Of the roughly 300,000 diagnosed cases of multiple sclerosis in the United States, about 80 percent of them are caused by a person’s immune system attacking its own nervous system. Specifically, the soldiers usually bent on destroying invaders concentrate instead on the myelin membrane that insulates nerve cells in the brain, spinal cord and optic nerve. Destroying this insulation causes electrical signals to not be effectively conducted, shutting down the routes of communication and leading to symptoms ranging from mild numbness to paralysis.
Of the current treatments for the disease, none of them are good options. Typically, the entire immune system is repressed, which, as you might expect, opens up the patient to a host of other potential afflictions. If only there were a way to alert the body that myelin is on the same side of the microscopic wars being waged every day.
Well, researchers at Northwestern University think they may have found that way.
One of the main soldiers of the immune system is the T-cell. Once programmed, these little buggers go out and destroy all kinds of pathogens, or in this case, native tissues. One way in which T-cells are programmed is through programming, where it is taught what surface proteins to bind to and attack. The second way is through deprogramming, where T-cells that have been produced that would bind to particular proteins are destroyed before they have the chance.
It’s that second form of programming that the researchers are utilizing. In a recent study, they attached a myelin antigen to a tiny nanoparticle and injected it into mice that had been afflicted by a disease very similar to MS. Once there, the nanoparticles were engulfed by macrophages in the immune system, causing the antigen to be expressed on their surface. Then, when T-cells came along that were able to bind to the myelin antigen, it caused a self-destruct sequence to be initiated. The whole process basically causes all of the T-cells that would otherwise attack myelin to destroy themselves.
What’s more, the nanoparticles are made of a polymer called Poly(lactide-co-glycolide) – or PLG – which already is used for biodegradable sutures and approved for use by the FDA. This means that once they complete their task, the body will naturally clear them away.
In the study, the new technique successfully kept the MS-like disease at bay for up to 100 days in the mice, which translates to years for the much slower human metabolism. The researchers hope this new study will open a floodgate, not only for potential MS therapies, but for therapies in every human auto-immune system disease. All they have to do is tailor the nanoparticles to carry the antigen for the cells they want the immune system to cease attacking.
The paper “Microparticles bearing encephalitogenic peptides induce t-cell tolerance and ameliorate experimental autoimmune encephalomyelitis” was published in Nature Biotechnology by Stephen Miller, Judy Gugenheim Research Professor of Microbiology-Immunology at Northwestern University Feinberg School of Medicine, and Lonnie Shea, professor of chemical and biological engineering at Northwestern’s McCormick School of Engineering and Applied Science.