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:Humans vary markedly in their propensity to develop asthma, despite often being exposed to similar environmental stimuli. Similarly, mouse strains vary in susceptibility to airways pathology in experimental asthma. Sensitization and aerosol challenge with ovalbumin (OVA) induces eosinophil accumulation, mucus production and airways obstruction in BALB/c and C57BL/6 mice. In contrast, CBA/Ca mice show relatively little pathology. Allergen-induced production of IL-4, IL-5, IL-10 and IFN-g was detected in all three strains, with BALB/c mice generating the highest levels of IL-4, IL-5 and IL-10. Microarray analysis was used to identify genes differentially regulated in lung tissue after OVA challenge. Differentially regulated genes in the lungs of the asthma-susceptible C57BL/6 and BALB/c strains numbered 242 and 145, respectively, whereas only 42 genes were differentially expressed in the resistant CBA/Ca strain. In C57BL/6 mice, transcripts were enriched for adhesion molecules and this was associated with high levels of eosinophil recruitment. Differentially regulated genes in the lungs of only the asthma-susceptible strains numbered 64 and several of these have not previously been associated with asthma. Many of the genes differentially regulated in the susceptible strains were enzymes involved in inflammation. Using network analysis, mRNA for the anti-apoptotic protein survivin was found to be up-regulated in the lungs following allergen challenge. Survivin mRNA and protein were also expressed at high levels in eosinophils recovered by bronchoalveolar lavage from BALB/c and C57BL/6 mice. We propose that rapid apoptosis of lung eosinophils due to low expression of survivin contributes to the limitation of pathology in CBA/Ca mice Humans vary markedly in their propensity to develop asthma, despite often being exposed to similar environmental stimuli. Similarly, mouse strains vary in susceptibility to airways pathology in experimental asthma. Sensitization and aerosol challenge with ovalbumin (OVA) induces eosinophil accumulation, mucus production and airways obstruction in BALB/c and C57BL/6 mice. In contrast, CBA/Ca mice show relatively little pathology. Allergen-induced production of IL-4, IL-5, IL-10 and IFN-g was detected in all three strains, with BALB/c mice generating the highest levels of IL-4, IL-5 and IL-10. Microarray analysis was used to identify genes differentially regulated in lung tissue after OVA challenge. Differentially regulated genes in the lungs of the asthma-susceptible C57BL/6 and BALB/c strains numbered 242 and 145, respectively, whereas only 42 genes were differentially expressed in the resistant CBA/Ca strain. In C57BL/6 mice, transcripts were enriched for adhesion molecules and this was associated with high levels of eosinophil recruitment. Differentially regulated genes in the lungs of only the asthma-susceptible strains numbered 64 and several of these have not previously been associated with asthma. Many of the genes differentially regulated in the susceptible strains were enzymes involved in inflammation. Using network analysis, mRNA for the anti-apoptotic protein survivin was found to be up-regulated in the lungs following allergen challenge. Survivin mRNA and protein were also expressed at high levels in eosinophils recovered by bronchoalveolar lavage from BALB/c and C57BL/6 mice. We propose that rapid apoptosis of lung eosinophils due to low expression of survivin contributes to the limitation of pathology in CBA/Ca mice Changes in gene expression in the lungs of 4 individual of BALB/c mice challenged with OVA were monitored using the lungs of 4 individual BALB/c mice challenged with PBS as the control. The microarray analysis was performed in quadruplicate. Changes in gene expression in the lungs of 4 individual of CBA/Ca mice challenged with OVA were monitored using the lungs of 4 individual CBA/Ca mice challenged with PBS as the control. The microarray analysis was performed in quadruplicate. Changes in gene expression in the lungs of 4 individual of BALB/c mice challenged with OVA were monitored using the lungs of 4 individual CBA/Ca mice challenged with OVA as the control. The microarray analysis was performed in quadruplicate. Twelve dual channel microarray slides were used in the overall design of this experiment.

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Effects of OVA challenge in mouse model of asthma

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