Dimethyl Fumarate and Monoethyl Fumarate Exhibit Differential Effects on Glutathione, Keap1 and Nrf2 Activation In Vitro (P1.204)

OBJECTIVE: To evaluate the effects of dimethyl fumarate (DMF) and monoethyl fumarate (MEF) on glutathione conjugation, Keap1 modification and activation of the Nrf2 pathway. BACKGROUND: Delayed-release DMF is approved in the U.S., Canada, and Australia for the treatment of multiple sclerosis. DMF is also one component of combination product with 3 different salts of MEF, and this combination is approved in Germany for the treatment of psoriasis. Previous studies have demonstrated the pharmacologic properties of DMF; however the properties of MEF have been under explored. Characterizing the pharmacodynamic properties of DMF and MEF will provide important insights into the mechanisms of action for delayed-release DMF versus combination products containing DMF and MEF salts. DESIGN/METHODS: DMF and MEF were applied to HEK293 cells expressing Keap1. Keap1 was immunopurified, digested and resultant peptides were analyzed by mass spectrometry to identify specific peptides modified by treatment. Primary human astrocytes were treated with DMF or MEF, and cellular glutathione was measured over 24 hours and cells were also analyzed for pharmacodynamic responses by reverse transcription polymerase chain reaction. RESULTS: DMF treatment resulted in a robust modification of specific cysteine residues in Keap1, an Nrf2 chaperone protein. MEF similarly modified Keap1, but the overall degree was significantly less. DMF produced an acute concentration-dependent depletion of glutathione; however levels recovered and rose above baseline by 24 hours. MEF did not cause acute reductions in glutathione, but did produce an increase by 24 hours. Consistent with Keap1 modification, DMF produced a robust transcriptional response in treated cells as did MEF, however the responses to MEF were of a lower magnitude. CONCLUSIONS: These studies demonstrate that DMF and MEF are both pharmacologically active, but have differing degrees of activities in multiple assay formats. These differences would be expected to result in divergent effects on downstream biology. Study Supported by: Biogen Idec Inc. Disclosure: Dr. Scannevin has received personal compensation for activities with Biogen Idec as an employee. Dr. Scannevin holds stock and/or stock options in Biogen Idec which sponsored research in which Dr. Scannevin was involved as an investigator. Dr. Brennan has received personal compensation for activities with Biogen Idec as an employee. Dr. Matos has received personal compensation for activities with Biogen Idec as an employee. Dr. Hronowski has received personal compensation for activities with Biogen Idec as an employee. Dr. Gao has received personal compensation for activities with Biogen Idec as an employee. Dr. Juhasz has received personal compensation for activities with Biogen Idec as an employee. Dr. Rhodes has received personal compensation for activities with Biogen Idec as an employee. Dr. Rhodes has received research support from Biogen Idec.