Knockdown of DLGAP5 inhibits microglia activation in spinal cord injury rats through limiting NF-κB activation

Background: Microglia-mediated neuroinflammation plays a significant role in the pathogenesis of spinal cord injury (SCI). This study aimed to investigate the role of DLG associated protein 5 (DLGAP5) in SCI.

Methods: DLGAP5 expression was assessed in an SCI rat model using immunofluorescence, qRT-PCR, and Western blotting. SCI rats received an intraspinal injection of adeno-associated virus (AAV) carrying shDLGAP5, and then Basso-Beattie-Bresnahan (BBB) scale was recorded, inclined plate test was performed, as well as the spinal dorsal horn tissues were stained with hematoxylin-eosin (H&E) and Cresyl violet (for marking Nissl body). KEGG pathway analysis predicted DLGAP5-related signaling pathways. The impact of DLGAP5 on microglial activation and inflammation was evaluated in primary microglia and BV2 cells using Western blotting, immunofluorescence, and qRT-PCR following lipopolysaccharide (LPS) stimulation.

Results: SCI rats exhibited significant DLGAP5 upregulation relative to sham controls. Knocking down DLGAP5 enhanced neurological outcomes and functional recovery after SCI. This intervention concomitantly suppressed M1 microglial activation, as shown by decreased levels of Iba-1, iNOS, and pro-inflammatory cytokines (IL-1β, TNF-α, IFN-γ), alongside increased anti-inflammatory cytokine IL-10. KEGG analysis suggested DLGAP5 positively regulates the NF-κB pathway. Mechanistically, DLGAP5 knockdown decreased p65 phosphorylation, and in vitro experiments further demonstrated that DLGAP5 knockdown attenuated LPS-induced microglial activation and inflammation, an effect that was reversed by p65 overexpression.

Conclusion: DLGAP5 knockdown mitigates SCI by suppressing microglial activation through limiting NF-κB activation.