A new type of vaccine developed by researchers at the University of Chicago Pritzker School of Molecular Engineering (PME) has shown in the lab that it can completely reverse autoimmune diseases—all without shutting down the rest of the immune system.

A typical vaccine teaches the human immune system to recognize a virus or bacteria as an enemy that should be attacked. The new “inverse vaccine” does just the opposite: it removes the immune system’s memory of one particular molecule. While such immune memory erasure would be unwanted for infectious diseases, it can stop autoimmune reactions like those seen in multiple sclerosis, type 1 diabetes, and rheumatoid arthritis, in which the immune system attacks a person’s healthy tissues.

The inverse vaccine, described in Nature Biomedical Engineering in September, takes advantage of a natural process in which the liver marks molecules from broken-down cells with “do not attack” flags to prevent autoimmune reactions to those cells as they die by natural processes. PME researchers coupled an antigen—a molecule being attacked by the immune system—with a molecule resembling a fragment of an aged cell that the liver would recognize as friend rather than foe.

“In the past, we showed that we could use this approach to prevent autoimmunity,” says Jeffrey Hubbell, the Eugene Bell Professor in Tissue Engineering and lead author of the paper. “But what is so exciting about this work is that we have shown that we can treat diseases like multiple sclerosis after there is already ongoing inflammation, which is more useful in a real-world context.”

The job of the immune system’s T cells is to recognize damaged or unwanted cells and molecules—such as viruses, bacteria, and cancers—as foreign to the body and get rid of them. Once T cells launch an initial attack against an antigen, they retain a memory of the invader to eliminate it more quickly in the future.

T cells can make mistakes, however, and recognize healthy cells as foreign. In people with multiple sclerosis, for instance, T cells mount an attack against myelin, the protective coating around nerves.

Hubbell and his colleagues knew that the body has a mechanism for ensuring that immune reactions don’t occur in response to every damaged cell in the body—a phenomenon known as peripheral immune tolerance, which is carried out in the liver. They discovered in recent years that tagging molecules with a sugar known as N-acetylgalactosamine (pGal) could mimic this process, sending the molecules to the liver, where tolerance to them develops.

“The idea is that we can attach any molecule we want to pGal and it will teach the immune system to tolerate it,” explains Hubbell. “Rather than rev up immunity as with a vaccine, we can tamp it down in a very specific way with an inverse vaccine.”

In the new study, the researchers focused on a multiple-sclerosis-like disease in which the immune system attacks myelin, leading to weakness and numbness, loss of vision, and eventually mobility problems and paralysis. The team linked myelin proteins to pGal and tested the effect of the new inverse vaccine. The immune system, they found, stopped attacking myelin, allowing nerves to function correctly again and reversing symptoms of disease in animals.

In a series of additional experiments, the scientists showed that the same approach worked to minimize other ongoing immune reactions.

Autoimmune diseases are generally treated with drugs that broadly shut down the immune system. Such treatments, says Hubbell, “can be very effective, but you’re also blocking the immune responses necessary to fight off infections and so there are a lot of side effects. If we could treat patients with an inverse vaccine instead, it could be much more specific and lead to fewer side effects.”

Researchers have carried out initial phase I safety trials of a glycosylation-modified antigen therapy in people with celiac disease—an autoimmune disease associated with eating wheat, barley, and rye—and phase I safety trials are underway in people with multiple sclerosis. Those trials are conducted by the pharmaceutical company Anokion SA, which helped fund the new work along with the Alper Family Foundation. Hubbell cofounded Anokion and is a consultant, board member, and equity holder with the company.

“There are no clinically approved inverse vaccines yet,” says Hubbell, “but we’re incredibly excited about moving this technology forward.”