By Rédaction Africa Links 24 with Elizabeth Cooney
Published on 2024-01-18 19:00:09
Long Covid has long been a mystery to scientists looking for its cause. Not knowing what triggers the persistent and distressing symptoms of this condition makes it challenging to treat, and it’s difficult to even say definitively who has it. New research published in Science has discovered proteins present in the blood of people with long Covid that could point to a much-needed diagnostic test and possible future therapeutic targets.
At the University of Zurich, scientists identified high levels of proteins involved in the complement system, which is an essential part of the immune system bridging innate and adaptive responses. These proteins were disrupted in people with long Covid symptoms but not in those who got better after the initial Covid-19 infection or in those who had recovered from long Covid symptoms after six months. The team also found damaged red blood cells and platelets as well as signs of harm to the endothelial cells that line blood vessels.
The biomarkers were discovered after high-throughput analyses of more than 6,500 proteins found in the blood serum of 113 people infected with Covid, including 40 people who developed long Covid, and controls who were not infected.
The study, led by Carlo Cervia-Hasler of University Hospital Zurich and the University of Zurich, continued to take samples over a year starting in 2020. Their results were later validated against a larger cohort from Mount Sinai in New York.
In this study, complement component changes could be a clue to why long Covid lingers. The results suggest that complement pathways are abnormal in people with long Covid and that complement dysregulation seems to normalize in those with long Covid that subsequently recover from the condition.
The reactivation of antibodies against prior herpesvirus infections, revealed by protein analysis, further supports the idea that people with long Covid are living with immune dysregulation, including increased inflammation, altered autoantibody profiles, and elevated herpesvirus antibody responses.
These changes in complement activation could become enough of a long Covid signature in blood samples to develop a diagnostic based on them. Combining these changes in complement activation with age, body mass index, and signs of abnormal blood clotting will help in developing a comprehensive diagnostic approach.
The team hopes to conduct more and larger trials to confirm what they found and look into longer-term effects. While there are drugs to treat forms of complement dysregulation found in certain genetic diseases, much more work needs to be done to establish the mechanism by which the complement system works in long Covid.
Other experts take a similarly cautious view of treatment and testing and hold it crucial to determine the extent to which dysregulated complement is the cause of long Covid and therefore a potential therapeutic target. It will be essential to validate whether complement pathways are useful biomarkers of long Covid. Although therapeutic interventions with coagulation and complement inhibitors in acute Covid-19 produced mixed results, the pathological features specific for long Covid suggest potential interventions for clinical testing. More research is required to develop diagnostic tools or therapeutic solutions.
Read the original article on Africa Health News
