The extracts of Dracaena cochinchinensis stemwood suppress inflammatory response and phagocytosis in lipopolysaccharide-activated microglial cells

Abstract

BackgroundNeuroinflammation is a pivotal process in the brain that contributes to the development of neurodegenerative diseases, such as Alzheimer's disease (AD). During neuroinflammation, the over-activation of microglial cells can drive the pathological processes underlying AD, including an increase in amyloid β (Aβ) production and accumulation, ultimately leading to neuronal and synaptic loss. Dracaena cochinchinensis (Lour.) S.C. Chen, also known as “Chan-daeng” in Thai, belongs to the Asparagaceae family. In Thai traditional medicine, it has been used as an antipyretic, pain reliever, and anti-inflammatory agent. However, the effects of D. cochinchinensis on neuroinflammation are yet to be determined. PurposeWe aimed to evaluate the anti-neuroinflammatory activities of D. cochinchinensis stemwood extract in activated microglia. MethodsIn this study, lipopolysaccharide (LPS), a potent pro-inflammatory stimulus, was used to activate microglial BV2 cells, as a cell model of neuroinflammation. Our investigation included several techniques, including qRT-PCR, ELISA, Western blotting, phagocytosis, and immunofluorescence staining, to examine the potential anti-inflammatory effects of D. cochinchinensis stemwood. ResultsD. cochinchinensis stemwood, named DCS, was extracted with ethanol and water. The extracts of DCS showed dose-dependent anti-inflammatory effects, markedly suppressing the LPS-mediated mRNA expression of pro-inflammatory factors, including IL-1β, TNF-α, and iNOS, while increasing expression of the anti-inflammatory biomarker Arg1 in both BV2 microglia and RAW264.7 macrophages. DCS extracts also decreased the protein levels of IL-1β, TNF-α, and iNOS. These findings were correlated with the suppression of phosphorylated proteins of p38, JNK, and Akt in the LPS-activated microglia. Moreover, DCS extracts significantly attenuated excessive phagocytosis of beads and Aβ fibrils during the LPS-mediated microglial activation. ConclusionTaken together, our results indicated that DCS extracts had anti-neuroinflammatory properties by suppressing the expression of pro-inflammatory factors, increasing the expression of the anti-inflammatory biomarker Arg1, and modulating excessive phagocytosis in activated microglia. These findings suggested that DCS extract could be a promising natural product for the treatment of neuroinflammatory and neurodegenerative diseases, like AD.