Scleroderma is a disease that affects collagen and causes hardened skin as well as thickening and narrowing of small arteries. The cause of the problems resulting in scleroderma is not known. Research to date has been unable to identify a single gene or environmental agent responsible for scleroderma. It is likely that the disease is triggered by a complex interaction of several factors.

The immune system is a set of organs and cells that work together to defend your body from harmful foreign substances. These substances are referred to as "antigens." The immune system produces antibodies to fight antigens and combat anything that is recognized as foreign to your body.

In autoimmune diseases, your immune system becomes overactive for a variety of reasons. The immune cells, and possibly some of the substances they secrete, called cytokines, stimulate collagen formation. The excess collagen is deposited in tissues such as the skin, blood vessels, and internal organs. However, scleroderma, unlike many other autoimmune diseases, does not respond to immunosuppressive therapies.

Chimerism refers to the existence of cells from two different individuals within the same person. During pregnancy, for example, fetal cells pass into the mother's blood. The immune system normally eliminates the "foreign" fetal cells after delivery. But research suggests that many women with scleroderma have retained some of the fetal cells; in one study, 46 percent of the women with scleroderma were found to have evidence of Y chromosome fetal cells, but only 4 percent of the women without the disease. Some researchers theorize that the fetal cells eventually mature to immune cells, including T cells, which stimulate the body to produce collagen (an excess of collagen is linked to scleroderma). Scientists also speculate that the fetal-turned-immune cells might later become activated by a virus or another environmental factor and attack the mother's own cells. Although this theory doesn't explain why some men or women who have never been pregnant develop scleroderma, it may help explain why ten times as many women develop scleroderma as men. This theory is being actively investigated.

There is evidence to suggest that exposure to certain viruses may trigger an aberrant autoimmune response in genetically prone individuals. It is possible that the structure of the virus closely resembles a structure in the body, and consequently the immune system attacks the body's cells as well as the invaders.

Workplace exposure to organic solvents

Scleroderma has been associated with high workplace exposure over a period of time to organic solvents (which includes industrial chemicals such as benzene, toluene, xylene, and trichoroethylene) and occupational exposure to polyvinyl chloride fumes.

Contaminated cooking oil

Other evidence that scleroderma may be linked to environmental factors developed after a tragic case in Spain in which contaminated rapeseed oil was marketed illegally as pure olive oil. The ingestion of the toxic oil killed 700 people and injured thousands more; doctors found that many survivors developed features of scleroderma, including skin hardening. Doctors called the new syndrome, marked by muscle cramps and other nerve disorders, "Toxic Oil Syndrome."

L-tryptophan

In the 1980s, disaster also struck many Americans taking an over-the-counter amino acid supplement known as L-tryptophan, which was thought to ease insomnia, migraine headaches, and other ills; a contaminated batch of L-trytophan sickened scores of people and led them to develop scleroderma-like symptoms. Although the symptoms were often painful and long-lasting, the contaminated L-tryptophan did not cause classic scleroderma, according to a study in the Annals of Internal Medicine.

Bleomycin

Bleomycin is a drug used to treat certain types of cancers. In some cases, it has been linked to the development of scleroderma.

Silicone breast implants

Recent concerns about silicone breast implants has led scientists to study this risk factor more closely. So far, the majority of studies suggests that silicone breast implants do not appear to increase the risk for scleroderma in either the recipient or in breast-fed babies. In the October 2003 issue of the Journal of Rheumatology, however, rheumatologists from the University of South Florida backed implant removal and proposed the creation of a silicone-related disorder marked by muscle and joint pain, fatigue, bladder irritability, and other neurological symptoms.

Researchers continue to study the cause and process of scleroderma, and as knowledge about this disease increases, better treatment and perhaps even a cure may be found.

References

First published April 1, 2000
Last updated September 10, 2003
Copyright © 2000 Accordant Health Services, Inc. All Rights Reserved.

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