The role of ACE-2
ACE-2 is a type I transmembrane metallocarboxyptidase with ACE homology
which is an enzyme known to be a key player in the renin-angiotensin
system (RAS) and a target of several drugs for the treatment of high
blood pressure. The expression of ACE and ACE-2 is not similar in human
tissue. ACE-2 is mainly expressed in vascular endothelial cells, renal
tubular epithelium, Leydig cells in the testicles and lung epithelial
cells. ACE-2 is a functional receptor of SARS-CoV and SARS-Cov-2 for
entry into host cells and subsequent viral replication. Viral entry into
respiratory tract cells is a critical step that causes lung injury. Men
are thought to be at greater risk of contracting the virus than women
because there is a high concentration of ACE-2 in Leydig cells. However,
the role of ACE-2 in the pathophysiology of SARS-Cov-2 infection is much
more complex than described, since ACE-2 is not only the receptor of the
virus entry, in fact the function of ACE-2 in infected lung tissue is
currently not very clear, especially in the two most serious stages such
as the second and third. where it seems to have a protective role. These
new findings could have a great impact on the development of effective
therapies for the virus, or to make appropriate use of drugs already on
the market that modulate the RAS system to better manage the infection.
An interesting line of research is that of anti-ACE-2 antibodies that
could be used to block the binding of SARS-CoV-2 to the receptor.
(Figure 1). Another possibility that we describe, is the usefulness that
a block upstream of the RAS system could have compared to a block
downstream at a specific stage of the infection. (7-8-9)