Lysophosphatidylcholine Acts as an Anti-hemostatic Molecule in the Saliva of the Blood-sucking Bug Rhodnius prolixus

Abstract

Blood-sucking arthropods possess a variety of antihemostatic factors in their salivary glands to maintain blood fluidity during feeding. In this work we demonstrate the anti-hemostatic properties of lysophosphatidylcholine (lysoPC) isolated from the salivary glands of Rhodnius prolixus. First, we examined salivary glands of fourth and fifth instar nymphs for their phospholipid composition. The lumen displayed an accumulation of its phospholipid content, mainly phosphatidylcholine and lysoPC, with a 6-fold increase for the latter. To determine the presence of phospholipids in the saliva, fourth instar nymphs were fed with a 32 P-enriched blood meal. After 28 days their saliva was collected and subjected to lipid extraction, thin-layer chromatography, and autoradiography. The results showed the presence in the saliva of the same phospholipids present in the lumen. We then examined possible biological roles of these phospholipids when compared with other known effects of lysoPC. The luminal lipid extract and purified lysoPC from the lumen and saliva were tested for inhibition of washed rabbit platelets' aggregation induced by ␣-thrombin and platelet-activating factor. Both the luminal lipid extract and salivary lysoPC showed an increasing inhibition of aggregation, which correlated with the response of the platelets to standard lysoPC (up to 13 g/ml). Next, salivary lysoPC was incubated with porcine arterial endothelial cells for 24 h. After incubation, culture medium was assayed for nitric oxide and showed increased nitric oxide production, similar to control cells exposed to standard lysoPC (up to 20 g/ ml). Together these data demonstrate the presence of lysoPC in the saliva of Rhodnius prolixus and its potential anti-hemostatic activities.Hematophagous arthropods rely on a wide array of antihemostatic substances to counteract vertebrate responses to blood loss and to obtain their blood meal successfully (1). These salivary compounds show distinct properties and are generally involved with inhibition of coagulation, platelet aggregation, and vasoconstriction (2). These molecules include peptides such as tachykinins (3), maxadilan (4), nitric oxide (NO) 1 -binding proteins such as nitrophorins (5), and prostaglandins (6). The small lesions elicited by the mouthparts of the arthropod most likely evoke platelet aggregation and vasoconstriction by the vertebrate host. Therefore, the formation of the platelet plug is specifically inhibited by collagen inhibitors, apyrases, catechol oxidases, thrombin inhibitors, NO-releasing proteins, fibrinogen receptor agonists, and a specific platelet aggregation inhibitor (7,8). The complexity of anti-hemostatic mechanisms has recently been addressed with the use of proteomic techniques (9, 10). Hundreds of gene sequences were obtained, and most of them await future tests concerning the anti-hemostatic properties of the proteins they code for.Lysophosphatidylcholine (lysoPC) is a component of oxidized low-density lipoprotein, which is involved in the pathogenesis of atheroscleros...

Paralytic activity of lysophosphatidylcholine from saliva of the waterbugBelostoma anurum

“…Among other activities, LPC is known to be a powerful modulator of endothelium-dependent arterial relaxation (Kugiyama et al, 1990). We showed that it is present in the saliva of a blood-sucking insect, R. prolixus, one of the main vectors of Chagas disease in South America (Golodne et al, 2003). In addition, we showed that it might act as an antihemostatic molecule during blood feeding, by blocking platelet aggregation and inducing NO production in cultured endothelial cells.…”

Trypanosoma cruziInfection Is Enhanced by Vector Saliva through Immunosuppressant Mechanisms Mediated by Lysophosphatidylcholine

“…Despite the fact that two bugderived biological fluids (feces and saliva) are inoculated into the bite wound, no vector-derived molecules have been described as playing a role in the mechanism of T. cruzi infection of vertebrate hosts. Previously, we demonstrated the presence of phospholipids in the saliva of a blood-sucking insect, Rhodnius prolixus, one of the main vectors of Chagas disease in South America (24). Also in that study, we showed that lysophosphatidylcholine (LPC) is a component of this insect's salivary secretion and may act as an antihemostatic molecule during blood feeding.…”

“…LPC was obtained by the extraction of total lipids from salivary glands and feces. It was purified by thin-layer chromatography as described previously (24). R. prolixus LPC from saliva is henceforth designated RpLPC.…”

Cell Signaling During Trypanosoma cruzi Development in Triatominae

“…Both of these products are important signaling molecules. We have shown the presence of lysophospholipids, mainly lysophosphatidylcholine (LPC), in the saliva and feces of R. prolixus [57,58]. LPC acts as a chemotactic molecule for monocytes and macrophages, but also plays a role in the production of NO by these cells, therefore enhancing T. cruzi infection through immunosuppression.…”