Multiple sclerosis (MS) is an
autoimmune disease characterized by inflammatory cell infiltration of the central nervous system (CNS) and multifocal
demyelination. Clinical data and clinical indicators demonstrate that
estrogen improves the relapse-remittance of MS patients. This study aimed to investigate the anti-inflammatory effects and the underlying mechanism(s) of action of
estrogen and
estrogen receptor α (ERα) in an
experimental autoimmune encephalomyelitis (EAE) mouse model of MS. An ERα recombinant lentivirus was constructed. Mouse neurons were cultured in serum-free culture medium, and ERα recombinant lentivirus with a multiplicity of
infection (MOI) of 5 was used to infect the neurons. Furthermore, neuronal ERα
mRNA and
protein expression were detected using real-time quantitative PCR and western blot analysis. We sterotaxically injected ERα recombinant lentivirus into the lateral ventricle of mouse brains, and successfully identified infected neurons using Flag immunofluorescence staining to determine the optimal dose. A total of 75 C57BL/6 mice were ovariectomized. After 2 weeks, EAE was induced with
myelin oligodendrocyte glycoprotein (MOG) 35-55
peptide. The EAE mice were divided into 5 groups: the
estrogen group (treatment with
estradiol), the ERα agonist group (treatment with
raloxifene), the ERα recombinant lentivirus group (ERα group, treatment with ERα recombinant lentivirus), the empty virus group and the
normal saline (NS) group; clinical symptoms and
body weight were compared among the groups. We assessed EAE-related parameters, detected pathological changes with immunohistochemistry and quantified the expression of
myelin basic protein (MBP),
matrix metalloproteinase-9 (MMP-9), and a subset of EAE-related
cytokines using
enzyme-linked
immunosorbent assay (ELISA). We successfully constructed an ERα recombinant lentivirus. C57BL/6 mouse neurons can survive in culture for at least 8 weeks. During that period, the recombinant lentivirus was able to infect the neurons, while sustaining green fluorescence
protein (GFP) expression. ERα recombinant lentivirus also infected the neurons at a MOI of 5. The ERα
mRNA and
protein expression levels were higher in the infected neurons compared to the uninfected ones. We successfully infected the CNS of C57BL/6 mice by stereotaxically injecting ERα recombinant lentivirus into the lateral ventricle of the mouse brains and induced EAE. The lentivirus-mediated overexpression of ERα reduced the incidence of EAE, ameliorated the clinical symptoms, inhibited inflammatory cell CNS infiltration, and reduced nerve fiber
demyelination. MMP-9,
tumor necrosis factor-α (TNF-α),
interferon-γ (IFN-γ),
interleukin (IL)-17 and
IL-23 expression levels were decreased, while those of MBP and
IL-4 were increased. These data demonstrate that it is possible to induce the overexpression of ERα using a recombinant lentivirus, and that this novel intervention ameliorates EAE in a mouse model. Mechanistically,
estrogen and ERα inhibit inflammatory responses, and ERα alleviates damage to the myelin sheath. Collectively, our findings support the potential use of ERα as a therapeutic target for the treatment of MS.