04/26/2020
Scientific research is strongly suggesting that the linchpin in the infection of human cells with the virus responsible for Covid 19 may be the ACE2 receptor. ACE2 receptors (angiotensin converting enzyme type two receptors) are found on lung cells and as recently discovered can also be expressed on cells found in the nasal passages. While there are other factors that contribute to the severity of a particular individual’s Covid 19 infection, the inherent number of ACE2 receptor sites appears to be a critical contributor. So who are the individuals likely to have an increased number of receptor sites?
Individuals with COPD, smokers, diabetics, and those with high blood pressure tend to have significantly increased expression of the ACE2 receptor on their lung cells. By giving the virus responsible for Covid 19 more sites to attach to, it is likely a key explanation for why there is such a discrepancy in the manifestations of Covid 19 amongst different individuals.
Per an article published in the Lancet, some research indicates that Asians with hypertension make even more ACE2 receptors. This may explain possible differences in mortality between those afflicted with Covid19 in Asia and those suffering from the same infection in other parts of the world. I want to caution that there are multiple other factors that likely play a role in determining the severity of an individual's Covid19 infection including, native lymphocyte counts and trained immunity. But, the number of receptor sites to which the virus can attach appears to also play critical role in determining the severity of an individual's Covid 19 infection. And it is clear that certain disease states cause a higher proliferation of the ACE2 receptor on lung cells with COPD (emphysema), smoking, diabetes, and hypertension being the most implicated.
Children tend to not manifest the ACE2 receptor until later in life, some scientists estimate it to be around the age of 10 and may explain in part why children appear to be unaffected by the current pandemic.
https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30116-8/fulltext
https://www.clinicalomics.com/topics/patient-care/smo
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7113798/