Upstream stimulating factor 2 aggravates neuropathic pain induced in spinal nerve ligation-induced mice via regulating SNHG5/miR-181b-5p.

Background: Upstream stimulating factor 2 (USF2) belongs to basic-Helix-Loop-Helix-Leucine Zipper transcription factor family, regulating expression of genes involved in immune response or energy metabolism network. Role of USF2 in neuropathic pain was evaluated.

Methods: Mice were intraspinally injected with adenovirus for knockdown of USF2 (Ad-shUSF2), and then subjected to spinal nerve ligation (SNL) to induce neuropathic pain. Distribution and expression of USF2 was detected by western blot and immunofluorescence. Mechanical and thermal pain sensitivity were examined by paw withdrawal thresholds (PWT) and paw withdrawal latency (PWL). Chromatin immunoprecipitation (ChIP) and luciferase activity assays were performed to detect binding ability between USF2 and SNHG5.

Results: The expression of USF2 was elevated and colocalized with astrocytes and microglia in L5 dorsal root ganglion (DRG) of SNL-induced mice. Injection of Ad-shUSF2 attenuated SNL-induced decrease of PWT and PWL in mice. Knockdown of USF2 increased level of IL-10, but decreased TNF-α, IL-1β, and IL-6 in SNL-induced mice. Silence of USF2 enhanced protein expression of CD206, while reduced expression of CD16 and CD32 in SNL-induced mice. USF2 bind to promoter of SNHG5, and weakened SNL-induced up-regulation of SNHG5. SNHG5 bind to miR-181b-5p, and miR-181b-5p to interact with CXCL5.

Conclusion: Silence of USF2 ameliorated neuropathic pain, suppressed activation of M1 microglia and inhibited inflammation in SNL-induced mice through regulation of SNHG5/miR-181b-5p/CXCL5 axis. Therefore, USF2/SNHG5/miR-181b-5p/CXCL5 might be a promising target for neuropathic pain. However, the effect of USF2/SNHG5/miR-181b-5p/CXCL5 on neuropathic pain should also be investigated in further research.