Researchers Find Further Evidence That Bile Acid Slows Vision Loss in Mice
January 19, 2012 – A recent Foundation-funded study shows that a synthetically derived bile acid slowed the rate of vision loss in mice with specific types of retinal degenerative diseases. According to researchers at the University of Iowa, tauroursodeoxycholic acid, or TUDCA, performed well in mouse models of autosomal recessive retinitis pigmentosa (RP) and Bardet-Biedl syndrome type 1 (BBS1), which causes a variety of physical and developmental symptoms, including obesity and RP. The results are consistent with those from earlier studies, also funded by the Foundation.
The Iowa team, which reported its study in the online issue of the journal Investigative Ophthalmology & Visual Science, believes that TUDCA holds the greatest potential for treating slower and later-onset retinal disease. It also thinks TUDCA may help control obesity in BBS1 patients, though the team cautions that further study is needed to understand TUDCA’s effect on weight loss.
The Foundation is currently funding a lab study at Oregon Health & Science University to determine the optimal oral dose of TUDCA for treating humans with retinal degenerations such as RP. If results of that study are favorable, the Foundation hopes to launch a clinical trial in early 2013.
“TUDCA looks very promising at this point, but we need to determine how much of the drug must be taken orally to reach the retina,” says Dr. Patricia Zilliox, the Foundation’s chief drug development officer. “We need to ensure we can get an effective dose to the back of the eye without causing unwanted side effects before we move it into a human trial.”
The natural form of the bile, most commonly found in bears, has been used in traditional Chinese medicine for thousands of years to treat a variety of ailments and conditions. There is even a 3,000-year-old scroll that mentions it as being a cure for blindness. TUDCA, the synthetic form, is currently used in Europe to treat gastrointestinal disorders. Recently, scientists have evaluated the drug for conditions such as diabetes, obesity and neurodegenerative disorders, including Huntington and Alzheimer diseases.
In retinal disease, TUDCA appears to work by blocking the death of photoreceptors, the rod and cones cells that provide vision. While programmed cell death, a process known as apoptosis, is a normal biological activity that helps the body rid itself of unneeded cells, disorders such as RP cause excess apoptosis.
The Iowa research team notes that TUDCA might be beneficial to patients with retinal degenerative diseases who are awaiting a future gene therapy or for whom the genetic cause of disease has not been identified.
Dr. Arlene Drack, lead investigator of the study, is the recipient of a Marjorie Carr Adams Women’s Career Development Award from the Foundation.