Histopatological parameters of the spinal cord in different phases of experimental autoimmune encephalomyelitis. A mouse model of multiple sclerosis examined by classical stainings combined with immunohistochemistry.

Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE) are characterized by three main histopathological parameters: inflammation, demyelination and axonal damage. In this study, these parameters were assessed in spinal cords of mice in the successive phases of EAE by quantitative histology and immunohistochemistry. The number of inflammatory lesions, the intensity of inflammation and expression of CD45 corresponded with the severity of clinical symptoms: they increased from the onset phase to the peak phase of the disease and subsided in the chronic phase. Demyelination increased in the peak phase and did not change in the chronic phase of EAE, although axonal damage gradually increased from the onset phase to the chronic phase, suggesting compensatory hypermyelination in that phase. The markers of myelin and axonal injury: myelin basic protein (MBP) and beta amyloid precursor protein (β-APP) showed changes (decrease and increase, respectively) of expression parallel to changes in demyelination and axonal damage. Results of this study indicate that although inflammation intensity subsides in the chronic phase of EAE, the neurodestructive processes: demyelination and axonal damage continue in that phase.