Muscle Cell Receptor Component Increases Myasthenia Gravis Treatment’s Punch, Study Shows

University of Pennsylvania researchers used a component of rats’ muscle cell receptors to increase the punch of a myasthenia gravis treatment derived from an electric ray — an ocean animal that administers a shock like an electric eel.

The team’s immune system suppression strategy alleviated the disease in rats and prevented it from developing in rats that did not have it.

Their study, “Acetylcholine receptor–specific immunosuppressive therapy of experimental autoimmune myasthenia gravis and myasthenia gravis,” appeared in the journal Annals of the New York Academy of Sciences.

Myasthenia gravis, or MG, is a chronic autoimmune disease whose hallmarks include impaired neuromuscular function, weakness, and fatigue. An autoimmune disease is one in which the immune system attacks healthy tissue instead of invaders.

The cause of myasthenia gravis is the body’s production of autoantibodies that attack acetylcholine receptors in the junction between nerve cells and muscles. Loss of the receptors leads to nerve-muscle communication dysfunction.

Scientists have believed that suppressing the immune system to short-circuit the production of the antibodies could be a way to halt or prevent myasthenia gravis. But extensive studies in a mouse model of the disease have failed to yield an effective immunosuppressive therapy. The mouse model is called Experimental Autoimmune Myasthenia Gravis, or EAMG.

Current immunosuppressive therapies do not focus on specific targets, like the autoantibodies the body produces against acetylcholine receptors. This means they are ineffective, take a long time to provide any benefits at all, and generate severe side effects.

A targeted immunosuppressive strategy that researchers tried in rats was immunizing them with acetylcholine receptors from the shock-generating organs of an electric ocean ray called the Torpedo californica. 

The treatment prevented the disease from developing in rats and rabbits that did not have it, but was unable to do a good job of treating animals that already had it.

This led to scientists treating the animals with the alpha1 component of the acetylcholine receptors before immunizing them with material from the rays. This technique led to greater success in treating the myasthenia gravis of the animals that already had it.

The University of Pennsylvania team discovered that treating the animals this way both prevented the disease in animals that did not have it and alleviated it in animals that did have it.

It also led to the production of fewer autoantibodies against the receptors.

Importantly, the rats whose myasthenia gravis was alleviated became resistant to the disease’s return.

The bottom line is that “after an effective short course of therapy, MG [myasthenia gravis] patients might remain healthy for a long time, perhaps indefinitely,” the researchers wrote.

“The effects of our AChR-specific therapy [acetylcholine receptor-specific therapy] on EAMG by immunization with cytoplasmic domains of human muscle AChR subunits suggest that the therapy is likely to work on human MG,” they said.

They added that scientists need to understand the mechanisms underlying this type of treatment and figure out optimized doses before testing it in humans.