Abstract
BACKGROUND: Identification of molecular markers, such as miRNAs is promising for the diagnosis of asthma and its clinical phenotypes. The aim of this study was to examine the changes in the expression of selected microRNAs in plasma exosomal fractions of severe asthma patients. The expression of miRNAs was determined in relation to the changes in inflammatory markers. METHOD: Severe asthma patients (n = 30) and healthy subjects (n = 30) were selected among the individuals referred to asthma and allergy clinic. Blood was collected from each participant to determine the serum high-sensitive C-reactive protein (hs-CRP) and total IgE. The exosomal fraction of plasma was isolated and processed for quantitation of miR-124, miR-125b, miR-133b, miR-130a and miR-125b-1-3p expression using quantitative real time-PCR (qRT-PCR). RESULTS: Serum hs-CRP and total IgE were significantly higher in asthma patients compared to controls. Expression of miR-124, miR-133b, and miR-130a was down-regulated in asthma patients as compared to controls (p < 0.0001). However, the expression of miR-125b was substantially higher in patients compared to controls (p < 0.0001). There was no significant difference in the expression of miR-125b-1-3p in the patients and controls. Data analysis revealed that among the miRNAs, changes in miR-125b in severe asthma patients were highly correlated with the serum levels of hs-CRP and IgE. CONCLUSION: Overexpression of miR-125b in severe asthma which was associated with serum IgE and hs-CRP may suggest that this molecule is linked to inflammatory reactions. Up-regulation of miR-125b together with decreased expression of miR-124, miR-133b, and miR-130a may suggest that this miRNA profile is useful for diagnosis and discrimination of clinical phenotypes of asthma.