Mogroside V attenuates inflammatory responses by modulating the miR-448-3p/ELL2/PDE4A axis in vitro

Various studies have revealed that natural compounds exert their bioactivities through regulation some miRNA expression. Our previous work demonstrated that Mogroside V (MV) exerts anti-inflammatory effects by downregulating miR-21-5p in LPS-stimulated RAW264.7 macrophages. Our miRNA-seq data implicate miR-448-3p as a potential mediator of the anti-inflammatory effects of MV. Functional inhibition of miR-448-3p exacerbated conditioned medium (CM)-induced inflammatory responses and diminished the protective effects of MV. However, the underlying mechanism by which miR-448-3p mediates the anti-inflammatory effects of MV remains unclear. Integrated target prediction and mRNA-seq analysis identified elongation factor for RNA polymerase II 2 (ELL2) as a candidate target of miR-448-3p, which was further validated by a dual-luciferase reporter assay. Knockdown of ELL2 not only decreased inflammatory cytokines levels but also enhanced the anti-inflammatory effects of MV in the macrophage-epithelial cell model. Further bioinformatic analysis highlighted Phosphodiesterase 4 A (PDE4A) as a potential downstream effector associated with ELL2. ELL2 overexpression reversed the downregulation of PDE4A by MV. ChIP assays demonstrated enrichment of ELL2 at a predicted PDE4A-associated region, suggesting a potential association between ELL2 and PDE4A expression regulation. Moreover, miR-448-3p overexpression enhanced the inhibitory effects of MV on the ELL2/PDE4A axis and augmented its anti-inflammatory effects whereas these effects were attenuated by PDE4A overexpression. In summary, MV attenuates CM-induced inflammatory responses through miR-448-3p/ELL2/PDE4A axis in vitro, which provides new insights into the molecular mechanisms underlying the anti-inflammatory effects of MV.