Scientists pinpoint mechanisms associated with severe COVID-19 blood clotting – National Institutes of Health

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Thursday, February 17, 2022

After studying blood samples from 244 patients hospitalized for COVID-19, a group of researchers, including those who work at the National Institutes of Health, identified rogue antibodies that correlate with severe illness and may help explain mechanisms associated with severe blood clotting. The researchers found circulatingantiphospholipid antibodies, which can be more common among people with autoimmunedisorders, such as lupus. However, these autoantibodies, which target a persons own organs and systems,canalso be activated in responseto viral infections and activate other immune responses.

Scientists compared the blood samples to those from healthy controls and found the COVID-19samples contained higher levels of the antibody IgG, which works with other immunecells,such as IgM, to respond to immune threats. Higher levels of IgG werealso associated with COVID-19 disease severity, such as in patients who required breathing assistance. The researchers observed similar patterns, but to a lesser extent,after analyzing blood samples from 100 patients hospitalized for sepsis, which can leavethe body in inflammatory shock following a bacterial or viral infection.

IgG helps bridge a gap between innate and adaptive immune responses a process that helps the body recognize, respond to, andremember danger. In normal cases, these features help protect the body from illness and infection. However, in some cases, this response can become hyperextended or altered and exacerbate illness. A unique finding from this study is that when researchers removed IgG from the COVID-19 bloodsamples, they saw molecular indicators of blood vessel stickiness fall. When they added thesesame IgG antibodies to the control samples, they saw a blood vessel inflammatory response that can lead to clotting.Since every organ has blood vessels in it, circulating factors that lead to the stickiness of healthy blood vessels during COVID-19 may help explain why the virus can affect many organs, including the heart, lungs, and brain. A query of this study was evaluating upstream factors involved with severe blood clotting and inflammation among people with severe COVID-19 illness.

The researchers note future studies could explore the potentialbenefitsof screeningpatients with COVID-19 or other forms of critical illness forantiphospholipidsand otherautoantibodies and at earlier points of infection. This mayhelp identify patientsat risk forextreme blood clotting, vascular inflammation, and respiratory failure.Corresponding studies could then assess the potential benefits ofproviding these patientswith treatmentsto protect blood vessels or fine-tune the immunesystem.

Yogen Kanthi, M.D.,a co-corresponding author,is available to discuss this research. Dr. Kanthi is a cardiologist, Clinical Lasker Research Scholar, and leads theLaboratory of Vascular Thrombosis and Inflammationat the National Heart, Lung, and Blood Institute.He is alsoan assistant professor of cardiovascular medicine at theUniversity of Michigan, Ann Arbor.

Endothelial cell-activating antibodies in COVID-19. Arthritis & Rheumatology, 2022. DOI: https://doi.org/10.1002/art.42094.

About the National Heart, Lung, and Blood Institute (NHLBI):NHLBI is the global leader in conducting and supporting research in heart, lung, and blood diseases and sleep disorders that advances scientific knowledge, improves public health, and saves lives. For more information, visithttps://www.nhlbi.nih.gov/.

About the National Institutes of Health (NIH):NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov.

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Scientists pinpoint mechanisms associated with severe COVID-19 blood clotting - National Institutes of Health