The virus that causes COVID-19 does not infect human brain cells, according to a study published in the journal Cell. The findings will raise hopes that problems caused by Sars-CoV-2, such as anosmia or parosmia, could be superficial and reversible.
This membrane, called the olfactory mucosa, is where the virus first reaches when it is inhaled. Inside it are olfactory sensory neurons (NSOs), which are responsible for initiating olfactory sensations. They are closely intertwined with a kind of support cell called a support cell, according to The Guardian.
In the new study, Belgian and German researchers claim that the virus infects the cells of the subcutaneous cells, but not the olfactory sensory neurons.
“This is just a critical distinction,” said lead author Peter Mombaerts, who heads Max Planck’s research unit for neurogenetics in Frankfurt, Germany: “Once you think olfactory neurons can be infected, there is a fast path in the olfactory bulb that leads to in the brain “.
The olfactory bulb, located in the front of the brain, is where the neuronal input about odors is first processed. If the virus entered this structure, it could theoretically spread to deeper regions of the brain, where it could cause lasting damage, especially since, unlike OSN, most neurons do not regenerate once lost.
But if the virus infects only the supporting cells, then the damage may be less lasting.
Both pathways could explain the olfactory dysfunction that affects about half of COVID-19 patients. In one in 10 of them, the loss or change of smell is long-term, perhaps even permanent.
Mombaerts says this could be the result of breaking support for OSNs, even if they themselves are not infected. They can function below normal or stop working until the support cells regenerate.
The group did not look at other neurological symptoms of COVID-19, such as fatigue and “brain fog” that accompany long-term illness.
No one doubts that the central nervous system is affected by the disease. The debate is whether these effects are caused by the fact that the virus infects neurons or an indirect mechanism, such as an inflammatory response in the blood that irrigates the brain, with different implications for prognosis and treatment.
The present study is the largest to date in COVID-19 patients and used a new technique to capture these early events.
If its findings are confirmed, those with COVID-19-related anosmia or parosmia may be reassured that the virus has not infected their brains and that future therapies targeting poorly studied sustenance cells may improve or improve them. it cures their condition.
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