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Tiny Particles Carrying Myelin Antigens Seen to Restore Immune Tolerance in MS Mice Model

July 5, 2017

In a new study, researchers managed to change the immune system by replacing inflammation with immune tolerance in a mouse model of multiple sclerosis (MS). They used so-called quantum dots, or nano-sized particles carrying pieces of myelin. The study, “Engineering Immunological Tolerance Using Quantum Dots to Tune the Density of Self-Antigen Display,” showed that processes that drive inflammation or immune tolerance are influenced by the concentration and forms of antigens. Antigens are tiny pieces of proteins, which are displayed as flags on the surface of all cells. The immune system uses these flags to distinguish between self and non-self cells, or structures. When a foreign antigen, like bacteria or a virus, is spotted, an immune reaction ensues. But in MS, the immune system mistakenly reacts to myelin antigens. Researchers are still searching why the immune system makes this mistake.

The study showed that when many quantum dots were loaded with a few myelin antigen molecules each, tolerance emerged. When exposing mice to a few quantum dots that were heavily loaded with antigens, it promoted inflammation. The quantum dots are an excellent tool to study these processes, and researchers can design them by making them hold a precisely defined number of antigens. They are also fluorescent, making it possible for researchers to track them as they travel through the body. Researchers found optimal composition of antigens on quantum dots, providing positive results. The mice were debilitated by the disease and partly paralyzed. They had become better with the treatment, for it eliminated paralysis. Experiments with this advanced technological solution may help researchers design MS therapies that are based on promoting regulatory T-cells rather than suppressing those that cause inflammation.

“One of our exciting findings is that tolerance and elimination of paralysis in a pre-clinical mouse model was much better when myelin peptides were displayed on many quantum dots at a low density of 25 per dot, instead of fewer quantum dots displaying the same number of peptides but at a high density of 65 per dot,” said Christopher Jewell, an assistant professor at the Fischell Department of Bioengineering at the University of Maryland and principal investigator on the study. “Developing specific knowledge or design guidelines such as these might enable more selective — and effective — therapies to treat MS and other diseases.”