An orally administered peptide hydrogel disentangles immune-microbiota crosstalk for long-term ulcerative colitis therapy

Ulcerative colitis (UC) is a global health challenge driven by immune dysregulation and gut microbiota imbalance.1 Current treatments, limited by insufficient efficacy and systemic toxicity during prolonged use, fail to resolve the intertwined immune-microbial pathology.2 Here, we report an orally administered self-assembled hydrogel C2-(IIRR)2I-NH2 (CIR), engineered from host defense peptides, which disrupts the immune-microbiota entanglement. The CIR hydrogel exhibits structural transformation at the inflamed sites rich in liposaccharide (LPS), a pro-inflammatory molecule derived from pathogenic bacteria. Stable {beta}-sheet nanofibers can transfer to bioactive -helix conformations, enabling localized therapeutic action with minimal off-target toxicity. In murine colitis models, CIR restores mucosal integrity and suppresses disease severity, outperforming the first-line drug 5-aminosalicylic acid (5-ASA). Microbiome profiling reveals its capacity to rebalance gut microbiota, depleting LPS produced pathogenic bacteria like Prevotellaceae. Transcriptomic analyses further indicate that CIR silences TLR4-mediated signaling pathway. By synergistically targeting immune dysregulation and microbial dysbiosis, this self-assembled peptide hydrogel establishes a paradigm-shifting strategy for UC, offering clinically translatable potential for multifactorial gastrointestinal disorders.