Can the activation of plasminogen/plasmin system of the host by metabolic products of Dirofilaria immitis participate in heartworm disease endarteritis?

Parasites & Vectors, Apr 2015

Background Proliferative endarteritis is one of the key pathological mechanisms of cardiopulmonary dirofilariosis, a cosmopolitan parasitosis caused by Dirofilaria immitis affecting dogs and cats around the world. It has been shown that the excretory/secretory antigens from D. immitis adult worms (DiES) bind plasminogen (PLG) and activate fibrinolysis, which can lead to a survival mechanism for the parasite in its intravascular environment. However, overproduction of plasmin (final product of the route) has been related to pathological processes similar to those described in proliferative endarteritis. The aim of this study is to relate the appearance of this pathological condition with the activation of the PLG/plasmin system of the host by DiES. Methods Cell proliferation through the crystal violet technique, cell migration by wound healing assay and degradation of the extracellular matrix by measuring collagen degradation and levels of matrix metalloproteinases were studied in an “in vitro” model using canine vascular endothelial and smooth muscle cells. These cells were treated with a mixture of DiES + PLG. Untreated cells, cells only stimulated with DiES or with PLG, or with a mixture of DiES + PLG + εACA (an inhibitor of the PLG-plasmin conversion) were employed as controls. In addition, the effect of DiES on the expression of the fibrinolytic activators tPA and uPA, the inhibitor PAI-1 and the PLG receptor Annexin A2 was analyzed in both types of cultures by western blot. Results Plasmin generated by DiES + PLG binding produced a significant increase in the cell proliferation and migration of the endothelial and smooth muscle cells, as well as an increase in the destruction of the extracellular matrix based on a further degradation of Type I Collagen and an increased level of matrix metalloproteinase-2. DiES also induce an increase in the expression of tPA and uPA in endothelial cells in culture, as well as a decrease in the expression of PAI-1 in both types of cells. Conclusions Our study reports an interrelationship between plasmin caused by fibrinolysis activation by metabolic products of D. immitis and the appearance of pathological events similar to those described in the emergence of proliferative endarteritis in the cardiopulmonary dirofilariosis.

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Can the activation of plasminogen/plasmin system of the host by metabolic products of Dirofilaria immitis participate in heartworm disease endarteritis?

Gonzlez-Miguel et al. Parasites & Vectors Can the activation of plasminogen/plasmin system of the host by metabolic products of Dirofilaria immitis participate in heartworm disease endarteritis? Javier Gonzlez-Miguel 0 Rodrigo Morchn 0 Elena Carretn 1 Jos Alberto Montoya-Alonso 1 Fernando Simn 0 0 Laboratory of Parasitology, Faculty of Pharmacy, Institute of Biomedical Research of Salamanca (IBSAL) and University of Salamanca , 37007 Salamanca , Spain 1 Internal Medicine, Faculty of Veterinary Medicine, University of Las Palmas de Gran Canaria , 35413 Arucas, Las Palmas , Spain Background: Proliferative endarteritis is one of the key pathological mechanisms of cardiopulmonary dirofilariosis, a cosmopolitan parasitosis caused by Dirofilaria immitis affecting dogs and cats around the world. It has been shown that the excretory/secretory antigens from D. immitis adult worms (DiES) bind plasminogen (PLG) and activate fibrinolysis, which can lead to a survival mechanism for the parasite in its intravascular environment. However, overproduction of plasmin (final product of the route) has been related to pathological processes similar to those described in proliferative endarteritis. The aim of this study is to relate the appearance of this pathological condition with the activation of the PLG/plasmin system of the host by DiES. Methods: Cell proliferation through the crystal violet technique, cell migration by wound healing assay and degradation of the extracellular matrix by measuring collagen degradation and levels of matrix metalloproteinases were studied in an in vitro model using canine vascular endothelial and smooth muscle cells. These cells were treated with a mixture of DiES + PLG. Untreated cells, cells only stimulated with DiES or with PLG, or with a mixture of DiES + PLG + ACA (an inhibitor of the PLG-plasmin conversion) were employed as controls. In addition, the effect of DiES on the expression of the fibrinolytic activators tPA and uPA, the inhibitor PAI-1 and the PLG receptor Annexin A2 was analyzed in both types of cultures by western blot. Results: Plasmin generated by DiES + PLG binding produced a significant increase in the cell proliferation and migration of the endothelial and smooth muscle cells, as well as an increase in the destruction of the extracellular matrix based on a further degradation of Type I Collagen and an increased level of matrix metalloproteinase-2. DiES also induce an increase in the expression of tPA and uPA in endothelial cells in culture, as well as a decrease in the expression of PAI-1 in both types of cells. Conclusions: Our study reports an interrelationship between plasmin caused by fibrinolysis activation by metabolic products of D. immitis and the appearance of pathological events similar to those described in the emergence of proliferative endarteritis in the cardiopulmonary dirofilariosis. Dirofilaria immitis; Excretory/secretory antigens; Fibrinolysis; Plasmin; Endothelial cells; Smooth muscle cells; Proliferative endarteritis - Background Dirofilaria immitis is the filaroid nematode that causes the canine and feline cardiopulmonary dirofilariosis, a vector-borne parasitosis with cosmopolitan distribution. D. immitis is also responsible for the human pulmonary dirofilariosis, a clinical entity characterized by the formation of benign lung nodules that may be confused with carcinomas in radiology [1]. The dog acts as definitive host and reservoir of the parasite. The adult worms lodge in its pulmonary artery and right ventricle of the heart causing a chronic inflammatory pathology at vascular level [2]. One of the key factors of the disease is the appearance of proliferative endarteritis, which has resulted in the formation of intravascular microvilli. This process has previously been described as being accompanied by an increase and migration of the arterial wall cells [3-6], as well as the destruction of the extracellular matrix (ECM) [7]. These changes cause disorganization of the endothelium and reduction of the vascular lumen in the pulmonary arteries, with the consequent extension of pathology to the pulmonary parenchyma [8]. On the other hand, the simultaneous death of groups of adult worms can trigger an acute disease characterized by the exacerbation of the inflammatory reactions and the emergence of serious thromboembolic events threatening the life of the affected hosts [9]. However, D. immitis possesses the ability to regulate these pathological mechanisms and survive for long periods (over 7 years) in their intravascular environment. Recently, it has been shown that both excretory/secretory and surface-associated antigens of D. immitis interact with the fibrinolytic system of the host binding PLG and generating plasmin [10,11]. PLG is a glycoprotein predominantly released by the liver into the blood circulation. After its activation PLG becomes a serine protease (plasmin), whose main target are the fibrin clots. Under physiological conditio (...truncated)


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Javier González-Miguel, Rodrigo Morchón, Elena Carretón, José Montoya-Alonso, Fernando Simón. Can the activation of plasminogen/plasmin system of the host by metabolic products of Dirofilaria immitis participate in heartworm disease endarteritis?, Parasites & Vectors, 2015, pp. 194, 8, DOI: 10.1186/s13071-015-0799-0