A potential new approach to diabetic eye disease
Researchers at the University of Michigan report that treatment with norrin, a naturally occurring signaling molecule, helped maintain retinal blood-vessel health and preserve vision in rats with diabetes. The findings, published in Diabetes, point to a possible future treatment strategy for diabetic retinopathy, a complication that can cause vision loss.
Diabetic retinopathy develops when diabetes damages blood vessels in the retina, the light-sensitive tissue at the back of the eye. Early disease may produce few or mild symptoms, but continued poor control of diabetes can lead to severe vision impairment or blindness.
Why current treatment can fall short
Existing therapies commonly target vascular endothelial growth factor, or VEGF. In diabetic retinopathy, excess VEGF contributes to abnormal blood-vessel growth and leakage. Anti-VEGF medicines can address those effects, but they generally require repeated injections and do not fully control the condition in about half of treated patients, according to the University of Michigan report.
The new work focuses on a different biological route: protecting the blood-retinal barrier itself. This barrier helps regulate the movement of water and nutrients between the bloodstream and retinal tissue. When it breaks down, leakage and related retinal damage can undermine vision.
Norrin levels fell as disease developed
The research team found that diabetic rats had lower levels of norrin as their vision declined. The researchers then injected norrin after the animals developed diabetes. The treatment prevented the loss of vision reported in the study and improved the integrity of the retinal vascular barrier.
Earlier experiments by the group had shown that norrin could reverse VEGF-related disruption of the blood-vessel barrier in cells. The rat study extends that work into an animal model of diabetic disease, linking norrin treatment to both vascular protection and vision outcomes.
What the result does—and does not—show
The result is preclinical. It demonstrates an effect in diabetic rats, not in people, and it does not establish that norrin is safe or effective for patients with diabetic retinopathy. Clinical research would be needed before any human treatment could be considered.
Still, the findings address a major unmet need. Rather than solely suppressing signals that promote leakage and abnormal vessel growth, a norrin-based approach could seek to reinforce the retinal barrier that diabetes disrupts. Whether that strategy can complement or improve upon current anti-VEGF treatment remains an open question for future studies.
Why it matters
Diabetic retinopathy remains a consequential complication of diabetes because retinal damage can progress before it produces obvious symptoms. The study adds evidence that maintaining vascular stability may be as important as responding to later-stage leakage or abnormal vessel growth.
For now, norrin should be viewed as an experimental lead rather than a treatment option. But the work offers a clearer biological target for efforts to prevent vision loss earlier in the course of diabetic retinal disease.
This article is based on reporting by Medical Xpress. Read the original article.
Originally published on medicalxpress.com
