title: In vitro evaluation of physiologically relevant concentrations of teriflunomide on activation and proliferation of primary rodent microglia.
abstract: BACKGROUND
  Teriflunomide, an inhibitor of dihydroorotate dehydrogenase, is thought to ameliorate multiple sclerosis by reducing activation-induced proliferation of lymphocytes, which is highly dependent on de novo pyrimidine synthesis. Nevertheless, its immunomodulatory effects on resident glial cells in the central nervous system are only poorly understood.
  
  
  METHODS
  In this study, we employed physiologically relevant concentrations of teriflunomide and investigated its effects on survival, proliferation, activation, and function of primary rat microglia in vitro.
  
  
  RESULTS
  We demonstrate that teriflunomide had no cytotoxic effect on microglia and had only a minor impact on microglial activation. In a concentration- and time-dependent manner, teriflunomide significantly downregulated surface expression of the co-stimulatory molecule CD86. Furthermore, in the highest concentration applied (5 μM), it slightly increased the expression of interleukin-10 in microglia in response to lipopolysaccharide. Treatment with low concentrations of teriflunomide (0.25-1 μM) did not have any impact on the activation or proliferation of microglia. At 5 μM concentration of teriflunomide, we observed a reduction of approximately 30 % in proliferation of microglia in mixed glial cell cultures.
  
  
  CONCLUSIONS
  Taken together, our in vitro findings suggest that at higher concentrations, teriflunomide potentially exerts its effects by reducing microglial proliferation and not by modulating the M1-/M2-like cell differentiation of primary rat microglia. Thus, teriflunomide has no major impact on the plasticity of microglia; however, the anti-proliferative and minimal anti-inflammatory effects might be clinically relevant for immune modulation in the treatment of neuroinflammatory CNS diseases such as multiple sclerosis.
authors.affiliation: Clinical Neuroimmunology and Neurochemistry, Department of Neurology, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany.|Center for Systems Neuroscience, University of Veterinary Medicine Hannover, 30559, Hannover, Germany.
authors.forename: Tanja
authors.initials: T
authors.lastname: Wostradowski
authors.affiliation: Clinical Neuroimmunology and Neurochemistry, Department of Neurology, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany.
authors.forename: Chittappen Kandiyil
authors.initials: CK
authors.lastname: Prajeeth
authors.affiliation: Clinical Neuroimmunology and Neurochemistry, Department of Neurology, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany.
authors.forename: Viktoria
authors.initials: V
authors.lastname: Gudi
authors.affiliation: Clinical Neuroimmunology and Neurochemistry, Department of Neurology, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany.|Center for Systems Neuroscience, University of Veterinary Medicine Hannover, 30559, Hannover, Germany.
authors.forename: Jessica
authors.initials: J
authors.lastname: Kronenberg
authors.affiliation: Clinical Neuroimmunology and Neurochemistry, Department of Neurology, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany.
authors.forename: Sina
authors.initials: S
authors.lastname: Witte
authors.affiliation: Clinical Neuroimmunology and Neurochemistry, Department of Neurology, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany.
authors.forename: Marina
authors.initials: M
authors.lastname: Brieskorn
authors.affiliation: Clinical Neuroimmunology and Neurochemistry, Department of Neurology, Hannover Medical School, Carl-Neuberg-Str.1, 30625, Hannover, Germany. Stangel.Martin@mh-hannover.de.|Center for Systems Neuroscience, University of Veterinary Medicine Hannover, 30559, Hannover, Germany. Stangel.Martin@mh-hannover.de.
authors.forename: Martin
authors.identifier: http://orcid.org/0000-0003-2504-5398
authors.initials: M
authors.lastname: Stangel
keywords: Anti-inflammatory (M2); Microglia; Multiple sclerosis; Pro-inflammatory (M1); Proliferation; Teriflunomide