A study by German scientists has shown that the SARS-CoV-2 coronavirus penetrates into the eyes and infects photoreceptors and retinal ganglion cells. The authors note that this may be one of the reasons why some patients with postcovid syndrome complain of eye problems. The article is published on the preprint server bioRxiv.org .
The researchers exposed mature retinal organoids to SARS-CoV-2, and then for some time, observed the activity of the virus and the rate of its replication. The results showed that the coronavirus infects retinal cells, which was confirmed by a PCR test, and immunofluorescence recorded the presence of SARS-CoV-2 nucleocapsid proteins in retinal organoids.
A detailed analysis revealed viral plaques in the photoreceptors and ganglion cells of the retina, which, according to the authors, indicates the breeding sites of the virus. In addition, it was found that SARS-CoV-2 increases the expression of several inflammatory genes, including the cytokine interleukin 33 (IL33), which is associated with retinal inflammation and degradation of photoreceptors. Scientists believe that the increased expression of cytokines is a consequence of the body’s immune response to the SARS-CoV-2 virus.
The authors also found that antibodies blocking angiotensin-converting enzyme 2 (ACE2) — the receptor through which the virus enters cells – reduce infection of retinal cells. This means that for the prevention and treatment of this complication, no special means are needed for the eyes, but the same antiviral drugs or vaccines aimed at blocking the ACE2 receptor are suitable.
When the researchers injected anti-ACE 2 antibodies into infected retinal tissues, the number of SARS-CoV-2 nucleocapsid proteins in the cells decreased significantly.
Based on the study results, the authors concluded that SARS-CoV-2 infection in the eyes and virus replication in retinal cells depend on ACE2 receptors, and drugs targeting them may be effective in treating patients with COVID-19 with symptoms of retinal infection.