Short-term exposure to dimethyl fumarate (DMF) inhibits LPS-induced IκBζ expression in macrophages

Yong Zhang; Jingshu Tang; Yujun Zhou; Qiong Xiao; Qiuyu Chen; Hongyue Wang; Jiaqi Lan; Lei Wu; Ying Peng

doi:10.3389/fphar.2023.1114897

Short-term exposure to dimethyl fumarate (DMF) inhibits LPS-induced IκBζ expression in macrophages

Front Pharmacol. 2023 Feb 1:14:1114897. doi: 10.3389/fphar.2023.1114897. eCollection 2023.

Authors

Yong Zhang¹, Jingshu Tang¹, Yujun Zhou¹, Qiong Xiao¹, Qiuyu Chen¹, Hongyue Wang¹, Jiaqi Lan¹, Lei Wu¹, Ying Peng¹

Affiliation

¹ State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.

Abstract

Background: The pharmacological activity of dimethyl fumarate (DMF) in treating psoriasis and multiple sclerosis (MS) is not fully understood. DMF is hydrolysed to monomethyl fumarate (MMF) in vivo, which is believed to account for the therapeutic effects of DMF. However, previous studies have provided evidence that DMF also enters the circulation. Given that DMF is short-lived in the blood, whether DMF has a therapeutic impact is still unclear. Methods: Lipopolysaccharide (LPS)-mediated RAW264.7 cell activation was used as a model of inflammation to explore the anti-inflammatory effects of short-term DMF exposure in vitro. Whole blood LPS stimulation assay was applied to compare the anti-inflammatory effects of DMF and MMF in vivo. Griess assay was performed to examined nitrite release. The expression of pro-inflammatory cytokines and transcription factors were measured by quantitative PCR (qPCR), ELISA and Western blot. Depletion of intracellular glutathione (GSH) was evaluated by Ellman's assay. Luciferase reporter assays were performed to evaluate DMF effects on Nrf2-ARE pathway activation, promoter activity of Nfkbiz and mRNA stability of Nfkbiz. Binding of STAT3 to the IκBζ promoter were examined using Chromatin immunoprecipitation (ChIP) assay. Results: Short-term exposure to DMF significantly inhibited the inflammatory response of RAW264.7 cells and suppressed LPS-induced IκBζ expression. Importantly, oral DMF but not oral MMF administration significantly inhibited IκBζ transcription in murine peripheral blood cells. We demonstrated that the expression of IκBζ is affected by the availability of intracellular GSH and regulated by the transcription factor Nrf2 and STAT3. DMF with strong electrophilicity can rapidly deplete intracellular GSH, activate the Nrf2-ARE pathway, and inhibit the binding of STAT3 to the IκBζ promoter, thereby suppressing IκBζ expression in macrophages. Conclusion: These results demonstrate the rapid anti-inflammatory effects of DMF in macrophages, providing evidence to support the direct anti-inflammatory activity of DMF.

Keywords: IκBζ; Nrf2; anti-inflammation; dimethyl fumarate; macrophage.

Grants and funding

This project was supported by the grants from National Natural Sciences Foundation of China (No. 82073835 and 81872855), CAMS Innovation Fund for Medical Sciences (No. 2021-I2M-1–054), and Disciplines construction project (201920200802).