Exopolysaccharides from Bifidobacterium longum supsp. Infantis and Bifidobacterium adolescentis protect gut epithelial cells from antibiotic- induced disruption but do not affect epithelial responses to Escherichia Coli

Antibiotic use is a major contributor to antimicrobial resistance (AMR) and can compromise gut epithelial integrity. However, strategies to mitigate these side effects remain limited. This study investigated whether exopolysaccharides (EPS) derived from <i>Bifidobacterium infantis</i> and <i>Bifidobacterium adolescentis</i> can protect intestinal epithelial cells from barrier disruption caused by doxycycline (DOX) and zinc oxide (ZnO). Using T84 cells, we found that both DOX and ZnO significantly reduced transepithelial electrical resistance (TEER), indicating impaired barrier function. EPS from <i>B. adolescentis</i> effectively preserved barrier integrity against both agents. In contrast, EPS from <i>B. infantis</i> was protective only against DOX at higher concentrations. DOX and ZnO downregulated genes involved in tight junction and inflammatory pathways. EPS effects on gene expression were strain-specific and partly restorative. IL-8 secretion was enhanced by <i>B. adolescentis</i> EPS and modulated during DOX exposure, suggesting immune pathway involvement. In contrast, neither EPS type affected <i>Escherichia coli</i> O119 adhesion or inflammatory responses in Caco-2 cells. These findings demonstrate that bifidobacterial EPS can mitigate antibiotic-induced epithelial damage in a structure- and strain-dependent manner, supporting their potential as adjunctive agents to preserve gut barrier function during antimicrobial treatment.