Gualou Guizhi Granule inhibits microglia-mediated neuroinflammation to protect against neuronal apoptosis in vitro and in vivo

Front Immunol. 2025 Jan 9:15:1527986. doi: 10.3389/fimmu.2024.1527986. eCollection 2024.

Abstract

Object: Neuroinflammation mediated by microglia has emerged as a critical factor in ischemic stroke and neuronal damage. Gualou Guizhi Granule (GLGZG) has been shown to suppress inflammation in lipopolysaccharide (LPS)-activated microglia, though the underlying mechanisms and its protective effects against neuronal apoptosis remain unclear. This study aims to investigate how GLGZG regulates the Notch signaling pathway in microglia to reduce neuroinflammation and protect neurons from apoptosis.

Method: Using in vitro and in vivo models, we explored GLGZG's impact on microglia activation, pro-inflammatory cytokines, and neuronal apoptosis. Microglial cells were activated with LPS, and primary neuronal cells were exposed to LPS-activated microglia to simulate neuroinflammation. Additionally, we investigated the effects of GLGZG in combination with N-[N-[3,5-difluorophenacetyl]-L-alanyl]-S-phenylglycine t-butyl ester (DAPT) or siRNA-Notch1 to further elucidate the involvement of the Notch signaling pathway.

Results: GLGZG significantly inhibited microglia activation and reduced neuroinflammation by de-creasing the levels of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α in both in vitro and in vivo models. GLGZG also effectively protected against microglia-induced neuronal apoptosis. Mechanistically, GLGZG down-regulated key components of the Notch signaling pathway, in-cluding Notch-1, NICD, RBPSUH, and Hes-1, in activated microglia. Combined treatment with GLGZG and DAPT or siRNA-Notch1 demonstrated enhanced inhibition of microglial activation and neuroinflammation.

Conclusion: Our findings reveal that GLGZG exerts its protective effects through the suppression of the Notch signaling pathway, thereby inhibiting microglia activation, reducing neuroinflammation, and safeguarding neurons from neuroinflammation-induced damage, offering potential as a therapeutic agent for ischemic stroke-induced neuroinflammation.

Keywords: Gualou Guizhi Granule; Notch; ischemic stroke; microglia; neuroinflammation.

MeSH terms

  • Animals
  • Apoptosis* / drug effects
  • Cells, Cultured
  • Cytokines / metabolism
  • Disease Models, Animal
  • Drugs, Chinese Herbal* / pharmacology
  • Drugs, Chinese Herbal* / therapeutic use
  • Lipopolysaccharides
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Microglia* / drug effects
  • Microglia* / metabolism
  • Neuroinflammatory Diseases* / drug therapy
  • Neuroinflammatory Diseases* / metabolism
  • Neurons* / drug effects
  • Neurons* / metabolism
  • Neurons* / pathology
  • Neuroprotective Agents / pharmacology
  • Neuroprotective Agents / therapeutic use
  • Receptors, Notch / metabolism
  • Signal Transduction* / drug effects

Substances

  • Drugs, Chinese Herbal
  • gua lou gui zhi
  • Cytokines
  • Neuroprotective Agents
  • Lipopolysaccharides
  • Receptors, Notch

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The National Natural Science Foundation of China (Grant No. 81803768 and 81873031), the Natural Science Foundation of Fujian Province, China (Grant No. 2024J01127, 2021J01926 and 2022J01864), and the school project of Fujian University of Traditional Chinese Medicine (Grant No. XJC2022009) supported this study.