A new study conducted by scientists at Johns Hopkins University adds to the growing evidence that your nose is the key entry point for the coronavirus.
The scientists reported the “hook” of cells used by SARS-CoV-2 to latch onto and infect cells is found up to 700 times more in cells lining the inside of the upper part of the nose than in the cells lining the rest of the nose and the windpipe. These supporting cells are necessary for the function and development of odor-sensing cells.
The findings “could advance the search for the best target for topical or local antiviral drugs to treat COVID-19,” the scientists wrote. It also offers further clues into why people with the virus sometimes lose their sense of smell.
“Loss of the sense of smell is associated with COVID-19, generally in the absence of other nasal symptoms, and our research may advance the search for a definitive reason for how and why that happens, and where we might best direct some treatments,” said Andrew Lane, professor of otolaryngology–head and neck surgery, and director of the division of rhinology and skull base surgery at the Johns Hopkins University School of Medicine.
Scientists have known SARS-CoV-2 latches on to a biological hook on many types of human cells, called an angiotensin-converting enzyme 2 — or ACE2 — receptor. The receptor reels in essential molecules.
“In a bid to explore the ACE2 link to COVID-19 in more detail, Lane, Mengfei Chen, Ph.D., a research associate in Lane’s lab at the Johns Hopkins University School of Medicine, and others on his team took a close look at ACE2 levels in nasal tissue specimens from 19 adult men and women with chronic rhinosinusitis (inflammation of nasal tissue) and in tissues from a control group of four people who had nasal surgeries for issues other than sinusitis,” the scientists wrote.
The researchers also studied tissue samples of the trachea from seven people who underwent surgery for abnormal narrowing of the trachea.
None of the participants had been diagnosed with COVID-19.
The Johns Hopkins team used fluorescent stains to identify ACE2 receptors and found high levels among nasal cells that give structural support. These are called sustentacular cells. These cells are in an area called the olfactory neuroepithelium, where odor-sensing neurons are found.
Scientists found 200-700 times more ACE2 proteins in the olfactory neuroepithelium than in samples from the nose and trachea.
“Because the cells with high levels of ACE2 are associated with odor sensing, the researchers suggest that infection of these cells may be the reason some people with COVID-19 experience loss of smell,” they wrote.
It’s also why they urge everyone to wear a face covering correctly — making sure to cover both your mouth and nose.
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