Fig 2: Lyn inhibitor Bafetinib intrathecally alleviated pain hyperalgesia in CCI mice. (A) Mechanical withdraw frequencies to 0.07 g after single intrathecal administration of different doses of Bafetinib on CCI mice; (B) mechanical withdraw frequencies to 0.4 g after single intrathecal administration of different doses of Bafetinib on CCI mice; (C) thermal pain thresholds after single intrathecal administration of different doses of Bafetinib on CCI mice; (D) mechanical withdraw frequencies to 0.07 g after continuous Bafetinib intrathecally on CCI mice; (E) mechanical withdraw frequencies to 0.4 g after continuous Bafetinib intrathecally on CCI mice; (F) Thermal pain thresholds after continuous Bafetinib intrathecally on CCI mice.

Fig 3: GEO database reanalysis showed the correlation between Lyn and inflammatory factors in neuropathic pain. (A) The expression levels of gene Lyn and Atf3 (a marker of nerve injury); (B) the correlation between Lyn and Atf3; (C) Lyn-based co-expression network analysis of the immune-related transcriptome. The purple nodes represent Lyn gene, and the pink nodes represent immune-related gene. The edges in red indicates upregulation, and blue indicates downregulation; (D) the GO analysis results of these co-expressed inflammatory factors; (E) the KEGG pathway enrichment results of these co-expressed inflammatory factors; (F) the correlation between Lyn and proinflammatory factors (IL-6 and IL-1ß), anti-inflammatory factor Arg1.

Fig 4: Chronic nerve injury induces the increased expression and phosphorylation of Lyn to mediate IRF5 phosphorylation and nuclear translocation in microglia. Nuclear phosphorylated IRF5 promotes the binding of transcription factors SP1, PU.1 to glycolytic gene promoters and enhances glycolysis of microglia, resulting in the increased production of lactate and other metabolites. Lactate facilitates the proliferation and pro-inflammatory phenotype transition of microglia to release inflammatory factors such as TNF, IL-1ß, HIF-1a, PGE2, which contributes vitally to M1 polarization and neruoinflammation. Lactate and other metabolites also facilitates the sEPSC of the postsynaptic neuron. Neruoinflammation and strengthened sEPSC both promote the progression of neuropathic pain. IRF5, interferon regulatory factor 5; TNF, tumour necrosis factor; IL-1ß, interleukin 1ß; HIF-1a, hypoxia inducible factor-1a; PGE2, prostaglandin E2; sEPSC, spontaneous excitatory postsynaptic currents.

Fig 5: Lyn facilitated the nuclear translocation of IRF5. (A) Representative images of protein expressions of n-p-IRF5, n-IRF5, cy-p-IRF5, cy-IRF5 after Bafetinib and siRNA-lyn intrathecally in CCI mice; (B) statistical analysis of protein expressions of n-p-IRF5, n-IRF5, cy-p-IRF5, cy-IRF5 after Bafetinib and siRNA-lyn intrathecally in CCI mice; (C) representative images of protein expressions of n-p-IRF5, n-IRF5, cy-p-IRF5, cy-IRF5 after Bafetinib and siRNA-lyn administration in cultured primary microglia; (D) statistical analysis of protein expressions of n-p-IRF5, n-IRF5, cy-p-IRF5, cy-IRF5 after Bafetinib and siRNA-lyn administration in cultured primary microglia.