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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 108, No. 6, 2013, pp. 679-685
Bioline Code: oc13115
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 108, No. 6, 2013, pp. 679-685

 en Leishmania amazonensis check for this species in other resources exhibits phosphatidylserine-dependent procoagulant activity, a process that is counteracted by sandfly saliva
Rochael, Natalia Cadaxo; Lima, Luize Gonçalves; Pereira de Oliveira, Sandra Maria; Barcinski, Marcello André; Saraiva, Elvira Maria; Monteiro, Robson Queiroz & Pinto-da-Silva, Lucia Helena

Abstract

Leishmania check for this species in other resources parasites expose phosphatidylserine (PS) on their surface, a process that has been associated with regulation of host’s immune responses. In this study we demonstrate that PS exposure by metacyclic promastigotes of Leishmania amazonensis check for this species in other resources favours blood coagulation. L. amazonensis accelerates in vitro coagulation of human plasma. In addition, L. amazonensis supports the assembly of the prothrombinase complex, thus promoting thrombin formation. This process was reversed by annexin V which blocks PS binding sites. During blood meal, Lutzomyia longipalpis check for this species in other resources sandfly inject saliva in the bite site, which has a series of pharmacologically active compounds that inhibit blood coagulation. Since saliva and parasites are co-injected in the host during natural transmission, we evaluated the anticoagulant properties of sandfly saliva in counteracting the procoagulant activity of L. amazonensis. Lu. longipalpis check for this species in other resources saliva reverses plasma clotting promoted by promastigotes. It also inhibits thrombin formation by the prothrombinase complex assembled either in phosphatidylcholine (PC)/PS vesicles or in L. amazonensis. Sandfly saliva inhibits factor X activation by the intrinsic tenase complex assembled on PC/PS vesicles and blocks factor Xa catalytic activity. Altogether our results show that metacyclic promastigotes of L. amazonensis are procoagulant due to PS exposure. Notably, this effect is efficiently counteracted by sandfly saliva.

Keywords
sandfly saliva; Leishmania amazonensis; phosphatidylserine; blood coagulation; Lutzomyia longipalpis

 
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