<i>Lactobacillus rhamnosus</i> CLK101 protects against ulcerative colitis in mice via intestinal barrier repair, microbiota homeostasis maintenance, and inflammatory signaling suppression

Abstract Ulcerative colitis (UC) is an inflammatory bowel disease with increasing incidence worldwide, highlighting the need for alternative therapeutic approaches beyond the current limited options. This study aims to systematically evaluate the probiotic properties of Lactobacillus rhamnosus CLK101 and its preventive effects against dextran sulfate sodium-induced murine colitis through genomic, 16S rRNA, and transcriptomic sequencing analyses. Genomic analysis revealed that L. rhamnosus CLK101 possesses genetic determinants supporting gastrointestinal fluid tolerance, intestinal adhesion, stress resistance, and immunomodulatory functions, indicating strong probiotic potential. In vivo experiments demonstrated that this strain significantly alleviated colitis symptoms, including reducing weight loss and disease activity index, normalizing immune organ indices, suppressing colon shortening, and improving colonic content morphology. Furthermore, it enhanced the expression of tight junction proteins (Claudin-1 and ZO-1), thereby restoring intestinal barrier function and mitigating oxidative stress damage. The probiotic treatment also increased the abundance of beneficial bacteria such as Firmicutes_D, Faecalibaculum rodentium, and Bifidobacterium, promoting microbial homeostasis. Additionally, it attenuated intestinal inflammation by suppressing key signaling pathways, including nuclear factor kappa B (NF-κB), Toll-like receptor (TLR), and tumor necrosis factor (TNF) pathways, while downregulating pro-inflammatory cytokine secretion. These findings indicate that L. rhamnosus CLK101 prevents colitis through multi-target mechanisms involving intestinal barrier repair, gut microbiota modulation, and the inhibition of inflammatory signaling pathways. The study provides a scientific basis for its development as a functional probiotic for UC management.