Analysis of neurogenesis during experimental autoimmune encephalomyelitis reveals pitfalls of bioluminescence imaging

PLoS One. 2015 Mar 17;10(3):e0118550. doi: 10.1371/journal.pone.0118550. eCollection 2015.

Abstract

Bioluminescence imaging is a sensitive approach for longitudinal neuroimaging. Transgenic mice expressing luciferase under the promoter of doublecortin (DCX-luc), a specific marker of neuronal progenitor cells (NPC), allow monitoring of neurogenesis in living mice. Since the extent and time course of neurogenesis during autoimmune brain inflammation are controversial, we investigated neurogenesis in MOG-peptide induced experimental allergic encephalomyelitis (EAE) using DCX-luc reporter mice. We observed a marked, 2- to 4-fold increase of the bioluminescence signal intensity 10 days after EAE induction and a gradual decline 1-2 weeks thereafter. In contrast, immunostaining for DCX revealed no differences between EAE and control mice 2 and 4 weeks after immunization in zones of adult murine neurogenesis such as the dentate gyrus. Ex vivo bioluminescence imaging showed similar luciferase expression in brain homogenates of EAE and control animals. Apart from complete immunization including MOG-peptide also incomplete immunization with complete Freund´s adjuvant and pertussis toxin resulted in a rapid increase of the in vivo bioluminescence signal. Blood-brain barrier (BBB) leakage was demonstrated 10 days after both complete and incomplete immunization and might explain the increased bioluminescence signal in vivo. We conclude, that acute autoimmune inflammation in EAE does not alter neurogenesis, at least at the stage of DCX-expressing NPC. Effects of immunization on the BBB integrity must be considered when luciferase is used as a reporter within the CNS during the active stage of EAE. Models with stable CNS-restricted luciferase expression could serve as technically convenient way to evaluate BBB integrity in a longitudinal manner.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood-Brain Barrier / metabolism
  • Doublecortin Domain Proteins
  • Doublecortin Protein
  • Encephalomyelitis, Autoimmune, Experimental / pathology*
  • Encephalomyelitis, Autoimmune, Experimental / prevention & control
  • Immunization
  • Luciferases / genetics
  • Luminescence*
  • Mice
  • Mice, Transgenic
  • Microtubule-Associated Proteins / genetics
  • Neurogenesis*
  • Neuropeptides / genetics
  • Optical Imaging*
  • Promoter Regions, Genetic / genetics

Substances

  • Dcx protein, mouse
  • Doublecortin Domain Proteins
  • Doublecortin Protein
  • Microtubule-Associated Proteins
  • Neuropeptides
  • Luciferases

Grants and funding

Part of the study was supported by a research grant from Bayer Healthcare to IK. This manuscript has been made possible through the financial support from the State Government of Salzburg (Austria) and through funding from the European Union’s Seventh Framework Program (FP7/2007-2013) under grant agreement n° HEALTH-F2-2011-279288 (IDEA) and n° HEALTH-346F2-2011-278850 (INMiND) to SCD. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.