De-regulated expression of microRNAs contributes to augmented T helper (TH) cell activity in experimental asthma

Background: Bronchial asthma is a heterogeneous chronic inflammatory disease, which is orchestrated by antigen-specific TH cells. By secreting cytokines, these cells shape the augmented immune response, which finally leads to structural changes of chronic inflamed airways. MicroRNA (miRNA), as small non-coding RNAs, are recognized as key regulatory elements in gene expression and have been linked with a number of complex human chronic inflammatory diseases. Yet, their implication in augmented TH cell activity in asthma has not been thoroughly investigated. Methods: T helper cell were isolated from murine lungs in the progression of ovalbumin- induced allergic airway inflammation and profiled by FACS, microarray and real-time RT-PCR. Results: Effector T helper cell subsets were FACS-sorted and characterized based on gene, protein and miRNA expression. These data were employed to identify TH- cell subset specific gene and miRNA expression levels. In addition, changes in gene and miRNA levels in the progression of experimental asthma were identified. Conclusion: The generated data provide evidence for TH cell subset specific miRNA expression as well as augmented expression of miRNA in the progression of experimental asthma. Furthermore, they permit the identification of miRNA-dependent and independent signalling pathways in TH cell subset important for disease development.