Effective inhibition of miR-330/SHIP1/NF-κB signaling pathway via miR-330 sponge repolarizes microglia differentiation

Neuroinflammation mediated by microglia has been identified as a vital pathogenesis in Parkinson's disease (PD). This study aimed to investigate the role and potential regulatory mechanism of microRNA-330 in the LPS-induced chronic neuroinflammatory model. Primary microglia chronic inflammation model and PD animal model were established by LPS treatment. Bulged microRNA-330 sponges containing 6 microRNA binding sites were constructed and delivered by plasmid or rAAV2/5-GFP vector. The expression levels of microRNA-330 were assessed by RT-qPCR. Primary microglia polarization was determined by flow cytometry, meanwhile, dopamine and pro-(anti-)inflammatory cytokines were measured by ELISA. Expression levels of GFAP, lba1, iNOS, Arg1, SHIP1, cytoplasmic and nuclear NF-κB were analyzed by Western blot. The behavioral deficit was determined by the rotarod test. The expression of microRNA-330 increased in the first 4 days and reached a plateau subsequently after LPS treatment. The sponges-mediated repression effect on M1 polarization were gradually enhanced with time. Treatment of miR-330 sponges increased the SHIP1 and Arg1 expression, and decreased the translocation of NF-κB and iNOS expression, suggesting the repression of inflammation. In the LPS-induced PD mice, administration of rAAV-Sponge-GFP suppressed activation of microglia, downregulated pro-inflammatory cytokines, resumed the secretion of dopamine, rescued the dopaminergic neurons, and alleviated motor dysfunction. Our results demonstrated that microRNA-330 sponges could sustainably suppress LPS-induced polarization of microglia both in vivo and in vitro probably by negatively regulating NF-κB activity via target SHIP1 in microglia, which might be a promising neuroprotective strategy in neurological diseases, such as PD. This article is protected by copyright. All rights reserved.