In patients with multiple sclerosis, the body turns on itself, launching an immune system attack that destroys the coating around nerve fibers in the central nervous system, leaving them exposed like bare wires. Similar to exposed electrical lines, the unprotected fibers touch and short out, leading to the neurodegenerative effects that are a hallmark of multiple sclerosis.
But what if doctors could stop the immune response that destroys the protective coating before the disease becomes debilitating? University of Florida researchers have received a $40,000 grant from the National Multiple Sclerosis Society to test a gene therapy technique in mice that aims to help the body not treat itself like a foreign invader— a process referred to as immune tolerance— in the earliest stages of multiple sclerosis. If the researchers can re-establish this tolerance, they could thwart the immune system attack, all with a technique that could be used on a wide number of patients.
“In previous years, we have learned a lot about how to manipulate tolerance using gene therapy,” said Brad Hoffman, an assistant professor of pediatrics in the UF College of Medicine. “Tolerance is your body’s way of not responding to substances that would otherwise induce an immune response so you don’t have an immune response to everything. In multiple sclerosis, the body loses that ability to distinguish between self and not-self so it starts to attack its own nervous system cells.”
About 2.3 million people worldwide suffer from multiple sclerosis, according to the National Multiple Sclerosis Society. The disease typically causes problems with vision, fatigue, speech, sensation and mobility. In advanced cases, multiple sclerosis can lead to blindness and paralysis.
Typically, gene therapy is used to correct a faulty gene in the body. In this case, researchers will deliver a gene responsible for a brain protein into the liver, via the harmless virus AAV, in hopes that it will spark production of regulatory T cells. These T cells, which suppress the immune system, are crucial because they could effectively shut down the immune attack in the brain, Hoffman said. The researchers are injecting the gene specifically into the liver because the organ filters out unwanted immune responses.
“Everything filters through the liver for detoxification,” Hoffman said. “Because of this, the liver has an innate capacity to induce immune tolerance. We have learned in other gene therapy studies that it is possible for the liver to make cells tolerant to the gene you are putting in.”