Sustained-release enteric formulations of Lactiplantibacillus plantarum based on granulation technology: preparation and therapeutic evaluation in acute colitis.

BACKGROUND: The clinical effectiveness of orally administered probiotics is often limited by poor survival during gastrointestinal transit and insufficient delivery to the intestinal site of action. Lactiplantibacillus plantarum, a probiotic with anti-inflammatory potential, is highly sensitive to gastric acid and bile salts, diminishing its therapeutic efficacy for intestinal diseases. The aim of this study was to develop an enteric sustained-release granule formulation of Lactobacillus plantarum to enhance probiotic stability, promote targeted intestinal delivery, and evaluate its therapeutic efficacy in the treatment of colitis. METHODS: Sustained-release enteric pellets containing Lactiplantibacillus plantarum were prepared using a low-temperature wet granulation and extrusion process, followed by coating with pH-responsive polymers (HPMCP or Eudragit L100). In vitro release behavior was evaluated in simulated gastric and intestinal fluids. Therapeutic efficacy was assessed in a dextran sulfate sodium (DSS)-induced acute colitis mouse model using histopathology, macrophage polarization, and gut microbiota analysis. RESULTS: The sustained-release granules exhibited a narrow and uniform particle size distribution, with diameters ranging from 40 to 80 mesh (180–425 μm). More than 85% of the granules were distributed within the 40–60 mesh fraction (250–425 μm). The micropellets exhibited adequate mechanical strength for handling and processing. The enteric-coated micropellets showed pronounced acid resistance, retaining over 70% bacterial viability after 2 h in simulated gastric fluid, compared with <30% for free bacterial powder. In simulated intestinal fluid, the micropellets achieved sustained bacterial release for over 2 h. In DSS-induced colitis mice, treatment with the granule formulations resulted in a more pronounced trend toward histological recovery. Moreover, the sustained-release granules promoted M2 macrophage polarization and partially restored gut microbial diversity, as evidenced by normalization of the Firmicutes-to-Bacteroidetes ratio. CONCLUSIONS: The sustained-release enteric pellet system effectively protects Lactiplantibacillus plantarum during gastrointestinal transit and achieves targeted intestinal release. Integrating mechanical shielding with pH-triggered dissolution significantly enhances probiotic gastrointestinal survival and therapeutic efficacy. This delivery platform represents a safe, scalable, and broadly applicable strategy for treating intestinal inflammatory diseases. Furthermore, the approach provides a versatile framework for delivering other probiotic strains or combinations.