Paeonol Relieves Chronic Neuropathic Pain by Reducing Communication Between Schwann Cells and Macrophages in the Dorsal Root Ganglia After Injury

This study investigated the mechanism underlying Paeonol’s therapeutic efficacy against neuropathic pain. GSE158892 dataset data were used to conduct a scRNA-seq analysis. In cell experiments, Schwann cells and macrophages were utilized to examine pain pathogenesis using specific inhibitors. Thirty-two SD rats were randomly divided into four groups: sham, chronic constriction injury (CCI), ibuprofen, and Paeonol. Behavioral tests combined with ELISA, PCR, western blot, immunohistochemistry, and immunofluorescence analyses were conducted. CellChat analysis demonstrated that, following peripheral nerve injury, Schwann cells secreted IL-34, which interacted with CSF1R on macrophages, leading to the infiltration and activation of macrophages. Paeonol reduced IL-34 production by Schwann cells induced with LPS. Conditioned medium from LPS-stimulated Schwann cells treated with Paeonol did not cause macrophage proliferation or migration, activation of the CSF1 pathway, or ROS production. In CCI rats, Paeonol alleviated mechanical and cold hyperalgesia, while reducing the production of serum inflammatory mediators. Additionally, Paeonol decreased the expression levels of IL-34, CSF1R, phosphorylated ERK (p-ERK), phosphorylated NF-κB (p-NF-κB), and components of the NLRP3 inflammasome in the dorsal root ganglia of CCI rats. Conclusion: Alleviation of neuropathic pain by Paeonol treatment may be achieved by inhibiting the IL-34–CSF1R interaction, suppressing Schwann cell–macrophage interactions, and reducing DRG neuroinflammation.