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Gut Bacteria Linked to Eye Disease

You mean to tell me that my digestive system may affect my eyesight? Yes, that’s right! It’s hard to believe that your gut could affect your vision, but it’s true.

A disease called autoimmune uveitis is an inflammatory eye disease that is responsible for 10 percent of visual disability in the United States. It occurs when the immune system behaves erratically and initiates T-cells to attack specific proteins in the eye. Recent studies indicate that the T-cells may be activated in the digestive system.

The National Eye Institute, (NEI), a division of the National Institutes of Health, performed a study on mice and found that gut bacteria could be the culprit in triggering autoimmune uveitis. Rachel Caspi, Ph.D., of the National Institute of Health, is the senior study author. Because non-activated cells cannot pass through the blood-tissue barrier between the eye and the body, it is possible that T-cells could be activated in the eye itself. However, Caspi believes it is less unlikely.

Caspi and the research team suspect that gut bacteria must be similar to proteins in the retina, instructing T-cells to look for that protein and attack it. “If indeed they can become activated in the intestinal tissue, this would explain how they are able to afterward enter the eye,” she said.

In the mice study, researchers discovered high levels of activated T-cells in the intestines of the mice instead of in the lymph nodes. This finding suggests that T-cells may become activated in the intestines before any signs of autoimmune uveitis appear. Researchers then gave the mice a combination of antibiotics designed to eliminate a wide range of gut bacteria. The mice with little gut bacteria developed autoimmune uveitis much later and with less intensity than the mice with normal gut bacteria (Source: Healthline).

Now, the challenge is to find which bacteria is responsible. Caspi and her team are actively working on identifying the specific bacterium that has the protein that matches autoimmune uveitis. Currently, there is no easy solution to finding the culprit, but Caspi said, “If found…we may be able in the future to use this knowledge to selectively eliminate the response that leads to the disease.”