Ingested (Oral) Adrenocorticotropic Hormone Inhibits IL-17 in the Central Nervous System in the Mouse Model of Multiple Sclerosis and Experimental Autoimmune Encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory autoimmune disease of the CNS that resembles multiple sclerosis and provides a useful animal model for the evaluation of mechanisms of action for potential immunomodulatory therapies. We have previously shown that oral adrenocorticotropic hormone (ACTH) decreased IL-17 in the gut lamina propria and the spleen and increased CD4⁺ Foxp3⁺ T regulatory cells and IL-10 in the spleen during EAE in the C57BL/6 mouse. However, we did not investigate the specific cellular alterations of proinflammatory and anti-inflammatory factors in the CNS. The aim was to determine if oral ACTH would have a similar clinical effect on inflammatory cytokines in the gut and define specific cellular effects in the CNS in an alternative strain of mice. SJL/J mice were immunized with proteolipid protein peptide 138-151 and gavaged with scrambled ACTH (scrambled α-melanocyte-stimulating hormone) or ACTH 1-39 during ongoing disease. Ingested (oral) ACTH attenuated ongoing clinical EAE disease, decreased IL-6 production, and increased T regulatory cells in the lamina propria and decreased CD4⁺ and γδ IL-17 production in the CNS. Ingested ACTH attenuated EAE clinical disease by decreasing IL-6 in the gut-associated lymphoid tissue and decreasing IL-17 in the CNS.