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| Dry eye syndrome might be caused by immune cells meant to protect them that instead disrupt moisterizing glands, researchers report in a new study. Photo by Guiliamar/Pixabay |
By Allen Cone, UPI
Researchers believe they have determined why people have dry eyes: Immune cells that protect them are disrupting moisterizing glands and causing the condition.
The discovery may lead to therapies that do more than minimize the symptoms of the leading cause of dry syndrome, Meibomian gland dysfunction, according to researchers at Duke University Medical Center. Their findings were published Wednesday in Science Translational Medicine.
[post_ads]"New treatments might be presented sooner than expected," Dr. Daniel R. Saban, a researcher at Duke and senior author on the new study, said in a press release. "The market is robust right now for new drugs that can modulate the immune system. With the new understanding of how immune cells are involved in this condition, the findings could be translatable with a drug that's already on the market and repurposed for relieving MGD."
Doctors now prescribe eyelid scrubs and anti-inflammatory drops to relieve some symptoms. It's a condition that afflicts afflicts 26 million people in the United States, according to a Gallup poll.
The condition is nearly twice as common in women than men and becomes more prevalent when people reach 50.
Dry eye occurs when tears fail to keep the surface of the eye adequately lubricated, leading to a scratchy sensation or the feeling that something is in the eye, according to the National Eye Institute.
Although the syndrome is brought on by allergies, contact lenses or a tendency to blink less while using computers and other electronic devices, the disease is linked to blockages in the glands of the eyelid, called Meibomian glands. Oils are secreted at the lid opening each time people blink to retain moisture and maintain a healthy eye.
"This study shows that some forms of Meibomian gland dysfunction are inflammatory diseases, and our studies in mice confirm what we see in the tears of people with blocked glands," said study co-author Dr. Preeya K. Gupta, an ophthalmologist. "This pathway may be a new target for therapeutic agents to help treat patients suffering from dry eye disease and MGD."
Immune cells called neutrophils, which relieve inflamed eyes, might also be disrupting the moisturizing glands, the researchers wrote.
For many patients, the disease is undetected and undiagnosed, but among others it is marked by small off-white beads along the eyelid that look like plugged pores or whiteheads.
"In addition to providing new treatment strategies, the presence of neutrophils in the eye could provide a biomarker to detect the disease or measure its severity," Saban said.
They are found in many tissues of the body. When pathogens such as bacteria make their way into the gut, T cells identify the invader and recruit neutrophils to fight the battle.
"When you sleep, neutrophils come into your tears," Saban said. "We don't know why, but they might be like the garbage truck, coming to collect all the waste while you sleep. Once your eyes open up, however, your tears become clear of these cells. But in these patients, their tears contain plenty of neutrophils even during the day."
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Researchers say that the more neutrophils present in the eye, the more severe the condition may be, with Dr. Nancy Reyes, another researcher on the study, point out that "the correlation between blocked glands and elevated neutrophils were unmistakable in studies of mice, which had eye inflammation in the form of allergic eye disease."
Also, they found elevated neutrophils the tears of humans with severe MGD and who suffered from conditions causing inflammation, including allergies, rosacea and autoimmune diseases.
"The neutrophils don't cause the blockage directly," Saban said. "They're being recruited around the gland and changing the actual glandular cells, which is causing them to malfunction. Even under the microscope, you can see that the glandular cells, instead of being plump and round, have changed. They look more like a shriveled raisin than a healthy grape."
The authors noted that all dry eye conditions might be related to inflammation from allergies or autoimmune conditions. In addition, not all inflammation in the eye leads to blockages in the glands, they said.
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