Ingested (Oral) Adrenocorticotropic Hormone Inhibits IL-17 in the Central Nervous System in the Mouse Model of...

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.