Effects of alpha hemolysin of E.coli on human platelets

KENIA PÉREZ VÁZQUEZ, MELISA PUCCI MOLINERIS, PABLO J. SCHWARZBAUM AND VANESA HERLAX

Congreso; Reunion Anual de Sociedades de Biociencias; 2021

Alpha hemolysin (HlyA) is the major virulence factor of uropathogenicEscherichia coli (UPEC) pathology, causing 50% of all extraintestinaldisease in humans ? such as urinary-tract infection, pyelonephritisand septicemia ? and the expression of HlyA was found tocorrelate with the severity of the infections produced. During sepsis,HlyA is released in the vasculature where it can directly interact withcell membranes of red blood cells (RBCs). Sublytic concentrations ofthe toxin caused changes in RBC morphology, activation of endogenoussphingomyelinases and externalization of ceramide. All theseevents induced the delivery of microvescicles containing the toxin inthe membranes. In this work we studied the interaction of HlyA withisolated platelets. Results show that a relatively low toxin concentration(10.36 nM) induced the release of lactate dehydrogenate, thusindicating a cytotoxic effect. Morphological changes of HlyA-treatedplatelets were observed by Scanning Electron Microscopy (SEM),evidencing a disruption in the external platelet structure. We alsomeasured the rise in intracellular calcium concentration, by flow cytometry,finding increments in the concentration of the cation directlycorrelated with toxin concentration. Overall results show that pureHlyA isolated from E.coli, caused cytotoxicity and morphologicalchanges in human platelets, providing the basis for futher studies onthe signaling pathways activated by this toxin in bloodstream cells.