According to a groundbreaking new study from the Peter Doherty Institute for Infection and Immunity, the cornea—the clear protective outer layer of the eye that helps us see—creates a sensitive and restricted immune response to combat infections without causing visual damage (Doherty Institute).
The study, which was published in Cell Reports, found that long-living memory T cells that track and combat viral infections are present in the cornea, contradicting the popular belief that T cells are not found in healthy corneas and thus expanding the knowledge of the eye’s immune response to infections.
The researchers studied cornea cells in Herpes Simplex Virus-infected mice using a multiphoton microscope, which offers live images of living, complete biological tissues.
Long-living memory T cells were created in the mice’s eyes to fight the infection, according to their findings. After the virus was eradicated, the memory T cells persisted in the cornea to prevent future infection.
Immune cells patrolled the cornea of healthy humans, according to advanced imaging—the first time cells have been shown moving in human eyes.
The cornea must stay transparent for humans to see because the retina receives focused light through the iris.
The existence of T cells in the corneas was formerly overlooked, as the eyes only create a mild immune response to avoid inflammation that would hinder the vision.
These findings have crucial implications for understanding how eyes ward against harmful infections, according to study author University of Melbourne Professor Scott Mueller, laboratory leader at the Doherty Institute.
Current understanding that T cells are not found in healthy corneas needs to be reconsidered, as our discovery shows tissue-resident memory T cells entering the cornea and remaining there for long periods. Our findings will improve the understanding of how to protect our eyes from infections that cause permanent blindness, such as Herpes Simplex Virus.”
Scott Mueller, Study Lead Author and Professor, Laboratory Head at the Doherty Institute, University of Melbourne
“This also has implications for understanding chronic conditions such as dry eye disease and common eye allergies where unwanted T cells might also cause disease,” Professor Mueller concluded.
The University of Melbourne’s Departments of Optometry and Vision Sciences and Department of Anatomy and Neuroscience, as well as Monash University’s Institute of Pharmaceutical Sciences, collaborated on this research.
Loi, J. K., et al. (2022) Corneal tissue-resident memory T cells form a unique immune compartment at the ocular surface. Cell Reports. doi.org/10.1016/j.celrep.2022.110852