Rat models as tool to develop new immunotherapies

Rat models (experimental autoimmune encephalomyelitis, EAE; myasthenia gravis, EAMG) have been developed that mimic certain aspects of the pathophysiology of multiple sclerosis (MS) and myasthenia gravis (MG) in humans. Rat EAE and EAMG are, therefore, widely used to evaluate immunotherapeutic strategies. Mucosal tolerance induced by oral or nasal administration of autoantigen effectively suppresses rat EAE and EAMG. Nasal administration of the cytokines interleukin (IL)-4, IL-10 or transforming growth factor (TGF)-beta1 also ameliorates clinical signs of rat EAE. However, neither mucosal tolerance nor cytokines affect clinical disease if administered during ongoing rat EAE or EAMG. Dendritic cells (DC) pulsed in vitro with autoantigen can mediate peripheral tolerance against rat EAE and EAMG, but do not affect ongoing EAE or EAMG. DC from healthy rats, modified in vitro by exposure to IFN-gamma or TGF-beta1, effectively suppress ongoing EAE and EAMG when given by the subcutaneous route. Most importantly, DC from EAMG rats, after being modified in vitro with IL-10, also inhibit ongoing rat EAMG. These results demonstrate that different strategies influencing T- and/or B-cell responses in rat EAE or EAMG are available, but that DC-based immunotherapies are the most promising, in order to ameliorate ongoing organ-specific autoaggressive immunity Based on these observations, autologous DC, after being modified in vitro with cytokines, constitute a basis for new immunotherapeutic strategies in MS, MG and other diseases with autoimmune background.