New autoantibody triggers inflammation and blood clots in Covid patients

US researchers have found a functional autoantibody in Covid-19 patients that contributes to the development of the disease and the “fire storm” of blood clots and the inflammation it induces.

A growing number of studies suggest that Covid-19 emulates many aspects of systemic autoimmune disorders, including releasing a burst of overactive immune cells that produce toxic networks of proteins and DNA called extracellular neutrophil traps, or NET.

For this study, the team analyzed the serum of more than 300 hospitalized Covid patients, looking for a new autoantibody that protects toxic NETs from destruction and produces a lasting harmful effect in a patient’s body. .

The results, published in JCI Insight, reveal markedly elevated levels of anti-NET antibodies in many participants. Those with higher levels of autoantibodies were more likely to develop severe symptoms of Covid-19.

“We are seeing a multitude of different antibodies produced in Covid-19 patients, and now we have discovered another clinically significant one that likely contributes to severe Covid,” said lead author Yu (Ray) Zuo, rheumatologist at Michigan Medicine, University of Michigan. .

“They are fueling the inflammatory storm that we see in the most severe cases of viral infection,” Zuo added.

Researchers generated NETs in the lab and incubated them with Covid patient serum. They found that serum from patients with higher levels of anti-NET antibodies had difficulty breaking down toxic traps.

The team also enriched healthy serum with anti-NET purified from infected patients. While a healthy person’s serum should completely disintegrate the extracellular traps, the purified anti-NET antibodies significantly hampered the process.

“We knew that people with severe forms of Covid have higher amounts of these extracellular neutrophil traps, which amplify inflammation and promote blood clots,” said Jason Knight, associate professor of rheumatology at Michigan Medicine.

“We have now discovered that this process is exacerbated by anti-NET antibodies, which disrupt our body’s immune homeostasis during Covid-19 infection,” Knight said.

However, how Covid-19 manages to trigger the production of a variety of autoantibodies, including anti-NETs, ​​remains unknown.

Further study of the autoimmune aspects of the virus, Zuo noted, will not only lead to a better understanding of the disease, but also likely shed light on the origins of autoimmune diseases.

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