Oral treatment with a hybrid protein between E. coli heat labile toxin B subunit and ABC synapsin peptide reduced central nervous system inflammation in experimental autoimmune encephalomyelitis (EAE)
Bibolini, Mario J.; Scerbo, Mar¨ªa Julia; Peinetti, Nahuel, Roth, German A., Monferran, Clara G.
Centro de Investigaciones en Qu¨ªmica Biol¨®gica de C¨®rdoba (CIQUIBIC, UNC¨CCONICET), Departamento de Qu¨ªmica Biol¨®gica, Facultad de Ciencias Qu¨ªmicas, Universidad Nacional de C¨®rdoba.
EAE is an established model for human multiple sclerosis (MS). In both diseases autoreactive T cell clones are peripherally generated and migrate into the central nervous system. Extensive inflammatory reactions mediated by infiltrating mononuclear cells and production of proinflammatory cytokines are responsible for demyelination, axonal disfunction and neurological disability. We have previously shown that oral tolerance induced in rats with LTBABC, a hybrid between the ABC domain of synapsin and the B subunit of Escherichia coli heat-labile enterotoxin (LTB) attenuated EAE clinical signs and diminished cellular reactivity against myelin basic protein. To further characterize this effect we analyzed histological changes and the presence of CD4+, CD8+, CD45+CD11b+, CD4+ producing INF-¦Ã or IL-17, and CD4+CD25+FoxP3+ cells infiltrating CNS. Rats were orally fed with 6 doses of LTBABC, LTB (0.3 nmol or equivalent amount in biological activity) or vehicle after encephalitogenic challenge. Spinal cords and brains were obtained during the EAE acute stage. Mononuclear cells infiltrating CNS were isolated and analyzed by flow cytometry. Rats treated with LTBABC showed the fewest inflammatory infiltrates in lumbar spinal cord sections stained with H & E (p<0.01); and they also exhibited lower percentages of CD4+, CD8+ and CD4+cells producing INF-¦Ã than the ones fed with vehicle or LTB (p<0.05). Diminished frequency of CD4+ IL-17+ cells were observed in the LTBABC group respect to control group (p<0.05). Frequency of infiltrating macrophages (CD45+CD11b+ cells) did not differ between groups. CD4+CD25+FoxP3+ regulatory T cells were expanded only in CNS of the LTBABC group (p<0.05). These results clearly indicate that oral tolerance induced by LTBABC reduced infiltration of T cells and increased the presence of CD4+CD25+FoxP3+ regulatory T cells in CNS, suggesting that synapsin peptides coupled to LTB has a protective effect with therapeutic potential in EAE and MS treatment.
