Lithospermic acid targeting heat shock protein 90 attenuates LPS-induced inflammatory response via NF-кB signalling pathway in BV2 microglial cells

Microglia function as a vital constituent in the maintenance of brain homeostasis. Aberrant microglial activation, however, may contribute to neurodegenerative diseases. Lithospermic acid (LA) is a plant-derived polycyclic phenolic carboxylic acid isolated from Salvia miltiorrhiza. The present study investigated the potential effects of lithospermic acid on LPS-induced neuroinflammation in BV2 microglial cells and determined the mechanism of action of this compound. Cells were pre-treated with lithospermic acid for 1 h and incubated with LPS for 24 h. qPCR, immunofluorescence, and immunoblot assays were used to determine the expression of iNOS, COX2, NF-kappa B p65, and HSP90 expression. ELISA was employed to measure the production of pro-inflammatory cytokines. Lithospermic acid dramatically reduced LPS-stimulated cell migration and decreased NF-kappa B p65 nuclear translocation. Furthermore, lithospermic acid also markedly decreased the production of pro-inflammatory cytokines, including IL-6, IL-1 beta, and TNF-alpha in a dose-dependent manner. Additionally, lithospermic acid inhibited NO and PGE2 production in response to LPS, and it also inhibited the expression of iNOS and COX2 in a dose-dependent manner. Molecular docking and experimental verification have demonstrated that lithospermic acid inhibits the activity and expression of HSP90. Small interfering RNA knockdown of HSP90 expression, which abrogated LPS-induced inflammation. These findings suggest that the lithospermic acid targeting HSP90 attenuates LPS-induced inflammatory response via the NF-kappa B signalling pathway in BV2 microglial cells. Collectively, lithospermic acid may offer therapeutic benefits for neurodegenerative disorders associated with microglial activation and could serve as a potential inhibitor/agent for the treatment of neuroinflammation.