Early platelet activation induced by alpha- hemolysin of Escherichia coli

KENIA PÉREZ VÁZQUEZ; PABLO SCHWARZBAUM; VANESA HERLAX

Congreso; L Reunión Anual de Sociedad Argentina de biofisica; 2022

Urinary tract infections are primarily caused by uropathogenic strains of Escherichia coli (UPEC). The infection that begins with the bladder colonization, if not treated, spread through the ureters to the kidneys, where the bacteria can gain access to the bloodstream. In case of bacteremia, the blood cells not only face the pathogens but also their secretion products, such as . alpha hemolysin (HlyA), an exotoxin that causes the activation and lysis of various mammalian cells. To describe the response of isolated human platelets to HlyA (XX to xx nM), we evaluated some of the mechanisms of early cell activation by flow cytometry and Transmission and Scanning Electronic Microscopy (TEM and SEM). Results indicate that the toxin induces an increase in cytosolic calcium concentration within the first 5 min. in a dependent concentration fashion. HlyA also induces morphological changes in platelets, promoting the rounding of them and the formation of microvesicles in the membrane. Furthermore, a major exposure of P-selectin (degranulation marker) and phosphatidylserine at the outer membrane leaflet, were observed in HlyA-treated platelets compared to control ones. Altogether these results suggest the establishment of a calcium-dependent activation process in HlyA-treated platelets that might induce the release of coagulation mediators the , extracellular vesicles formation and, ultimately, platelet death.