Sjögren’s syndrome is an autoimmune disorder characterized by the destruction of exocrine glands, like those that produce tears and saliva. Lupus is an autoimmune disease characterized by inflammation of various body tissues. People suffering from both these disorders produce antibodies and mount an immune response against a peptide, Ro60, that occurs naturally in the body. While this autoimmune response may not be the cause of these diseases, it likely contributes to their severity. An article published by Clinical Immunology shows that specific proteins derived from bacteria in the microbiome can activate the production of these self-destructive antibodies, suggesting that the microbiome could play a role in initiating autoimmunity.
Researchers at the University of Virginia used T cell hybridoma activation and epitope mapping to discover which peptides activate the specific Ro60 immune response. When they compared these molecules with molecules known to be produced by the human microbiome, they found several instances of proteins produced by the microbiome that could potentially activate antibodies against Ro60.
The most potent peptide from the screening was derived from a specific bacterium, Capnocytophaga ochracea, that is commonly found in people’s mouths and is sometimes pathogenic. According to their data, these bacteria should produce a protein that most strongly activates the antibodies against Ro60. After experimentation, they found that the microbe alone was not able to activate the antibodies. However, a synthetically produced version of the protein from C. ochracea, was successful in activating the antibodies.
This work is important because it suggests that host bacteria may have a strong connection in generating autoimmune responses. At least in the cases of Lupus and Sjögren’s syndrome, certain bacteria may induce humans to create antibodies against natural body products, and this immune response contributes to the diseases.