What causes severe COVID symptoms?

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Since the earliest months of the COVID-19 pandemic, physicians and scientists worldwide have been working to understand how exactly the virus makes us sick.

That task, already complicated by COVID’s rapid spread, is made more challenging by some of its unusual, seemingly inexplicable symptoms, such as blood pressure dysregulation and blood clots.

In a study from the University of Chicago, scientists found that the immune system may unintentionally contribute to the disease’s strangest symptoms.

The findings showed that some people with severe COVID-19 can develop autoantibodies—antibodies directed against a person’s own proteins—that disturb a critical component involved in blood pressure regulation.

SARS-CoV-2, the virus that causes COVID-19, infects the body by way of biomolecular hijacking.

The virus is covered with spike-shaped proteins that enter cells by attaching to the receptor ACE2, found on cells lining the mouth, nose, and lungs.

ACE2 normally functions as a critical regulator of blood pressure by interacting with the peptide angiotensin II (AngII).

The team wanted to know if the body was generating antibodies against the virus’s spike protein, could some of these antibodies also erroneously bind to AngII and thus disturb this key blood pressure regulation system?

Since AngII and the ACE2 receptor together play significant roles in regulating blood pressure, interfering with either could trigger any number of problems.

In the study, researchers used samples and clinical data and analyzed plasma samples from 115 patients hospitalized for severe COVID-19.

Of these, they found that 63 percent had autoantibodies targeting AngII—exactly what Swartz had predicted.

Moreover, the antibody’s presence coincided with lower blood oxygenation, increased blood pressure dysregulation, and higher overall disease severity.

While not everyone with the autoantibodies experienced severe symptoms, and not everyone with severe symptoms had autoantibodies, the correlation with illness severity — particularly that related to blood pressure regulation — was strong.

The team points out that antibodies against AngII are transient, but their existence shows that the body can produce autoimmune responses to COVID-19.

Understanding the full breadth of that response may offer new clues to fighting the disease.

Further study may examine whether antibodies against AngII emerge after most COVID symptoms subside and whether any recurrence coincides with symptoms of long COVID-19.

If you care about COVID, please read studies about a universal antibody therapy to fight all COVID-19 variants, and how vitamin B could help fight COVID-19.

For more information about COVID, please see recent studies about an important cause of COVID-19 deaths in older people, and this face mask can capture and deactivate COVID-19 virus.

The study was conducted by Melody Swartz et al and published in Sciences Advances.

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