Summary: Researchers have found that SARS-CoV-2 can penetrate the blood-retinal barrier, potentially causing long-term eye damage. The study found that the virus induces a hyperinflammatory response and cell death in the retina.
This advancement highlights the importance of monitoring the eye health of COVID-19 patients. The findings could lead to new treatments to prevent and treat eye complications related to COVID-19.
Highlights:
- Barrier Violation: SARS-CoV-2 can penetrate the blood-retinal barrier and infect the eyes.
- Inflammatory reaction: The virus causes hyperinflammation and cell death in the retina.
- Health Monitoring: Patients with COVID-19 should have their eyes checked for potential damage.
Source: University of Missouri-Columbia
The blood-retinal barrier is designed to protect our vision from infections by preventing microbial pathogens from reaching the retina where they could trigger an inflammatory response that can lead to vision loss.
But researchers at the University of Missouri School of Medicine have found that the virus that causes COVID-19 can break down this protective barrier in the retina, with potential long-term consequences for the eyes.
Pawan Kumar Singh, PhD, assistant professor of ophthalmology, leads a team researching new ways to prevent and treat infectious eye diseases.
Using a humanized ACE2 mouse model, the team discovered that SARS-CoV-2, the virus that causes COVID-19, can infect the inside of the eyes even when the virus does not enter the body through the surface of the eyes.
Instead, they found that when viruses enter the body through inhalation, they not only infect organs like the lungs, but also reach highly protected organs like the eyes through the blood-retinal barrier by infecting cells. lining this barrier.
“This finding is important as we improve our understanding of the long-term effects of SARS-CoV-2 infection,” Singh said.
“Previously, researchers primarily focused on exposure of the virus to the ocular surface. However, our results reveal that SARS-CoV-2 not only reaches the eye during systemic infection, but induces a hyperinflammatory response in the retina and causes cell death in the blood-retinal barrier.
“The longer viral remnants remain in the eye, the risk of damage to the retina and visual function increases. »
Singh also found that prolonged presence of the SARS-CoV-2 spike antigen can cause retinal microaneurysm, retinal artery and vein occlusion, and vascular leakage.
“For those who have been diagnosed with COVID-19, we recommend asking your ophthalmologist to check for signs of pathological changes in the retina,” Singh said.
“Even those who were asymptomatic could suffer eye damage over time due to complications associated with COVID-19. »
While viruses and bacteria have been shown to cross the blood-retinal barrier in immunocompromised people, this research is the first to suggest that the virus that causes COVID-19 could cross the barrier even in otherwise individuals. healthy, leading to an infection manifesting itself. inside the eye itself.
Immunocompromised patients or those with hypertension or diabetes may experience worse outcomes if they are not diagnosed for ocular symptoms associated with COVID-19.
“Now that we know the risk of COVID-19 to the retina, our goal is to better understand the cellular and molecular mechanisms by which this virus crosses the blood-retinal barrier and the associated pathological consequences in the hope of illuminating the development of therapies to prevent and treat COVID-19-induced ocular complications before a patient’s vision is compromised,” Singh said.
In addition to Singh, the University of Missouri School of Medicine research team included Vaishnavi Balendiran, MD, vitreoretinal surgery researcher; Monu Monu and Faraz Ahmad, postdoctoral fellows in the Department of Ophthalmology; and Rachel M. Olson, PhD, scientific director of the College of Veterinary Medicine’s Infectious Disease Research Laboratory.
Funding: This research was supported by funding from the University of Missouri and National Institutes of Health (NIH)/National Eye Institute (NEI) grant R01EY032495.
About this research news on COVID-19 and visual neuroscience
Author: Rochita Ghosh
Source: University of Missouri-Columbia
Contact: Rochita Ghosh – University of Missouri-Columbia
Picture: Image is credited to Neuroscience News
Original research: Free access.
“SARS-CoV-2 infects cells lining the blood-retinal barrier and induces a hyperinflammatory immune response in the retina via systemic exposure” by Pawan Kumar Singh et al. PLOS Pathogens
Abstract
SARS-CoV-2 infects cells lining the blood-retinal barrier and induces a hyperinflammatory immune response in the retina via systemic exposure
SARS-CoV-2 has been shown to cause extensive ocular abnormalities and visual impairment in COVID-19 patients. However, the understanding of SARS-CoV-2 in ocular transmission, tropism and associated pathologies is limited.
The presence of viral RNA in corneal/conjunctival tissues and tears, as well as the presence of viral entry receptors on the ocular surface, has led to speculation that the eye may serve as a potential route of transmission of the SARS-CoV-2.
Here, we investigated the interaction of SARS-CoV-2 with cells lining the blood-retinal barrier (BRB) and the role of the eye in its transmission and tropism.
The results of our study suggest that ocular exposure to SARS-CoV-2 does not cause lung infection or moribund disease in K18-hACE2 mice despite the prolonged presence of viral remnants in various ocular tissues.
In contrast, intranasal exposure not only resulted in the presence of SARS-CoV-2 Spike (S) protein in different ocular tissues but also induced a hyperinflammatory immune response in the retina.
Additionally, long-term exposure to viral protein S caused microaneurysm, retinal pigmented epithelium (RPE) mottling, retinal atrophy, and vein occlusion in mouse eyes.
Notably, cells lining the BRB, the outer barrier, the RPE, and the inner barrier, the retinal vascular endothelium, were highly permissive to SARS-CoV-2 replication.
Unexpectedly, primary human corneal epithelial cells were relatively resistant to SARS-CoV-2 infection. Cells lining the BRB showed induced expression of viral entry receptors and increased susceptibility to SARS-CoV-2-induced cell death.
Furthermore, hyperglycemic conditions enhanced viral entry receptor expression, infectivity, and susceptibility to SARS-CoV-2-induced cell death in BRB cells, confirming the increased pathological manifestations reported in populations comorbidities.
Collectively, our study provides the first evidence of ocular tropism of SARS-CoV-2 via cells lining the BRB and that the virus can infect the retina through systemic permeation and induce retinal inflammation.
News Source : neurosciencenews.com
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