Downregulation of lncRNA NEAT1 Ameliorates LPS-Induced Inflammatory Responses by Promoting Macrophage M2 Polarization via miR-125a-5p/TRAF6/TAK1 Axis

The lncRNA nuclear enriched abundant transcript 1 (NEAT1) promotes sepsis-inflammatory responses and acute kidney injury (AKI), but little known about the underlying mechanisms. This study aims to investigate the roles of NEAT1 in regulating macrophage polarization and its potential for alleviating inflammatory responses during sepsis pathogenesis. Mouse RAW264.7 macrophages were treated with lipopolysaccharide (LPS) as a cellular inflammatory model. NEAT1 shRNA, miR-125a-5p mimics, and TRAF6-overexpressing vector were used to transfect RAW264.7 cells. NEAT1, miR-125a-5p, and mRNA levels of functional genes were detected by quantitative RT-PCR. Protein abundances were analyzed by western blotting. Macrophage polarization was evaluated by flow cytometry. The bindings of miR-125a-5p with NEAT1 or TRAF6 gene were validated by dual luciferase reporter assay. LPS treatment promoted NEAT1 and suppressed miR-125a-5p expression in mouse macrophage cells. NEAT1 silencing by shRNAs promoted macrophage M2 polarization under LPS treatment, which upregulated miR-125a-5p expression, repressed TRAF6 expression and TAK1 protein phosphorylation in macrophages. These cellular and molecular changes induced by NEAT1 shRNAs were abrogated by miR-125a-5p inhibitors. Moreover, miR-125a-5p mimics suppressed TRAF6 expression and TAK1 protein phosphorylation in LPS-treated macrophages, thus causing macrophage M2 polarization under LPS treatment. TRAF6 overexpression abrogated the miR-125a-5p mimics-induced macrophage M2 polarization. miR-125a-5p could directly bind to NEAT1 or TRAF6 gene in macrophages. lncRNA NEAT1 knockdown ameliorates LPS-induced inflammation by promoting macrophage M2 polarization via miR-125a-5p/TRAF6/TAK1 axis.