Aim: This study investigated the effects of Muno-IgY®, a multi-pathogen-specific immunoglobulin Y (IgY), on microbial growth, adhesion, fermentation activity, and immune signaling using a multi-tiered in vitro approach.

Methods: IgY activity was first evaluated in Caco-2 adhesion and invasion assays using adherent-invasive Escherichia coli (AIEC) at optimized concentrations, followed by assessment in a SHIME® in vitro gut model inoculated with human fecal microbiota enriched in Enterobacteriaceae. Microbial composition, fermentation markers, and metabolite production were analyzed, and downstream effects on epithelial barrier integrity and immune signaling were evaluated using a Caco-2/peripheral blood mononuclear cell (PBMC) co-culture model exposed to SHIME® effluents.

Results: Muno-IgY® significantly reduced AIEC adhesion/invasion from 39.76% in controls to 13.08% and 9.13% at 3 and 6 mg/mL, respectively (P < 0.05). In the SHIME® model, IgY significantly increased acetate and propionate production (P < 0.05), alongside a marked increase in ammonium concentration (P < 0.01). Microbial biomass increased modestly, while alpha- and beta-diversity indices were not significantly altered. The compositional shifts indicated enrichment of beneficial and mucin-associated taxa and reduction of opportunistic or pathogenic species in the Muno-IgY® group. In Caco-2/PBMC co-cultures, IgY-treated effluent decreased transepithelial electrical resistance (TEER) indicating reduced barrier integrity (P < 0.05) but significantly decreased pro-inflammatory cytokines Interferon-γ (IFN-γ) and Interleukin-22 (IL-22) (P < 0.05).

Conclusions: Muno-IgY® demonstrates the ability to inhibit pathogen adhesion and modulate microbial composition and immune responses in vitro. These findings support its potential as a non-antibiotic approach for microbiome-targeted interventions, although further validation in vivo is required.

Background:Klebsiella pneumoniae can colonize the gastrointestinal tract, yet its interactions with intestinal mucus remain poorly defined. In this study, we examined the capacity of Klebsiella pneumoniae (K. pneumoniae) to adhere and use intestinal mucus and its associated glycans.

Methods: Multiple commercial and clinical K. pneumoniae isolates were tested for adhesion to porcine and human Mucin 2 (MUC2) using fluorescence-based assays and microscopy. In vivo mucus localization was examined in colonized mice by fluorescent in situ hybridization (FISH). Genomic analyses of K. pneumoniae genomes were performed to identify glycosyl hydrolases and sugar utilization pathways. Growth on mucin-derived monosaccharides or intact mucus was assessed in minimal media. Biofilm formation and aminoglycoside susceptibility were measured in the presence or absence of mucus.

Results: All K. pneumoniae strains adhered robustly to porcine and human MUC2 in vitro and we found K. pneumoniae localized to the murine mucus layer in vivo. Genomic analysis of over 1,000 K. pneumoniae isolates revealed that most strains possess glycosyl hydrolases targeting internal galactose, N-acetyl-glucosamine (GlcNAc), and N-acetyl-galactosamine (GalNAc) glycan sugars, though they lack enzymes to cleave terminal fucose or N-acetyl-neuraminic acid. Consistent with this finding, we found that K. pneumoniae alone could not grow in minimal media with intact mucus as a sole carbon source. However, we found that K. pneumoniae could grow with free mucus glycan-derived sugars galactose, GlcNAc, GalNAc fucose and N-acetyl-neuraminic acid. Mucus did not alter biofilm formation, but it significantly increased sensitivity to gentamicin, kanamycin and streptomycin.

Conclusion: These findings identify mucus as an important modulator of K. pneumoniae colonization and antibiotic responsiveness.