Optimization of a new EAE induction strategy by subcutaneous administration of a Eukaryotic RpfE- MOG(35-55) Expressing Plasmid

Abstract Multiple Sclerosis (MS) is considered as the common autoimmune inflammatory disease; while, Experimental Autoimmune Encephalomyelitis (EAE) is the most recognized common animal model of the human MS disease. The present study aimed at introducing a new and simple method for induction of chronic EAE in C57BL/6J mice by using a eukaryotic vector. In this method, Resuscitation-promoting factor-E (RpfE) as an adjuvant, and Myeline oligodendrocyte glycoprotein (MOG(35−55)), as neuro-antigen were cloned into pcDNA3.1(+) IRES GFP. Thereafter, the mice received two doses of plasmids in the 1st and 7th days of experiment as follows: group A, 16–16 µg; group B, 32 − 16 µg; group C, 32–32 µg; group D, 64–64 µg and group E was the control group. The clinical scores during 9 weeks were documented before they were euthanized. There were not only significant differences in the clinical symptoms initiation and severity amongst groups but also in the time of showing highest inflammatory responses, which was about two weeks after clinical symptoms onset. Histopathological results revealed different degrees of demyelination as well as CD4+, CD8+, and CD20+ cell infiltration into the CNS tissues. High doses of the recombinant plasmid (64–64 µg) led to higher CD4+ cell accumulation, lesser demyelination, and delayed EAE induction (week 5); while, lower doses (up to 32–32 µg) resulted in higher CD8+ cells penetration, greater demyelination, and earlier EAE initiation (week four). To sum up, different doses of this eukaryotic plasmid is suggested as a simpler and about 3-times cheaper technique for induction of different pathological features of EAE model in mice.