A biodegradable nanoparticle has proven to be the perfect vehicle to stealthily deliver an antigen that tricks the immune system into stopping its attack on myelin and halt a model of relapsing-remitting multiple sclerosis in mice, according to new research. The nanoparticles are made of the same material used to make surgical sutures that dissolve harmlessly in the body (and are FDA approved).
The potential treatment developed by researchers at the Feinberg School of Medicine at Northwestern University in Chicago works by “introducing” myelin to the body’s immune cells (T-cells) at the same time they are “meeting” healthy tissue, thereby educating the immune cells to leave the myelin alone.
In the study, researchers attached myelin antigens to the nanoparticles and injected them intravenously into the mice. The particles entered the spleen, which filters the blood and helps the body dispose of aging and dying blood cells. There, the particles were engulfed by macrophages, a type of immune cell, which then displayed the antigens on their cell surface. The immune system viewed the nanoparticles as ordinary dying blood cells and nothing to be concerned about. This created immune tolerance to the antigen by directly inhibiting the activity of myelin responsive T cells and by increasing the numbers of regulatory T cells which further calmed the autoimmune response.
Though trials in humans are likely two years away, according to estimates, the procedure has generated hope that one day treatment options will include nanoparticle therapy. Nanoparticles have many advantages; they can be readily produced in a laboratory and standardized for manufacturing. They would make the potential therapy cheaper and more accessible to a general population.
"The key here is that this antigen/particle-based approach to induction of tolerance is selective and targeted. Unlike generalized immunosuppression, which is the current therapy used for autoimmune diseases, this new process does not shut down the whole immune system," said Christine Kelley, National Institute of Biomedical Imaging and Bioengineering director of the division of Discovery Science and Technology at the National Institutes of Health, which supported the research.
The approach may also be used to treat any autoimmune disease. For diabetes, little bits of pancreatic beta cells could be attached to the nanoparticles. For a food allergy, the part of the food that causes the allergic response could be attached.
The study was published in the journal Nature Biotechnology.