Live-cell imaging of the transparent cornea of ​​the eye reveals an amazing resident – specialized body cells that surround the tissues, ready to attack bacteria.
“We thought the central cornea had no immune cells,” said EsenAkpek, a coroner specialist and coroner at Johns Hopkins University in Baltimore, Maryland.
The study, published in Cell Reports1 on May 24, could help researchers better understand eye infections and develop treatments that target facial infections, said Tanima Bose, an orthopedic surgeon at the pharmaceutical company Novartis in Kundl, Austria.
Immune response
The cornea has a depressive response to infection, in part because aggressive immune cells can damage a clear layer of tissue and block vision, says another author Scott Mueller, an orthopedic surgeon at the University of Melbourne, Australia. For this reason, immune cells respond quickly but raw to infection, such as dendritic cells and macrophages, mainly located in the outer parts of the cornea and emerge only when needed.
But in almost every tissue in the body long-lived immune cells, known as T cells, quickly attack the germs they have encountered before – a process called ‘immune memory’. Mueller and his colleagues wondered if such cells lived in the cornea.
Using a powerful multiphoton microscope to study live tissue, the researchers examined the cornea mice whose eyes were infected with the herpes simplex virus. They found that cytotoxic T cells and T-helper cells – precursors of the immune system – had entered the cornea and persisted for about a month after infection. Further research, including several microscopy techniques, revealed that cytotoxic T cells evolved into long-term memory cells that reside in the cornea.
Researchers then used live-cell images to examine the corneas of six healthy adults. They found the same cells in shape, size and speed in T cells guarding mice. “It was lightbulb time,” Mueller said. “We were somewhat surprised and delighted to see that there is indeed a memory of the immune system” in the cornea, says Mueller, who is now working to obtain tissue from organ donors to ensure the proper type of immune cells in humans.
Future opportunities
The researchers said the findings could improve understanding of diseases such as chronic dry eye disease, progressive loss of cornea in people with autoimmune diseases, and rejection of cornea-transplant.
Akpek wonders if these long-lived immune cells are involved in shingles – a painful rash, caused by the varicella-zoster virus, which affects about one third of people in the United States during their lifetime. About 8 percent of cases of shingles occur in the eye, resulting in loss of vision. “It makes me wonder if there is anything wrong with memory T cells in people with recurrent illnesses,” Akpek said.
Source Journal Reference:SmritiMallapaty. A surprise in the eye: long-lived T cells patrol the cornea, Nature News, (2022), https://www.nature.com/articles/d41586-022-01578-2
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