Role of ATP homeostasis in the microparticles produced by erythrocytes infected with Plasmodium falciparum

ALVAREZ, CORA LILIA; ESPELT, MARÍA VICTORIA; OSTUNI, MARIANO ANIBAL; SEMBLAT, JEAN-PHILIPPE; LAPOUMEROULIE, CLAUDINE; HATTAB, CLAUDE; REPETTO, SILVIA; GONZALEZ, DÉBORA; BARBIERI VAN HAASTER, MATÍAS; SCHWARZBAUM, PABLO JULIO

Rosario, Santa Fe

Congreso; Reunión Anual de la Sociedad Argentina de Fisiología; 2019

SAFIS

Malaria is a worldwide disease caused by the infection of red blood cells (RBCs) with Plasmodium falciparum. Previous studies have demonstrated that infected RBCs produce microparticles (MPs) of 0.1-1 μm by plasma membrane blebbing. RBCs release ATP when challenged by various physio- and pathological stimuli. The resulting extracellular ATP (ATPe) can control vasodilatation. Interestingly, malaria patients show microcirculatory impairments which seems to be associated with altered ATPe homeostasis. ATPe regulation depends on the balance between ATPase activity and ATP release. This balance can be altered by MPs, which display their own capacity to regulate ATPe.The aim of this study was to determine whether MPs can contribute to ATPe homeostasis of P. falciparum infected RBCs.MPs were isolated from culture supernatant by centrifugation from both infected and control RBCs. Luciferin-luciferase-based luminometry was used to measure the ATP content and the rate of ATPe hydrolysis of MPs.Transmission electron microscopy of MPs showed rounded membrane vesicles (diameter: 131 ± 35 nm). The ATP content of MPs, determined after permeabilization with digitonin, was higher in MPs obtained from infected RBCs culture than from control RBCs culture (2603 ± 1007 and 1659 ± 678 nM ATP/mg of protein, respectively). MPs were exposed to various ATP concentrations (450-1800 nM) and the time course of ATPe decay was determined. Initial rate values of ATPe presented a linear function with [ATPe]s, from which KATP accounted for the slope. KATP was 3 fold higher in MPs obtained from infected RBCs than from control RBCs culture (0.99 ± 0.05 and 0.32 ± 0.03 nM ATP/(mg min), respectively).Our results show that infection triggers the formation of MPs. These MPs exhibited ATPe hydrolysis in the nM range. Previous results, in which infected RBCs exhibited higher ectoATPase activity than non-infected RBCs, correlated with higher ATPe hydrolysis observed in MPs obtained from infected RBCs culture than in MPs obtained from control RBCs culture.