The NRF2 pathway as potential biomarker for dimethyl fumarate treatment in multiple sclerosis

Abstract

Objective: Immunological studies have demonstrated a plethora of beneficial effects of dimethyl fumarate (DMF) on various cell types. However, the cellular and molecular targets are incompletely understood and response markers are scarce. Here, we focus on the relation between nuclear factor (erythroid-derived 2)-like 2 (NRF2) pathway induction under DMF therapy and the composition of the blood immune cell compartment and clinical efficacy in relapsing-remitting multiple sclerosis (MS) patients.

Methods: We explored effects of DMF on peripheral immune cell subsets by flow cytometric and transcriptional analysis of serial blood samples obtained from 43 MS patients during the first year of therapy.

Results: Gene expression analysis proved activation of NRF2 signaling under DMF therapy that was paralleled by a temporal expansion of FoxP3⁺ regulatory T cells, CD56^bright natural killer cells, plasmacytoid dendritic cells, and a decrease in CD8⁺ T cells, B cells, and type 1 myeloid dendritic cells. In a subgroup of 28 patients with completely available clinical data, individuals with higher levels of the NRF2 target gene NAD(P)H quinone dehydrogenase 1 (NQO1) 4-6 weeks after DMF therapy initiation were more likely to achieve no evidence of disease activity status 1 year later. The degree of NQO1 induction further correlated with patient age.

Interpretation: We demonstrate that positive effects of DMF on the clinical outcome are paralleled by induction of the antioxidant NRF2 transcriptional pathway and a shift toward regulatory immune cell subsets in the periphery. Our data identify a role of the NRF2 pathway as potential biomarker for DMF treatment in MS.

Figure 1

DMF induces the NRF2 transcriptional pathway but not HCAR2 expression in PBMC. mRNA expression levels of KEAP1 (A), NFE2L2 (NRF2), (B) and its target genes NQO1 (C) and AKR1C1 (D) as well as HCAR2 (E) were analyzed by qRT‐PCR (9–11 HD and 25–30 DMF‐treated MS patients per time point, *P < 0.05, **P < 0.01, ***P < 0.001). HD, healthy donor; baseline (T0), 4–6 weeks (T1), 3 months (T2), 6 months (T3), and 1 year (T4) of DMF intake.

Figure 2

DMF therapy modulates the frequency of immune cell subsets in the blood of MS patients. The frequency of Treg (A), CD56^bright NK cells (B), pDC (C), mDC1 (D), mDC2 (E), CD4⁺ cells (F), Th1 (G), Th2 (H), Th17 (I), CD56^dim NK cells (J), CD8⁺ T cells (K), and B cells (L) in the peripheral blood of HD and DMF‐treated MS patients as assessed by flow cytometry (9–11 HD and 10–30 DMF‐treated MS patients per time point; *P < 0.05, **P < 0.01). HD, healthy donor; baseline (T0), 4–6 weeks (T1), 3 months (T2), 6 months (T3), and 1 year (T4) of DMF intake.

Figure 3

Age‐dependent NQO1 induction correlates with Treg frequencies and NEDA status after 1 year of DMF therapy. Analysis of relations between NEDA status (T4), NQO1 induction (T1), Treg frequency (T2), and patient age (T0) (18–25 DMF‐treated MS patients were included in the 1 year analysis; *P < 0.05). N = no, Y = yes; baseline (T0), 4–6 weeks (T1), 3 months (T2), 6 months (T3), and 1 year (T4) of DMF intake.