Tick saliva can help fight heart disease and stroke, Dutch scientists announced in the American Heart Association’s Circulation magazine. All thanks to one of the proteins found in the secretion of the tick’s mouth apparatus
Ticks have three life stages: larva, nymph and imago (mature specimen). Representatives of each of these stages feed on the host’s blood. With the help of scissor jaws, they tear the host’s skin and suck its blood for several days. Small blood vessels are damaged during a tick attack. This is a signal for the host organism to start a series of reactions related to the blood clotting process.
The authors of the study remind that although blood clotting is an extremely important and vital property, it can also play a negative role – e.g. in triggering heart attacks or strokes.
In healthy people, clotting protects against bleeding in the event of an injury. In people with a bleeding disorder, clots can form, narrowing or blocking the vessels in the brain or coronary artery, causing a stroke or a heart attack, respectively.
And here we come back to the ticks. Despite the disruption of the skin and the formation of a wound, clotting does not occur in the affected organism. Researchers from the University of Amsterdam have established (on the example of the popular tick species – Ixodes damini, also known as the deer tick) that one protein is responsible for this, which, along with the tick’s saliva, enters the host’s body. They found that it had properties similar to anticoagulants (anticoagulants).
By analyzing the mechanism of action of the newly discovered protein, the researchers concluded that it has a direct effect on two blood coagulation factors: X and V.
Clotting factors are proteins produced in the liver. There are a dozen of them in total. Tissue damage sets off a complex process in which the factors activate and change each other one by one, resulting in the formation of a clot. This process is called a cascade.
In a key step of the cascade, the active form of factor X, in combination with factor V and surface phospholipids, forms a prothrombinase complex that converts soluble prothrombin into insoluble thrombin. Thrombin, in turn, converts fibrinogen (a plasma protein circulating in the blood) into fibrin (a water-insoluble protein), which forms the network of fibers that form the backbone of the clot.
Under the influence of the newly discovered protein in the saliva of ticks, the interaction between these two factors – X and V – is blocked, and the clotting process is temporarily stopped.
The authors of the study emphasize that their discovery sheds new light on the course of the coagulation cascade. We have known for a long time what factors are needed to activate factor V, but the role of factor X in this process was not known. Thanks to the ticks, we know that it is very important here, scientists say.
Based on their work, they add, the blood coagulation model should be updated. Our research also allows us to better understand the process of blood clotting, which may contribute to the development of new, improved anticoagulants for diseases such as heart attacks, strokes or other disorders related to clotting disorders, they explain.