Abstract
Purpose :
To analyse the expression of human host cell specific attachment, entry and anti-viral response genes to SARS-CoV-2 in various layers of human eyes. To investigate if such host factors may be modulated by eye drops for prophylaxis.
Methods :
Donor eyes from healthy controls(n=5), COVID-19 infected(n=5) and COVID-19 recovered(n=2) were studied by immunofluorescence or dissected and analysed for gene expression. Expression of ACE2, TMPRSS2, CTSL, MxA, type-1, 2 and 3 IFNs(interferons) were assessed. Ocular surface impression cytology(IC) and nasal swabs from controls(n=12) before and after trehalose eye drops; and IC from dry eye disease(DED) patients(n=7) and controls(n=8) obtained during pre-pandemic period was used to for gene expression analysis.
Results :
Gene expression and immunofluorescence revealed significantly higher distribution of ACE2, TMPRSS2, CTSL and antiviral interferon in ocular surface layers compared to retinal and other layers. Increased ocular surface expression of ACE2 and TMPRSS2; along with decreased expression of type-1 IFNs(IFNalpha) was observed in COVID-19 infected eyes compared to healthy donors and COVID-19 recovered eyes. Similar host factor expression profile was observed from IC of pre-pandemic DED patients. Prophylactic use of trehalose eye drops significantly enhanced Type-1 IFN while reducing ACE2 in ocular surface and nasolacrimal ducts of volunteers which may possibly halt the entry & transmission of COVID-19 through ocular portals.
Conclusions :
Consistent expression of ACE2, TMPRSS2 and CTSL were observed in ocular surface tissues highlighting potential for SARS-CoV-2 adhesion & transmission. Pharmacological induction of IFNα-mediated antiviral MxA can possibly protect the ocular surface and nasolacrimal duct from respiratory viral infections.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.