“This finding could potentially be used to halt autoimmune diseases other than multiple sclerosis (MS), such as Type 1 diabetes and rheumatoid arthritis, and immune-mediated diseases, such as food allergy and asthma,” said Professor Nicholas King from Sydney Medical School at the University of Sydney.
“We still have many experiments to do to confirm this but our research is a genuine coup which promises to make an impact on a range of illnesses.”
Professor King and Professor Stephen Miller at Northwestern University in the US have published their findings in Nature Biotechnology this week.
Dr Daniel Getts, Northwestern University and lead author of the paper, was formerly Professor King’s PhD student at the University of Sydney.
The delicate covering of myelin on nerve cells enables them to transmit electrical signals. In multiple sclerosis cells of the immune system suddenly recognise and destroy this coating.
The cause of MS remains unknown. In humans, this debilitating disease causes symptoms that vary from mild limb numbness to paralysis and blindness.
“To date immunosuppressant therapy to control MS has had varying success but has always been a double-edged sword. When you suppress the immune system you remove the ability of the body to fight off infectious organisms and destroy emerging cancers,” said Professor King.
The researchers injected small myelin proteins attached to nanoparticles, measuring 500 nanometers in diameter, into the bloodstream of mice. The nanoparticles travel to the spleen where they are taken up by cells called macrophages, which are able to engulf any debris that goes by and remove it from the body.
“These macrophages normally get rid of old and dead cells from the body and are believed to send local signals into the surrounding spleen that tell the immune system not to respond to the proteins from these broken down ‘self’ cells,” said Professor King.
Once taken up by the macrophages, the ultimate effect of the nanoparticles is to suppress the immune response to the myelin proteins directly (and increase the number of ‘regulatory T cells’ that damp down this response). The myelin can then recoat the nerve cells.
“A big advantage of this new approach is that it does not cause blanket immunosuppression, but only causes a specific tolerance to the myelin proteins,” Professor King said.
“This technique is also much cheaper to produce and easier to standardise than other techniques,” said Professor King.
“The nanoparticle we have used is biodegradable and breaks down naturally in the body. It is already approved by the Federal Drug Administration, which will enable clinical trials in humans sooner rather than later. The entire team is very excited about these results. We believe this breakthrough will open the door to affordable future treatment of many autoimmune diseases.”
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