United States and Europe are Epicenter New Crown Epidemic

The United States and European countries have become the epicenter of the new crown epidemic. 

It can be seen that the virus is regardless of nationality. If you do not protect it properly, the virus will ruthlessly plunder.

In addition to protection factors, recent studies have shown that neocoronavirus may have more than one receptor. Receptors are highly expressed in white people, which may cause white people to be more susceptible to infection.

SARS coronavirus has three receptors, and so can new coronavirus

Recently, the Guoshuai Cai team at the University of South Carolina posted a paper on the preprint website Preprint. The results of this study suggest that smokers, the elderly, and white people may be more susceptible to the new crown virus.

Based on 80% homology between the new crown virus and SARS virus, and the two viruses have similar receptor domains, this suggests that the new crown virus and SARS virus may enter human cells through a common receptor.

Previous studies have shown that in addition to the ACE2 receptor, there are two other receptors that are involved in the entry of SARS coronavirus into human cells, namely the DC-SIGN and L-SIGN receptors.

We already know very well that the new coronavirus can enter our human cells through the ACE2 receptor, and little research has been done on the other two receptors.

DC-SIGN and L-SIGN are homologous C-type lectin receptors, capable of recognizing the carbon chain structure of viral glycoproteins, and playing an important role in virus capture, anchoring of host cells and large-scale reproduction in humans.

DC-SIGN is expressed on the surface of dendritic cells, and L-SIGN is expressed on the endothelial cells of sinusoids and lymph nodes.

Previous studies have shown that DC-SIGN is an independent receptor and can cooperate with the ACE2 receptor to endorse SARS coronavirus into cells.

L-SIGN is also a potential receptor for SARS coronavirus and a double-edged sword. After L-SIGN internalizes the virus, it degrades the virus in a proteasome-dependent manner.

Smokers, older people, and whites may be more susceptible

The authors of the paper analyzed the expression of ACE2, DC-SIGN and L-SIGN receptors in lung tissues of different populations using information from known databases.

The analysis found that there was no significant difference in expression of ACE-2 receptors between Caucasians and Asians. However, other problems were found in the study.

ACE2 and DC-SIGN expression levels are higher in the lungs of smokers, especially those who have smoked.

DC-SIGN has a higher expression level in the elderly population over 60 years old, and the expression level has nothing to do with gender.

In addition, the expression of L-SIGN gene in the lungs of Caucasians (whites) was higher than that of Asians, suggesting that whites are more susceptible to the new coronavirus.

The data from these laboratories have some agreement with clinical data, and current research shows that smokers and the elderly have a higher mortality rate after new coronary pneumonia infection.

Researchers speculate that upregulation of ACE2 in alveolar cells in smokers may lead to increased susceptibility to new crown virus.

Dendritic cells are immune cells of our body. DC-SIGN of dendritic cells is up-regulated, which makes it easier for viruses to enter host cells. At the same time, smoking-activated dendritic cells and the activation of the immune system may further lead to the occurrence of cytokine storms (immune storms) in critically ill patients.

In the elderly over 60 years old, the expression of DC-SIGN receptors increases, and the functions of organs and immune systems decrease. On the basis of the susceptibility of new crown virus, it is also easy to develop into severe diseases.

Based on these data, the authors concluded that elderly people over 60 years, smokers (or people who have smoked), and white people are more likely to be infected with the new crown virus, and the DC-SIGN of immune cells is affected. Body upregulation is more likely to induce a cytokine storm.

What's wrong with this research?

The entire study has a small amount of data, and the lung specimens are from lung cancer patients. It is not clear whether similar conclusions can be drawn from normal healthy people.

The most important defect, the entire experiment was speculated based on previous studies of SARS corona virus, and it can be determined that the ACE2 receptor is the receptor of the new coronavirus.

Whether DC-SIGN and L-SIGN are truly receptors for new coronaviruses, no data are available at this time.