The researchers found that the “part” of cells that the virus attaches to, is spread up to 700 times in the lining of the upper part of the nose, compared to the lining of the rest of the nose or the trachea.
These support cells play a vital role in the function and development of odor-sensing cells and may be damaged when a pathogen attacks them.
The research team from Johns Hopkins University says that the results may lead to drugs or other treatments that target these cells, until a vaccine is developed.
Dr Andrew Lynn, professor of otolaryngology at Johns Hopkins University School of Medicine and lead author of the study, said: “Loss of smell is associated with“ Covid-19 ”, generally in the absence of other nasal symptoms. Our study may advance the search for a specific cause. How, why and where we can better target some treatments. ”
In the study, published in the European Respiratory Journal, the team looked at nasal tissue samples from 19 adult men and women with chronic sinusitis, an infection of the nasal tissue.
They also examined tracheal tissue samples from 7 people who had undergone surgery for an abnormal narrowing of the windpipe.
These samples were compared to four people who underwent nasal surgeries, for reasons other than sinusitis. Children were not tested because they had low levels of ACE2 in the cells lining their nose.
The researchers specifically studied the angiotensin-converting enzyme 2 (ACE2) receptor, which is the receptor that the virus uses to enter and infect human cells.
They found high levels of the enzyme ACE2 among the nasal cells in an area called the olfactory neuron epithelium, where the odor-sensing neurons are located.
Cells in the olfactory nerve epithelium have between 200 and 700 times more ACE2 receptors, compared to other samples from the nose and trachea.
The researchers say the results could lead to the development of drugs, or even a topical cream, to be placed inside the nostrils that target these cells and prevent infection transmission.
And given that odor-sensing cells contain the highest levels of ACE2, the team believes this is the reason why some Covid-19 patients lose their sense of smell.