Zanthoxylum zanthoxyloides inhibits lipopolysaccharide- and synthetic hemozoin-induced neuroinflammation in BV-2 microglia: roles of NF-κB transcription factor and NLRP3 inflammasome activation

Objectives The effects of a root extract of Zanthoxylum zanthoxyloides on neuroinflammation in BV-2 microglia stimulated with LPS and hemozoin were investigated. Methods ELISA, enzyme immunoassay and Griess assay were used to evaluate levels of cytokines, PGE(2) and NO in culture supernatants, respectively. Microglia-mediated neurotoxicity was evaluated using a BV-2 microglia-HT-22 neuron transwell co-culture. Key findings Treatment with Z. zanthoxyloides caused reduced elevated levels of TNF alpha, IL-6, IL-1 beta, NO and PGE(2), while increasing the levels of IL-10. In addition, there were reduced levels of iNOS and COX-2 proteins. This was accompanied by a prevention of microglia-mediated damage to HT-22 mouse hippocampal neurons. Z. zanthoxyloides reduced elevated levels of phospho-I kappa B and phospho-p65, while preventing degradation of I kappa B protein and DNA binding of p65. Further mechanistic studies revealed that Z. zanthoxyloides reduced the levels of pro-IL-1 beta and IL-1 beta in hemozoin-activated BV-2 microglia. This was accompanied by a reduction in caspase-1 activity and NLRP3 protein expression. Bioassay-guided fractionation resulted in the isolation of skimmianine as an anti-inflammatory compound in Z. zanthoxyloides. Conclusion This is the first report showing the inhibition of neuroinflammation in LPS- and hemozoin-activated BV-2 microglia by the root extract of Z. zanthoxyloides by targeting the activation of both NF-kappa B and NLRP3 inflammasome.

Automated summary

The root extract of Zanthoxylum zanthoxyloides has shown effectiveness in reducing neuroinflammation in BV-2 microglia stimulated with LPS and hemozoin by regulating cytokine levels, inhibiting iNOS and COX-2 proteins, and preventing microglia-mediated damage to neurons. The extract targets NF-kappa B and NLRP3 inflammasome activation, and skimmianine was identified as an anti-inflammatory compound in Z. zanthoxyloides.