Post by Nadica (She/Her) on Jun 12, 2024 0:57:13 GMT
fortune.com/well/article/covid-eye-health-retinal-damage/
SARS-CoV-2 infects cells lining the blood-retinal barrier and induces a hyperinflammatory immune response in the retina via systemic exposure - Published April 10, 2024
Abstract
SARS-CoV-2 has been shown to cause wide-ranging ocular abnormalities and vision impairment in COVID-19 patients. However, there is limited understanding of SARS-CoV-2 in ocular transmission, tropism, and associated pathologies. The presence of viral RNA in corneal/conjunctival tissue and tears, along with the evidence of viral entry receptors on the ocular surface, has led to speculation that the eye may serve as a potential route of SARS-CoV-2 transmission. 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 from our study suggest that SARS-CoV-2 ocular exposure does not cause lung infection and moribund illness in K18-hACE2 mice despite the extended presence of viral remnants in various ocular tissues. In contrast, intranasal exposure not only resulted in SARS-CoV-2 spike (S) protein presence in different ocular tissues but also induces a hyperinflammatory immune response in the retina. Additionally, the long-term exposure to viral S-protein caused microaneurysm, retinal pigmented epithelium (RPE) mottling, retinal atrophy, and vein occlusion in mouse eyes. Notably, cells lining the BRB, the outer barrier, RPE, and the inner barrier, retinal vascular endothelium, were highly permissive to SARS-CoV-2 replication. Unexpectedly, primary human corneal epithelial cells were comparatively resistant to SARS-CoV-2 infection. The cells lining the BRB showed induced expression of viral entry receptors and increased susceptibility towards SARS-CoV-2-induced cell death. Furthermore, hyperglycemic conditions enhanced the viral entry receptor expression, infectivity, and susceptibility of SARS-CoV-2-induced cell death in the BRB cells, confirming the reported heightened pathological manifestations in comorbid populations. Collectively, our study provides the first evidence of SARS-CoV-2 ocular tropism via cells lining the BRB and that the virus can infect the retina via systemic permeation and induce retinal inflammation.
Author summary
SARS-CoV-2 is known to cause several ocular manifestations in COVID-19 patients; however, the role of eyes in viral transmission and ocular tissue tropism remains elusive. The presence of viral remnants in various ocular tissues and fluids from COVID-19 patients has led to an assumption that SARS-CoV-2 may be transmitted through the eyes. Here, we show that SARS-CoV-2 ocular tropism is through cells lining the BRB. SARS-CoV-2 not only infects the various parts of the eye via systemic exposure but also induces a hyperinflammatory immune and antiviral response in the retina. Unexpectedly, the corneal epithelium was found to be resistant to SARS-CoV-2 infection, and ocular exposure of SARS-CoV-2 failed to cause lung pathology and moribund illness. Cells lining the BRB showed induced expression of viral entry receptors and enhanced susceptibility towards SARS-CoV-2-induced cell death, which is further potentiated with comorbidities such as hyperglycemia. Our findings from this study shed light on the role of BRB in SARS-CoV-2 ocular tropism and the role of eyes in viral transmission.
FROM NEWS ARTICLE:
If you’ve had COVID-19, you may want to have your eyes checked. SARS-CoV-2, the coronavirus that causes the disease, can infect the inside of your eyes, according to research published in April in the journal PLOS Pathogens. This holds true even if the virus didn’t enter your body through the surface of your eyes.
Pawan Kumar Singh, PhD, an assistant professor of ophthalmology at the University of Missouri School of Medicine, led a team of researchers who found that inhaled viruses can reach highly protected organs such as the eyes, potentially causing long-term damage. SARS-CoV-2 does so by breaching the blood-retinal barrier, layers of cells that shield the retina, the part of your eye that senses light, from microbial pathogens.
“Earlier, researchers were primarily focused on the ocular surface exposure of the virus,” Singh said in a news release. “However, our findings 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.”
Using a humanized mice model, Singh and his team showed that the prolonged presence of SARS-CoV-2 spike proteins can cause problems such as:
Retinal artery and vein occlusion: An “eye stroke” that happens when a retinal blood vessel is blocked
Retinal microaneurysm: The swelling and leaking of tiny blood vessels called capillaries in the back of the eye, often seen in people with diabetes
Vascular leakage: Leaky blood vessels in the eyes
“For those who have been diagnosed with COVID-19, we recommend you ask your ophthalmologist to check for signs of pathological changes to the retina,” Singh said. “Even those who were asymptomatic could suffer from damage in the eyes over time because of COVID-19-associated complications.”
What are symptoms of retinal disease?
The following symptoms may indicate retinal disease, according to the National Eye Institute:
Blindness
Blurry or wavy vision
“Curtain” or shadow over your field of vision
Dull color vision
Flashes of light in one or both eyes
Floating spots in your vision
Loss of central vision
Sudden increase in floaters
Sudden vision loss
If you don’t have an ophthalmologist, your primary care physician can refer you to one and help determine the best course of treatment.
Though the blood-retinal barrier of people with compromised immune systems is known to be susceptible to bacteria and viruses, MU claims Singh’s study is the first to suggest SARS-CoV-2 can infect that of otherwise healthy people. That said, immunocompromised people and those with diabetes or high blood pressure may face more severe COVID-related eye health issues if left untreated.
“Now that we know the risk of COVID-19 to the retina, our goal is to better understand the cellular and molecular mechanisms of how this virus breaches the blood-retinal barrier and associated pathological consequences in hopes of informing development of therapies to prevent and treat COVID-19-induced eye complications before a patient’s vision is compromised,” Singh said.
Keywords: Long Covid, Vision, Retina, Aneurysm, Stroke
SARS-CoV-2 infects cells lining the blood-retinal barrier and induces a hyperinflammatory immune response in the retina via systemic exposure - Published April 10, 2024
Abstract
SARS-CoV-2 has been shown to cause wide-ranging ocular abnormalities and vision impairment in COVID-19 patients. However, there is limited understanding of SARS-CoV-2 in ocular transmission, tropism, and associated pathologies. The presence of viral RNA in corneal/conjunctival tissue and tears, along with the evidence of viral entry receptors on the ocular surface, has led to speculation that the eye may serve as a potential route of SARS-CoV-2 transmission. 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 from our study suggest that SARS-CoV-2 ocular exposure does not cause lung infection and moribund illness in K18-hACE2 mice despite the extended presence of viral remnants in various ocular tissues. In contrast, intranasal exposure not only resulted in SARS-CoV-2 spike (S) protein presence in different ocular tissues but also induces a hyperinflammatory immune response in the retina. Additionally, the long-term exposure to viral S-protein caused microaneurysm, retinal pigmented epithelium (RPE) mottling, retinal atrophy, and vein occlusion in mouse eyes. Notably, cells lining the BRB, the outer barrier, RPE, and the inner barrier, retinal vascular endothelium, were highly permissive to SARS-CoV-2 replication. Unexpectedly, primary human corneal epithelial cells were comparatively resistant to SARS-CoV-2 infection. The cells lining the BRB showed induced expression of viral entry receptors and increased susceptibility towards SARS-CoV-2-induced cell death. Furthermore, hyperglycemic conditions enhanced the viral entry receptor expression, infectivity, and susceptibility of SARS-CoV-2-induced cell death in the BRB cells, confirming the reported heightened pathological manifestations in comorbid populations. Collectively, our study provides the first evidence of SARS-CoV-2 ocular tropism via cells lining the BRB and that the virus can infect the retina via systemic permeation and induce retinal inflammation.
Author summary
SARS-CoV-2 is known to cause several ocular manifestations in COVID-19 patients; however, the role of eyes in viral transmission and ocular tissue tropism remains elusive. The presence of viral remnants in various ocular tissues and fluids from COVID-19 patients has led to an assumption that SARS-CoV-2 may be transmitted through the eyes. Here, we show that SARS-CoV-2 ocular tropism is through cells lining the BRB. SARS-CoV-2 not only infects the various parts of the eye via systemic exposure but also induces a hyperinflammatory immune and antiviral response in the retina. Unexpectedly, the corneal epithelium was found to be resistant to SARS-CoV-2 infection, and ocular exposure of SARS-CoV-2 failed to cause lung pathology and moribund illness. Cells lining the BRB showed induced expression of viral entry receptors and enhanced susceptibility towards SARS-CoV-2-induced cell death, which is further potentiated with comorbidities such as hyperglycemia. Our findings from this study shed light on the role of BRB in SARS-CoV-2 ocular tropism and the role of eyes in viral transmission.
FROM NEWS ARTICLE:
If you’ve had COVID-19, you may want to have your eyes checked. SARS-CoV-2, the coronavirus that causes the disease, can infect the inside of your eyes, according to research published in April in the journal PLOS Pathogens. This holds true even if the virus didn’t enter your body through the surface of your eyes.
Pawan Kumar Singh, PhD, an assistant professor of ophthalmology at the University of Missouri School of Medicine, led a team of researchers who found that inhaled viruses can reach highly protected organs such as the eyes, potentially causing long-term damage. SARS-CoV-2 does so by breaching the blood-retinal barrier, layers of cells that shield the retina, the part of your eye that senses light, from microbial pathogens.
“Earlier, researchers were primarily focused on the ocular surface exposure of the virus,” Singh said in a news release. “However, our findings 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.”
Using a humanized mice model, Singh and his team showed that the prolonged presence of SARS-CoV-2 spike proteins can cause problems such as:
Retinal artery and vein occlusion: An “eye stroke” that happens when a retinal blood vessel is blocked
Retinal microaneurysm: The swelling and leaking of tiny blood vessels called capillaries in the back of the eye, often seen in people with diabetes
Vascular leakage: Leaky blood vessels in the eyes
“For those who have been diagnosed with COVID-19, we recommend you ask your ophthalmologist to check for signs of pathological changes to the retina,” Singh said. “Even those who were asymptomatic could suffer from damage in the eyes over time because of COVID-19-associated complications.”
What are symptoms of retinal disease?
The following symptoms may indicate retinal disease, according to the National Eye Institute:
Blindness
Blurry or wavy vision
“Curtain” or shadow over your field of vision
Dull color vision
Flashes of light in one or both eyes
Floating spots in your vision
Loss of central vision
Sudden increase in floaters
Sudden vision loss
If you don’t have an ophthalmologist, your primary care physician can refer you to one and help determine the best course of treatment.
Though the blood-retinal barrier of people with compromised immune systems is known to be susceptible to bacteria and viruses, MU claims Singh’s study is the first to suggest SARS-CoV-2 can infect that of otherwise healthy people. That said, immunocompromised people and those with diabetes or high blood pressure may face more severe COVID-related eye health issues if left untreated.
“Now that we know the risk of COVID-19 to the retina, our goal is to better understand the cellular and molecular mechanisms of how this virus breaches the blood-retinal barrier and associated pathological consequences in hopes of informing development of therapies to prevent and treat COVID-19-induced eye complications before a patient’s vision is compromised,” Singh said.
Keywords: Long Covid, Vision, Retina, Aneurysm, Stroke