Part of the mystery of long Covid is revealed in a molecular portrait – 01/18/2024 – Science

European and American researchers have drawn the most complete molecular portrait of the effects of so-called long Covid, the name given to the persistent symptoms that appear after infection with the Sars-CoV-2 pandemic virus.

By measuring the presence of thousands of proteins in the blood of patients with long Covid, they discovered that the problem deregulates part of the body’s defense system, in addition to disrupting processes linked to the maintenance of blood vessels.

In addition to dispelling part of the mystery that still surrounds the long-term effects of Covid-19, the study may provide more specific alternatives for the treatment of these patients, say the study authors, led by Onur Boyman, from the University of Zurich, in Switzerland. Boyman and his Swiss, Swedish and American colleagues have just published their findings on the topic in the specialized journal Science.

Although most people with Covid-19 manage to recover from the symptoms of the disease a few weeks after infection, it is estimated that around 5% of patients end up developing long-term repercussions that are classified as long Covid, in a process that can be drag on for several months and even years.

The symptoms vary in their number and in the way they affect different people, but among the most common are the constant feeling of tiredness and a worsening of mental performance.

To try to understand what is happening to the bodies of people with this condition, researchers set out to investigate the molecular profile of the blood of those with long Covid. To do this, they followed 113 people with Covid-19 from the moment the presence of the virus was confirmed until one year after infection.

The scientists also followed 39 people who did not catch the disease, as a control group. After 6 months, 40 of the patients in the original group had symptoms of long Covid. A year later, that number dropped to 22 (10 had recovered and 8 stopped attending clinical reassessments, so they may or may not have continued to have symptoms).

From the blood samples, what the researchers did was use a platform called SomaScan, which is based on more than 7,000 molecular “hooks” made up of nucleic acids (the same type of substance that makes up DNA and its “cousin”, RNA). The hooks, called aptamers, can connect specifically with different types of proteins, which helps scientists identify which of these molecules are circulating in the blood.

Based on this methodology, Boyman and his colleagues found that the main difference between people with long Covid and healthy people is the deregulation in important molecules for the so-called complement system, which is part of the body’s innate defense mechanisms and, under normal conditions , helps counterattack invaders (such as bacteria) and eliminate damaged cells.

Everything indicates that these complement system molecules are forming chains capable of inserting themselves into the membrane of the cells of those with long Covid, causing damage to them. Furthermore, the researchers also identified dysfunctions in molecules important for blood vessels and coagulation. There is evidence of an increase in the destruction of red blood cells (red blood cells, which carry oxygen and carbon dioxide in the blood) and the formation of “pellets” of defense cells and platelets (essential parts for wound healing).

Knowing these details is important to accurately attack the origin of long Covid symptoms, something that should be improved based on the new study.