Coronavirus Seems to Turn Antibodies Against Us, Tricking Them into Attacking Brain

The coronavirus that causes COVID-19 may turn our antibodies against us so they attack the brain, according to a small study.

Researchers looked at 11 intensive care COVID-19 patients in two hospitals in Germany who had unexplained neurological problems. These included epileptic seizures, involuntary muscle jerking, nerve problems, issues moving their eyes, delirium, and uncontrollable muscle contractions. Symptoms were not caused by other conditions or their ICU treatment, the team said.

The study was submitted to the pre-print website medRxiv, and has not been through the rigorous peer review process required to publish in scientific journals. Researchers partly release findings in this way to prompt debate on a topic, and this approach is particularly useful in a fast-moving situation like a pandemic.

According to the team, COVID-19 patients in intensive care are known to occasionally develop neurological problems, but the coronavirus that causes the disease is not often found in their cerebrospinal fluid.

This prompted them to investigate whether the virus itself was affecting the patients, or if the germ was triggering an unwanted response in the immune system. Specifically, they wanted to see if what are known as autoantibodies had a role to play. Antibodies normally attack invaders, and are described as autoantibodies when the they attack the body instead.

The team collected the patients' blood and cerebrospinal fluid and looked for the coronavirus, and antibodies known to affect the brain and nerves. The coronavirus was not found in any of the patients' cerebrospinal fluid. All of the participants had anti-neuronal autoantibodies in their blood or cerebrospinal fluid.

Next, in experiments using slices of mouse brain, they watched to see if antibodies from the fluid bound to the tissue, and found most did.

Four of the patients were found to have an antibody associated with brain complications. It is unclear if these antibodies were having a direct effect or if they were a bystander, Benedict D. Michael, from the University of Liverpool's Institute of Infection and Global Health, U.K., who did not work on the study told Newsweek.

The study suggests that some neurological complications in COVID-19 patients may be triggered by an immune response to the virus. Alternatively, the virus may cause some initial damage to the nervous tissue, which may release tissue components that trigger an immune response against the tissue itself. "Such a mechanism has been recognized with some herpesvirus infections," Cris S. Constantinescu, professor of neurology at the U.K.'s University of Nottingham Queen's Medical Centre, who did not work on the article, told Newsweek.

In the coming months, the authors wrote, it will become clearer whether such neurological problems last after patients have recovered from COVID-19 and the coronavirus has left their bodies.

Pointing to the study's limitations, Michael said: "These findings in 11 patients with very different symptoms and signs need to be studied in larger numbers. Of those who had antibodies which appeared to bind to mouse brain cells, work is needed to understand what these antibodies are, what exactly they are targeting and crucially, are they actually the cause of the patients symptoms or signs, or simply a bystander of some other immune process which we do not yet understand."

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A stock images shows illustrated virus particles superimposed on a brain scan image. Getty