Gelatin tannate ameliorates acute colitis in mice by reinforcing mucus layer and modulating gut microbiota composition: Emerging role for ‘gut barrier protectors’ in IBD?

Background: Gelatin tannate, a gelatin powder containing tannic acids, is commonly employed as an intestinal astringent. Neither information nor animal model exist to confirm its efficacy or unravel mechanisms of action. Objective: To evaluate the action of gelatin tannate in murine dextran sodium sulphate (DSS)-induced acute colitis. Methods: Mice were exposed to DSS and received gelatin tannate by gavage. At sacrifice, colon histological degree of inflammation was assessed. Stool samples were cultured for microbiological analysis. Colon samples were analysed by two-photon confocal microscopy and atomic force microscopy. Elisa was performed on murine serum to assess lipopolysac-charide and peptidoglycan levels. Results: Gelatin tannate treatment reduced disease activity, bodyweight loss, and preserved colonic length. It produced a decrease in the amount of enterobacteria and enterococci. At confocal microscopy, intestinal samples from healthy and treated mice displayed similar structure in mucus layer thickness and composition; samples from placebo group had no mucus layer or a thinner stratus. Atomic force microscopy confirmed these findings. Treated mice showed lower blood LPS levels vs. control. Conclusions: Gelatin tannate decreased the severity of colitis. Acting as a gut barrier enhancer, it re-establishes gut homeostasis by recovering intestinal permeability and mucus layer integrity in gut mucosa and by modulating microbiota composition.