Propionate-engineered probiotics reduce radiation-induced intestinal damage.

Radiation enteritis is a common complication in patients undergoing abdominal radiotherapy. Current management strategies face significant limitations: clinical agents like amifostine are hindered by systemic side effects and demanding administration; direct supplementation with radioprotective metabolites such as propionate suffers from low bioavailability and transient action; and conventional probiotics lack targeted therapeutic output. To address these challenges, we engineered Escherichia coli Nissle 1917 to function as a living therapeutic that continuously produces and delivers propionate directly in the gut. This propionate-engineered probiotic achieved a production yield of 181.33 ± 4.27 mg/L in vitro. In a mouse model of abdominal irradiation, this engineered bacterium alleviated radiation-induced intestinal damage by continuously releasing propionate and enhancing intestinal epithelial barrier function. Multi-omics analysis revealed that the engineered bacterium could restore intestinal microbiota homeostasis, enhancing the abundance of advantageous bacteria with radioprotective properties (e.g., Dubosiella, Akkermansia). Moreover, it modulated intestinal microbiota metabolism, influencing the metabolism of ascorbic acid, aldoses, and other metabolites. Additionally, it protected the intestinal mucosal barrier from radiation-induced damage, which was associated with the modulation of the SOCS1/JAK2/STAT3 signaling pathway. This study introduces a novel biological therapy to mitigate the side effects of radiotherapy and could open new avenues for preventing and treating radiation-induced intestinal injury.