Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of Microbiology and Immunology

Bronchial asthma is an airway chronic disease characterized by Th2 inflammatory response and tissue remodeling after exposure to inhaled allergens. MicroRNAs (miRNAs) are short non-coding RNAs that are important regulators of gene expression of different immunological molecules. However, the role of miRNAs, specifically miRNA-21 and miRNA-155, in the regulation of allergic airway inflammation is unexplored. The aim of this study was to compare the serum expression levels of miRNA-21 and miRNA-155 in asthmatic patients with that of healthy controls and to correlate their levels with serum IL-4 levels. The study was conducted on 30 asthmatic patients and 30 healthy individuals who served as the control group. The expression levels of miRNA-21 and miRNA-155 were evaluated in the serum of both groups by quantitative reverse transcription PCR while serum levels of IL-4 were determined using the ELISA technique. Asthmatic patients showed significantly higher serum miRNA-21 (P < 0.001) and miRNA-155 (P < 0.001) expression levels and higher serum IL-4 levels (P < 0.001) compared to the controls. There was a statistically significant positive correlation between the expression levels miRNA-21 and IL4 serum levels in the asthmatic patients (rs = 0.609, P = < 0.001). However, no correlation was detected between the expression levels miRNA-155 and each of IL-4 (rs = 0.278, P = 0.136) and miRNA-21 (rs = 0.188, P = 0.321). MiRNA-21 and miRNA-155 are potential non-invasive biomarkers in asthma diagnosis and response to therapy. The effect of miRNA-21 and miRNA-155 on Th2 response and cytokine production can be mediated by different pathways. Further studies are required to investigate the role of miRNA-21 and miRNA-155 in the pathogenesis of different asthma phenotypes

Issued also as CD