OP26 Programmable probiotic local delivery of anti-TNF-α nanobody to alleviate DSS-induced colitis

Abstract Background Biological agents represented by Infliximab have brought a milestone leap forward in the treatment of IBD. However, the overall response rate of anti-TNF-α antibodies in clinical practice is just 40-60% and the adverse reactions caused by the lack of gut-selective further limit its clinical application. Systemic effects of intravenous administration may be an essential cause of paradoxical response and immune adaptive succession (secondary loss of response). Rapid advances in synthetic biology allow targeted delivery of antibody drugs via engineered probiotics to improve bioavailability while reducing the risk of systemic effects. Methods Here, we developed an engineered probiotic (EcN-VHH2M3) that intelligently responds to the inflammatory marker thiosulfate and produces the anti-TNF-α nanobody VHH2M3. At the same time, controlled release of anti-TNF-α biologic was achieved in response to colitis marker nitrate and quorum sensing mechanism. The dextran sulfate sodium (DSS)-induced colitis model was used to explore the feasibility of EcN-VHH2M3 for the IBD treatment. The disease activity index of the subject animals was detected and evaluated. The colon length and spleen weight were measured and HE staining. Real-time polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) are used to detect cytokine expression levels in colon tissue. Results In vivo results showed that EcN-VHH2M3 group significantly reduced disease activity index and restored intestinal mucosal barrier compared with control group. DSS administration resulted in hyperemia, ulceration, and thickening of the bowel wall, which were reduced in the treatment group. In addition, spleen weight and colon length were close to the control group. EcN-VHH2M3 treatments significantly decreased the expression levels of pro-inflammatory cytokines IL-1β, TNF-α, and IFN-γ, while the expression of anti-inflammatory cytokines IL-10 and TGF-β was enhanced. Conclusion Inflammatory microenvironment-responsive programmable probiotics effectively alleviate DSS-induced colitis in mice and restore the intestinal mucosal barrier through the targeted release of anti-TNF-α nanobody. This study preliminarily confirmed that the controlled intestinal release of anti-TNF biologics by engineered probiotics provides a promising paradigm for IBD treatment with non-gut-selective antibodies.