Antagonistic activity of Lactobacillus acidophilus LB against intracellular Salmonella enterica serovar typhimurium infecting human enterocyte-like Caco-2/TC-7 cells

To gain further insight into the mechanism by which lactobacilli develop an timicrobial activity, we have examined how Lactobacillus acidophilus LB inh ibits the promoted cellular injuries and intracellular lifestyle of Salmone lla enterica serovar Typhimurium SL1344 infecting the cultured, fully diffe rentiated human intestinal cell line Caco-2/TC-7, We showed that the spent culture supernatant of strain LB (LB-SCS) decreases the number of apical se rovar Typhimurium-induced F-actin rearrangements in infected cells. LB-SCS treatment efficiently decreased transcellular passage of S, enterica serova r Typhimurium. Moreover, LB-SCS treatment inhibited intracellular grow-th o f serovar Typhimurium, since treated intracellular bacteria displayed a sma ll, rounded morphology resembling that of resting bacteria. We also showed that LB-SCS treatment inhibits adhesion-dependent serovar Typhimurium-induc ed interleukin-8 production.