Monoclonal Antibody Against Mature Interleukin-18 Ameliorates Colitis in Mice and Improves Epithelial Barrier Function

Background: Antitumor necrosis factor (TNF)-α antibodies have improved the outcome of inflammatory bowel disease (IBD); but half of patients remain unresponsive to treatment. Interleukin-18 (IL-18) gene polymorphism is associated with resistance to anti-TNF-α antibodies, but therapies targeting IL-18 have not been clinically applied. Only the mature protein is biologically active, and we aimed to investigate whether specific inhibition of mature IL-18 using a monoclonal antibody (mAb) against a neoepitope of caspase-cleaved mature IL-18 could be an innovative treatment for IBD. Methods: The expression of precursor and mature IL-18 in patients with UC was examined. Colitis was induced in C57/BL6 mice by administering dextran sulfate sodium (DSS), followed by injection with anti-IL-18 neoepitope mAb. Colon tissues were collected and subjected to histological analysis, immunohistochemistry, immunoblotting, and quantitative polymerase chain reaction. Colon epithelial permeability and microbiota composition were analyzed. Results: Mature IL-18 expression was elevated in colon tissues of patients with active ulcerative colitis. Administration of anti-IL-18 neoepitope mAb ameliorated acute and chronic DSS-induced colitis; reduced interferon-γ, TNF-α, and chemokine (CXC motif) ligand-2 production and epithelial cell permeability; promoted goblet cell function; and altered the intestinal microbiome composition. The suppressive effect of anti-IL-18 neoepitope mAb was superior to that of anti-whole IL-18 mAb. Furthermore, combination therapy with anti-TNF-α Ab suppressed acute and chronic colitis additively by suppressing cytokine expressions and reducing cell permeability by upregulating claudin1 and occludin expression. Conclusions: Anti-IL-18 neoepitope mAb ameliorates acute and chronic colitis, suggesting that this mAb will be an innovative therapeutic option for IBD.