Decreased microRNA 16 and 451a expression in hypertrophic adenoid tissue is associated with allergy

Introduction
MicroRNAs (miRNAs) regulate gene expression and play a role in many biological processes. Their imbalance may result in the development of numerous diseases, including allergy. Exact mechanisms causing allergic inflammation are still unclear, but recent studies show that miRNAs are involved in its pathogenesis. Adenoid hypertrophy (AH) and allergy often coexist, although the reason for that is still being investigated.

Aim
To compare the expression of several miRNAs in adenoid tissue and nasal mucosa from children with and without allergy and to investigate whether miRNA levels correlate with the patient’s allergy status.

Material and methods
Samples were taken from 37 patients and divided into two groups: allergic and non-allergic subjects. MiRNA was isolated from the adenoid tissue and nasal swabs collected during the adenoidectomy procedure, and transcribed into cDNA. MiRNA expression was measured with TaqMan MicroRNA Assays and analyzed with DataAssist software.

Results
MiR-16 and miR-451a expression was significantly decreased in the adenoid tissue of allergic children. Other miRNAs were not different between allergic and non-allergic patients. The expression of miRNA in the nasal mucosa did not differ between allergic and non-allergic patients.

Conclusions
MiRNAs are present in the adenoid tissue and have a distinct expression pattern in allergic patients compared to controls. This suggests that the molecular mechanism of AH formation in allergic patients is different and might explain why the allergy affects the prevalence of AH. Further studies are needed to better understand the role of miRNAs in the induction of allergic-type inflammation.