Led by Mark Noble of the University of Rochester Medical Center, researchers discovered for the first time how specific toxic waste products that accumulate in LSDs cause multiple dysfunctions in affected cells. They also found that several drugs already approved for other uses have the unexpected ability of overcoming the cellular toxic build-up, providing new opportunities for treatment.
Two postdoctoral fellows in the department of biomedical genetics, Christopher Folts and Nicole Scott-Hewett, conducted the experiments to better understand the biology of lysosomal disorders. They showed that just like the stomach, lysosomes are usually more acidic than other parts of the cell and toxic substances that accumulate in several LSDs disrupt maintenance of the acidic environment.
They also demonstrated that restoring the normal acidity of the lysosome with drug treatment was sufficient to prevent multiple disruptions of normal lysosome function and to maintain critical cell functions, such as division and survival.
In a mouse model of Krabbe disease (one of the most severe LSDs), Noble’s team found that their lead study drug, colforsin, increased survival as effectively as seen in studies where disease-causing mutations were corrected by gene therapy. Colforsin is approved in Japan to treat cardiac disease, which provides information to investigators about its use in humans.
Treating Multiple Disorders
Increased survival in mice occurred even though treatment was started later than is necessary for gene therapy.
The treatment also decreased damage to the brain and improved quality of life in the diseased mice. All of these outcomes are critical goals in the treatment of children with Krabbe disease or related illnesses, says Noble.
“One of the great challenges in these diseases is that they are both rare and come in many different varieties, and advances have tended to focus on single diseases,” Noble says. “In contrast, our findings suggest our treatments will be relevant to multiple disorders. Also, we saw benefits of our treatment even without needing to correct the underlying genetic defects. That gives us great hope that we could combine our treatments with other candidate approaches to gain additional benefits.”
If the results translate to humans, Noble says, the repurposed drugs might improve the quality of life for afflicted children while more difficult experimental genetic treatments are pursued.
Lysosome dysfunction is recognized as important in other diseases, such as diabetes and macular degeneration. The latest discoveries, Noble adds, may extend beyond the treatment of lysosomal storage disorders.