Introduction: The angiotensin-converting enzyme 2 (ACE2)
as well as the transmembrane protease serine type 2 (TM
PRSS2) have been found to play roles in cell entry for severe
acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the
virus causing coronavirus disease 2019 (COVID-19). SARS
CoV-2 infection risk and severity of COVID-19 might be indi
cated by the expression of ACE2 and TMPRSS2 in the lung.
Methods: A high-salt diet rat model and renin-angiotensin
aldosterone system (RAAS) blockade were used to test
whether these factors affect ACE2 and TMPRSS2 expression
in the lung. A normal (0.3% NaCl), a medium (2% NaCl), or a
high (8% NaCl) salt diet was fed to rats for 12 weeks, along
with enalapril or telmisartan, before examining the lung for
histopathological alteration. Using immunofluorescence
and qRT-PCR, the localization as well as mRNA expression of
ACE2 and TMPRSS2 were investigated. Results: The findings
provide evidence that both TMPRSS2 and ACE2 are highly
expressed in bronchial epithelial cells as well as ACE2 was
also expressed in alveolar type 2 cells. High-salt diet expo
sure in rats leads to elevated ACE2 expression on protein lev
el. Treatment with RAAS blockers had no effect on lung tis
sue expression of ACE2 and TMPRSS2. Conclusions: These
findings offer biological support regarding the safety of
these drugs that are often prescribed to COVID-19 patients
with cardiovascular comorbidity. High salt intake, on the
other hand, might adversely affect COVID-19 outcome. Our
preclinical data should stimulate clinical studies addressing
this point of concern.