What are ACE2 receptors?
News reports frequently state that SARS-CoV-2, the virus that causes the COVID-19 pandemic, uses its spike protein to bind to angiotensin-converting enzyme 2 (ACE2) receptors on human cells to cause infection. But what are these receptors, and what role do they play in the body?
First, receptors are molecular structures of cells to which other molecules such as hormones, neurotransmitters, toxins or drugs specifically bind to produce the expected response.
The renin-angiotensin system (RAS) comprises a series of reactions that occur in the body to regulate blood pressure and electrolyte balance. Angiotensin-converting enzyme 2 (ACE2) is a crucial substance in this blood pressure regulatory system.
ACE2 is found in various tissues of the body, such as the nervous system, myocardium, respiratory tract, kidneys, and vascular system. ACE2 converts angiotensin I to angiotensin II, which causes vasoconstriction (narrowing of blood vessels), thereby raising blood pressure. Drugs that inhibit the action of ACE2 are effective in relaxing veins and arteries and lowering blood pressure. These drugs are known as angiotensin-converting enzyme (ACE) inhibitors.
It is known that the SARS-CoV-2 virus, like other coronaviruses, enters lung cells by binding to the ACE2 receptor. This could be the reason why, in general, greater disease severity is observed in hypertensive patients, smokers, and men, who have higher concentrations of ACE2 in their blood.
References
- Soria Arcos F et al. Controversy regarding ACE inhibitors /ARBs in COVID-19 Rev Esp Cardiol. 2020 Jun; 73(6): 516.
- Salazar M et al, COVID-19, hypertension and cardiovascular disease . Hypertens Risk Vasc . 2020 Jun 18
- Cai G et al. Tobacco smoking increases the lung gene expression of ACE2, the receptor of SARS-CoV-2. Am J Respir Crit Care Med . 2020 Apr 24