CrATP interferes in the promastigote-macrophage interaction inLeishmania amazonensisinfection

Abstract

SUMMARYRecent have shown the relationship between Ecto-Nucleoside-Triphosphate-Diphosphohydrolases (Ecto-NTPDases or ecto-nucleotidases) and virulence and infectivity in trypanosomatids. In this work, the inhibition of the ecto-ATPase activities and promastigote growth ofLeishmania amazonensisby CrATP was characterized. Furthermore, this compound was used to investigate the role of ecto-nucleotidase in the interaction ofL. amazonensiswith resident peritoneal macrophages obtained from BALB/c mice. CrATP partially inhibits the ecto-ATPase activity, presenting Ki values of 575·7±199·1 and 383·5±79·0μm, in the presence or absence of 5 mmMgCl2, respectively. The apparent Kms for ATP (2·9±0·5 mmto Mg2+-dependent ecto-ATPase and 0·4±0·2 mmto Mg2+-independent ecto-ATPase activities) are not significantly altered by CrATP, suggesting a reversible non-competitive inhibition of both enzymes. When CrATP was added to the cultivation medium at 500μm, it drastically inhibited the cellular growth. The interaction of promastigote forms ofL. amazonensiswith BALB/c peritoneal macrophages is strongly affected by CrATP. When the parasites were treated with 500μmCrATP before interacting with macrophages, the adhesion and endocytic indices were strongly reduced to 53·0±14·8% and 39·8±1·1%, respectively. These results indicate that ecto-nucleotidase plays an important role in the infection process caused byLeishmania amazonensis.