Expression of miRNA 155, FOXP3 and ROR gamma, in children with moderate and severe atopic dermatitis.

BACKGROUND: Atopic dermatitis is a disease characterized by a chronic inflammatory process in the skin, but its link to miRNA 155 is less known. The aim of the study was to evaluate the expression of microRNA155, and T helper type 17 cells and Treg cells in children with atopic dermatitis.

METHODS: The study population consisted of: children seen for atopic dermatitis at the outpatient ambulatory of Dermatology at the Children Hospital Regina Margherita, Torino, Italy,( n = 23); healthy control subjects ( n =23). Blood samples were taken during routine control analysis and the expression of miRNA 155 and the production of FOXP3 and RORˠ was determined using PCR real time.

RESULTS: The analysis of miR-155 shows that the over-expression of miR-155 is statistically significant (p = 0.0040) in the group of patients with atopic dermatitis compared to the healthy control group. Analysis of mRNAs of FOXP3 and RORˠ shows a FOXP3 mRNA expression statistically higher in the group of patients (p = 0.0057). The Th17 / Treg ratio is significantly smaller in patients with atopic dermatitis (p = 0.0012). Also the ratio miR-155/Th17/Treg is larger in the group of patients with atopic dermatitis (p = 0.0002).

CONCLUSIONS: Our results suggest that increased miR-155 and FOXP3 and RORˠ responses may provide a link to immune dysregulation associated with atopic dermatitis. Although a point-by-point correlation between miR-155 and the ratio Th17/Treg is not demonstrated, our findings shows that these two elements do not appear to be completely unrelated to each other.