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Gene expression profiling of experimental asthma reveals a possible role of paraoxonase-1 in asthma

ABSTRACT: Background: Several studies indicate that asthma is a polygenic disease, and its complexity originates from the interaction of an unknown number of genes with environmental factors. Objective: In this study we aimed to identify new genes, gene groups and pathways involved in the pathogenesis of experimental asthma. Methods: In an ovalbumin-induced murine model of asthma we applied microarray gene expression analysis of the lung at different time points in the asthmatic process. Advanced statistical methods were used to relate gene expression changes to cellular processes and to integrate our results into multiple levels of information available in public databases. Results: According to the observed marked neutrophil infiltration found early, at 4 hours after the first allergen challenge, gene expression pattern reflected mainly an acute inflammatory response and strong chemotactic activity. At 24 hours after the third allergen challenge, gene set enrichment analysis revealed significant overrepresentation of gene sets corresponding to Th2 type inflammation models. Among the top downregulated transcripts, an antioxidant enzyme, paraoxonase-1 (PON1) was identified. Reduced PON1 protein expression in the lung was confirmed by immunohistochemical analysis. In human asthmatic patients we found that serum PON1 activity was reduced at exacerbation, but increased parallel with improving asthma symptoms. PON1 gene polymorphisms did not influence the susceptibility to the disease. Conclusion: Our observations suggest that an altered PON1 activity might be involved in the pathogenesis of asthma, and PON1 might be a potential new therapeutic target as well as a new diagnostic tool for following up the effect of therapy.

ORGANISM(S): Mus musculus

PROVIDER: GSE11911 | GEO | 2009/07/06

SECONDARY ACCESSION(S): PRJNA105753

REPOSITORIES: GEO

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Project description:Background: Several studies indicate that asthma is a polygenic disease, and its complexity originates from the interaction of an unknown number of genes with environmental factors. Objective: In this study we aimed to identify new genes, gene groups and pathways involved in the pathogenesis of experimental asthma. Methods: In an ovalbumin-induced murine model of asthma we applied microarray gene expression analysis of the lung at different time points in the asthmatic process. Advanced statistical methods were used to relate gene expression changes to cellular processes and to integrate our results into multiple levels of information available in public databases. Results: According to the observed marked neutrophil infiltration found early, at 4 hours after the first allergen challenge, gene expression pattern reflected mainly an acute inflammatory response and strong chemotactic activity. At 24 hours after the third allergen challenge, gene set enrichment analysis revealed significant overrepresentation of gene sets corresponding to Th2 type inflammation models. Among the top downregulated transcripts, an antioxidant enzyme, paraoxonase-1 (PON1) was identified. Reduced PON1 protein expression in the lung was confirmed by immunohistochemical analysis. In human asthmatic patients we found that serum PON1 activity was reduced at exacerbation, but increased parallel with improving asthma symptoms. PON1 gene polymorphisms did not influence the susceptibility to the disease. Conclusion: Our observations suggest that an altered PON1 activity might be involved in the pathogenesis of asthma, and PON1 might be a potential new therapeutic target as well as a new diagnostic tool for following up the effect of therapy. Experiment Overall Design: Experimental design: Experiment Overall Design: Three groups of mice (6 mice/group) were sensitized and challenged with allergen (OVA), one group (control group) was sensitized and challenged with placebo (PBS) and served as a control. On day 28 and 30, 4 h after the first and third allergen challenge, mice in groups 1 and 2 were anaesthetized by an intraperitoneal injection of ketamine and xylazine, BAL was isolated and the lungs were removed for further analysis. On day 31, 24h after the third (last) allergen challenge mice in group 3 and the controls were anaesthetized, and airway hyper-responsiveness (AHR) was assessed. After the AHR measurements, BAL sampling and lung tissue collection were performed, the same way as it was carried out in groups 1 and 2. Cellular composition of BAL, and lung histology were examined in all mice in all groups. AHR was measured in controls and group 3 on day 31. 1000 ng-1000 ng quality-checked total lung tissue RNA samples from OVA sensitized and challenged mice from group 1, 2 and 3 were identically labeled with Cy5 dye, while lung tissue RNA samples from group 4 (control, placebo sensitized and challenged) were pooled and labeled with Cy3 dye, and served as a common reference.

Project description:Background: Most asthmatic patients have high serum levels of IgE directed against common environmental allergens such as house dust mite, animal danders and moulds. However the presence of specific IgE against individual allergens alone does not account for asthma. Many individuals are atopic but not asthmatic. Precise knowledge of the serum IgE specificity repertoire in asthmatic and non-asthmatic patients would substantially help in understanding the pathogenesis of the disease and at the same time facilitate the treatment and the implementation of preventive measures. Methods: We developed a microarray immunoassay containing 103 common allergens to study the IgE reactivity profiles of 485 asthmatic and 342 non-asthmatic individuals from families whose members had a documented history of asthma and atopy. The results were analyzed using k-means clustering to investigate whether IgE reactivity profiles correlated with asthma, disease severity and age of onset as well as with other atopic conditions such as rhinitis, conjunctivitis and eczema. We trained an artificial neural network (ANN) using the serum reactivity data to identify individuals as asthmatic and non-asthmatic. Results: Individual sera showed clear differences in the number and the combinations of allergens recognized as well as in the level of specific IgE. While the presence of specific IgE against single allergens correlated poorly with the pathological conditions examined k-means clustering analysis unraveled that a particular profile was significantly associated with asthma (p <1E-8). An ANN-based algorithm, calibrated with the profile reactivity data correctly classified as asthmatic or non-asthmatic 78% of the individual examined. Conclusions: Our analysis demonstrates that asthma may be a higher-order phenomenon related to patterns of response and not attributable to single antibody reactions. This information sheds new light on the risk of developing the disease and can be readily utilized in combination with an ANN-based tool to distinguish asthmatic and non-asthmatic individuals on the basis of their serum reactivity profile. The study consisted of a total of 872 sera samples: 485 individuals were diagnosed with asthma, 342 were classified as non asthmatic, a remaining 45 were classified as unconfirmed asthma diagnosis. The serum IgE reactivity profiles were analyzed against 103 allergens representative of 11 distinct allergen classes. Quantification of bound IgE: The fluorescence signal was acquired using ProScanArray Express™ version 3.0 software. PMC reading values of individual spots were corrected against the internal negative control to identify signals above background. Duplicate measurements of individual allergens were utilized. The signal collected from the allergens was interpolated with an external calibration curve to obtain the IU/ml value (see supplementary file GSE20020_IU_ml values.txt), and translated into a Class Score by plotting the data in a standard reactivity scale (see Sample data tables). Class Score values: (CLASS 0 (less than 0.35 IU/ml); CLASS 1 (0.35-0.7 IU/ml); CLASS 2 (0.71-3.5 IU/ml); CLASS 3 (3.51-17.5 IU/ml); CLASS 4 (17.51-50 IU/ml); CLASS 5 (50.01-100 IU/ml).

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:Resiquimod is a nucleoside analog belonging to the imidazoquinoline family of compounds which is known to signal through Toll-like receptor 7. Resiquimod treatment has been demonstrated to inhibit the development of allergen induced asthma in experimental models. Despite this demonstrated effectiveness, little is known about the molecular events responsible for this effect. The aim of the present study was to elucidate the molecular processes which were altered following resiquimod treatment and antigen challenge in a mouse model of allergic asthma. Employing microarray analysis, we have characterized the 'asthmatic' transcriptome of the murine lung and determined that it includes genes involved in: the control of cell cycle progression, airway remodelling, the complement and coagulation cascades, and chemokine signalling. We have demonstrated that systemic resiquimod administration resulted in the recruitment of NK cells to the lungs of the mice, although no causal relationship between NK cell recruitment and treatment efficacy was found. Furthermore, results of our studies demonstrated that resiquimod treatment resulted in the normalization of the expression of genes involved with airway remodelling and chemokine signalling, and in the modulation of the expression of genes including cytokines and chemokines, adhesion molecules, and B-cell related genes, involved in several aspects of immune function and antigen presentation. Overall, our findings identified several genes, important in the development of asthma pathology, that were normalized following resiquimod treatment thus improving our understanding of the molecular consequences of resiquimod treatment in the lung milieu. Experiment Overall Design: A total of 18 samples, from 6 sets of biological replicates, were analyzed. 9 A/J and 9 C57BL/6 mice were divided into three equal groups. All animals were sensitized to ovalbumin, one group received PBS aerosol challenges, the other two received 1% ovalbumin aerosol challenges. Of the two ovalbumin challenged groups, one recieved resiquimod 24hours before each challenge.

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Gene expression profiling of experimental asthma reveals a possible role of paraoxonase-1 in asthma

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