Unknown,Transcriptomics,Genomics,Proteomics

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Transcriptome analysis of alveolar macrophages in asthma

ABSTRACT: Purpose: The goal of this study is to investigate the alteration of gene expression pattern of alveolar macrophages by allergen challenge in human asthmatics. Method: By using subsegmental bronchial provocation with allergen (SBP-AG) protocol, we obtained BAL fluids, before and 48 hours after allergen challenge in the subjects enrolled in the protocol. Alveolar macrophages were purified from the BAL fluids and total RNA was isolated. Next-generation sequencing data were generated by using the Illumina system. Results: Using an optimized data analysis workflow, we mapped about 75 million sequence reads per sample to the human genome and identified 29,691 transcripts in the macrophage mRNAs. Among them, the change in the expression profiles of 37 transcripts were statistically significant. Conclusions: It has been well accepted that Th2 cytokine enriched environment transforms the phenotype of macrophages into alternatively activated form. However, the details of a genome-wide gene expression profiles of macrophages were not well investigated. Using RNA-seq technology, we provided comprehensive data of macrophage gene expression profiles in allergic lung inflammation. Our data could offer a framework to study biologic functions of alternatively activated macrophage in chronic inflammatory diseases. mRNA profiles of alveolar macrophages obtained from asthmatics, before and after allergen challenge.

ORGANISM(S): Homo sapiens

SUBMITTER: Gye Young Park

PROVIDER: E-GEOD-65039 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: A subset of asthmatics does not respond to steroid therapy and therefore is at risk for escalation of disease severity. The cause of corticosteroid resistant (CR) asthma is unknown. Gene microarray technologies have the potential to substantiate new hypotheses regarding the etiology of corticosteroid resistance. Methods: Gene microarray analysis was performed with bronchoalveolar lavage (BAL) cells of CR and corticosteroid sensitive (CS) asthmatics. Increased gene expression was verified with real time PCR and at the protein level by ELISA. Findings: Microarray analyses demonstrated significantly higher levels (over two-fold increase, p<0.05) of TNF-alpha, IL-1alpha, IL-1beta, IL-6, CXCL1, CXCL2, CXCL3, CXCL8 (IL-8), CCL3, CCL4, CCL20 gene expression in BAL cells of CR than CS asthmatics. These findings, confirmed by RT-PCR in additional BAL samples, were consistent with classical macrophage activation by bacterial products. In contrast, markers of alternatively-activated macrophages, Arginase I and CCL24, were decreased in CR asthmatics. Genes associated with activation of the LPS signaling pathway (EGR1, DUSP2, MAIL, TNFAIP3) were significantly elevated in CR BAL samples (p<0.05). CR asthmatics had significantly higher amounts (1444.0Â±457.3 pg per mg of total protein) of LPS in BAL fluid than CS asthmatics (270.5Â±216.0 pg; p<0.05). Prolonged exposure to LPS induced functional steroid resistance to dexamethasone (DEX) in normal monocytes, demonstrated by persistently elevated IL-6 levels in the presence of DEX. Interpretation: Classical macrophage activation and induction of LPS signaling pathways along with high endotoxin levels detected in BAL fluid from CR asthmatics suggest that LPS exposure may contribute to CR asthma. Experiment Overall Design: Patients with a diagnosis of asthma according to American Thoracic Society criteria were selected for evaluation. Asthmatics had a baseline FEV1% predicted of 55% to 85% of predicted, a beta2-adrenergic response of â¥12% of baseline FEV1% predicted and/or a methacholine PC20 value of â¤8 mg/ml. Asthma patients were further subdivided in CR and CS groups, based on their response to steroids. The definition was based on change in FEV1 % predicted over a one-week course of 40 mg/day of oral prednisone. Asthmatic patients were defined as CS if they had an increase in FEV1% predicted of greater than 15% after a one-week course of prednisone, and as CR if less than 12% change in FEV1% predicted was observed. None of the asthmatic subjects recruited for this study had evidence for other types of lung diseases. None of the subjects had received systemic corticosteroid therapy for at least one month prior to bronchoscopy. All subjects provided written informed consent to participate in the study. The study was approved by the Institutional Review Board at National Jewish Medical and Research Center, Denver, CO. Gene array studies of BAL macrophages were performed in 3 CR and 3 CS asthmatics.

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Transcriptome analysis of alveolar macrophages in asthma

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