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Silk cocoon protein may hold key to underlying causes of major eye disease

Queensland researchers are harnessing sericin produced by mutant silkworms to investigate the protein’s role as an antioxidant agent against unstable molecules in the eye responsible for diseases like macular degeneration and glaucoma.

Queensland Eye Institute’s chief scientist Professor Traian Chirila, senior research officer Dr Shuko Suzuki and research assistant Dr Onur Sakiragaoglu are among the first team of researchers to assess the biological and clinical responses of various eye cells when exposed to two proteins that make up the silk thread – fibroin and sericin.

As part of their investigation, they discovered sericin isolated from silk cocoons and added to cells grown in the laboratory may display antioxidative effect. The protein has shown to be a more effective for the growth of the corneal and retinal cells.

Much of the research has focused on tackling free radicals, which are unstable molecules that can chemically damage other molecules in the body. They are produced during the normal metabolism of cells but can be generated in excess due to exposure to harmful factors or when the body is suffering from disease.

The researchers state that the balance between free radicals and antioxidants is essential normal body function, but when disrupted this can lead to oxidative stress, with the body no longer able to control the damaging effects of free radicals.

Oxidative stress and the presence of free radical molecules have been associated with major degenerative eye diseases such as age-related macular degeneration (AMD), glaucoma and diabetic retinopathy.

While current treatments are aimed at slowing vision loss, the researchers note there is no therapy to reverse the toxic effects caused by oxidative stress on the retina and photoreceptor cells, and no treatments can restore their function.

“Retinal cell transplants have thus far proven to be of limited value to patients, as the healthy cells are eventually exposed to the same high levels of oxidative stress once they are transplanted,” they stated.

However, with their research demonstrating the antioxidative effect of sericin, the QEI team can now advance investigations using sericin isolated from silk cocoons to promote the growth of vital eye cells.

The protein is produced by the silkworms of a mutant silkmoth developed by Japanese scientists. The resulting cocoons contain only one protein, sericin, which removes the need for extraction or purification processes.

Their efforts are now focused on further monitoring and assessment of the antioxidative effect of these membranes on the growth of retinal photoreceptor cells.

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