Decreased neural stem/progenitor cell proliferation in mice with chronic/nonremitting experimental autoimmune encephalomyelitis.

It has been reported that autoimmune inflammatory processes in human multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), may induce an alteration in neurogenesis. Studies with transgenic EAE mice have demonstrated an enhancement of neurogenesis in the subventricular zone (SVZ). In contrast, a reduction of stem cell proliferation in the same region has been observed by Pluchino et al. [Brain 2008;131:2564-2578] in myelin oligodendrocyte glycoprotein (MOG)-induced EAE mice. We immunized female C57BL/6 mice with MOG 35-55 peptide and successfully developed chronic/nonremitting EAE, which is believed to be analogous to the progressive form of MS. On day 21 postimmunization, coronal brain sections were collected and stained with anti-5-bromo-2'-deoxyuridine (BrdU) antibody. By counting the number of BrdU-labeled cells, we demonstrated that the neural stem/progenitor cell (NSC/NPC) proliferation decreased in the SVZ, which basically confirms the study of Pluchino et al. on the changes in the SVZ. A reduction of NSC/NPC proliferation also occurred in the hippocampal subgranular zone of the dentate gyrus. The hippocampus is well known to be an important region involved in learning and memory; thus, our finding may offer a possible explanation for the cognitive impairment in human chronic MS.