Part #2:
Potentially more vulnerable / more at-risk populations:
There is very convincing evidence that the original SARS virus (SARS-CoV-1) and the current SARS-CoV-2 virus causing COVID-19 infection bind to a receptor protein found on the surface of human cells. The receptor protein is called Angiotensin Converting Enzyme 2 (ACE2).
ACE2 is expressed on certain cells in our body. Some of them include: many different cell types found in our respiratory tract and lungs, heart, kidneys, intestines, etc.
Some recently-published articles (links at the bottom of this post) indicate some fascinating things about ACE2-producing cells:
-From a study of lung cell cultures (derived from lung transplant donor lungs):
A novel coronavirus (2019-nCov) was identified in Wuhan, Hubei Province, China in December of 2019. This new coronavirus has resulted in thousands of cases of lethal disease in China, with additional patients being identified in a rapidly growing number internationally. 2019-nCov was reported to...
www.biorxiv.org
-ACE2 gene expression (indirect measure of the receptor production) seems to be concentrated in a relatively small fraction of lung cells. Specifically, the majority of cells are type-II alveolar cells (AT2 cells). These cells also seem to produce certain enzymes/factors that the virus needs to replicate optimally
-There
may be differences in the expression of ACE2 based on sex (Males > Females). There was on average, about 4x more cells expressing ACE2 in the 2 male donor samples versus the 6 female donor samples
-There
may be differences in expression of ACE2 based on race. There was ~5x more ACE2 expression in the donor sample from an Asian male as compared to the donor samples from "white and african american" donor samples. These are small samples sizes though...take with grains of salt.
This is an evolving research area though...here's a research report that provides some supportive evidence to the research above:
www.nature.com
And here's one that did not observe significant differences based on race or sex or age (>60 vs. <60):
In current severe global emergency situation of 2019-nCov outbreak, it is imperative to identify vulnerable and susceptible groups for effective protection and care. Recently, studies found that 2019-nCov and SARS-nCov share the same receptor, ACE2. In this study, we analyzed four large-scale...
www.preprints.org
But, these researchers
DID observe a significantly higher ACE2 gene expression in smokers' samples versus non-smokers' samples.
Much of the variation in results can be related to different research methods (single-cell analysis versus multiple-cell/combined different cell analysis).
But, there's some interesting findings that relate to emerging trends as the pandemic evolves:
The geographic variation / variation by country in severity of illness, transmittability, etc. is very likely to at least be influenced to some extent by:
- Variations in genetics that modulate ACE2 expression / function
- Variations in ACE2 expression/function induced by smoking and other external/concomitant factors
Interestingly enough, the reportedly higher risk/higher severity illness a/w hypertension is likely related in some way to ACE2 alterations in poorly-controlled/active hypertension. It will be interesting to see with further analysis if "well managed hypertension" presents less (or equal) risk than "poorly managed" hypertension.
What would I advise a patient/friend/family member as the COVID epidemic progresses???
- STOP SMOKING (probably vaping too) as soon as possible
- Continue to take your meds for treating any heart disease/hypertension. Start taking them regularly if you're notoriously poorly-adherent to those medications.
(edits to make bulletpoints, bolding...no significant content chages)
Other Links to relevant articles:
A novel coronavirus (2019-nCov) was identified in Wuhan, Hubei Province, China in December of 2019. This new coronavirus has resulted in thousands of cases of lethal disease in China, with additional patients being identified in a rapidly growing number internationally. 2019-nCov was reported to...
www.biorxiv.org
www.nature.com
ACE 2, a novel homologue of angiotensin converting enzyme, has recently been identified. This study used QRT-PCR to quantitatively map the transcriptional expression profile of ACE 2 (and the two isoforms of ACE) in 72 human tissues. While confirming that ACE 2 expression is high in renal and...
www.ncbi.nlm.nih.gov
We previously identified the major pathological changes in the respiratory and immune systems of patients who died of severe acute respiratory syndrome (SARS) but gained little information on the organ distribution of SARS-associated coronavirus (SARS-CoV). In the present study, we used a murine...
www.ncbi.nlm.nih.gov
Severe acute respiratory syndrome (SARS) is an acute infectious disease that spreads mainly via the respiratory route. A distinct coronavirus (SARS-CoV) has been identified as the aetiological agent of SARS. Recently, a metallopeptidase named angiotensin-converting enzyme 2 (ACE2) has been...
www.ncbi.nlm.nih.gov
www.ncbi.nlm.nih.gov