Most of MDA's disorders are related to genetic flaws, but some — myasthenia gravis, Lambert-Eaton syndrome, polymyositis and dermatomyositis — stem from a different kind of problem. These diseases are known as autoimmune, and they result from a mistake in the body's immune system so that it attacks its own tissues. In MDA's autoimmune disorders, the target of the immune system's attack is muscle tissue, nerve tissue that sends signals to muscles, or sometimes blood vessels around muscle cells.
J. Edwin Blalock of the University of Alabama at Birmingham is developing vaccines that could fight MG. Etanercept for dermatomyositis. In a new clinical trial, MDA researchers are studying the use of etanercept (Enbrel) in dermatomyositis. Etanercept is a drug developed for rheumatoid arthritis by Immunex and Wyeth-Ayerst Pharmaceuticals.
The drug blocks tumor necrosis factor, a natural body chemical involved in inflammation. In dermatomyositis, the immune system causes inflammation around muscle cells and the blood vessels in muscles. Current treatments involve global suppression of the immune system and can be highly toxic.
Disarming an immune response by preventing a "second signal." MDA-supported researchers are attempting to treat the autoimmune disease myasthenia gravis (MG) by "disarming" activated T cells, key players in the immune response. If T cells see their targets (in this case, bits of muscle cells called acetylcholine receptor proteins) displayed on cells that line the nasal passages, they apparently lose their ability to go into battle. The strategy has shown promise in rats. (See "MG Nasal Spray Works in Rats," Quest, vol. 6, no. 6.) Vaccines against an immune response. In a different approach to treating MG, other MDA-supported investigators have developed two "vaccines" that show promise in rats. The vaccines appear to turn the immune system's weaponry against its own mistakes. These vaccines, which also have potential for the treatment of other autoimmune disorders, block only those T cells, B cells and proteins that are involved in an unwanted immune response. (See "Vaccines May Someday Treat MG.")
