Metal ion coordinated tea polyphenol nanocoating for enhanced probiotic therapy in inflammatory bowel disease

Probiotics encapsulated with metal-phenolic networks (MPNs) present a promising approach for treating inflammatory bowel diseases (IBD). However, current MPN systems predominantly use tannic acid (TA) as the phenolic source, with limited exploration of other polyphenols, and face challenges in long-term stability and biocompatibility. Herein, three alternative tea polyphenols, gallic acid (GA), epigallocatechin (EGC) and epigallocatechin gallate (EGCG), were coordinated with ferric ions, to fabricate MPN-coated Lactobacillus rhamnosus LGG (MPN@L). These were compared with TA-based MPN@L to evaluate their effectiveness in alleviating IBD. All MPN@L complexes demonstrated superior adhesion and retention compared to uncoated probiotics in both ex vivo and in vivo models. Specifically, EGC@L exhibited the highest survival rate throughout gastrointestinal digestion, with a 2.7 log CFU/mL improvement over uncoated probiotics, and showed optimal retention in murine intestine with a fluorescence intensity of 24.3 × 10⁶ p/s/cm²/sr by day four. All MPN@L formation effectively alleviated ulcerative colitis by reducing myeloperoxidase levels, modulating cytokines profiles, and enhancing gut microbiota. EGC@L particularly increased beneficial bacterial genera, including Lactobacillus, Adlercreutzia, and Oscillospira, while decreasing the pro-inflammatory genera. This study highlights the potential of MPN-based probiotic microencapsulation to enhanced treatment for gastrointestinal disorders, expending the application of probiotic microencapsulation in IBD therapy.