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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 abolish the collagen-mediated acceleration of PRP clotting.Human citrated-anticoagulated (A) PRP or (B) PPP supplemented with PC/PS was pretreated with dipetalodipin (1 μM) or triplatin (2 μM). Preparations were then incubated with collagen (50 μg/ml, final concentration) or vehicle solvent (control) and activated with 16.6 mM CaCl2. Mean ± SEM (n = 5); *P < .05; **P < .01; ***P < .001; NS, non-significant; analysis of variance (ANOVA) with Tukey's posttest.
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pntd.0003869.g001: Dipetalodipin and triplatin abolish the collagen-mediated acceleration of PRP clotting.Human citrated-anticoagulated (A) PRP or (B) PPP supplemented with PC/PS was pretreated with dipetalodipin (1 μM) or triplatin (2 μM). Preparations were then incubated with collagen (50 μg/ml, final concentration) or vehicle solvent (control) and activated with 16.6 mM CaCl2. Mean ± SEM (n = 5); *P < .05; **P < .01; ***P < .001; NS, non-significant; analysis of variance (ANOVA) with Tukey's posttest.

Mentions: Because dipetalodipin and triplatin inhibit platelet aggregation induced by low concentrations of collagen, we first evaluated their effect in counteracting the collagen-mediated acceleration of human plasma clotting. Coagulation experiments were performed using either platelet rich plasma (PRP) or platelet poor plasma (PPP). Consistent with previous reports collagen accelerated plasma clotting [19,21], regardless of whether platelets or phospholipids were present in the procoagulant lipid surface (Fig 1A and 1B). However, dipatelodipin and triplatin only abolished this effect in the presence of platelets (Fig 1A). Thus, as shown in Fig 1A, dipetalodipin (1 μM) or triplatin (2 μM) prolonged PRP clotting by 1.3-fold compared to collagen measurements (155.9 ± 12.2 s and 161.4 ± 12.8 s versus 118.5 ± 4.0 s). Addition of collagen to PPP also resulted in a significant shortening of the clotting time, but this effect was not abolished by either dipetalodipin or triplatin (Fig 1B).


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 abolish the collagen-mediated acceleration of PRP clotting.Human citrated-anticoagulated (A) PRP or (B) PPP supplemented with PC/PS was pretreated with dipetalodipin (1 μM) or triplatin (2 μM). Preparations were then incubated with collagen (50 μg/ml, final concentration) or vehicle solvent (control) and activated with 16.6 mM CaCl2. Mean ± SEM (n = 5); *P < .05; **P < .01; ***P < .001; NS, non-significant; analysis of variance (ANOVA) with Tukey's posttest.
© Copyright Policy
Related In: Results  -  Collection

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

pntd.0003869.g001: Dipetalodipin and triplatin abolish the collagen-mediated acceleration of PRP clotting.Human citrated-anticoagulated (A) PRP or (B) PPP supplemented with PC/PS was pretreated with dipetalodipin (1 μM) or triplatin (2 μM). Preparations were then incubated with collagen (50 μg/ml, final concentration) or vehicle solvent (control) and activated with 16.6 mM CaCl2. Mean ± SEM (n = 5); *P < .05; **P < .01; ***P < .001; NS, non-significant; analysis of variance (ANOVA) with Tukey's posttest.
Mentions: Because dipetalodipin and triplatin inhibit platelet aggregation induced by low concentrations of collagen, we first evaluated their effect in counteracting the collagen-mediated acceleration of human plasma clotting. Coagulation experiments were performed using either platelet rich plasma (PRP) or platelet poor plasma (PPP). Consistent with previous reports collagen accelerated plasma clotting [19,21], regardless of whether platelets or phospholipids were present in the procoagulant lipid surface (Fig 1A and 1B). However, dipatelodipin and triplatin only abolished this effect in the presence of platelets (Fig 1A). Thus, as shown in Fig 1A, dipetalodipin (1 μM) or triplatin (2 μM) prolonged PRP clotting by 1.3-fold compared to collagen measurements (155.9 ± 12.2 s and 161.4 ± 12.8 s versus 118.5 ± 4.0 s). Addition of collagen to PPP also resulted in a significant shortening of the clotting time, but this effect was not abolished by either dipetalodipin or triplatin (Fig 1B).

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