A typically harmless type of virus might sometimes trigger celiac disease, a new study suggests.
Celiac disease is caused by an abnormal immune response to the protein gluten, which is found in wheat, rye and barley. The condition damages the lining of the small intestine, and the only effective treatment is a gluten-free diet.
The new study found that when mice were infected with particular strains of a common human intestinal reovirus, their immune system could not tolerate gluten.
Patients with celiac disease also had much higher levels of antibodies against reoviruses than those without the autoimmune disease, the researchers said.
“This study clearly shows that a virus that is not clinically symptomatic can still do bad things to the immune system and set the stage for an autoimmune disorder, and for celiac disease in particular,” said senior study author Dr. Bana Jabri. She is director of research at the University of Chicago’s Celiac Disease Center.
“However, the specific virus and its genes, the interaction between the microbe and the host, and the health status of the host are all going to matter as well,” Jabri added in a university news release.
The findings were published April 7 in the journal Science.
The trigger for the immune system response in autoimmune disease can be a protein or carbohydrate. Viruses are nothing more than a simple protein. They have a specific amino acid sequence and as little as five linked amino acids will trigger and immune response. The small size of viruses makes it easier for them to slip through the gut lining to stimulate that immune response.
Gluten is a very complex protein, much too large to migrate through even the leakiest gut. However, when not fully digested, smaller amino acid strings can leak through to stimulate the immune response.
I suspect that the amino acid sequence of these reoviruses matches a portion of the gluten protein. Once the immune system reacts to the virus, it also reacts to the gluten.
If that protein sequence is also found in the wall of the large intestine, the immune system will then attack the colon and the diagnosis is Celiac disease. This process is called “molecular mimicry.”
Molecular mimicry can occur in any tissue in the body. If the protein sequence of a virus or food particle mimics thyroid tissue, we call it Hashimoto’s thyroiditis. If it mimics the myelin sheath of the nervous system, the diagnosis is MS. The list goes on and on.
Carbohydrates can trigger an immune response with as little as two linked sugars. Lactose is comprised of one molecule of glucose and one of galactose. When separated, they are the primary source of fuel in the body. When joined you can develop “lactose intolerance” and possibly an autoimmune disease.
The Bottom Line:
It is important to discover the triggers in autoimmune disease. However, it is equally important to maintain the health of the gut lining and modulate the immune system to effectively treat autoimmune disease.