Dimethyl fumarate modulates antioxidant and lipid metabolism in oligodendrocytes

Abstract

Oxidative stress contributes to pathology associated with inflammatory brain disorders and therapies that upregulate antioxidant pathways may be neuroprotective in diseases such as multiple sclerosis. Dimethyl fumarate, a small molecule therapeutic for multiple sclerosis, activates cellular antioxidant signaling pathways and may promote myelin preservation. However, it is still unclear what mechanisms may underlie this neuroprotection and whether dimethyl fumarate affects oligodendrocyte responses to oxidative stress. Here, we examine metabolic alterations in oligodendrocytes treated with dimethyl fumarate by using a global metabolomic platform that employs both hydrophilic interaction liquid chromatography-mass spectrometry and shotgun lipidomics. Prolonged treatment of oligodendrocytes with dimethyl fumarate induces changes in citric acid cycle intermediates, glutathione, and lipids, indicating that this compound can directly impact oligodendrocyte metabolism. These metabolic alterations are also associated with protection from oxidant challenge. This study provides insight into the mechanisms by which dimethyl fumarate could preserve myelin integrity in patients with multiple sclerosis.

Keywords: Hydrophilic interaction liquid chromatography; Metabolomics; Neuroprotection; Oligodendrocyte; Shotgun lipidomics.

Graphical abstract

Fig. 1

DMF treatment alters oligodendrocyte metabolism. Principal component analysis of the metabolic alterations associated with 10 µM DMF treatment at 24 (A) and 72 h (B). (C) Box and whisker plot of glutamine, showing significant upregulation after 24 h treatment (p=0.002, q=0.007), but a return to control levels by 72 h (p=0.89, q=0.13). (D) Box and whisker plot of arginine, which is increased at 24 h (p=0.002, q=0.05), but downregulated after 72 h of DMF treatment (p=0.02; q=0.012). *q-value <0.05, **q-value <0.01; N=6 replicates per group, representative of two separate experiments.

Fig. 2

DMF treatment perturbs TCA cycle metabolism in oligodendrocytes. Box and whisker plots for succinate (A), fumarate (B), and malate (C) all showing upregulation after DMF treatment for 24 and 72 h compared to vehicle-treated controls (succinate p=0.004, q=0.009 at 24 h, p=0.046; q=0.021 at 72 h; fumarate p=0.017, q=0.020 at 24 h, p = 0.001, q=0.002 at 72 h; and malate p=0.002; q=0.003 at 24 h, p=0.020, q=0.040 at 72 h). *q-value <0.05, **q-value <0.01; N=6 replicates per group, representative of two separate experiments.

Fig. 3

DMF induces glutathione and protects oligodendroglial cells from oxidative stress. (A) Box and whisker plot of GSH levels after 24 and 72 h of treatment with 10 µM DMF. GSH is significantly increased at both time points (**q<0.01, p=0.0006, q=0.004 at 24 h and p=0.003, q=0.004 at 72 h). (B) MTT assay of MO3.13 cells treated with DMF for 24 h and exposed to 400 µM hydrogen peroxide for 2 h. Hydrogen peroxide-treated cells show a significant loss of viability compared to vehicle controls and DMF treatment at both 1 and 10 µM did not significantly alter this reduction in viability. (C) MTT assay of MO3.13 cells treated with DMF for 72 h and challenged with hydrogen peroxide. In contrast to vehicle-treated controls, hydrogen peroxide-treated cells show reduced viability that was rescued by pre-treatment with DMF. *p-value <0.05, Kruskal–Wallis test, N=12 replicates per group, experiment repeated 3 times.

Fig. 4

DMF treatment alters lipid metabolism in oligodendroglial cells. MO3. 13 cells were treated with DMF for 24 or 72 h and their lipids were analyzed by using shotgun lipidomics. (A) Lipid profile of MO3.13 cells after 24 h of DMF treatment. Decreased levels of PC (p<0.01) and SM (p<0.05) but increased PE (p<0.01), PI (p<0.01) species were detected. (B) Lipid profile of MO3.13 cells after 72 h of DMF treatment. Both PC (p<0.01) and SM (p<0.01) are significantly increased compared to vehicle controls. **p<0.01, *p-value <0.05, Kruskal–Wallis test, N=6 replicates per condition, repeated three times.