blood was collected immediately prior to, and two hours after allergen challenge. Transcriptome analysis was performed using Affymetrix GeneChip® Human Gene 1.0 ST arrays, with and without globin mRNA reduction (PAX-GR and PAX-NGR, respectively) in 4 subjects. Replication studies for expression of nine genes contributing to the top canonical pathway, Nrf2-mediated oxidative stress response pathway, were performed with 5 independent subjects with microarray data, also with the same 4 subjects had microarray results and 8 other independent subjects with QPCR. Data were analyzed using paired t-test and Partek® Genomics Suite™. Results: The number of differentially expressed probe sets from PAX-NGR samples was twice that of PAX-GR samples. Paired analysis of each subjects' pre- and post-sample additionally demonstrated twice the power to detect differentially expressed probe sets. The Nrf2-mediated oxidative stress response pathway was identified as the top canonical pathway in the PAX-NGR samples. ATP-binding cassette sub-family C member 1 (ABCC1) gene was significantly reduced two hours after allergen challenge in the 5 subjects’ microarray dataset and the 2 QPCR replication datasets with P < 0.05. Conclusions: Globin mRNA reduction does not provide benefits to detect differentially expressed genes during allergen inhalation challenge. Allergen inhalation challenge is associated with decreased peripheral blood cell transcript level of ABCC1 gene. 26 array were analyzed. We first identified differentially expreed genes between post- and pre-challenge samples from 4 asthmatic subjects by using globin reduction samples and non-globin reduction samples (16 arrays). Then we replicated our findings using 10 arrays from 5 asthmatic subjects challenged with allergen. Includes 4 normal blood samples.

Project description:Background: Mycobacterium bovis, the causative agent of bovine tuberculosis, is a major cause of mortality in global cattle populations. Macrophages are among the first cells types to encounter M. bovis following exposure and the response elicited by these cells is pivotal in determining the outcome of infection. Here, a functional genomics approach was undertaken to investigate global gene expression profiles in bovine monocyte-derived macrophages (MDM) purified from seven age-matched non-related females, in response to in vitro challenge with M. bovis (multiplicity of infection 2:1). Total cellular RNA was extracted from non-challenged control and M. bovis-challenged MDM for all animals at intervals of 2 hours, 6 hours and 24 hours post-challenge and prepared for global gene expression analysis using the Affymetrix® GeneChip® Bovine Genome Array. Results: Comparison of M. bovis-challenged MDM gene expression profiles with the non-challenged MDM controls at each time point identified 3,529 differentially expressed genes after 2 hours post-challenge, with 5,211 and 6,150 differentially expressed genes detected at the 6 hour and 24 hour time points, respectively (adjusted P-value threshold ≤ 0.05). Notably, the number of downregulated genes exceeded the number of upregulated genes in the M. bovis-challenged MDM across all time points; however, the fold-change in expression for the upregulated genes was markedly larger than that for the downregulated genes. Systems analysis revealed enrichment for genes involved in: (1) the inflammatory response; (2) cell signalling pathways, including Toll-like receptors and intracellular pathogen recognition receptors (PRRs)-receptors; and (3) apoptosis. Conclusions: The increased number of downregulated genes is consistent with previous studies showing that M. bovis infection is associated with the repression of host gene expression. The results also support important roles for MYD88-independent signalling and intracellular PRRs in mediating the host response to M. bovis, which to our knowledge have not been reported previously. Affymetrix GeneChip® Bovine Genome Arrays were used to examine gene expression of bovine monocyte-derived macrophages (MDM) after in vitro challenge with Mycobacterium bovis across a time series of 2 hr, 6 hr and 24 hr post-challenge. A 0 hr control treatment was also generated and seven different age-matched female Holstein-Friesian cattle were used for each time-point/treatment combination for a total of 49 microarrays.

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Expression data from peripheral blood - blood draws at Pre and Post time points of Allergen inhalation challenge (PAX.GR)

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