Research finds possible genetic trigger for autoimmune disease

American researchers have pinpointed a genetic trigger that could be linked to systemic autoimmune diseases such as lupus and Sjögren's syndrome.

They found that elements in the body's genetic makeup could trigger the kind of immune response usually caused by external viruses.

The scientists discovered that the abnormal expression of genetic elements called "L1 retroelements" could trigger an immune response similar to that produced by external viruses. This can lead to an overproduction of interferons, molecules produced by the body in response to viruses and other pathogens to mobilize the immune system.

The researchers studied kidney biopsy samples from 24 patients suffering from lupus and saliva gland tissue from 31 patients with Sjögren's syndrome (a syndrome that causes the mouth, eyes and other parts of the body, such as joints, to dry out). These were compared to healthy tissue samples.

"In a number of these diseases, such as lupus and Sjögren's syndrome, a class of interferon known as type 1 interferon is made in abundance and plays a key role, contributing to the immune dysfunction," explains Dr. Mary K. Crow, the study's senior author and physician-in-chief at New York-based Hospital for Special Surgery.

In light of their findings, the researchers suggest that virus-like DNA sequences in the human genome can remain dormant or can manifest or mutate, causing reactions that may contribute to auto-immune disease.

Autoimmune disease remains something of a mystery for the medical world. In spite of the growing number of people affected -- some 22 million in the U.S. -- it is difficult to explain what causes the immune system to malfunction and attack healthy organs.

Autoimmune disease is thought to be caused by a combination of factors, such as imbalanced gut flora, environmental factors and viral infections.

Further research is now required to study the role of both exogenous and endogenous viruses in the development of autoimmune disease and to identify new treatment possibilities.

The findings were published in the journal "Arthritis & Rheumatology."