In a study that reshapes what we know about COVID-19 and its most perplexing symptoms, scientists have discovered that the blood coagulation protein fibrin causes the unusual clotting and inflammation that have become hallmarks of the disease, while also suppressing the body's ability to clear the virus. Importantly, the team also identified a new antibody therapy to combat all of these deleterious effects. Published in Nature, the study by Gladstone Institutes and collaborators overturns the prevailing theory that blood clotting is merely a consequence of inflammation in COVID-19.
Through experiments in the lab and with mice, the researchers show that blood clotting is instead a primary effect, driving other problems-; including toxic inflammation, impaired viral clearance, and neurological symptoms prevalent in those with COVID-19 and long COVID. The trigger is fibrin, a protein in the blood that normally enables healthy blood coagulation, but has previously been shown to have toxic inflammatory effects. In the new study, scientists found that fibrin becomes even more toxic in COVID-19 as it binds to both the virus and immune cells, creating unusual clots that lead to inflammation, fibrosis, and loss of neurons.
Knowing that fibrin is the instigator of inflammation and neurological symptoms, we can build a new path forward for treating the disease at the root. In our experiments in mice, neutralizing blood toxicity with fibrin antibody therapy can protect the brain and body.