Effect of lactoferrin on enteroaggregative E. coli (EAEC).
We previously demonstrated that lactoferrin inhibits adherence of enteropathogenic Escherichia coli to HEp-2 cells and decreases invasiveness of Shigella flexneri in HeLa cells by disruption of the type III secretory system (TTSS) of both enteropathogens. To determine whether these effects were specific to the TTSS, we assessed the activity of bovine lactoferrin on enteroaggregative E. coli (EAEC), enteropathogens whose virulence is not TTSS dependent. Bovine lactoferrin at a concentration of 1.0 and 0.1 mg/mL inhibited EAEC growth. Saturation with iron reversed the bacteriostatic effect. Lactoferrin under nonbacteriostatic conditions decreased EAEC adherence to HEp-2 cells as evaluated by microscopy and CFUs; this effect was not iron dependent. Lactoferrin inhibited EAEC biofilm formation and increased autoagglutination. Lactoferrin blocks EAEC adherence by inducing release and degradation of aggregative adherence fimbria, a key element of EAEC pathogenesis. We hypothesized that lactoferrin binding to lipid A of lipopolysaccharide disrupts the virulence proteins anchored to the bacterial outermembrane. These data suggest that the effect of lactoferrin on surface proteins is not restricted to organisms having a TTSS.
Ochoa
Theresa J
TJ
Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
Brown
Eric L
EL
Guion
Chase E
CE
Chen
Jane Z
JZ
McMahon
Robert J
RJ
Cleary
Thomas G
TG
D018830:Adhesins, Escherichia coli / Q000378:metabolism; D000371:Agglutination / Q000187:drug effects; D000818:Animals; D001422:Bacterial Adhesion / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects; D002417:Cattle; D004926:Escherichia coli / Q000166:cytology* / Q000187:drug effects* / Q000254:growth & development; D007501:Iron / Q000378:metabolism; D007781:Lactoferrin / Q000494:pharmacology*
C108511:AafA protein, E coli; D018830:Adhesins, Escherichia coli; D007501:Iron; D007781:Lactoferrin