by More than four years after the start of the Covid pandemic, the disease still has mysteries to solve. One of them is the “Long Covid”: Some people can endure persistent, debilitating symptoms for many months after an initial coronavirus infection. and hay few clues Why does this happen?
A study published this Thursday in the journal Science compared the blood of patients with confirmed SARS-CoV-2 infection with that of uninfected, and found that patients experiencing long Covid had changes in proteins of blood serum, which indicated an activation of the immune system, in addition to coagulation alterations.
The researchers from the University of Zurich explained that these findings provide a resource for potential biomarkers for diagnosis and can be used to develop new treatments.
around the 5 percent of people infected with Covid do not recover from the acute illness and develop long term complications. They suffer from symptoms ranging from fatigue and brain fog to muscle pain and breathing problems. Current hypotheses about the factors contributing to Long Covid include tissue damage, viral reservoirs, autoimmunity, and persistent inflammation. but there are no diagnostic tests nor therapeutic solutions for affected patients.
As described in Science, the Zurich researchers followed a 39 healthy people and 113 patients with Covid up to one year after initial confirmation of acute infection, to identify biomarkers associated with Long Covid.
At 6 months, 40 patients They had prolonged Covid symptoms. Repeated clinical evaluations were combined with blood draws, resulting in a total of 268 blood samples.
They measured 6,500 proteins in serum and the main candidate biomarkers were identified using computational tools and evaluated experimentally.
“Patients with long Covid showed increased complement activation During acute illness, which also persisted at 6-month follow-up. The complement system is part of the innate immune system and contributes to immunity by attacking pathogens and damaged cells, among other functions,” says the Science work.
Interestingly, blood complement levels normalized in long Covid patients who recovered before 6 months of follow-up. The plugin system can be activated by various triggersresulting in the formation of the terminal complement complex (TCC).
The complement system is a network of proteins that function in a cascade, activating each other to help recognize and destroy harmful elements. The problem is that if this mechanism is deregulated, it can be harmful to the body.
“This study demonstrated that the complement system was active in persistent Covid: When patients have this condition, they also have this system active. And what’s interesting is that in the group of patients with persistent Covid, there were some who were lucky and recovered. And in those cases, the complement system also returned to normal“, noted in the work Onur Boyman, author of the study and head of Clinical Immunology and Allergology at the Faculty of Medicine of the University of Zurich.
In conclusion, researchers from Switzerland said that “the data suggests that active long Covid is accompanied by a “signature” of blood proteins marked by increased complement activation and thromboinflammation.” And they concluded: “In addition to offering a basis for new diagnostic solutions, our work supports clinical research on complement modulators for patients suffering from Long Covid.”
