Synbiotic effect of quercetin and probiotic Lactobacillus SP. protects intestinal barrier from E. coli-induced challenge in Caco-2 cells

Many studies reported the positive synergy between polyphenols and probiotics. Probiotics are known for their positive and beneficial effects on human intestinal health, and their interactions with polyphenolic compounds and metabolites may increase health benefits improving intestinal barrier function and modulating the gut microbiota. Here a symbiotic strategy of quercetin (QUE) and Lactobacillus acidophilus LA5 antimicrobial and antiadhesion properties against E. coli was evaluated on intestinal Caco-2 differentiated cells. Our study demonstrates that QUE improves LA5 auto-aggregation and LA5 and E. coli coaggregation. Additionally, LA5 decreased the adhesion of E. coli to Caco-2 cells mainly via exclusion antagonism than competition assay. Interestingly, QUE did not affect LA5 effects on E. coli adhesion, but synergically improved the barrier function of Caco-2 cells improving TEER values, claudin-1 expression and reducing proinflammatory COX-2 expression. Data confirmed the LA5 and QUE synergism supporting their combined use in the prevention or treatment of pathogen diseases.