In vitro study of gut microbiota-mediated response to Salmonella Typhimurium with a focus on dynamics and immune modulation

Salmonella enterica serovar Typhimurium is a major foodborne pathogen that disrupts gut microbial balance and induces intestinal inflammation. Microbial analysis revealed that S. Typhimurium infection increased the abundance of short-chain fatty acid (SCFA)-producing bacteria, including Bacteroides, Parabacteroides, and members of the Clostridia group, while decreasing Escherichia-Shigella in an in vitro fecal fermentation model. Co‑culture experiments demonstrated that gut microbiota inhibited S. Typhimurium growth and host cell interactions while attenuating cytotoxicity and inflammatory responses (IL‑1β, IL‑6, and c‑Jun) in Caco-2 cells in a dose‑dependent manner. Interestingly, gut microbiota improved epithelial cell viability, indicating barrier‑protective and immunomodulatory functions. These findings demonstrate that human gut microbiota plays a crucial role in mitigating the pathogenicity of S. Typhimurium and maintaining intestinal homeostasis, supporting the potential of microbiota‑based strategies for infection control.