Oral delivery of recombinant Lactococcus lactis expressing an IL-23 inhibitor as a potential therapeutic strategy for experimental colitis

Interleukin 23 (IL-23) is a key mediator of immune-mediated intestinal inflammation and plays an important role in the pathogenesis of inflammatory bowel disease. Inhibition of IL-23 signaling has therefore been validated as a therapeutic target in IBD. Here, we tested small binding proteins of non-immunoglobulin origin targeting either the IL-23 cytokine p19 subunit or the IL-23 receptor subunit IL-23R, designated ILP and REX binders, respectively. ILP317 and REX115 variants of formerly identified protein collections were tested in murine experimental colitis. Lactococcus lactis bacteria engineered for ILP317 or REX115 expression were administered to experimental mice via yogurt-coated food pellets before and during dextran sulfate sodium (DSS) and trinitrobenzenesulfonic acid (TNBS)-induced colitis. To compare both protein blockers, ILP317 and REX115 binders were administered intraperitoneally as soluble recombinant proteins. General health status, colon macroscopic and histological changes, mucosal tissue cell infiltration, local and systemic inflammatory cytokines were analyzed. In DSS- and TNBS-induced colitis, intraperitoneal administration of soluble ILP317 or REX115 reduced disease severity, including disease activity index, colon shortening, and mucosal inflammatory cell infiltration. Oral administration of recombinant L. lactis expressing ILP317 also showed consistent protective effects, whereas oral L. lactis expressing REX115 produced less pronounced effects in several experimental settings. Overall, ILP317 appeared more effective than REX115 when delivered orally by recombinant L. lactis. Oral administration of non-colonizing L. lactis expressing an IL-23p19 inhibitor may represent a promising preclinical strategy for the development of novel, non-invasive approaches to modulate intestinal inflammation.