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Salivary Thromboxane A2-Binding Proteins from Triatomine Vectors of Chagas Disease Inhibit Platelet-Mediated Neutrophil Extracellular Traps (NETs) Formation and Arterial Thrombosis.

Mizurini DM, Aslan JS, Gomes T, Ma D, Francischetti IM, Monteiro RQ - PLoS Negl Trop Dis (2015)

Bottom Line: Effective antithrombotic doses of dipetalodipin and triplatin did not increase blood loss, which was estimated using the tail transection method.This ability may contribute to the antithrombotic effects in vivo.Our results provide new insight into the antihemostatic effects of TXA2-binding proteins and may have important significance in elucidating the mechanisms of saliva to avoid host's hemostatic responses and innate immune system.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.

ABSTRACT

Background: The saliva of blood-feeding arthropods contains a notable diversity of molecules that target the hemostatic and immune systems of the host. Dipetalodipin and triplatin are triatomine salivary proteins that exhibit high affinity binding to prostanoids, such as TXA2, thus resulting in potent inhibitory effect on platelet aggregation in vitro. It was recently demonstrated that platelet-derived TXA2 mediates the formation of neutrophil extracellular traps (NETs), a newly recognized link between inflammation and thrombosis that promote thrombus growth and stability.

Methodology/principal findings: This study evaluated the ability of dipetalodipin and triplatin to block NETs formation in vitro. We also investigated the in vivo antithrombotic activity of TXA2 binding proteins by employing two murine models of experimental thrombosis. Remarkably, we observed that both inhibitors abolished the platelet-mediated formation of NETs in vitro. Dipetalodipin and triplatin significantly increased carotid artery occlusion time in a FeCl3-induced injury model. Treatment with TXA2-binding proteins also protected mice from lethal pulmonary thromboembolism evoked by the intravenous injection of collagen and epinephrine. Effective antithrombotic doses of dipetalodipin and triplatin did not increase blood loss, which was estimated using the tail transection method.

Conclusions/significance: Salivary TXA2-binding proteins, dipetalodipin and triplatin, are capable to prevent platelet-mediated NETs formation in vitro. This ability may contribute to the antithrombotic effects in vivo. Notably, both molecules inhibit arterial thrombosis without promoting excessive bleeding. Our results provide new insight into the antihemostatic effects of TXA2-binding proteins and may have important significance in elucidating the mechanisms of saliva to avoid host's hemostatic responses and innate immune system.

No MeSH data available.


Related in: MedlinePlus

Dipetalodipin and triplatin are antithrombotic in vivo.Thrombosis was induced in the carotid artery of mice via local application with 7.5% FeCl3. Blood flow was monitored with a perivascular flow probe for 60 min or until stable occlusion occurred. (A) Dipetalodipin or (B) triplatin was injected into the caudal vein 15 min before injury. Each symbol represents one individual. *P < 0.05 vs control, **P < 0.01 vs control; ANOVA with the Dunnett posttest.
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pntd.0003869.g003: Dipetalodipin and triplatin are antithrombotic in vivo.Thrombosis was induced in the carotid artery of mice via local application with 7.5% FeCl3. Blood flow was monitored with a perivascular flow probe for 60 min or until stable occlusion occurred. (A) Dipetalodipin or (B) triplatin was injected into the caudal vein 15 min before injury. Each symbol represents one individual. *P < 0.05 vs control, **P < 0.01 vs control; ANOVA with the Dunnett posttest.

Mentions: The in vivo antithrombotic activity of dipetalodipin and triplatin was evaluated by employing two murine models of experimental thrombosis. First, the effect of the TXA2-binding proteins on thrombus formation was assessed using a FeCl3-induced carotid artery injury [20]. Thrombus formation was estimated using a Doppler flow probe that allows for the monitoring of carotid blood flow until the vessel occludes, or for up to 60 min if occlusion does not occur. Fig 3 shows that 7.5% FeCl3 applied on top of the carotid artery resulted in a reproducible occlusive thrombosis (all animals showed complete vessel occlusion within 20 minutes). Time to occlusion was not statistically significant between control mice and the mice treated either with 0.2 mg/kg dipetalodipin or triplatin, although 4 out of 10 dipetalodipin-treated mice and 2 out of 9 triplatin-treated mice were resistant to arterial occlusion (Fig 3). It is possible that thrombosis induction at this FeCl3 concentration is less sensitive for the subtle effect of low doses of dipetalodipin and triplatin. In contrast, treatment with 0.5 mg/kg of either dipetalodipin or triplatin produced significant resistance to thrombosis, as most animals showed no occlusion over the 60 min period (Fig 3).


Salivary Thromboxane A2-Binding Proteins from Triatomine Vectors of Chagas Disease Inhibit Platelet-Mediated Neutrophil Extracellular Traps (NETs) Formation and Arterial Thrombosis.

Mizurini DM, Aslan JS, Gomes T, Ma D, Francischetti IM, Monteiro RQ - PLoS Negl Trop Dis (2015)

Dipetalodipin and triplatin are antithrombotic in vivo.Thrombosis was induced in the carotid artery of mice via local application with 7.5% FeCl3. Blood flow was monitored with a perivascular flow probe for 60 min or until stable occlusion occurred. (A) Dipetalodipin or (B) triplatin was injected into the caudal vein 15 min before injury. Each symbol represents one individual. *P < 0.05 vs control, **P < 0.01 vs control; ANOVA with the Dunnett posttest.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482233&req=5

pntd.0003869.g003: Dipetalodipin and triplatin are antithrombotic in vivo.Thrombosis was induced in the carotid artery of mice via local application with 7.5% FeCl3. Blood flow was monitored with a perivascular flow probe for 60 min or until stable occlusion occurred. (A) Dipetalodipin or (B) triplatin was injected into the caudal vein 15 min before injury. Each symbol represents one individual. *P < 0.05 vs control, **P < 0.01 vs control; ANOVA with the Dunnett posttest.
Mentions: The in vivo antithrombotic activity of dipetalodipin and triplatin was evaluated by employing two murine models of experimental thrombosis. First, the effect of the TXA2-binding proteins on thrombus formation was assessed using a FeCl3-induced carotid artery injury [20]. Thrombus formation was estimated using a Doppler flow probe that allows for the monitoring of carotid blood flow until the vessel occludes, or for up to 60 min if occlusion does not occur. Fig 3 shows that 7.5% FeCl3 applied on top of the carotid artery resulted in a reproducible occlusive thrombosis (all animals showed complete vessel occlusion within 20 minutes). Time to occlusion was not statistically significant between control mice and the mice treated either with 0.2 mg/kg dipetalodipin or triplatin, although 4 out of 10 dipetalodipin-treated mice and 2 out of 9 triplatin-treated mice were resistant to arterial occlusion (Fig 3). It is possible that thrombosis induction at this FeCl3 concentration is less sensitive for the subtle effect of low doses of dipetalodipin and triplatin. In contrast, treatment with 0.5 mg/kg of either dipetalodipin or triplatin produced significant resistance to thrombosis, as most animals showed no occlusion over the 60 min period (Fig 3).

Bottom Line: Effective antithrombotic doses of dipetalodipin and triplatin did not increase blood loss, which was estimated using the tail transection method.This ability may contribute to the antithrombotic effects in vivo.Our results provide new insight into the antihemostatic effects of TXA2-binding proteins and may have important significance in elucidating the mechanisms of saliva to avoid host's hemostatic responses and innate immune system.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.

ABSTRACT

Background: The saliva of blood-feeding arthropods contains a notable diversity of molecules that target the hemostatic and immune systems of the host. Dipetalodipin and triplatin are triatomine salivary proteins that exhibit high affinity binding to prostanoids, such as TXA2, thus resulting in potent inhibitory effect on platelet aggregation in vitro. It was recently demonstrated that platelet-derived TXA2 mediates the formation of neutrophil extracellular traps (NETs), a newly recognized link between inflammation and thrombosis that promote thrombus growth and stability.

Methodology/principal findings: This study evaluated the ability of dipetalodipin and triplatin to block NETs formation in vitro. We also investigated the in vivo antithrombotic activity of TXA2 binding proteins by employing two murine models of experimental thrombosis. Remarkably, we observed that both inhibitors abolished the platelet-mediated formation of NETs in vitro. Dipetalodipin and triplatin significantly increased carotid artery occlusion time in a FeCl3-induced injury model. Treatment with TXA2-binding proteins also protected mice from lethal pulmonary thromboembolism evoked by the intravenous injection of collagen and epinephrine. Effective antithrombotic doses of dipetalodipin and triplatin did not increase blood loss, which was estimated using the tail transection method.

Conclusions/significance: Salivary TXA2-binding proteins, dipetalodipin and triplatin, are capable to prevent platelet-mediated NETs formation in vitro. This ability may contribute to the antithrombotic effects in vivo. Notably, both molecules inhibit arterial thrombosis without promoting excessive bleeding. Our results provide new insight into the antihemostatic effects of TXA2-binding proteins and may have important significance in elucidating the mechanisms of saliva to avoid host's hemostatic responses and innate immune system.

No MeSH data available.


Related in: MedlinePlus