angiotensin converting enzyme (ACE), ACE2, corona virus, COV-2, entry point for COV-2, clinical features, cytokine storm, drugs for treatment of COVID-19

1. CORONA VIRUS COV-2 RECEPTOR:
FROM
ANGIOTENSIN CONVERTING ENZYME
TO
ANGIOTENSIN CONVERTING ENZYME 2
TO
COVID-19
By
Kevin KF Ng, MD, PhD
Former Associate Professor of Medicine
Division of Clinical Pharmacology
University of Miami, Miami, FL., USA
Email: kevinng68@gmail.com
A slide presentation for HealthCare Providers March 2020

2. Lecture outline
▪ History of the angiotensin converting enzyme
▪ Discovery of plasma converting enzyme, pulmonary angiotensin
converting enzyme (ACE) and angiotensin converting enzyme 2
(ACE2)
▪ Functions of angiotensin converting enzymes ACE and ACE2
▪ Functions of angiotensin II (1-8 )and angiotensin (1-7)
▪ ACE2 as receptor for corona virus SARS-COV-2
▪ Blockade of ACE2 as a therapeutic approach for SARS_COVD-19
▪ Potential treatment for COVD-19 and cytokine storm
▪ Summary

3. History of angiotensin converting enzyme and
SARS-COV-2 receptor
ACE2
CoV-2

4. https://www.nature.com/articles/216762a0

5. https://www.ahajournals.org/doi/full/10.1161/01.res.87.5.e1?url_ver=Z39.88
-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed

6. https://www.ahajournals.org/journal/hyp

7. https://www.nature.com/articles/nature02145

8. Schematic overview of the renin-angiotensin system.
https://www.researchgate.net/figure/Schematic-overview-of-the-renin-angiotensin-system_fig1_265250938

9. Schematic overview of the renin-angiotensin system
with ACE2 as receptor for corona virus (COV-2)
Adapted fromhttps://www.researchgate.net/figure/Schematic-overview-of-the-renin-angiotensin-system_fig1_265250938

10. The domain structure and membrane topology of
somatic ACE, ACE2, and collectrin
https://www.hindawi.com/journals/ijhy/2012/307315/
Molecular weight ACE 136,000 Da
Molecular weight ACE2 92,000 Da

11. Schematic diagram of the role of ACE and ACE2
in the renin–angiotensin system
https://www.semanticscholar.org/paper/Trilogy-of-ACE2%3A-a-peptidase-in-the-
system%2C-a-SARS-Kuba-Imai/c4b3097c2bf40d1c75ca5e8c2b334742cd836545
10 amino acids
8 amino acids
7 amino acids
Molecular weight ACE 136,000 Da
Molecular weight ACE2 92,000 Da

12. Opposing arms of the renin angiotensin system (2014)
Adapted from https://www.frontiersin.org/articles/10.3389/fphys.2014.00227/full
receptor

13. Function of ACE2 as SARS-COV-2-rceptor
https://www.semanticscholar.org/paper/Trilogy-of-ACE2%3A-a-peptidase-in-the-
system%2C-a-SARS-Kuba-Imai/c4b3097c2bf40d1c75ca5e8c2b334742cd836545/figure/2

14. Micrograph of SARS-COV-2 virions (red) isolated from a patient
https://en.wikipedia.org/wiki/Severe_acute_respiratory_syndrome_coronavirus_2

15. ANATOMY OF A CORONA VIRUS
▪ A coronavirus particle consists of four structural proteins:
▪ the nucleocapsid,
▪ envelope,
▪ membrane and
▪ spike.
▪ The nucleocapsid forms the genetic core, encapsulated in a
ball formed by the envelope and membrane proteins.
▪ The spike protein forms club-shaped protrusions that stick
out all over the ball, resembling a crown or the sun’s corona.
▪ These protrusions bind to receptors on host cells.
▪ RNA sequence approximately 30,000 bases in length
https://www.scientificamerican.com/article/how-coronaviruses-cause-infection-from-colds-to-deadly-pneumonia1/
50-200 nm

16. Anatomy of SARS-CoV-2 and spike protein
https://www.livescience.com/how-coronavirus-infects-cells.html
Intact S protein: 520 kDa
https://jvi.asm.org/content/80/14/6794

17. Angiotensin converting enzyme in plasma membrane
Angiotensin converting enzyme (ACE)
Angiotensin converting enzyme 2 (ACE-2)
Phospholipid bilayer

18. Angiotensin converting enzyme 2 receptor

19. Distribution of ACE2 in human tissues
https://en.wikipedia.org/wiki/Angiotensin-converting_enzyme_2

20. Portal of entry of corona virus into a vulnerable cell
https://www.nih.gov/news-events/nih-research-matters/novel-
coronavirus-structure-reveals-targets-vaccines-treatments
spike protein
receptor

21. https://www.nytimes.com/interactive/2020/03/11/science/how-coronavirus-hijacks-your-cells.html

22. https://www.nytimes.com/interactive/2020/03/11/science/how-coronavirus-hijacks-your-cells.html

23. https://www.nytimes.com/interactive/2020/03/11/science/how-coronavirus-hijacks-your-cells.html

24. https://www.nytimes.com/interactive/2020/03/11/science/how-coronavirus-hijacks-your-cells.html

25. The Incubation Period of COVID-19 from
Publicly Reported Confirmed Cases
https://www.doximity.com/collections/ea6646ec-9e7c-4d76-aaf0-35aa4fa0d2d9?_eda_link_uuid=e1ef76f9-
c23d-4703-9f41-97548153c7ba&_r=1&_ref=digest&_t=7685900&clicked=true&featured_item=docnews-
articles%2F7986760&position=1&source=email_doc_news%3A%3Ainterest_digest&utm_campaign=doc_news%
3A%3Ainterest_digest&utm_source=doximity-eda&utm_medium=email

26. Confirmed cases of coronavirus disease (COVID-19) in Top 10 countries
March 23, 2020 3.00 PM
https://google.org/crisisresponse/covid19-map

27. First Case of 2019 Novel Coronavirus in the United States
35 year old man who returned from China presented with cough and fever and
later recovered with iv remdesivir
https://www.nejm.org/doi/full/10.1056/NEJMoa2001191
I/V remdesivir

29. First Case of 2019 Novel Coronavirus in the United States:
Tests for Coronavirus (2019-nCOV)
https://www.nejm.org/doi/full/10.1056/NEJMoa2001191

30. Inflammatory markers in patients with COVID-19 pneumonia
▪ 80.0% of 30 patients showed decreased
lymphocyte count
▪ 66.7% of 27 patients showed increased ESR
▪ 100% of 27 patients showed elevated hs-CRP
▪ 100% of 175 patients showed hypokalemia
▪ Interpretation: acute inflammation with weak
immune response and over-reactive renin-
angiotensin system.
https://www.ajronline.org/doi/full/10.2214/AJR.20.22975
49-year-old man. CT image obtained on day 7 after
onset of symptoms shows multiple lesions involving
multiple lobes of bilateral lungs.

31. Complications of COVID-19 in China
▪ As of 1 March 2020, a total of 79,968 confirmed cases in mainland China :
▪ 14,475 (18.1%) with severe illness
▪ 2873 deaths (3.5%)
▪ Complications include:
▪ acute respiratory distress syndrome (ARDS)
▪ arrhythmia
▪ shock
▪ acute kidney injury
▪ acute cardiac injury
▪ liver dysfunction
▪ secondary infection
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7068984/

32. Complications of COVID-19 in United States
▪ As of March 23, 2020, a total of 42,161 confirmed cases in United States:
▪ 508 deaths (0.12%)
▪ 187 recovered (0.4%)
▪ Complications (in China) include:
▪ acute respiratory distress syndrome (ARDS)
▪ arrhythmia
▪ shock
▪ acute kidney injury
▪ acute cardiac injury
▪ liver dysfunction
▪ secondary infection
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7068984/

33. Host immune response
▪ Virus-cell interactions produce a diverse set of immune mediators against
the invading virus .
▪ Plasma cytokines and chemokines found in COVID-19 patients include:
▪ IL-1, IL-2, IL-4, IL-7, IL-10, IL-12, IL-13, IL-17, GCSF, macrophage colony-stimulating factor
(MCSF), IP-10, MCP-1, MIP-1α, hepatocyte growth factor (HGF), IFN-γ and TNF-α.
▪ A pathological report of COVID-19 pneumonia indicated that COVID-19
caused an inflammatory response in the lower airway triggering a series
of immune responses which led to the production of cytokine storm in the
body.
▪ All COVID-19 have been shown to have elevated serum ferritin, which had
been used as a diagnostic test for cytokine storm.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7068984/

34. FDA Approves First Rapid COVID-19 Test
▪ The Food and Drug Administration has approved the first rapid point-of-care
COVID-19 test, that can deliver results in about 45 minutes
▪ The agency has approved about a dozen other COVID-19 tests in response
to the public health emergency caused by the coronavirus pandemic

35. Potential Therapeutic Targets on COV-2 and Host cell
soap, chlorine, alcohol
ACE2 blocker
hydroxychloroquine
^^^^^ antiviral
Remdesivir
Targets on Life Cycle of a COV-2

36. How SARS-CoV-2 enters the cell ?

37. SARS-CoV-2 docks on ACE-2 Receptor

38. Chloroquine blocks ACE-2 Receptor preventing
entry of SARS-CoV-2

39. Potential Pipeline Medications May Help Patients With
Novel Coronavirus 2020
▪ Remdesivir nucleoside inhibitor
▪ Hydroxychloroquine anti-malarial. ACE-2 blocker
▪ Umifenovir antiviral activity against several coronavirus
▪ Baloxavir antiviral for influenza in the US
▪ Favipiravir antiviral against COVID-19
▪ Lopinavir and Ritonavir combination of the antiretrovirals for HIV virus.
▪ Corticosteroids treatment of severe coronavirus infections
https://www.pharmacytimes.com/news/potential-pipeline-medications-for-the-coronavirus

40. WHO published an overview of the potential therapeutic
candidates for the treatment of COVID-19 in February 2020
▪ 76 regimens have been proposed (as of February 17, 2020) for the treatment of
patients infected with the virus.
▪ Thirty-eight of these candidates are in the preclinical state with minimal information
available on their proposed mechanism, uses, doses routes, or planned trials.
▪ Sixteen of the remaining regimens contain an interferon-based product.
▪ The rest include a variety of antimicrobials, corticosteroids, convalescent plasma,
and biologics.
▪ No COV-2 vaccine is available at this time.
https://www.pharmacytimes.com/news/potential-pipeline-medications-for-the-coronavirus

41. WHO launches global megatrial of the four most promising
coronavirus treatments
▪ On March 21st 2020, the World Health Organization (WHO) announced a large global
trial, called SOLIDARITY, to find out whether any can treat infections with the new
coronavirus for the dangerous respiratory disease.
1. Remdesivir
2. Chloroquine and hydroxychloroquine
3. Combination of Ritonavir and lopinavir
4. Combination of Ritonavir/lopinavir and interferon-beta
https://www.sciencemag.org/news/2020/03/who-launches-
global-megatrial-four-most-promising-coronavirus-treatments

42. Cytokine storm treatment
Drugs for the treatment of cytokine storm can be classified into the following types:
▪ OX40 IG
▪ ACE inhibitors
▪ Angiotensin II Receptor Blockers
▪ Corticosteroids
▪ Gemfibrozil
▪ Free radical scavengers
▪ TNF-alpha blockers
▪ Drugs targeting IL-1, IL-6, IL-18
▪ interferon-gamma
https://www.sinobiological.com/resource/cytokines/cytokine-storm
≈ 150 cytokines

43. Summary
▪ The concept of entry of COV-2 into susceptible cells comes in steps.
▪ The first step is the discovery of the plasma angiotensin converting
enzyme in 1956.
▪ The second step is the discovery of angiotensin converting enzyme
(ACE) in the lungs in 1967.
▪ The third step is the discovery of angiotensin converting enzyme 2
(ACE2) in alveolar epithelium and vascular endothelium in 2000.
▪ The fourth step is the discovery of ACE2 as a receptor for SARS-
COV-2 in 2020.
▪ Blockade of ACE2 by chloroquine or hydroxychloroquine becomes an
idea for the treatment of COVID-19 (corona virus disease 2019).

44. ANY QUESTION?
Please contact
Kevin KF Ng, MD, PhD
Email: kevinng68@gmail.com