The Angiostrongylus vasorum Excretory/Secretory and Surface Proteome Contains Putative Modulators of the Host Coagulation

Abstract

Angiostrongylus vasorum is a cardiopulmonary nematode of canids and is, among others, associated with bleeding disorders in dogs. The pathogenesis of such coagulopathies remains unclear. A deep proteomic characterization of sex specific A. vasorum excretory/secretory proteins (ESP) and of cuticular surface proteins was performed, and the effect of ESP on host coagulation and fibrinolysis was evaluated in vitro. Proteins were quantified by liquid chromatography coupled to mass spectrometry and functionally characterized through gene ontology and pathway enrichment analysis. In total, 1069 ESP (944 from female and 959 from male specimens) and 1195 surface proteins (705 and 1135, respectively) were identified. Among these were putative modulators of host coagulation, e.g., von Willebrand factor type D domain protein orthologues as well as several proteases, including serine type proteases, protease inhibitors and proteasome subunits. The effect of ESP on dog coagulation and fibrinolysis was evaluated on canine endothelial cells and by rotational thromboelastometry (ROTEM). After stimulation with ESP, tissue factor and serpin E1 transcript expression increased. ROTEM revealed minimal interaction of ESP with dog blood and ESP did not influence the onset of fibrinolysis, leading to the conclusion that Angiostrongylus vasorum ESP and surface proteins are not solely responsible for bleeding in dogs and that the interaction with the host’s vascular hemostasis is limited. It is likely that coagulopathies in A. vasorum infected dogs are the result of a multifactorial response of the host to this parasitic infection.

Demonstration of hyperfibrinolysis on the VCM Vet in a dog with Angiostrongylus vasorum

“…3 Currently, the mechanism of coagulopathy in A. vasorum patients is not entirely known; however, hyperfibrinolysis and hypofibrinogenaemia remain a consistent finding. 3,4,12,13 Emesis is a known side effect of tranexamic acid usage, 14 and may represent a contraindication to patients with the potential for intracranial bleeding and/or vasculitis due to risk of increasing intracranial pressure with vomiting; however, previous studies have shown that 1 mg/kg maropitant intravenously can completely abolish emetic events at up to 50 mg/kg of tranexamic acid. 15 Fortunately, the largest scale study to date documented a low rate of adverse events, occurring in only 1.7% of dogs and 3% of cats.…”

“…It should be noted, however, that not all patients with A. vasorum infection present with coagulopathy, and not all patients that present with bleeding have hyperfibrinolysis 3 . Currently, the mechanism of coagulopathy in A. vasorum patients is not entirely known; however, hyperfibrinolysis and hypofibrinogenaemia remain a consistent finding 3,4,12,13 …”

Epistaxis associated with Angiostrongylus vasorum infection in a dog

“…15,50,51 Several hypotheses have been offered, including development of DIC, thrombocytopenia, hyperfibrinolysis or, more recently, complex interactions between host's homeostasis and A. vasorum surface proteins. [52][53][54] Young dogs are more likely to be infected by the parasite, especially due to their exploratory behaviour; however, studies on the impact of age at the time of infestation or parasitic burden on the development of bleeding diathesis are lacking. 5 DIC is the excessive activation of haemostasis, which can eventually result in haemorrhage by consumption of platelets and coagulation factors.…”

Fibrinolysis in Dogs with Intracavitary Effusion: A Review

“…In fact, humans having a low to moderate degree of ongoing fibrinolysis, with increased fibrinolytic markers, such as plasmin/α2-PI complex, D-dimer, and tPA, escaping identification by ROTEM [ 52 ]. More recently, to overcome this problem, tPA-modified TEG and ROTEM assays were developed and were found to be more sensitive in revealing fibrinolysis, both in humans and dogs [ 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. Assays for D-dimer and FDPs are both available in veterinary [ 61 , 62 , 63 , 64 , 65 ] and human medicine [ 52 ].…”