Abstract
Allergic inflammation is the foundation of allergic rhinitis and asthma. Although microRNAs are implicated in the pathogenesis of various diseases, information regarding the functional role of microRNAs in allergic diseases is limited. Herein, we reported that microRNA-302e (miR-302e) serves as an important regulator of allergic inflammation in human mast cell line, HMC-1 cells. Our results showed that miR-302e is the dominant member of miR-302 family expressed in HMC-1 cells. Moreover, the expression of miR-302e was significantly decreased in response to phorbol 12-myristate 13-acetate (PMA) and calcium ionophore A23187 or ovalbumin (OVA) stimulation. Overexpression of miR-302e blocked PMA/A23187 or OVA induced the increase in inflammatory cytokines levels, such as IL-1β, IL-6, tumor necrosis factor (TNF)-α and thymic stromal lymphopoietin, while miR-302 inhibition further promoted the release of these cytokines. Mechanistically, we found that miR-302e is a novel miRNA that targets RelA, a gene known to be involved in regulating inflammation, through binding to the 3'-UTR of RelA mRNA. Ectopic miR-302e remarkably suppressed the luciferase activity and expression of RelA, whereas down-regulation of miR-302e increased RelA luciferase activity and expression. Pharmacological inhibition of NF-κB reversed the augmented effect of miR-302e down-regulation on inflammatory cytokines level. Taken together, the present study demonstrates miR-302e limits allergic inflammation through inhibition of NF-κB activation, suggesting miR-302e may play an anti-inflammatory role in allergic diseases and function as a novel therapeutic target for the treatment of these diseases.