lncRNA SNHG6 Knockdown Promotes Microglial M2 Polarization and Alleviates Spinal Cord Injury via Regulating the miR-182-5p/NEUROD4 Axis

Spinal cord injury (SCI) is one of the devastating neurological disorders that leads to a loss of motor and sensory functions. Long non-coding RNA small nucleolar RNA host gene 6 (lncRNA SNHG6) plays a crucial role in inflammatory regulation across various diseases. This study investigates the role of SNHG6 in SCI development and its underlying regulatory mechanisms. Two experimental models were established: an in vitro model using LPS-challenged (100 ng/mL) mouse microglia BV2 cells and an in vivo model employing controlled spinal cord impact in mice. SNHG6, miR-182-5p, and NEUROD4 expression levels were quantified through RT-qPCR and Western blot. Functional and histological assessments were performed using the Basso mouse scale (BMS) and Nissl staining, respectively. Putative binding sites between SNHG6 and miR-182-5p, as well as between miR-182-5p and NEUROD4, were predicted using the ENCORI/starBase platform. These molecular interactions were validated through dual-luciferase reporter assays and RNA pull-down experiments, with further confirmation by qRT-PCR and Western blot analyses. Both LPS-stimulated BV2 cells and spinal cord tissues from SCI mice exhibited elevated SNHG6 expression. Downregulation of SNHG6 enhanced LPS-induced polarization of BV2 cells from M1-type to M2-type, significantly modulated the expression of pro-inflammatory factors (TNF-α, IL-1β, and IL-6) and anti-inflammatory factors (TGF-β, IL-10, and IL-13), and reduced injury severity in SCI mice. Our mechanistic studies revealed that SNHG6 functions as a molecular sponge for miR-182-5p to regulate NEUROD4 expression. This study demonstrates that SNHG6 knockdown promotes microglial M2-type polarization and alleviates inflammatory responses through modulation of the miR-182-5p/NEUROD4 axis, suggesting SNHG6 as a potential therapeutic target for SCI treatment.