Prolongation of functional life-span of neutrophils by recombinant verotoxin 2.

OBJECTIVE

Verotoxin-producing Escherichia coli (VTEC) strains of serotype O157 : H7 have been implicated in a wide spectrum of diseases, including blood diarrhea, hemorrhagic colitis and hemolytic uremic syndrome (HUS). To further explore the pathological role of verotoxin (VT) in HUS and other VTEC associated diseases, we investigated the effects of recombinant verotoxin 2 (rVT2) on the biological activity of neutrophils.

METHODS

The technique of flow cytometry, a fluorescent probe 2,7-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester (BCECF/AM), and the assay of reduced cytochrome c to detect superoxide production were used in this study.

RESULTS

gammaVT2 significantly inhibited spontaneous apoptosis in neutrophils. Neutrophils with prolonged survival due to gammaVT2 maintained various biological functions, such as the expression of adhesion molecules (shading CD62L and raising CD11b/CD18), adherence to human umbilical vein endothelial cells (HUVECs), and generation of superoxide (O(2)(-)).

CONCLUSIONS

Prolongation of the functional life-span of neutrophils by gammaVT2 may accelerate inflammatory responses at sites of inflammation. This may play a crucial role in neutrophil-mediated tissue injury in HUS and other VTEC-associated diseases.