Effects of alpha hemolysin of E.coli on human platelets

KENIA PÉREZ VÁZQUEZ; MELISA PUCCI MOLINERIS; PABLO SCHWARZBAUM; VANESA HERLAX

Congreso; Reunion anual de Sociedades de Biociencias; 2020

Alpha hemolysin (HlyA) is the major virulence factor of uropathogenic Escherichia coli (UPEC) pathology, causing 50% of all extraintestinal disease in humans ? such as urinary-tract infection, pyelonephritis and septicemia ? and the expression of HlyA was found to correlate with the se-verity of the infections produced. In the example of sepsis, the toxin is released in the vascula-ture. Once in circulation, HlyA can directly interact with red blood cells (RBCs) membranes. Sublytic concentrations of the toxin caused changes in RBC morphology, activation of endoge-nous sphingomyelinases and externalization of ceramide. All these events were causative of the delivery of microvescicles containing the toxin in the membranes. In this work we present results related to the interaction of HlyA with platelets, another of the main cells in circulation. Results show that low toxin concentration (10.36 nM) induces the delivery of lactate dehydrogenate (LDH) in fresh isolated human platelets, indicating a cytotoxic effect. Morphological changes of treated platelets were observed by Scanning Electron Microscopy (SEM). We also measure the rise in intracellular calcium concentration by flow cytometry, finding that this increase was toxin concentration - dependent. These results show, for the first time, a cytotoxic effect and induction of morphological changes in human platelets treated with the exotoxin Hly of E.coli, providing the basis for further studies in pathways activated by this toxin in bloodstream cells.