Engineered probiotic alleviates ulcerative colitis by inhibiting M1 macrophage polarization via glycolytic reprogramming

Ulcerative colitis (UC) remains a significant therapeutic challenge due to its complex pathogenesis involving oxidative stress, immune dysregulation, and gut microbiota dysbiosis. Melanin, a natural biopolymer with robust anti‐inflammatory and antioxidant properties, presents a promising treatment avenue for UC. Probiotics, particularly Escherichia coli Nissle 1917 (EcN), have gained recognition for their role in restoring gut homeostasis. In this study, we genetically engineered EcN to overexpress tyrosinase (EcN‐T), facilitating the biosynthesis of melanin specifically for UC treatment. The engineered probiotics demonstrated superior therapeutic efficacy compared to either melanin or EcN administered alone, highlighting a synergistic effect. EcN‐T not only exhibited significant capabilities in scavenging reactive oxygen species and restoring gut microbiota but also possessed the characteristic of enhancing gut colonization time, thereby extending the dosing frequency. Moreover, EcN‐T showcased novel mechanisms, such as the restoration of the intestinal mucosal barrier and the elevation of short‐chain fatty acid levels. Additionally, EcN‐T inhibited M1 macrophage polarization through Hypoxia‐Inducible Factor 1‐alpha (HIF‐1α)dependent glycolytic reprogramming, underscoring its immunomodulatory potential. Collectively, these findings provide new insights into the therapeutic potential of EcN‐T for UC treatment, offering a novel strategy that enhances treatment efficacy while potentially reducing side effects associated with conventional therapies.