Angiotensin converting enzyme 2, or ACE2, is an exopeptidase expressed primarily by vascular endothelial cells in the heart and kidneys, but also in respiratory epithelia[1] and in the gastrointestinal tract. It is the target of several coronaviruses, including SARS-CoV and SARS-CoV-2.
2
Biochemistry
ACE2
is a transmembrane metallocarboxypeptidase composed of 805 amino acids. Zinc
and chloride ions act as cofactors. The extracellular region consists of two
domains, a zinc metallopeptidase domain and a C-terminal collectrin homology
domain. The enzyme exhibits homology to angiotensin converting enzyme (ACE).
ACE2
is encoded by the ACE2 gene on the X chromosome (gene locus Xp22.2). In
addition to being expressed as a transmembrane protein, a soluble form exists
in serum.
3
Function
ACE2
cleaves angiotensin II into angiotensin (1-7), which has anti-inflammatory and
lung protective effects via MAS and AT2 receptors.
4
Clinical
4.1
Infectiology
ACE2
serves as a major entry point for some coronaviruses. The pathogens bind to the
enzyme with their spike proteins and enter the host cell by subsequent
fusion.[2] ACE2 expression increases from the pharynx to the alveoli. In
addition, SARS-CoV-2 is thought to have a higher affinity for ACE2 than
SARS-CoV. This would explain more rapid and effective viral transmission in the
COVID-19 pandemic.
Patients
taking drugs that increase the expression of ACE2 - for example, ACE inhibitors
or sartans, may be at higher risk of infection and should be switched to
calcium antagonists, according to some authors.[3][4] In contrast, the relevant
professional societies see no need for action at this time (4/2020).[5][6]
4.2
Pharmacology
Human
recombinant ACE2 (APN01) is an experimental therapeutic approach being tested
in acute respiratory distress syndrome (ARDS) and pulmonary hypertension.[7]
Furthermore, it is currently (2020) being tested for the treatment of
COVID-19.[8][9]
5
Sources
1. Hong
Peng Jia et al. ACE2 Receptor Expression and Severe Acute Respiratory Syndrome
Coronavirus Infection Depend on Differentiation of Human Airway Epithelia, J
Virol. 2005 Dec; 79(23): 14614-14621, retrieved 2020 Mar 27.
2. Kuba
K et al. A crucial role of angiotensin converting enzyme 2 (ACE2) in SARS
coronavirus-induced lung injury, Nat Med. 2005 Aug;11(8):875-9. epub 2005 Jul
10, retrieved 2020 Mar 30.
3. Zheng
Y et al. COVID-19 and the cardiovascular system, Nat Rev Cardiol (2020),
retrieved 30 Mar 2020.
4. Fang,
L. et al. Are patients with hypertension and diabetes mellitus at increased
risk for COVID-19 infection?, The Lancet, March 2020, retrieved 27/03/2020.
5. ESC
Position Statement of the ESC Council on Hypertension on ACE Inhibitors and
Angiotensin Receptor Blockers, retrieved March 27, 2020.
6. The
Renal Association, UK position statement for patients: novel corona virus
infection and the use of blood pressure medications. retrieved 03/27/2020.
7. Zhang
H, Baker A Recombinant human ACE2: acing out angiotensin II in ARDS therapy,
Crit Care. 2017 Dec 13;21(1):305, retrieved 2020 Mar 30.
8. Zhang
H et al. Angiotensin-converting enzyme 2 (ACE2) as a SARS-CoV-2 receptor:
molecular mechanisms and potential therapeutic target, Intensive Care Med. 2020
Apr;46(4):586-590, retrieved 2020 Mar 30.
9. clinicaltrials.gov
APN01, retrieved 03/30/2020.
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