A new study shows how spike protein crosses the blood-brain barrier
From:
University of Washington Health Sciences/UW Medicine
December 17, 2020 -- The SARS-CoV-2
virus, like many viruses before it, is bad news for the brain. In a new study,
researchers found that the spike protein, often depicted as the red arms of the
virus, can cross the blood-brain barrier in mice. The spike proteins alone can
cause brain fog. Since the spike protein enters the brain, the virus also is
likely to cross into the brain.
More and more evidence is coming out
that people with COVID-19 are suffering from cognitive effects, such as brain
fog and fatigue.
And researchers are discovering why. The
SARS-CoV-2 virus, like many viruses before it, is bad news for the brain. In a
study published Dec.16 in Nature Neuroscience, researchers found
that the spike protein, often depicted as the red arms of the virus, can cross
the blood-brain barrier in mice.
This strongly suggests that SARS-CoV-2,
the cause of COVID-19, can enter the brain.
The spike protein, often called the S1
protein, dictates which cells the virus can enter. Usually, the virus does the
same thing as its binding protein, said corresponding author William A. Banks,
a professor of medicine at the University of Washington School of Medicine and
a Puget Sound Veterans Affairs Healthcare System physician and researcher.
Banks said binding proteins like S1 usually by themselves cause damage as they
detach from the virus and cause inflammation.
"The S1 protein likely causes the
brain to release cytokines and inflammatory products," he said.
In science circles, the intense
inflammation caused by the COVID-19 infection is called a cytokine storm. The
immune system, upon seeing the virus and its proteins, overreacts in its
attempt to kill the invading virus. The infected person is left with brain fog,
fatigue and other cognitive issues.
Banks and his team saw this reaction
with the HIV virus and wanted to see if the same was happening with SARS CoV-2.
Banks said the S1 protein in SARS-CoV2
and the gp 120 protein in HIV-1 function similarly. They are glycoproteins --
proteins that have a lot of sugars on them, hallmarks of proteins that bind to
other receptors. Both these proteins function as the arms and hand for their
viruses by grabbing onto other receptors. Both cross the blood-brain barrier
and S1, like gp120, is likely toxic to brain tissues.
"It was like déjà vu," said
Banks, who has done extensive work on HIV-1, gp120, and the blood-brain
barrier.
The Banks' lab studies the blood-brain
barrier in Alzheimer's, obesity, diabetes, and HIV. But they put their work on
hold and all 15 people in the lab started their experiments on the S1 protein
in April. They enlisted long-time collaborator Jacob Raber, a professor in the
departments of Behavioral Neuroscience, Neurology, and Radiation Medicine, and
his teams at Oregon Health & Science University.
The study could explain many of the
complications from COVID-19.
"We know that when you have the
COVID infection you have trouble breathing and that's because there's infection
in your lung, but an additional explanation is that the virus enters the
respiratory centers of the brain and causes problems there as well," said
Banks.
Raber said in their experiments
transport of S1 was faster in the olfactory bulb and kidney of males than
females. This observation might relate to the increased susceptibility of men
to more severe COVID-19 outcomes.
As for people taking the virus lightly,
Banks has a message:
"You do not want to mess with this
virus," he said. "Many of the effects that the COVID virus has could
be accentuated or perpetuated or even caused by virus getting in the brain and
those effects could last for a very long time."
This study was partially supported by a
National Institute on Aging-funded COVID-19 supplement to a shared RF1 grant of
Banks and Raber.
https://www.sciencedaily.com/releases/2020/12/201217154046.htm
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