Magnolol attenuates depressive-like behaviors by polarizing microglia towards the M2 phenotype through the regulation of Nrf2/HO-1/NLRP3 signaling pathway.

Abstract

PURPOSE:

Magnolol (MA) exhibits anti-depressant effect by inhibiting inflammation. However, its effect on microglia polarization remains not fully understood. Herein, our study was performed to evaluate the effect of MA on microglia polarization in chronic unpredictable mild stress (CUMS)-induced depression and explore its potential mechanism.

STUDY DESIGN:

The CUMS procedure was conducted, and the mice were intragastrically treated with MA. BV2 cells were pretreated with MA prior to LPS/ATP challenge.

METHODS:

The levels of TNF-α, IL-1β, IL-6 and IL-4, IL-10 in brain and BV2 cells were examined by ELISA. The mRNA expressions of Arg1, Ym1, Fizz1 and Klf4 in brains were measured. ROS content was determined using flow cytometry. Immunofluorescence was employed to evaluate Iba-1 level, Nrf2 nuclear translocation, Iba-1+CD16/32+ and Iba-1+CD206+ cell population. The protein expressions of Nrf2, HO-1, NLRP3, caspase-1 p20 and IL-1β in brains and BV2 cells were investigated by western blot. Nrf2 siRNA was induced in experiments to explore the role of Nrf2 in MA-mediated microglia polarization. The ubiquitination of Nrf2 was visualized by Co-IP.

RESULTS:

The treatment with MA notably relieved depressive like behaviors, suppressed pro-inflammatory cytokines, promoted anti-inflammatory cytokines and the transcription of M2 phenotype microglia-specific indicators. MA upregulated the expression of Nrf2, HO-1, downregulated the expression of NLRP3, caspase-1 p20, IL-1β both in vivo and in vitro. MA also reduced ROS concentration, promoted Nrf2 nucleus translocation and prevented Nrf2 ubiquitination. Nrf2 Knockdown by siRNA abolished the MA-mediated microglia polarization.

CONCLUSION:

The present research demonstrated that MA attenuated CUMS-stimulated depression by inhibiting M1 polarization and inducing M2 polarization via Nrf2/HO-1/NLRP3 signaling.

• Authors: Weiwei Tao, Yuwen Hu, Zhaoyang Chen, Yuxin Dai, Yue Hu, Mingming Qi
• Journal: Phytomedicine : international journal of phytotherapy and phytopharmacology (Phytomedicine) Vol. 91 Pg. 153692 (Oct 2021) ISSN: 1618-095X [Electronic] Germany
• PMID: 34411834 (Publication Type: Journal Article)
• Copyright: Copyright © 2021. Published by Elsevier GmbH.

Chemical References

• Biphenyl Compounds
• Klf4 protein, mouse
• Kruppel-Like Factor 4
• Lignans
• Lipopolysaccharides
• Membrane Proteins
• NF-E2-Related Factor 2
• NLR Family, Pyrin Domain-Containing 3 Protein
• Nfe2l2 protein, mouse
• Nlrp3 protein, mouse
• magnolol
• Heme Oxygenase-1
• Hmox1 protein, mouse

Topics

• Animals
• Biphenyl Compounds (pharmacology)
• Cell Polarity
• Depression (drug therapy)
• Heme Oxygenase-1
• Kruppel-Like Factor 4
• Lignans (pharmacology)
• Lipopolysaccharides
• Membrane Proteins
• Mice
• Microglia (cytology, drug effects)
• NF-E2-Related Factor 2 (metabolism)
• NLR Family, Pyrin Domain-Containing 3 Protein
• Signal Transduction (drug effects)