Scientists identify mechanisms associated with severe COVID-19 blood clotting
February 26, 2022:
After studying blood samples from 244 patients hospitalized with COVID-19, a group of researchers, including those working at the National Institutes of Health, have identified “rogue antibodies” that correlate with severe illness and may help explain the mechanisms associated with severe blood clotting. The researchers found circulating antiphospholipid antibodies, which may be more common in people with autoimmune diseases, such as lupus. However, these “auto-antibodies”, which target a person’s own organs and systems, can also be activated in response to viral infections and activate other immune responses.
Scientists compared blood samples to healthy controls and found that COVID-19 samples contained higher levels of IgG antibody, which works with other immune cells, such as IgM, to respond to immune threats. Higher levels of IgG were also associated with COVID-19 disease severity, such as in patients who required respiratory support. The researchers observed similar patterns, but to a lesser extent, after analyzing blood samples from 100 patients hospitalized with sepsis, which can leave the body in inflammatory shock following a bacterial or viral infection.
IgGs help bridge the gap between innate and adaptive immune responses – a process that helps the body recognize, respond to and remember danger. In normal cases, these characteristics help protect the body against disease and infection. However, in some cases, this response may become hyperextended or impaired and exacerbate the disease. A unique finding from this study is that when researchers removed IgG from COVID-19 blood samples, they saw molecular indicators of “blood vessel viscosity” drop. When they added these same IgG antibodies to control samples, they saw an inflammatory response from blood vessels that could lead to clotting.
Since every organ contains blood vessels, the circulating factors that lead to ‘stickiness’ of healthy blood vessels during COVID-19 may help explain why the virus can affect many organs, including the heart, lungs and the brain. One question in this study assessed “upstream” factors involved in severe blood clotting and inflammation in people with severe COVID-19 disease.
The researchers note that future studies could explore the potential benefits of screening patients with COVID-19 or other forms of severe disease for antiphospholipids and other autoantibodies and at earlier points of infection. This can help identify patients at risk for extreme blood clotting, vascular inflammation, and respiratory failure.
Corresponding studies could then assess the potential benefits of providing these patients with treatments to protect blood vessels or fine-tune the immune system. ET Health