Abstract / Summary
Irritable bowel syndrome (IBS) is a disorder of gut–brain interaction characterized by visceral hypersensitivity, impaired intestinal barrier, immune activation, and gut microbiota dysbiosis, for which standardized treatment remains limited. In this study, we evaluated Lactiplantibacillus plantarum CKDB008 (LP) and Lacticaseibacillus rhamnosus LDTM7511 (= CKDB511; LR), each administered at low (1 × 10⁸ colony forming unit [CFU]/day) and high (1 × 10⁹ CFU/day) doses for 14 days in an acetic acid-induced post-inflammatory IBS-like rat model. Visceral hypersensitivity was assessed by the abdominal withdrawal reflex (AWR) test, and serum and distal colonic markers of stress, immunity, barrier function, and gut microbiota were analyzed. LR consistently attenuated visceral hypersensitivity at both doses, whereas LP reduced serum cortisol more strongly at the high dose, indicating distinct response profiles across endpoints. Serum IgE was significantly reduced in all probiotic-treated groups regardless of strain or dose ( P < 0.01), and distal colonic zonula occludens-1 expression was upregulated primarily in the LR-treated groups, reflecting limited and marker-specific modulation of barrier-related readouts. In the gut microbiota, Kineothrix alysoides was significantly depleted in the low-dose LP group after false discovery rate correction ( Q < 0.05), with a positive correlation observed between its abundance and AWR area under the curve. Predicted microbial pathway profiles also showed changes primarily in the LR-treated groups relative to IBS at the suggestive level. Collectively, these findings provide preliminary preclinical evidence that LP and LR alleviate several IBS-related phenotypes in this rat model, supporting their further evaluation as candidate probiotic strains for IBS.