Lactoferrin and lactoferrin chimera inhibit damage caused by enteropathogenic Escherichia coli in HEp-2 cells

Enteropathogenic Escherichia coli (EPEC) is an important cause of infant diarrhea in developing countries. It produces a characteristic intestinal histopathological lesion on enterocytes known as 'attaching and effacing' (A/E), and these two steps are mediated by a type-III secretory system. In the present study, we evaluated the effect on the initial host cell attachment step produced by bovine lactoferrin (bLF) and three synthetic peptides: lactoferricin (LFcin), lactoferrampin (LFampin) and LFchimera. A special focus was given to the hemolytic activity and EPEC-induced actin polymerization in HEp-2 cells, as well as to the espA gene expression, which produces the protein responsible for primary contact with the host cells. Results show that EPEC attachment to HEp-2 cells was significantly suppressed by bLF and LFchimera at 125 and 40 μM, respectively. EPEC-mediated actin polymerization was blocked by bLF and LFchimera at 88 and 99%, respectively. LFchimera inhibited the attachment and A/E lesion caused by EPEC in a dose-dependent manner. In the presence of 125 μM bLF, the expression level of the espA gene was decreased by 50% compared to the untreated control. LFchimera at concentrations of 20 μM and 40 μM diminished the level of espA gene expression 100 and 1000 fold, respectively (P < 0.001). Although bLF, LFchimera, LFcin, and LFampin all significantly blocked the hemolysis produced by EPEC (P < 0.001), the two former compounds produced this effect at lower concentrations. These two compounds, bLF and LFchimera, were able to inhibit the first steps of the mechanism of the damage used by EPEC. This data suggests that LFchimera could provide protection against enteropathogens that share this mechanism.