Campus researchers discover eye-based bacteria killer

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Researchers at the UC Berkeley School of Optometry have discovered that protein molecules in the human cornea contain pathogen-killing properties that may help explain why the human body is relatively immune to infections.

Headed by Suzanne Fleiszig, a professor of vision science and optometry in the school, and funded in part by a grant from the Bill and Melinda Gates Foundation, researchers at Fleiszig’s lab found that small fragments of the protein keratin contains antimicrobial properties capable of killing off a number of different infections.

Originally thought to be purely a structural protein, researchers found that the keratin fragment derived from cytokeratin 6A helped protect the cornea of the eye from getting bacterial infections.

Researchers took cells from the cornea and exposed them to the bacterium Pseudomonas aeruginosa, which is found in infections like pneumonia and those resulting from cystic fibrosis. They discovered that the cells were able to kill the infection.

“What happened is that we divided all the molecules in the cell by size and tested them for antimicrobial activity,” Fleiszig said. “It turned out that most of the antimicrobial activity was among the smallest sized molecules.”

While the fragments might have the potential to be used in pharmaceuticals, said David Evans, an associate research scientist in Fleiszig’s lab, the full effects of the results are mostly conceptual at this point.

“We don’t really fully understand it yet,” he said. “All we know is that it does kill the bacteria quickly, and it makes them die within 15 minutes of exposure.”

A paper detailing the full results of the discovery will be published in the October issue of the Journal of Clinical Investigation.

Michael Zasloff, a professor of surgery at Georgetown University’s Transplant Institute, said the discovery enriches scientists’ understanding of how the eye fights off infections and that it will shake up the medical and scientific communities.

“It adds to our understanding of the diversity of the defenses that we have available to us,” he said. “It teaches us that something that we might have thought to have one function can be used in a completely different and unanticipated way.”

According to Fleiszig, there might be other types of keratin in addition to cytokeratin 6A that contain antimicrobial properties, and further research might unlock the possibilities of other molecules.

“Keratins are abundant in nature in all species and in different forms,” she said. “It could also answer the question why we won’t get infections elsewhere on our bodies.”

Contact Andy Nguyen at [email protected].

A previous version of this article incorrectly stated that researchers found that there was antimicrobial activity “in the smallest size molecules.” In fact, “most of the antimicrobial activity was among the smallest sized molecules,” according to Fleiszig. It also incorrectly stated that Fleiszig said keratin “is abundant in nature in all spaces and in different forms.” In face, she said keratins are abundant in nature in all “species.”