New Study Reveals COVID-19’s Hidden Retinal Risks
An experimental study in mice shows that SARS-CoV-2 infection can damage the retina, with long-term implications for vision. The findings, published in PNAS Nexus, suggest that COVID-19 may play a role in age-related macular degeneration (AMD) by triggering inflammation.
As the SARS-CoV-2 coronavirus continues to evolve and infect the global population, many individuals are likely to suffer from post-acute sequelae of SARS-CoV-2 infection (PASC). Manifestations of PASC include vision symptoms, but little is known about the ability of SARS-CoV-2 to infect and impact the retinal cells.
David Williams and Nan Hultgren, University of California, Los Angeles (UCLA), led a study in which transgenic mice that express human SARS-CoV-2 receptor ACE2 were infected with the virus, and then their retinas and lungs were examined five days later.
SARS-CoV-2 was found in the retinal pigment epithelium. There was no relationship between the viral load in the eyes and the lungs, suggesting significant retinal infection can occur even in the absence of severe respiratory disease. Experiments in cultured human retinal pigment epithelium cells confirmed the result.
Widespread inflammation across the retinal pigment epithelium
The presence of toxic viral proteins caused retinal pigment epithelium cells to change shape and made the cells more sensitive to oxidative stress. These changes reduced the ability of retinal epithelial cells to maintain the blood-retina barrier and to recycle photoreceptor components.
It also caused complement activation and production of cytokines and chemokines, resulting in an inflammatory response that spread across the RPE layer. This inflammatory signature has similarities to that associated with the onset of age-related macular degeneration (AMD), resulting from RPE pathology that eventually leads to photoreceptor cell loss.
The findings of the study suggest that post-acute sequelae of SARS-CoV-2 infection of the RPE may have long-term implications for vision, perhaps comparable to the increased occurrence of AMD found among individuals infected by HIV, but with greater public health consequences due to the much larger number of SARS-CoV-2 infections.
Reference: Productive infection of the retinal pigment epithelium by SARS-CoV-2: Initial effects and consideration of long-term consequences, PNAS Nexus, Volume 3, Issue 12, December 2024, pgae500, https://doi.org/10.1093/pnasnexus/pgae500
Source: PNASNEXUS