Preprint Article Version 1 This version is not peer-reviewed

Tobacco-Use Disparity in Gene Expression of ACE2, the Receptor of 2019-nCov

Version 1 : Received: 3 February 2020 / Approved: 5 February 2020 / Online: 5 February 2020 (02:56:53 CET)
Version 2 : Received: 12 February 2020 / Approved: 14 February 2020 / Online: 14 February 2020 (04:32:49 CET)
Version 3 : Received: 27 February 2020 / Approved: 2 March 2020 / Online: 2 March 2020 (01:38:52 CET)

How to cite: Cai, G. Tobacco-Use Disparity in Gene Expression of ACE2, the Receptor of 2019-nCov. Preprints 2020, 2020020051 (doi: 10.20944/preprints202002.0051.v1). Cai, G. Tobacco-Use Disparity in Gene Expression of ACE2, the Receptor of 2019-nCov. Preprints 2020, 2020020051 (doi: 10.20944/preprints202002.0051.v1).

Abstract

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 datasets of normal lung tissue to investigate the disparities related to race, age, gender and smoking status in ACE2 gene expression. No significant disparities in ACE2 gene expression were found between racial groups (Asian vs Caucasian), age groups (>60 vs <60) or gender groups (male vs female). However, we observed significantly higher ACE2 gene expression in smoker samples compared to non-smoker samples. This indicates the smokers may be more susceptible to 2019-nCov and thus smoking history should be considered in identifying susceptible population and standardizing treatment regimen.

Subject Areas

Wuhan 2019-nCov; ACE2; expression; susceptibility; race; age; gender; smoking

Comments (30)

Comment 1
Received: 6 February 2020
Commenter: Leo Hopkins
The commenter has declared there is no conflict of interests.
Comment: Very good article. One question - The article stipulates "tobacco smoking" - Question, do we know yet what in tobacco smoking causes the significant increase of ACE2 receptor sites and how does this compare with vapeing ? - In other words, is it the nicotine itself which causes the problem or other chemicals found in tobacco smoke that are not present in vaping? Also, does this ACE2 expression significantly reduce over time once a person quite smoking?
+ Respond to this comment
Response 1 to Comment 1
Received: 7 February 2020
Commenter: Guoshuai Cai
The commenter has declared there is no conflict of interests.
Comment: Excellent questions, Leo. We currently have no clue on the causality. We are looking at the ACE2 expression in populations with different smoking histories and will publish the results soon. -Guoshuai
Response 2 to Comment 1
Received: 8 February 2020
Commenter: SFN
The commenter has declared there is no conflict of interests.
Comment: I second Leo Hopkins in wondering what it is about tobacco smoke that would increase ACE2 receptor sites, especially in light of other studies that indicate that exposure to cigarette smoke/nicotine upregulates ACE1 and actually ''downregulates'' ACE2, which is potentially the reason that tobacco use is associated with elevated blood pressure. And isn't it also the case that there are legitimate, well-established differences in ACE2 allele frequencies (and thus gene expression) between those of different ethnicities? Both of these factors would appear to indicate the opposite of what was found in this review. I will be very interested to see the results of further research on this topic.
Response 3 to Comment 1
Received: 13 February 2020
The commenter has declared there is no conflict of interests.
Comment: According to this article, it would appear that Nicotine may be the key agent in upregulating ACE2 expression: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6295500/ So e-cigarettes, patches etc may be just as problematic as smoking in this regard. This upregulation also has implications regarding blood pressure control, incidentally.
Response 4 to Comment 1
Received: 14 February 2020
Commenter: Guoshuai Cai
The commenter has declared there is no conflict of interests.
Comment: We have done the analysis on former smokers and current smokers in published the result in v2. We found Smokers especially former smokers have upregulated ''ACE2'' in lung. Asian and Caucasian current smokers may have different expression of ''ACE2'', which may indicate an existence of gene-smoking interaction.
Response 5 to Comment 1
Received: 4 March 2020
Commenter: k raghavendra singh
The commenter has declared there is no conflict of interests.
Comment: Conclusion paragraph is good ending with blessings to Wuhan and overall limitations of the study which tells smoking may be only but not confirmation to elevated ACE2 Expression.
Response 6 to Comment 1
Received: 11 March 2020
Commenter: Klaus K.
The commenter has declared there is no conflict of interests.
Comment: I found it strange that the author of this study found "significantly higher ACE2 gene expression in smoker samples compared to non-smoker samples", since nicotine has been found to ''downregulate'' ACE2 in smokers. This nicotine-AC2 relation could explain why smokers are so hugely underrepresented among the COVID-19 caes in the Chinese studies. Does the author have an explanation for his unexpected finding? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6295500/
Response 7 to Comment 1
Received: 23 March 2020
Commenter: David Holley
The commenter has declared there is no conflict of interests.
Comment: Please define tobacco smoking. Are we discussing cigarette smoking where the smoke is fully inhaled into the lungs or cigar smoking where it is not?
Response 8 to Comment 1
Received: 1 April 2020
Commenter: Michelle Minton
The commenter has declared there is no conflict of interests.
Comment: To add to Leo Hopkins's question, the fact that nicotine causes transient vasoconstriction would seem to play a role in how/why smoking increases ACE2 expression. ACE2 is part of the crucial compensatory axis that, when working properly, act to inhibit RAS and vasoconstriction. For example, moderate cardiovascular exercise, which like nicotine causes transient vasoconstriction, appears to trigger the upregulation of ACE2. [1] Thus, ACE2, even if high levels make one more susceptible to SARS-CoV-2 infection, may also play an important beneficial role in ameliorating the effects of severe COVID-19. [2] Presumably, how ACE2 affects COVID-19 progression is more important to mortality risk in patients with a pre-existing imbalance of RAS and the compensatory axis, such as those with hypertension, heart diseases, or kidney disease. But, this is only something that will hopefully be answered by clinical trials currently underway. Until then, I don't think it would responsible to jump to conclusions about how ACE2 levels (or anything that alters ACE2 levels) affects COVID-19 susceptibility or mortality. [1] Daniel Massote Magalhãesa, et al. Two protocols of aerobic exercise modulate the counter-regulatory axis of the renin-angiotensin system. Heliyon, January 2020. DOI: 10.1016/j.heliyon.2020.e03208. https://www.sciencedirect.com/science/article/pii/S2405844020300530. [2] Muthiah Vaduganathan, et al. Renin–Angiotensin–Aldosterone System Inhibitors in Patients with Covid-19. NEJM March 2020. DOI: 10.1056/NEJMsr2005760. https://www.nejm.org/doi/full/10.1056/NEJMsr2005760.
Comment 2
Received: 9 February 2020
The commenter has declared there is no conflict of interests.
Comment: Hello, is there any study or statistics about levels of ace2 after one quits smoking? Or do you have any idea how much time it would need to see these levels drop?
+ Respond to this comment
Response 1 to Comment 2
Received: 14 February 2020
Commenter: Guoshuai Cai
The commenter has declared there is no conflict of interests.
Comment: There question is interesting and important but might be complicated with gene-smoking interactions. It is discussed in the v2 paper, "Bulk and Single-Cell Transcriptomics Identify Tobacco-Use Disparity in Lung Gene Expression of ACE2, the Receptor of 2019-nCov".
Comment 3
Received: 9 February 2020
Commenter: Baran Ozmen
The commenter has declared there is no conflict of interests.
Comment: Can you refine your data to only include Han Chinese in the comparison between ACE2 expression? All critically sick seems to be Han Chinese no matter the passport.
+ Respond to this comment
Response 1 to Comment 3
Received: 13 February 2020
The commenter has declared there is no conflict of interests.
Comment: Is it possible to clarify the relevance if this in asthmatics? Some smokers start of as slightly asthmatic but continue doing so through their life regardless. Others, share overlap with asthma and COPD. Is it specifically tobacco / smokers expressing ACE2 that's appear to be more susceptible or those who express it with other comorbidities?
Response 2 to Comment 3
Received: 18 February 2020
Commenter: Guoshuai Cai
The commenter has declared there is no conflict of interests.
Comment: That is very interesting and meaningful. Unfortunately there is no detailed information about sub-population in current datasets. Look forward to see further studies on Han Chinese population.
Comment 4
Received: 10 February 2020
Commenter: Simon Edge
The commenter has declared there is no conflict of interests.
Comment: Something that really jumps out is the gender mortality rates, which is 70% male, 30% female - I think this needs to be explained by something other than gender as viruses do not normally target one gender over another.

So, 48% of Chinese males are smokers (which is a huge percentage), whereas only 5% of Chinese women smoke - this could be the answer to this puzzle...
+ Respond to this comment
Response 1 to Comment 4
Received: 23 February 2020
Commenter: Tim G.
The commenter has declared there is no conflict of interests.
Comment: This *seems* like the most logical conclusion, especially in light that smoking creates a higher ACE2 gene expression *and* compounded to the tentative facts that ACE2 receptors are more present in both Asians and the male gender.... *However*, there is a very confusing chart being shared now for more than a week, which claims to be an authentic Chinese transcript of case studies of the virus in 1000+ patients. According to the chart, only male non-smokers are over-represented. As this demographic is *less than* 20% of the population, this would imply that only 1 in 4 Chinese individuals would even have a possibility of infection - which doesn't seem to collate with the nature of this outbreak as reported. Either the chart is wrong, or ACE2 receptors have no pertinence to this virus and the outbreak.
Comment 5
Received: 20 February 2020
Commenter: WD Aguilar
The commenter has declared there is no conflict of interests.
Comment: If it’s hitting smokers harder, and so many more men in China smoke than women--and are getting sicker than women (or more of them), that seems to imply that it’s not secondhand smoke? Would it be something the smoker “only” is taking in?
+ Respond to this comment
Response 1 to Comment 5
Received: 26 February 2020
Commenter: Katharine O'rouke
The commenter has declared there is no conflict of interests.
Comment: https://www.medrxiv.org/content/10.1101/2020.02.06.20020974v1.full.pdf
The above research coming from actual case studies shows that smokers represent only approx 2% of mortalities.

Smoking it seems likeli confers a benefit with respect to this coronavirus. Smoking has played a significant plague inhibiting role in the past including in the case of the black death.
Response 2 to Comment 5
Received: 3 March 2020
Commenter: Shelby Moore III
The commenter has declared there is no conflict of interests.
Comment: In that study, smokers and ex-smokers are twice as likely to have more severe illness and thrice more likely to die:

https://www.medrxiv.org/content/10.1101/2020.02.06.20020974v1.full.pdf#page=21
Response 3 to Comment 5
Received: 28 March 2020
Commenter: Shannon Purkey
The commenter has declared there is no conflict of interests.
Comment: Katharine O'rouke is correct. ACE2 gene expression may be higher in smokers, but I suspect L-Tyrosine is the achilles heal. If you have a chance, study how L-Tyrosine is utilized by the coronavirus. Nicotine and L-Tyrosine don't play well together. I'm definitely not a doctor, but this is the reason smokers have high survival rates in China. It looks like a similar situation in South Korea where the young female nonsmokers are dying. Sad situation
Comment 6
Received: 5 March 2020
Commenter: Santiago Vaca
The commenter has declared there is no conflict of interests.
Comment: The article mentioned above shows clearly that most of 2019-nCov patients where Non-smokers (85.4% never smokers against 12.6 current smokers) which corresponds to nicotine downregulating ACE 2 (also very clear in other studies). Since ACE 2 is the receptor for the coronavirus....the conclusion is quite obvious.
+ Respond to this comment
Comment 7
Received: 8 March 2020
Commenter: Rebecca Lee
The commenter has declared there is no conflict of interests.
Comment: You replied to someone who asked a question about smoking and the expression of ACE2 by saying, "We found smokers especially former smokers have upregulated ACE2 in lung." Are you saying that former smokers have higher levels of ACE2 than current smokers? If that is true, does that mean that the expression of ACE2 does not reduce or increases once the person quits smoking?
+ Respond to this comment
Comment 8
Received: 11 March 2020
Commenter: Konstantinos Farsalinos (Click to see Publons profile: )
The commenter has declared there is no conflict of interests.
Comment: Published studies presenting case series of patients with COVID-19 infection have shown unusually LOW prevalence of smoking among cases. The largest of these studies, analyzing data from 1099 cases in China, found a smoking prevalence of just 12.6% (Guan et al., New Engl J Med 2020. DOI: 10.1056/NEJMoa2002032). This prevalence is low considering that 58.1% of the cases were men and smoking prevalence among Chinese men is 50%. I expect smokers to experience more complications (or be more likely to progress to serious disease) due to underlying smoking-related comorbidities. Thus, it is still too early to make any definite conclusions but data suggest an unusually low prevalence of smoking among COVID-19 cases. We need data from a larger series of cases.
+ Respond to this comment
Comment 9
Received: 19 March 2020
Commenter: Steph Squires
The commenter has declared there is no conflict of interests.
Comment: The problem I see is that your title and abstract doesn't acknowledge the database used. Your samples from four databases are the normal tissues from patients who also have tumors. Until I examined the full paper, I had the impression these tissues were from covid patients.

Since higher expression of ACE2 is not normal for smokers according to the extensive prior research, a high expression in the normal cells of cancer patients, which you found, could help to explain the increased susceptibility of cancer patients to covid. It indicates that a cancer patient who is a smoker would be at higher risk.

Your presentation of the findings should clearly state the valid and important conclusions, especially those which could save a life. Those cancer patients who are smoking may be encouraged to quit, in hopes that ACE2 receptor expression will be reduced before they are exposed to the virus.

On the other hand, smokers should not be encouraged to quit during covid pandemic. This is obvious from the work on covid patients, indicating a reduced risk of hospitalization for current smokers, which is attributable to the known downregulation of ACE2 in smokers.
I think it is reasonable to advise smokers to be moderate or reduce smoking for the benefit of general lung health, however to suggest that quitting nicotine is timely, which would increase susceptibility to covid by upregulating ACE2, is wrong. Except for the cancer patients, they should wait until the danger of the pandemic is past.

It is concerning to see research misinterpreted by the media due to misunderstandings, especially in a way that puts the health of a population in jeopardy. The true conclusions should be made clear to everyone, so they can give appropriate cautions for the pandemic. The easy way to correct this issue is simply to add the words "in normal tissues of cancer patients" at the end of your title.

Thank you for your contribution to the research on ACE2, which is so important now! Be well, everyone.
+ Respond to this comment
Comment 10
Received: 20 March 2020
Commenter: George Tee
The commenter has declared there is no conflict of interests.
Comment: Great article but I would like to hear more on comment 7. Are do former smokers really have upregulated ACE2? Do former smokers have higher levels of ACE2 then current smokers. Do we know how recently the former smokers quit? And should we expect the same results from people that vape since nicotine is also used?
+ Respond to this comment
Comment 11
Received: 25 March 2020
Commenter: Leigh Taylor Ward
The commenter has declared there is no conflict of interests.
Comment: Second- and third-hand smoke must be a factor in locales where nearly 50% of the population smokes. Making distinctions between smokers and non-smokers in these locales could be misleading.
+ Respond to this comment
Comment 12
Received: 28 March 2020
The commenter has declared there is no conflict of interests.
Comment: In response 2 to comment 5 the following is given:
https://www.medrxiv.org/content/10.1101/2020.02.06.20020974v1.full.pdf The link gives you the fulle article written on the subject of the 2019 noCoVi outbreak in China. In Table 1 numbers are given for all kinds of categories of 2019 noCoVi patients:
41 out of 173 deaths also suffered from hypertension
28 out of 173 deaths also suffered from diabetes
10 out of 173 deaths also suffered from coronary heart disease
29 out of 172 deaths were current smokers

Are there any overlaps in these numbers? For example: did 28 out of the 41 sufferers of hypertension also have diabetes? And did the 29 current smokers suffer from any of the above?

Reports about 1,099 COVID-19 patients in China discovered that most were also suffering from hypertension, coronary artery disease, diabetes and renal disease, all health problems that likely were being treated with ACEIs (angiotensin-converting enzyme inhibitor) or ARBs (angiotensin receptor blockers).
Similar reports have been coming out of Italy, where an estimated 52 percent of COVID fatalities were also taking an ACE inhibitor.
Dr Malcolm Kendrick, a UK GP, estimates that people who are taking any blood pressure medication are four times more likely to die from the virus.
People who are taking an ACE inhibitor or an ARB drug for heart problems should stay at home and not meet up with people, say researchers from Louisiana State University.
The drugs also increase the chances of catching the virus in the first place. ACEIs in particular increase the receptors around the lungs that the corona virus also binds to, the ACE2s.
Many taking the medication are elderly and are being treated for cardiovascular diseases including a heart attack, high blood pressure (hypertension), diabetes or chronic kidney disease. The ARBs are also prescribed to reduce blood pressure levels.
https://academic.oup.com/jtm/advance-article/doi/10.1093/jtm/taaa041/5809509

So if one is a smoker (which means less ACE2 receptors) and one leads an otherwise healthy lifestyle then a smoker is less likely to die from 2019 noCoVi. If that smoker also drinks a lot, eats a lot of junk food, uses medical drugs then he is probably as likely or more so to die from 2019 noCoVi (called CoVid-19 in Europe).

Begs the question: what influence does lifestyle and medicine use have on your changes of surviving 2019 noCoVi?
I wish we would see more articles like the one from China with numbers in categories, especially from countries like Germany, France, UK, Netherlands, Canada or USA.
+ Respond to this comment
Response 1 to Comment 12
Received: 30 March 2020
The commenter has declared there is no conflict of interests.
Comment: Important typo in sentence "Begs the question......." -> changes should be chances
Comment 13
Received: 2 April 2020
Commenter: Francesca Manning
The commenter has declared there is no conflict of interests.
Comment: I feel that the focus on the up vs down regulation of the ACE2 receptors misses something. This study shows that disproportionately low numbers of smokers are ending up in hospital, not that they are not becoming infected.

Various studies have shown that nicotine stimulates the cholinergic anti-inflammatory pathway thus blocking the cytokine storm responsible for covid-19 deaths. Therefore it is surely more likely that smokers are simply not getting as sick as non-smokers, due to the anti-inflammatory role played by nicotine.
+ Respond to this comment
Comment 14
Received: 22 April 2020
Commenter: Robert C. Speth
The commenter has declared there is no conflict of interests.
Comment: Hasn't anyone looked closely at the data in Figure 1b? I find it astonishing that the author is claiming that it indicates significant differences given the high variability and overlapping error bars. Over two months should be sufficient for a peer-review and acceptance of this paper in the standard biomedical literature if the conclusions are valid.
+ Respond to this comment

We encourage comments and feedback from a broad range of readers. See criteria for comments and our diversity statement.

Leave a public comment
Send a private comment to the author(s)
Views 0
Downloads 0
Comments 30
Metrics 0


×
Alerts
Notify me about updates to this article or when a peer-reviewed version is published.