TGF-β1 inhibits CXCL1/CXCR2 signaling pathway to alleviate neuropathic pain in a spinal nerve ligation rat model

Neuropathic pain (NPP) is a chronic and refractory condition resulting from injury or disease of the nervous system. This study aims to elucidate the molecular mechanism by which TGF-β1 alleviates neuropathic pain through modulation of the CXCL1/CXCR2 signaling pathway. A rat model of neuropathic pain was established via spinal nerve ligation (SNL). Mechanical allodynia and thermal hyperalgesia were assessed using electronic von Frey filaments and the plantar test, respectively. Histopathological changes, cellular apoptosis, and levels of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) in spinal cord tissues were evaluated using hematoxylin and eosin (H&E) staining, TUNEL assay, and enzyme-linked immunosorbent assay (ELISA). Bioinformatics analysis (based on the GSE24982 dataset), quantitative real-time PCR (qRT-PCR), Western blotting, immunofluorescence staining, and dual-luciferase reporter assays were employed to investigate the regulatory role of TGF-β1 in the CXCL1/CXCR2 pathway. The direct inhibitory effect of TGF-β1 on CXCL1 expression was confirmed using primary astrocyte cultures, while intrathecal administration of a CXCL1 neutralizing antibody or the CXCR2 antagonist SB225002 was used to assess the functional impact of pathway blockade. SNL induced significant mechanical allodynia and thermal hyperalgesia, accompanied by spinal cord tissue damage, increased neuronal apoptosis, and elevated levels of pro-inflammatory cytokines. Expression of CXCL1 and CXCR2 was markedly upregulated following SNL. Double-immunofluorescence staining and quantitative co-localization analysis showed that CXCL1 signals were associated with GFAP-positive regions, whereas CXCR2 signals were associated with NeuN-positive regions, suggesting possible involvement of the CXCL1/CXCR2 axis in glia-neuron signaling. In primary astrocytes, TGF-β1 treatment was associated with SMAD2/3 signaling and reduced CXCL1 promoter activity and expression. In vivo, TGF-β1 attenuated pain-related behaviors, apoptosis, and neuroinflammation, whereas CXCL1 administration partially reversed these protective effects. TGF-β1 attenuates SNL-induced neuropathic pain at least partly by suppressing CXCL1 expression and modulating a CXCL1/CXCR2 axis that may be involved in glia-neuron signaling.