For the first time, scientists from the Hospital for Special Surgery (HSS) have uncovered a role for genetic elements called LINE-1 that may be responsible for triggering or aggravating an innate immune response. The findings may pave the way for development of new therapies for autoimmune diseases, like lupus nephritis and Sjogren’s syndrome.
Mary Crow, senior author of the study, and her team at HSS published their work in the journal Arthritis & Rheumatology.
LINE-1 (L1) are a class of genetic elements called retrotransposons, derived from viruses thousands of years ago. They are long regions of DNA that have the ability to amplify themselves and are found widespread across eukaryotic organisms. They have been linked to other diseases such as cancer; however, this study is the first to implicate them in autoimmune diseases.
Autoimmune diseases, such as lupus and Sjogren’s syndrome, occur when the body’s immune system attacks itself and harms vital organs. How this process occurs is poorly understood, but scientists believe the pathology straddles a complex interplay between the environment and genetics.
In innate immunity triggered by a virus or other pathogen, intermediate molecules are produced to mobilize the immune system. "In a number of these diseases, such as lupus and Sjogren'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," said Crow.
Crow and her team put forward the question: Can L1 genetic elements trigger an innate immune response?
To answer this question, they set out to understand why interferons were being produced in excess in kidney and salivary gland biopsies, from patients with lupus and Sjogren’s syndrome, respectively.
"Our findings support the hypothesis that L1 retroelements, perhaps along with other virus-derived genomic elements, may contribute to the development of autoimmune disorders characterized by high levels of type 1 interferon," she said. "Although it may not be the only cause, it's intriguing to think that virus-derived elements in our own genome are either quiet and don't cause any trouble, or they get stirred up and contribute to disease."
- here’s the release