Multiple sclerosis (MS) is an inflammatory and neurodegenerative disease characterized by myelin and axonal pathology. In a viral model of MS, we tested whether axonopathy initiation and development are based on an impaired transport of neurofilaments. Spinal cords of Theiler's murine encephalomyelitis virus (TMEV)-infected and mock-infected mice and TMEV infected neuroblastoma N1E-115 cells were analyzed by microarray analysis, light microscopy and electron and laser confocal microscopy. In vivo axonal accumulation of non-phosphorylated neurofilaments after TMEV infection revealed a temporal development caused by the impairments of the axonal traffic consisting of the downregulation of kinesin family member 5A, dynein cytoplasmic heavy chain 1, tau-1 and β-tubulin III expression. In addition, alterations of the protein metabolism were also noticed. In vitro, the TMEV-infected N1E-115 cells developed tandem-repeated swellings similar to in vivo alterations. Furthermore, the hypothesis of an underlying axonal self-destruction program involving nicotinamide adenine dinucleotide depletion was supported by molecular findings. The obtained data indicate that neurofilament accumulation in TME is mainly the result of dysregulation of their axonal transport machinery and impairment of neurofilament phosphorylation and protein metabolism. The present findings allow a more precise understanding of the complex interactions responsible for initiation and development of axonopathies in inflammatory degenerative diseases.
Objectives: Theiler’s murine encephalomyelitis virus (TMEV) infection of mice is a widely used animal model for demyelinating disorders, such as multiple sclerosis (MS). The aim of the present study was to identify topographical differences of TMEV spread and demyelination in the brain of experimentally infected susceptible SJL/J mice and resistant C57BL/6 mice. Methods: Demyelination was confirmed by Luxol fast blue and cresyl violet staining and axonal damage by neurofilament-specific and β-amyloid precursor protein-specific immunohistochemistry. Viral dissemination within the central nervous system (CNS) was quantified by immunohistochemistry and in situ hybridization. Further, the phenotype of infected cells was determined by confocal laser scanning microscopy. Results: An early transient infection of periventricular cells followed by demyelination and axonopathies around the fourth ventricle in SJL/J mice was noticed. Periventricular and brain stem demyelination was associated with a predominant infection of microglia/macrophages and oligodendrocytes. Conclusions: Summarized, the demonstration of ependymal infection and subjacent spread into the brain parenchyma as well as regional virus clearance despite ongoing demyelination and axonal damage in other CNS compartments allows new insights into TME pathogenesis. This novel aspect of TMEV CNS interaction will enhance the understanding of region-specific susceptibilities to injury and regenerative capacities of the brain in this MS model.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.