Unknown,Transcriptomics,Genomics,Proteomics

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DNA Methylation Changes in Allergic Patients Correlate with Symptom Severity [gene expression]

ABSTRACT: Altered DNA methylation patterns in CD4+ T-cells indicate the importance of epigenetic mechanisms in inflammatory diseases. However, the identification of these alterations is complicated by the heterogeneity of most inflammatory diseases. Seasonal allergic rhinitis (SAR) is an optimal disease model for the study of DNA methylation because of its well-defined phenotype and etiology. We generated genome-wide DNA methylation (Npatients = 8, Ncontrols = 8) and gene expression (Npatients= 9, Ncontrols = 10) profiles of CD4+ T-cells from SAR patients and healthy controls using Illumina’s HumanMethylation450 and HT-12 microarrays, respectively. DNA methylation profiles clearly and robustly distinguished SAR patients from controls, during and outside the pollen season. Moreover, we found that this methylation signature correlated with symptom severity. In agreement with previously published studies, gene expression profiles of the same samples failed to separate patients and controls. Separation by methylation (Npatients = 12, Ncontrols = 12), but not by gene expression (Npatients = 21, Ncontrols = 21) was also observed in an in vitro model system in which purified PBMCs from patients and healthy controls were challenged with allergen. We observed changes in the proportions of memory T-cell populations between patients (Npatients = 35) and controls (Ncontrols= 9), which could explain the observed difference in DNA methylation. Our data highlight the potential of epigenomics in the stratification of immune disease and represents the first successful molecular classification of SAR using CD4+ T cells. Total RNA was isolated from CD4+ T-cells of patients with seasonal allergic rhinitis and healthy controls both during and outside the pollen season. Total RNA was amplified and hybridized to Illumina HT12 version 4 human whole-genome arrays (Illumina, San Diego, CA).

ORGANISM(S): Homo sapiens

SUBMITTER: Colm Nestor

PROVIDER: E-GEOD-50101 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Analysis of gene-expression profiles by microarrays can be very useful to characterize new potential candidate genes, key regulatory networks, and to define phenotypes or molecular signatures to improve the diagnosis or classification of the disease. We have used this approach in the study of one of the major causes of allergic diseases in Mediterranean countries, the olive pollen response, in order to find differential molecular markers among five clinical groups, Non-allergic, Asymptomatic, Allergic but not to olive pollen, Non-treated, olive pollen allergic patients and Olive pollen allergic patients (under specific-immunotherapy). The results of gene-expression by principal components analysis (PCA) clearly showed five clusters of samples that correlated with the five clinical groups. Analysis of differential gene-expression by multiple testing, and functional analysis by KEGG and Gene-Ontology revealed differential genes and pathways among the 5 clinical groups. The study population comprised 28 subjects, selected from a previous immunological study (Aguerri et al. Eur. J. Inflammation 2012, in press), from Andalusia, who were recruited in 2 olive pollen exposure situations: during (April-June) and outside the pollen season (October-December). We established 5 groups, and 6 subjects from each group were selected for gene-expression analysis: Group 1, non-allergic subjects; Group 2, asymptomatic subjects (diagnosed with olive pollen allergy by skin testing, with no seasonal respiratory symptoms [rhinitis and/or asthma], and who consulted for adverse reaction to drugs); Group 3, patients who were allergic, but not to olive pollen; Group 4, non-treated olive pollenM-bM-^@M-^Sallergic; and Group 5, olive pollenM-bM-^@M-^Sallergic patients (receiving olive pollenM-bM-^@M-^Sspecific immunotherapy).The subjects were unrelated and recruited at the Allergy Service of 4 hospitals in Andalusia (Granada, JaM-CM-)n, Sevilla, and MM-CM-!laga). Olive pollenM-bM-^@M-^Sallergic patients fulfilled the following criteria: seasonal rhinitis and/or asthma from April to June, a positive skin prick test result for O. europaea pollen extract (ALK AbellM-CM-3, Madrid, Spain), and no previous immunotherapy. Informed consent was obtained from each subject. Ethical approval for the study was obtained from the Ethical and Research Committee of the participating hospitals. PBMCs were isolated from heparin-containing peripheral blood samples taken during and outside pollen season, by gradient centrifugation on Lymphoprep (Comercial Rafer, Zaragoza, Spain) following the manufacturerM-bM-^@M-^Ys instructions.

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DNA Methylation Changes in Allergic Patients Correlate with Symptom Severity [gene expression]

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