Celiac disease is an autoimmune condition characterized by an intolerance to gluten.
Precisely what causes such an intolerance, however, remains unclear.
In a new study, researchers have found that infection with reoviruses might play a role, a finding that might bring us closer to a vaccination against celiac disease.
According to the National Institute of Diabetes and Digestive and Kidney Diseases, as many as in the United States have celiac disease, although the majority of these are unaware that they are affected.
The condition is triggered by an abnormal immune response upon consumption of foods containing gluten – a protein found in wheat, barley, and rye.
When a person with celiac disease eats gluten, their immune system responds by attacking the lining of the small intestine.
This can cause digestive symptoms – such as stomach pain and diarrhea – as well as long-term symptoms including fatigue, iron-deficiency anemia, bone or joint pain, migraines, and arthritis.
At present, the only way to manage celiac disease is to avoid foods containing gluten.
However, the researchers of the new study – including Dr. Terence Dermody, chair of the Department of Pediatrics at the University of Pittsburgh School of Medicine in Pennsylvania - say their findings indicate that vaccination against certain viruses could help to prevent the disease.
The researchers published their results today in the journal Science.
The link to reoviruses
Dermody and colleagues have long investigated the health implications of reoviruses.
They are a group of RNA viruses that are associated with gastrointestinal infections but which present no symptoms for most people.
For the new study, the team set out to determine whether there might be a link between reovirus infection and celiac disease.
To reach their findings, the researchers assessed the effects of two genetically different strains of human reoviruses on immune responses to gluten in mice.
The team found that one of the strains not only prompted an inflammatory immune response in the rodents, but it also led to the loss of oral tolerance to gluten.
On assessing the immune responses of those with and without celiac disease, the researchers found that those with celiac disease had significantly higher levels of antibodies to reoviruses.
Additionally, the analysis revealed that a higher level of reovirus antibodies was associated with increased expression of the IRF1 gene, which is a key player in the loss of oral tolerance to gluten.
“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 of the Department of Medicine and Pediatrics at the University of Chicago Celiac Disease Center.
‘Long-term consequences’ for children
Dermody and team said their findings indicate that an initial reovirus infection may leave a “permanent mark” on the immune system that later triggers an autoimmune response to gluten.
This could have significant implications for children who are genetically predisposed to celiac disease, the researchers note.
In the United States, solid foods are normally introduced to babies at around 6 months of age, and these foods often contain gluten.
Young children have greater susceptibility to viral infections such as reoviruses. Combined with a high genetic risk of celiac disease, early gluten exposure may fuel its development.
"During the first year of life, the immune system is still maturing, so for a child with a particular genetic background, getting a particular virus at that time can leave a kind of scar that then has long-term consequences," explained Jabri.
"That's why we believe that once we have more studies, we may want to think about whether children at high risk of developing celiac disease should be vaccinated,” she added.