Paeoniflorin regulates microglia-astrocyte crosstalk, inhibits inflammatory response, and alleviates neuropathic pain through HSP90AA1/HMGB1 signaling pathway.

Given the unclear, complex pathogenesis of neuropathic pain and the potential of paeoniflorin in relieving neuropathic pain, this study aimed to further clarify the therapeutic effect of paeoniflorin on neuropathic pain and to preliminarily explore the possible protective mechanisms of paeoniflorin. Chronic constrictive injury-induced Sprague Dawley rats and lipopolysaccharide-induced BV-2 cells were used for in vivo and in vitro experiments, respectively. The exosome uptake assay of mouse astrocytes (PKH-67 fluorescent labeling) and the mechanical nociceptive assay (the von Frey fibrous filaments) were performed. The effects of paeoniflorin and its downstream mechanisms on microglial and astrocyte activation, inflammation-associated proteins and exosome marker were determined. Paeoniflorin alleviated mechanical abnormal pain, decreased levels of ionized calcium binding adapter molecule-1 (Iba-1), glial fibrillary acidic protein, Heat Shock Protein 90 Alpha Family Class A Member 1 (HSP90AA1, inflammatory factor) and High Mobility Group Box 1 (HMGB1, inflammation-related protein), and inhibited neuronal apoptosis in chronic constrictive injury rats or lipopolysaccharide-induced BV-2 cells. However, these effects were offset by HSP90AA1 overexpression in lipopolysaccharide-induced BV-2 cells. Exosomes of BV-2 cells could be absorbed by mouse astrocytes. In addition, HSP90AA1 overexpression reversed the effects of paeoniflorin on HMGB1 expression and inflammatory factors and proteins in mouse astrocytes co-cultured with exosome. Collectively, paeoniflorin alleviates neuropathic pain and inhibits inflammatory responses in chronic constrictive injury by modulating microglia-astrocyte crosstalk through HSP90AA1/HMGB1 pathways, which further evidences the potential of paeoniflorin in the treatment of neuropathic pain.