Complications of COVID-19 are often caused by the presence of several blood clots that block the flow of blood to vital organs. According to a recent discovery, the formation of these clots is in many cases due to an abnormal production of antibodies that attack our own cells and activate the coagulation cascade.
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Despite the good news of recent weeks on vaccines developed against COVID-19, we must resign ourselves to having to deal with the disease for a few more months, until the vaccines are produced on a large scale and we can immunize a good part Population.
Many people will become ill during this time and it remains important to continue to seek new treatment approaches to reduce the serious complications of infection.
COVID-19 is not a respiratory infection like any other. Among the many atypical clinical manifestations of this disease (loss of smell and heart and kidney damage, for example), one of the most curious phenomena is the high incidence of coagulation disorders in patients who develop severe complications of the disease. .
These thromboses (formation of clots) can lead to an interruption of blood circulation to vital organs (lungs, heart, brain, kidney) and thus cause several serious accidents (heart attack, stroke, pulmonary embolism, renal failure) which can lead to death. patients.
The origin of these blood clots has just been elucidated by the work of a group of American researchers whose results were recently published in Science Translational Medicine(1).
In this study of 172 patients with severe COVID-19 who were hospitalized due to the disease, they found that half of the patients had developed autoantibodies, that is, antibodies that instead of defending the body against pathogens, instead attack our own cells.
These autoantibodies present in COVID-19 patients are the same as those found in patients with an autoimmune disease called antiphospholipid syndrome: in this disease, these autoantibodies which circulate in the blood interact with phospholipids present in the membrane of cells, especially blood platelets and the cells that line blood vessels, which causes clots to form.
The patients with the highest blood levels of these autoantibodies were also those who had developed the most severe forms of COVID-19, indicating that this immune disorder likely plays a very important role in the development of complications of this disease.
The researchers also observed that these clots contained large amounts of neutrophils, a type of immune cell that forms the body’s first line of defense against infections.
In patients with COVID-19, these neutrophils are overactive and explode at the site of the clot, generating an inflammatory environment that attracts other coagulation factors circulating in the blood.
A vicious circle then sets in, with inflammation which activates coagulation, and coagulation which leads to even more inflammation, leading to the appearance of a multitude of blood clots obstructing the passage of blood to vital organs.
These observations are very important, for two main reasons:
- Biochemical tests to measure the presence of autoantibodies present in antiphospholipid syndrome are already available and can therefore be used to identify patients most likely to benefit from treatment with anticoagulants to prevent the development of serious complications of COVID-19;
- Some drugs like dipyridamole are already approved to treat stroke and prevent blood clots in people who receive mechanical heart valves, and it will be possible to test this molecule to see if it can also reduce the risk of clotting in people. COVID-19 patients.
- Scientific research on COVID caused our biochemical understanding of the molecular processes associated with infection with this coronavirus to explode within months.
- This remarkable feat by researchers around the world is materialized by the implementation of new therapeutic intervention strategies, based on a rational approach to these infection mechanisms.
- Vaccinate to better prevent infection, but also better treat those who will be seriously infected, this is how we will come to terms with this pandemic in the coming months.
(1) Zuo Y et al. Prothrombotic autoantibodies in serum from patients hospitalized with COVID-19. Science Trans. Med., published on November 2, 2020.