Eric Boilard, researcher at Laval University, a specialist in blood platelets.
June 25, 2020 20h35
COVID-19: the surprising role of platelets in the blood
We already knew that the COVID-19 is a disease complex that could take all kinds of forms. And a study conducted at the University Laval, and Morocco just to add an “actor” extra ” a bit surprising for a lung disease : the platelet blood.
“Here in Quebec,” explains the researcher of the UL and a specialist in blood platelets, Eric Boilard, we had all the instruments needed to do the analysis, but as the city has not been severely affected, we did not have enough cases for our study. And the moroccan team with which we worked, it was the opposite : they had no instruments, but they were really in the heat of the action, they worked day and night. Then they sent us the samples and we did the analysis.”
It is still a “pre-publication” that has not been formally published in the scientific literature and should be interpreted with caution, but its results go in the same direction that a study just published in the medical journal Blood, which gives them “weight”.
The study included 71 people who came to the hospital with a COVID-19 “non-severe”, 34 severe cases and 81 people who had similar symptoms but which proved not to have the new coronavirus. By comparing the cases “positive” and “negative”, Mr. Boilard and his colleagues have found that the platelets of people with the COVID-19 were “hyperactivées” while others were not : they bustled and dropped in the blood a part of their contents (granules and hormones).
The fact that they begin to clump together to form clots — is not (or more) a surprise, since we now know that many people died of this disease showed a lot of thromboses (blood vessels that were blocked by clots). Many doctors prescribe already of anticoagulants to their patients with the COVID-19.
“However, nuance Mr. Boilard, many clinicians also report to thromboses very important in spite of the anticoagulants.”
Platelets can be activated “indirectly” by a virus, by killing the cells, are “holes” that are microscopic in some walls — and the role of platelets is to clog it. But the work of Mr. Boilard has shown in the past that platelets can be activated “directly” by the only presence of virus in the blood, since they are involved in the immune response. And the latest study suggests that the COVID-19 may well have this effect. In this case, the “pathways of activation are not inhibited by the drugs anti-clotting, he says. They are now trying how platelets are activated in order to block this pathway in parallel with anti-coagulants”.
In addition, this study also shows that, as with other viruses and bacteria, platelets, release of hormones, immune in the presence of the COVID-19 : the “cytokines”, which are primarily used to signal alarm, and which attract immune cells. However, we now know that a good portion of the damage caused by this coronavirus from a runaway immune system called “cytokine storm”.
It is quite surprising that nothing was known on the pads and COVID-19 [because] it according to our work, [they] play a double role : in the formation of blood clots AND the storm cytokinique,” said Mr. Boilard. It is unknown at what point exactly platelets are involved in this storm, but “it must be a good contribution because there are really a lot more platelets in the blood that white blood cells [editor’s note : immune cells that produce the cytokines].”