# The Biflavonoid Agathisflavone Regulates Microglial and Astrocytic Inflammatory Profiles via Glucocorticoid Receptor

## TL;DR

Agathisflavone reduces inflammation in brain cells by interacting with glucocorticoid receptors, potentially offering new ways to treat neuroinflammation.

## Contribution

This study identifies the glucocorticoid receptor as a key mediator of agathisflavone's anti-inflammatory effects in glial cells.

## Key findings

- Agathisflavone increases microglial branching and reduces CD68/GFAP expression, effects blocked by a GR antagonist.
- Agathisflavone decreases pro-inflammatory IL-1β and increases regulatory IL-10, with the latter inhibited by GR antagonism.
- Molecular docking shows agathisflavone binds strongly to the glucocorticoid receptor compared to other ligands.

## Abstract

Nuclear receptors such as glucocorticoid receptors (GRs) are transcription factors with prominent regulatory effects on neuroinflammation. Agathisflavone is a biflavonoid that demonstrates neurogenic, neuroprotective, anti-inflammatory, antioxidant, and pro-myelinogenic effects in vitro. This study investigated whether the control of glial reactivity by agathisflavone is mediated by GRs. Primary cultures of astrocytes and microglia were induced to neuroinflammation by lipopolysaccharides (LPSs) and exposed to agathisflavone or not in the presence or absence of mifepristone, a GR antagonist. The microglia morphology and reactivity were evaluated by immunofluorescence against calcium-binding ionized adapter (Iba-1) and CD68. The astrocyte morphology and reactivity were evaluated by immunofluorescence against glial fibrillary acidic protein (GFAP). The inflammatory profile was evaluated by RT-qPCR. Molecular docking was performed to characterize agathisflavone and GR interactions. Microglial branching was increased in response to agathisflavone, an effect that was inhibited by mifepristone. CD68 and GFAP expression was decreased by agathisflavone but not in the presence of mifepristone. Agathisflavone decreased the expression of the pro-inflammatory cytokine IL-1β and increased the expression of the regulatory cytokine IL-10. The increase in IL-10 mRNA was inhibited by the GR antagonist. The in silico analysis showed that agathisflavone binds to a pocket at the glucocorticoid receptor. These interactions were stronger than mifepristone, dexamethasone, and the agathisflavone monomer apigenin. These results indicate that the GR is involved in the regulatory effects of agathisflavone on microglia and astrocyte inflammation, contributing to the elucidation of the molecular mechanisms of agathisflavone’s effects in the nervous system.