The ocular surface is considered an important route for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. The expression level of the SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) is vital for viral infection. However, the regulation of ACE2 expression on the ocular surface is still unknown. We aimed to determine the change in ACE2 expression in inflamed corneal epithelium and explore potential drugs to reduce the expression of ACE2 on the ocular surface.
The expression of the SARS-CoV-2 receptors ACE2 and TMPRSS2 in human corneal epithelial cells (HCECs) was examined by qPCR and Western blotting. The altered expression of ACE2 in inflammatory corneal epithelium was evaluated in TNFα- and IL-1β-stimulated HCECs and inflamed mouse corneal epithelium, and the effect of resveratrol on ACE2 expression in HCECs was detected by immunofluorescence and Western blot analysis.
ACE2 and TMPRSS2 are expressed on the human corneal epithelial cells. ACE2 expression is upregulated in HCECs by stimulation with TNFα and IL-1β and inflamed mouse corneas, including dry eye and alkali-burned corneas. In addition, resveratrol attenuates the increased expression of ACE2 induced by TNFα in HCECs.
This study demonstrates that ACE2 is highly expressed in HCECs and can be upregulated by stimulation with inflammatory cytokines and inflamed mouse corneal epithelium. Resveratrol may be able to reduce the increased expression of ACE2 on the inflammatory ocular surface. Our work suggests that patients with an inflammatory ocular surface may display higher ACE2 expression, which increases the risk of SARS-CoV-2 infection.