This article is part of the Arthritis Archives.
Dateline: August 26, 2002
Glycosaminoglycans (GAGs) As Cause Of Rheumatoid Arthritis
Rheumatoid arthritis, an autoimmune disease which afflicts 2.1 million Americans, is the result of the body's own immune cells attacking cartilage and joints. What actually goes haywire in the immune system of a person with rheumatoid arthritis to cause the pain and destruction associated with the disease?
Studies done by Dr. Julia Ying Wang of Brigham & Women's Hospital in Boston and Harvard Medical School and colleague Dr. Michael H. Roehrl of Harvard are taking researchers down a new path. Their findings were presented at the annual meeting of the American Chemical Society on August 21, 2002.
Rheumatoid arthritis research which preceded the work of Wang and Roehrl largely focused on peptides, or fragments of protein. The Harvard researchers suggest instead that glycosaminoglycans, or GAGs, are the lead suspect in what causes rheumatoid arthritis.
Glycosaminoglycans are naturally-occurring carbohydrates found in:
- the cartilage
- connective tissue
- joint fluid
- the skin
Glycosaminoglycans are complex carbohydrates, not affected by the carbohydrates, starches and sugars, we consume.
The Theory About Glycosaminoglycans
Simply stated, Wang's theory proposes that immune system cells, or antibodies, target glycosaminoglycans. The antibodies bind to GAGs, accumulate in the joints, and trigger the pain and inflammation associated with rheumatoid arthritis.
In Wang and Roehrl's study, mice were injected with GAGs. The mice developed chronic rheumatoid arthritis-like symptoms including:
- inflammation
- swelling
- bone erosions
Glycosaminoglycan antibodies have since been discovered in the tissue of rheumatoid arthritis patients. It should be emphasized that this is the first time glycosaminoglycan antibodies have been observed in either animals or humans.
Theories to consider:
- GAG antibodies may develop as a result of bacterial infection.
- High levels of GAG may result when bacteria produce enzymes which break down connective tissue and release carbohydrates.
- Many bacteria have GAG on their cell surface. In rheumatoid arthritis, immune cells may mistakenly target naturally-occurring GAGs in the body's tissues in the same way they would target GAG on the surface of bacterial invaders.
Glycosaminoglycan Research Draws Attention
The research of Wang and Roehrl has drawn a lot of attention in the arthritis world. A statement from the medical director of the Arthritis Foundation, John Klippel, M.D., underscored the potential and enormous importance of the GAG research.
Future studies will likely attempt to block the binding of GAG antibodies to glycosaminoglycan, offering prospects for new and better drugs as well as screening tools for rheumatoid arthritis.
Related Resources
Sources: Arthritis Foundation Statement on GAGs Class of Carbohydrates, Arthritis Foundation; Carbohydrates May Be Culprit Behind Painful Rheumatoid Arthritis, Anita Manning, USA TODAY, 8/22/02; Carbohydrate Attack May Be Arthritis Culprit, Anne Harding REUTERS HEALTH, 8/21/02
First published: 08/26/2002
