Antineuroinflammatory and Neuroprotective Effects of Gyejibokryeong-Hwan in Lipopolysaccharide-Stimulated BV2 Microglia

Microglia, the central nervous system's innate immune cells, mediate neuroinflammation and are implicated in a variety of neuropathologies. The present study investigated the antineuroinflammatory and neuroprotective effects of Gyejibokryeong-hwan (GBH), a traditional Korean medicine, in lipopolysaccharide- (LPS-) stimulated murine BV2 microglia. BV2 cells were pretreated with GBH, fluoxetine (FXT), or amitriptyline (AMT) for 1 h and then stimulated with LPS (100 ng/mL). The expression levels of nitric oxide (NO), cytokines, and chemokines were determined by the Griess method, ELISA, or real-time PCR. Western blotting was used to measure various transcription factors and mitogen activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt activity. GBH significantly reduced the levels of NO, inducible nitric oxide synthase (iNOS), cyclooxygenase-(COX-) 2, tumor necrosis factor- (TNF-) alpha, interleukin- (IL-) 1 beta, IL-6, macrophage inhibitory protein- (MIP-) 1 alpha, macrophage chemoattractant protein- (MCP-) 1, and IFN-gamma inducible protein- (IP-) 10, regulated upon activation normal T cell expressed sequence (RANTES) in a dose-dependent manner. Expression of nuclear factor- (NF-) kappa B p65 was significantly decreased and phosphorylation of extracellular signal-regulated kinase (Erk), c-Jun NH2-terminal kinase (JNK), and PI3K/Akt by GBH, but not p38 MAPK, was decreased. Furthermore, production of anti-inflammatory cytokine IL-10 was increased and Heme oxygenase-1 (HO-1) was upregulated via the nuclear factor-E2-related factor 2 (NRF2)/cAMP response element-binding protein (CREB) pathway, collectively indicating the neuroprotective effects of GBH. We concluded that GBH may suppress neuroinflammatory responses by inhibiting NF-kappa B activation and upregulating the neuroprotective factor, HO-1. These results suggest that GBH has potential as anti-inflammatory and neuroprotective agents against microglia-mediated neuroinflammatory disorders.