MicroRNA-133b Ameliorates Allergic Inflammation and Symptom in Murine Model of Allergic Rhinitis by Targeting Nlrp3

Background: Emerging evidences indicate that post-transcriptional regulation by microRNAs is critical in allergic rhinitis (AR) pathogenesis. MircroRNA-133b (miR-133b) was recently suggested as a potential predictor of AR. However, the in vivo effect of miR-133b on AR is unclear. Methods: AR model was established in BALB/c mice by intraperitoneal sensitization and intranasal challenge with ovalbumin (OVA). MiR-133b agomir was then intranasally administrated to mice after OVA challenge for another 7 days. The symptom of nasal rubbing and sneezing were recorded after the last OVA challenge. Nasal mucosa tissues and serum were collected. MiR-133b expression, serum OVA-specific immunoglobulin E (IgE) concentration, proinflammatory cytokines (TNF-α, IL-4, IL-5, IL-10 and IFN-γ) levels, and Nlrp3 inflammasome activation were measured by RT-PCR, ELISA, western blotting or immunohistochemistry, respectively. Histopathologic changes were evaluated using hematoxylin and eosin and Sirius red staining. The luciferase activity and protein expression of Nlrp3 were also determined. Results: MiR-133b expression was significantly decreased in nasal mucosa of AR mice, which was restored by nasal administration with miR-133b agomir. Upregulation of miR-133b markedly reduced the concentration of OVA-specific IgE, the frequencies of nasal rubbing and sneezing, and the levels of cytokines (TNF-α, IL-4, IL-5 and IFN-γ). Levels of IL-4, IL-5, IL-10 and IFN-γ produced by cervical lymph node cells were significantly lowered in miR-133b agomir-treated mice. Moreover, miR-133b also appeared to strongly attenuate pathological alterations and eosinophils and mast cells infiltration in nasal mucosa. Notably, we demonstrated for the first time that miR-133b negatively regulated Nlrp3 expression through binding with the 3’ untranslated region of Nlrp3. Consequently, infection of miR-133b in nasal mucosa remarkably suppressed the Nlrp3 inflammasome activation, as evidenced by reduced Nlrp3, Caspase-1, ASC, IL-18 and IL-1 expressions. Conclusion: MiR-133b alleviates allergic symptom in AR mice by inhibition of Nlrp3 inflammasome-meditated inflammation. These findings provide us an insight into the potential role of miR-133b in relation to AR treatment.