Two Nature Portfolio items (Nature Biotechnology and Nature) report engineered nonpathogenic E. coli strains that detect gastrointestinal bleeding and secrete an adhesive protein plus therapeutic factors to adhere to inflamed mucosa and promote healing in mouse models of inflammatory bowel disease (IBD). The constructs combine a blood‑inducible gene circuit, barnacle‑derived adhesive CP43K and a gut‑barrier factor (TFF3) to enable sustained localized therapy after a single administration. In mouse DSS colitis and IL‑10 knockout models the engineered bacteria improved weight recovery, reversed colonic shortening, reduced bleeding and promoted mucosal repair. The approach demonstrated adhesion for up to 10 days (rectal) or 7 days (oral) and relied on bleeding‑triggered adhesion to sustain localization. Authors deposited sequence data and provide source data with the publications. Why it matters: this is a translational synthetic‑biology demonstration of autonomous, pathology‑triggered biologics for local, sustained treatment of gastrointestinal disease—an approach with potential to reduce systemic exposure and enable repeatable, on‑demand therapeutic delivery.