Altered microRNA expression of nasal mucosa in long-term asthma and allergic rhinitis.

BACKGROUND: Asthma and allergic rhinitis (AR) commonly coexist and can be taken as manifestations of one syndrome. Evidence exists that microRNAs (miRNAs) are important in controlling inflammatory processes and they are considered promising biomarkers. However, little is known about the differences in miRNA expression in patients with chronic allergic airway disease. This study evaluated the inflammatory and miRNA profiles of the nasal mucosa of patients with long-term asthma with and without AR. METHODS: We analyzed inflammatory cells, cytokines, and miRNAs in nasal biopsies and measured exhaled and nasal nitric oxide levels during the nonpollen season in 117 middle-aged men who had suffered mainly from allergic asthma for approximately 20 years and also in 33 healthy controls. RESULTS: The differences in the number of nasal eosinophils and cytokine expression levels were modest in nasal biopsies taken from asthmatics. Downregulation of miR-18a, miR-126, let-7e, miR-155, and miR-224 and upregulation of miR-498, miR-187, miR-874, miR-143, and miR-886-3p were observed in asthmatic patients in comparison to controls. The differences in miRNA expression were mainly similar in asthmatics with and without AR. With regard to asthma severity, a trend of increased miRNA expression in persistent asthma was seen, whereas the downregulation of certain miRNAs was most distinct in nonpersistent-asthma patients. CONCLUSIONS: Differences in miRNA expression in the nasal mucosa of subjects with long-term asthma and AR can be seen also when no markers of Th2-type inflammation are detected. Asthma severity had only a minor impact on miRNA expression.