the important entry level for coronavirus

A recent study looked at high levels of protein in nasal epithelial cells to which the coronavirus binds.

We are currently experiencing the almost global spread of the life-threatening coronavirus. Researchers are trying to understand how this virus enters the human body. So far, we know that the coronavirus enters cells through a protein called angiotensin converting enzyme 2 receptors (ACE2). The location of this protein can be an essential element in understanding the spread of the virus.

In a survey study in Europe, around 85% of people reported disorders in their sense of smell. This prompted a group of researchers from Johns Hopkins Medicine to study ACE2 receptors in nasal and tracheal samples from humans. They examined four healthy people and 19 patients who were infected with an inflammatory disease of the nose. They also examined tissue samples from the windpipe from seven people who were operated on for windpipe.

The European Respiratory Journal published a summary of the research.

The scientists observed that ACE2 receptors were up to 700 times more abundant in the sustentacle cells that line the top of the nose than in the epithelium of the rest of the nose and the trachea that lead to the lungs. The tentacle cells help the odor-sensitive neurons of the nasal epithelium. These findings in the nose can help us understand the mechanism of olfactory loss seen in coronavirus infected patients, even when no other symptoms are present. The researchers also highlight that this area of ​​the nose is more prone to infection, and urge people to wear their mask properly.

There is also a possibility that the coronavirus could get into the brain through the nose and cause neurological symptoms in patients. The ACE2 protein levels could be correlated with the severity of the disease. For example, obese individuals with more severe illness may have high ACE2 protein levels, and the low levels in children explain the lower prevalence in children.

These preliminary results could shed light on the advancement of new topical antiviral therapeutics. However, there is a need to advance these results by examining nasal samples from COVID-19 infected patients.

Reference: Mengfei Chen, Wenjuan Shen, Nicholas R. Rowan, Heather Kulaga, Alexander Hillel, Murugappan Ramanathan, Andrew P. Lane. Elevated ACE2 expression in olfactory neuroepithelium: implications for anosmia and SARS_CoV-2 entry and replication of the upper airways. Eur Respir J 2020; in the press (https://doi.org/10.1183/13993003.01948-2020).

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