Levo-tetrahydropalmatine ameliorates neuropathic pain by inhibiting the activation of the Clec7a-MAPK/NF-κB-NLRP3 inflammasome axis

Background: Because of the complex pathogenesis of neuropathic pain (NP), the therapeutic efficacy of existing drugs is not satisfactory. Accumulating studies have indicated that neuroinflammation may play a key role in NP onset and progression. Levo-tetrahydropalmatine (l-THP) has been extensively used for relieving chronic pain for decades. However, its potential mechanisms against NP have not yet been fully elucidated. Purpose: Exploring and elucidating the therapeutic effect and pharmacological mechanism of L-THP in treating NP. Methods: RNA-seq and bioinformatics analyses were carried out to identify effective target profiling of I-THP in chronic constrictive injury (CCI) rats. The I-THP related hub targets and signaling pathways were obtained via bioinformatics analysis, then subjected to in-depth analyses through experiments in vivo. A gain-of-function study further confirmed the role of Clec7a in L-THP-mediated pain relief. Finally, the interaction between LTHP and Clec7a was verified through molecular docking and surface plasmon resonance (SPR). Results: L-THP treatment effectively alleviated mechanical and thermal allodynia in NP model rats. Functionally, the I-THP effective targets were mainly enriched in inflammatory response-related pathways. Furthermore, Clec7a-MAPK/NF-kappa B-NLRP3 inflammasome axis was selected as one of the potential pathways of L-THP against NP. Mechanically, L-THP markedly reduced CCI-induced Clec7a overexpression, significantly inhibited the Clec7a-triggered phosphorylation of MAPK and NF-kappa B-p65, and decreased the expression of pyroptosis-related protein NLRP3 and Caspase-1-p20. The analgesic effect of L-THP on NP was partly eliminated when transfecting the overexpression vector virus pLVSO5-Clec7a. Importantly, molecular docking and SPR data revealed that L-THP directly binds with the Clec7a protein. Conclusion: This study is the first to indicate that L-THP may exert an analgesic effect through inhibiting neuroinflammation via the Clec7a-MAPK/NF-kappa B-NLRP3 inflammasome axis, supporting the clinical utility of L-THP in NP therapy.