Researchers in Amsterdam have found that the coronavirus also hits the brain hard.This can explain why people lose their sense of smell and taste, 'forget' to breathe, and also why so many patients report long term concentration loss, palpitations and memory loss.
Swollen and deformed cells. Sticky pellets and weblike structures of defense proteins. Tissues full of activated immune cells that died fighting..
Amsterdam researchers "were completely baffled by what they saw", when studying the brains of 21 deceased corona patients under a microscope.
The virus appears to not only cause extensive damage to the lungs, but also to the brains.
Admittedly, all patients that Paul van de Valk and his fellow researchers at the Amsterdam UMC studied had died from the corona virus.
"We don't know if we would find the same damage in patients that became less ill from the virus", says van der Valk.
But what the study does show, is that corona is much more than just a respiratory disease.
"It can almost be called a systemic disease", says van der Valk. "Just about every organ in the body is affected".
The researcher did not find many virus particles in the deceased patients. In fact, they found none at all in the brains.
They did, however, find extensive inflammation damage. In the lungs, obviously. But also in the liver, the kidneys, the heart and the brains.
In nearly all patients they found extensive damage to the olfactory nerve. This would explain the remarkable loss of smell and taste in many patients.
Striking is also the damage to a part of the brain, high in the neck, that is responisble, amongst other things, for the automatic reflex of breathing.
"We know that many patients keep walking around with too little oxygen in the blood, until they acutely get very stuffy", says van der Valk.
"it is tempting to correlate this with a damaged respiratory center in the brain".
The damage is practically everywhere. "The cerebellum, the cerebrum, everywhere we looked we found inflammatory damages", says the pathologist.
"We were baffled and impressed by the brainf deformations we found". For example, the team found tight clusters of 'microglial cells' everywhere, the team writes in an article in the Lancet Microbe. Those are antennas that regulate the immune response.
"They are super-activated, almost out of control. In all likelyhood they made a futile last effort to stop the immune response".
The brain has it's own private immune system, that usually is tuned to very low activity, to prevent the immune system in the brain to become agitated too fast and cause damage.
Yet apparently, corona virus manages to affect and deregulate even this delicate secluded part of the immune system.
"The immunological clinical picture we see here is very rare", the researchers say. "Yet, with Covid, we see it in nearly all patients"
This could explain the so-called 'long Covid', the phenomenon where patients that often weren't even that ill from corona report that they suffer from amnesia, headaches, extreme fatigue, and 'brain mist' for months after having recovered from the disease.
"We don't have any conclusive evidence yet, but it is quite possible that 'long covid' is caused by this", says van der Valk.
Other studies already pointed at a striking correlation between long covid and a disturbed autonomic nervous system: patients often suffer from heart rythm disturbance and breathing disorders.
"More and more, it is starting to look like that this coronavirus mostly targets the innate immune response system, the body's frontline defense system, and makes it go haywire", says internist-immunologist Pieter van Paassen (UMC Maastricht) when asked.
"That is an important new idea, and their study supports that".
Van Paassen recently conducted a studies of 228 corona patients (
https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.120.050656).
In the worst cases he observed immune cells called neutrophiles cast a web when viewed under a microscope, exactly the same as what van der Valk's team observed in their study.
"Those cells are trying to catch the virus in their webs, but while doing that they also activate the coagulation route, which likely is the reason for the extreme blood clotting we observe in patients", says van Paassen.
"The big question is, how long does this clinical picture last", says van der Valk.
He recounts horrible stories from people that are left disabled for months.
"This could imply that, once triggered, the immune response does not know how to stop".
On the other hand, the immunological clinical picture observed has many similarities with the paralysis disease Guillain-Barré."And that disease's clinical picture does end eventually. So there is still good hope that these effects from corona are also not going to last forever", says van der Valk.
The researchers are very curious to see what effects dexamethason, which is now a standard medicine used on corona patients in hospitals to reduce inflammatory damages, will have. Patients are now also always treated with anti-coagulents, to prevent blood clotting.
The new finds show that this new corona virus strikes surprisingly different than other respiratory virusses, like flu and the common cold."This is some kind of hit-and-run virus", says van der Valk. "It visits briefly, causes major damage, and then leaves the body again, leaving some patients with many additional problems caused by hyperreaction of their immune system".
Translated from
https://www.volkskrant.nl/wetenschap/coronavirus-veroorzaakt-chaos-in-de-hersenen~bac7630e/
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