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Nan Hultgren, Barry Burgess, David S Williams; SARS-CoV2 Infection damages RPE Function and Suvival. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2984.
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SARS-CoV2 infection affect a wide range of tissues in the human body. Viral presence has been reported in the ocular environment and alterations in the retina by Optical Coherence Tomography have been reported in COVID patients. However, it is unclear if and how retinal cells are directly affected by the virus. Using cell culture models along with pseudotyped virus, we tested the hypothesis that the presence of SARS-CoV2 negatively affects several critical functions of the retinal pigmented epithelial (RPE) cells, and could have long-term effects on retinal health.
Polarized human ARPE-19 cells and wild type iPS-RPE cells were cultured using recently published protocols from our lab. Two main steps of the viral life cycle were modeled: 1) viral entry, using lentivirus pseudotyped with SARS-CoV2 Spike protein; 2) viral replication, by testing expression of SARS-CoV2 protein E and 3a, following lentiviral transduction. Cells were maintained on Trans-well filters for up to 6-weeks. Barrier function was evaluated by measuring trans-epithelial resistance (TER) and immunofluorescence labeling of tight-junction proteins. Phagocytic capacity was evaluated by testing ingestion and degradation of photoreceptor outer segments (POSs). General RPE morphology was evaluated using transmission electron microscopy. Changes in gene expression was examined by qPCR and Western Blot analysis.
We confirmed a previous finding that RPE cells express the receptor ACE2 and protease TMPRSS2 necessary for viral entry. Using Spike-protein pseudotyped lentivirus, we found that human RPE, but not fibroblasts, can be infected via a Spike-ACE2 mediated mechanism. This specific mechanism of viral-entry alone (as opposed to VSV-mediated entry) caused significant changes in cell physiology, including alterations in cell junction and protein trafficking. Using expression of lentiviral SARS-CoV2 components, we found that the presence of protein E induced expression of several pro-inflammatory cytokines in the RPE cell, while protein 3a activated apoptosis in the RPE cells. These data suggest that SARS-CoV2 can infect and cause serious damage to RPE function and survival.
Damage to the RPE cells often precedes photoreceptor degeneration. Given our findings that SARS-CoV2 can cause severe damage to the function and survival of RPE cells, COVID19 patients may be at increased risk of long-term RPE pathogenesis and associated visual impairment.
This is a 2021 ARVO Annual Meeting abstract.
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