Dimethyl Fumarate Suppresses Inflammation In Vitro Via Both Nrf2-Dependent and Nrf2-Independent Pathways (P02.108)

Objective: To investigate if the active ingredient of BG-12 (dimethyl fumarate [DMF]) inhibits macrophage inflammation in vitro via nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-dependent and/or Nrf2-independent pathways. Background BG-12 is in Phase 3 development for relapsing-remitting multiple sclerosis. In DEFINE, BG-12 achieved statistical significance on the primary and secondary endpoints versus placebo. In preclinical studies, DMF reduced CNS inflammation in murine and rat experimental autoimmune encephalomyelitis (EAE). CNS inflammation in EAE and multiple sclerosis is thought to be mediated in part by inflammatory cytokine production by activated macrophages/microglia. The disease-modifying effect of DMF in EAE is associated with activation of the Nrf2 pathway and concurrent suppression of microglial activation. However, it is not known whether this suppression is dependent on Nrf2. Design/Methods: Macrophage cultures derived from the bone marrow of Nrf2+/+ and Nrf2-/- mice were stimulated in vitro for 6 hours by bacterial lipopolysaccharide (LPS). Before LPS stimulation, some cultures were pretreated with DMF. Total RNA was extracted, and transcripts were analysed using real-time reverse transcription polymerase chain reaction. Whole-cell protein extracts were prepared and phosphoproteins were analyzed using Western blots. Results: With LPS stimulation, Nrf2-/- macrophages showed a 3-fold increase in IL1-beta mRNA relative to Nrf2+/+ macrophages. LPS-induced IL-10 mRNA was also increased in Nrf2-/- versus Nrf2+/+ cells. Increased inflammatory capacity of Nrf2-/- macrophages correlated with increased phosphorylation of the proinflammatory p38 MAP kinase. DMF pretreatment suppressed the induction of IL1-beta and IL-10 mRNA in Nrf2+/+ cells but not in Nrf2-/- cells. Interestingly, at higher doses, DMF-mediated suppression of LPS-induced cytokines extended to Nrf2-/- cells. Conclusions: DMF suppresses inflammation in macrophages in vitro via both Nrf2-dependent and Nrf2-independent pathways. Inhibition of macrophage function may contribute to the therapeutic effect of BG-12 as part of its anti-inflammatory and cytoprotective mechanisms of action. Supported by: Biogen Idec Inc. Disclosure: Dr. Bista has received personal compensation for activities with Biogen Idec Inc as an employee. Dr. Zeng has received personal compensation for activities with Biogen Idec as an employee. Ms. Ryan has received personal compensation for activities with Biogen Idec as an employee. Dr. Lukashev has received personal compensation for activities with Biogen Idec as an employee. Dr. Yamamoto has received research support from Chugai Pharmaceutical Company.