Clinical and Histopathological Assessment on an Animal Model with Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is a disease of the Central Nervous System (CNS) which alters over 2 million people, and involves an abnormal autoimmune response directed against the brain, nerves and spinal cord. The antigen or the autoimmune target still remains unknown, a fact for which MS is considered to be an immune mediated disease. The pathology involves mainly the white matter, but the gray matter demyelination plays an important role in its pathogenesis. In 80% of the cases with MS, the disease develops relapses. Experimental autoimmune encephalomyelitis (EAE) is the most used model to study MS and for assessing potential treatments. In the present study we report on the histopathological characterization of an EAE model in C57BL/6 mice immunized by injection with myelin oligodendrocyte glycoprotein, MOG35-55 in complete Freud's adjuvant supplemented with pertussis toxin. On a group of 10 immunized animals and on 5 control animals, we followed the development and grading signs of motor deficiency, and after a survival of 34 days, the study aimed to evaluate the histopathological changes in the telencephalon, brainstem, cervical spinal cord, the optic nerve and retina. We utilized histochemistry, immunohistochemistry, and densitometric image analysis methods to assess myelin loss [Luxol fast blue, immunohistochemistry for the presence of microglia (Iba1) and reactive astrocytes (GFAP)]. Moreover, the study includes a first analysis of the detailed histopathological changes of the optic nerve and retina on an EAE model, all of these as the background for testing drugs with potential therapeutic role in MS.