Researchers at the University of Florida have developed a new gene therapy that shows promise in fighting multiple sclerosis (MS). Testing the technique in mice, the team found that the treatment was effective in preventing animals from developing the mouse equivalent of the disease, and almost completely reversed the symptoms in those that were already suffering from it.

MS is a debilitating immunological disease where the body's immune system mistakenly attacks myelin, the tissue that surrounds and protects nerves. Once damaged, the exposed nerves can effectively short-circuit, resulting in issues with muscles, vision, speech and motor control. Potential treatments being studied include training the body to better tolerate myelin, drugs that target the immune system's B cells, blocking proteins that cause inflammation in the body, or even "rebooting" the entire immune system.

This new treatment works by reigning in the overreacting T cells that are attacking the myelin. The researchers deliver a specific gene, which hitches a ride on a harmless virus, into the livers of mice, and once in the liver that gene codes for a protein called myelin oligodendrocyte glycoprotein. Since the liver plays a key role in inducing immune tolerance, that protein increases the production of regulatory T cells, suppressing the immune system's attack on the body.

"Using a clinically tested gene therapy platform, we are able to induce very specific regulatory cells that target the self-reactive cells that are responsible for causing multiple sclerosis," says Brad E. Hoffman, co-author of the study.

In the first round of experiments, the researchers found that the gene therapy was effective in preventing experimental autoimmune encephalomyelitis (the mouse version of MS), with none of the five mice tested going on to develop the disease. When tested on mice that already had the disease, the treatment significantly reversed the symptoms just eight days after the gene therapy was delivered. Even seven months after treatment, the mouse models still showed no signs of the disease, while untreated mice developed problems after two weeks.

Another round of tests found that the therapy was even more effective if the protein was combined with a drug called rapamycin. Often used to prevent patients' bodies from rejecting transplanted organs, rapamycin works by increasing the numbers of regulatory T cells and block other aggressive types of T cells.

The researchers tested the combination of the gene therapy and rapamycin on two groups of mice that had had their hind legs paralyzed by the disease. Sure enough, 71 percent of the mice in one group and 80 percent in the other were almost completely healed.

While the results are promising, particularly in halting a form of MS that progresses rapidly, the team says there is still a long way to go before the treatment reaches human clinical trials. Other animal models will be tested first, and in order to be effective in the more complicated human version of the disease, researchers will need to find ways to target the many proteins that may play a role in MS.

"If we can provide long-term remission for people and a long-term quality of life, that is a very promising outcome," says Hoffman.

The research was published in the journal Molecular Therapy.

Source: University of Florida