title: Protective effects of monomethyl fumarate at the inflamed blood-brain barrier.
abstract: BACKGROUND
  Reactive oxygen species play a key role in the pathogenesis of multiple sclerosis as they induce blood-brain barrier disruption and enhance transendothelial leukocyte migration. Thus, therapeutic compounds with antioxidant and anti-inflammatory potential could have clinical value in multiple sclerosis. The aim of the current study was to elucidate the therapeutic effects of monomethyl fumarate on inflammatory-mediated changes in blood-brain barrier function and gain insight into the underlying mechanism.
  
  
  METHODS
  The effects of monomethyl fumarate on monocyte transendothelial migration across and adhesion to inflamed human brain endothelial cells (hCMEC/D3) were quantified using standardized in vitro migration and adhesion assays. Flow cytometry analysis and qPCR were used to measure the concomitant effects of monomethyl fumarate treatment on protein expression of cell adhesion molecules. Furthermore, the effects of monomethyl fumarate on the expression and nuclear localization of proteins involved in the activation of antioxidant and inflammatory pathways in human brain endothelial cells were elucidated using nuclear fractionation and Western blotting. Statistical analysis was performed using one-way ANOVA followed by the Bonferroni post-hoc test.
  
  
  RESULTS
  Our results show that monomethyl fumarate induced nuclear translocation of nuclear factor (erythroid-derived 2)-like 2 and concomitant production of the antioxidant enzymes heme oxygenase-1 and NADPH:quinone oxidoreductase-1 in brain endothelial cells. Importantly, monomethyl fumarate treatment markedly decreased monocyte transendothelial migration across and adhesion to inflamed human brain endothelial cells. Treatment of brain endothelial cells with monomethyl fumarate resulted in a striking reduction of vascular cell adhesion molecule expression. Surprisingly, monomethyl fumarate did not affect nuclear translocation of nuclear factor-кB suggesting that monomethyl fumarate potentially affects activity of nuclear factor-ĸB downstream of nuclear translocation.
  
  
  CONCLUSIONS
  Taken together, we show that monomethyl fumarate, the primary metabolite of dimethyl fumarate, which is currently used in the clinics for the treatment of relapsing-remitting multiple sclerosis, demonstrates beneficial therapeutic effects at the inflamed blood-brain barrier.
authors.affiliation: Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: jamielim85@gmail.com.
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Lim
authors.affiliation: Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: sma.vanderpol@vumc.nl.
authors.forename: Susanne M A
authors.initials: SM
authors.lastname: van der Pol
authors.affiliation: Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: fd00042@surrey.ac.uk.
authors.forename: Flaminia
authors.initials: F
authors.lastname: Di Dio
authors.affiliation: Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: aj.vanhethof@vumc.nl.
authors.forename: Bert
authors.initials: B
authors.lastname: van Het Hof
authors.affiliation: Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: G.Kooij@vumc.nl.
authors.forename: Gijs
authors.initials: G
authors.lastname: Kooij
authors.affiliation: Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: he.devries@vumc.nl.
authors.forename: Helga E
authors.initials: HE
authors.lastname: de Vries
authors.affiliation: Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: j.vanhorssen@vumc.nl.
authors.forename: Jack
authors.initials: J
authors.lastname: van Horssen
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D001812:Blood-Brain Barrier / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D002448:Cell Adhesion / Q000187:drug effects; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002478:Cells, Cultured; D018920:Coculture Techniques; D019610:Cytoprotection; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005650:Fumarates / Q000494:pharmacology*; D051547:Heme Oxygenase-1 / Q000378:metabolism; D006801:Humans; D007962:Leukocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008298:Maleates / Q000494:pharmacology*; D009103:Multiple Sclerosis / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D057705:Transendothelial and Transepithelial Migration / Q000187:drug effects*
chemical_list: D000893:Anti-Inflammatory Agents; D000975:Antioxidants; D015815:Cell Adhesion Molecules; D005650:Fumarates; D008298:Maleates; D051267:NF-E2-Related Factor 2; D016328:NF-kappa B; C495635:NFE2L2 protein, human; C073341:citraconic acid; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human
keywords: Blood–brain barrier; Cell adhesion molecules; Leukocyte transendothelial migration; Monomethyl fumarate; NF-ĸB; Nrf2