A murine experimental model of the unique pulmonary thrombotic effect induced by the venom of the snake Bothrops lanceolatus

Abstract

BackgroundThe venom of Bothrops lanceolatus, a viperid species endemic to the Lesser Antillean Island of Martinique, induces a unique clinical manifestation, i.e., thrombosis. Previous clinical observations indicate that thromboses are more common in patients bitten by juvenile specimens. There is a need to develop an experimental model of this effect in order to study the mechanisms involved. Methodology/principal findingsThe venoms of juvenile and adult specimens of B. lanceolatus were compared by (a) describing their proteome, (b) assessing their ability to induced thrombosis in a mouse model, and (c) evaluating their in vitro procoagulant activity and in vivo hemostasis alterations. Venom proteomes of juvenile and adult specimens were highly similar. When injected by the intraperitoneal (i.p.) route, the venom of juvenile specimens induced the formation of abundant thrombi in the pulmonary vasculature, whereas this effect was less frequent in the case of adult venom. Thrombosis was not abrogated by the metalloproteinase inhibitor Batimastat. Both venoms showed a weak in vitro procoagulant effect on citrated mouse plasma and bovine fibrinogen. When administered intravenously (i.v.) venoms did not affect classical clotting tests (prothrombin time and activated partial thromboplastin time) but caused a partial drop in fibrinogen concentration. The venom of juvenile specimens induced partial alterations in some rotational thromboelastometry parameters after i.v. injection. No alterations in coagulation tests were observed when venoms were administered i.p., but juvenile and adult venoms induced a marked thrombocytopenia. Conclusions/significanceAn experimental model of the thrombotic effect induced by B. lanceolatus venom was developed. This effect is more pronounced in the case of venom of juvenile specimens, despite the observation that juvenile and adult venom proteomes are similar. Adult and juvenile venoms do not induce a consumption coagulopathy characteristic of other Bothrops sp venoms. Both venoms induce a conspicuous thrombocytopenia. This experimental model reproduces the main clinical findings described in these envenomings and should be useful to understand the mechanisms of this thrombotic effect. Author summaryEnvenomings by the viperid species Bothrops lanceolatus, endemic of the Caribbean Island of Martinique, are characterized by a unique thrombotic effect responsible for infarcts in various organs. Until now, no experimental in vivo models of this effect have been described. In this study, we developed a mouse model of thrombosis by using the intraperitoneal route of venom injection. The venom of juvenile specimens of B. lanceolatus induced the formation of abundant thrombi in the lungs, whereas the effect was much less pronounced with the venom of adult specimens. This difference in the ability of juvenile and adult venoms occurs despite both venoms having highly similar proteomic profiles. Both adult and juvenile venoms showed a weak in vitro procoagulant effect on plasma and fibrinogen, underscoring a thrombin-like (pseudo-procoagulant) activity. In vivo, the venoms did not affect the classical clotting tests (prothrombin time and activated partial thromboplastin time) but induced a partial drop in fibrinogen concentration and limited alterations in rotational thromboelastometry parameters when injected by the i.v. route. In contrast, few alterations of these parameters were observed after i.p. injection of venoms, in conditions in which thrombosis occurred, hence evidencing the lack of a consumption coagulopathy. After i.p. injection both venoms induced a pronounced thrombocytopenia. This experimental model reproduces some of the main clinical manifestations of envenoming by this species. This model can be used to identify the toxins responsible for the thrombotic effect, to study the mechanism(s) of thrombosis and to assess the preclinical efficacy of antivenoms.