Anti-inflammatory and barrier-protective effects of metabolites from Lactobacillus co-fermentation with linoleic acid and human fecal microbiota.

This study investigated the protective effects of metabolites generated from the co-fermentation of Lactobacillus, linoleic acid (LA) and human fecal microbiota on gut microbiota composition, intestinal inflammation and barrier function. While probiotic-derived conjugated linoleic acid (CLA) production has been reported, the functional effects of CLA-enriched metabolites derived from co-fermentation with human fecal microbiota remain unclear. Using an integrated approach including in vitro fermentation of healthy human fecal microbiota, lipopolysaccharide (LPS)-induced RAW264.7/Caco-2 co-culture models and antibiotic-depleted, dextran sulfate sodium (DSS)-induced colitis mouse model, we found that co-fermentation with LA and either Limosilactobacillus reuteri M94 or Lactiplantibacillus plantarum DPUL-77 significantly recovered microbial composition and markedly enhanced CLA production (6-7-fold, p < 0.0001) in the fecal fermentation systems. Both in vitro and in vivo, co-fermentation metabolites reduced pro-inflammatory cytokine expression by 60-80% (p < 0.001) and increased interleukin-10 (IL-10) levels by 3-4-fold (p < 0.01). Moreover, these metabolites improved intestinal barrier function, as evidenced by enhanced tight junction protein expression, restored epithelial integrity and reduced permeability in both models (p < 0.05-0.001), with greater effects observed in the Lactobacillus + LA groups. Notably, CLA-enriched metabolites exhibited enhanced biological efficacy; however, the specific contribution of CLA to these effects cannot be conclusively determined. Overall, these findings suggested that co-fermentation of Lactobacillus, LA and human fecal microbiota generates bioactive metabolites associated with reduced intestinal inflammation and improved barrier function. Further studies are required to clarify the roles of specific metabolites and the underlying mechanisms.