Sufferers of celiac disease have an intolerance to the dietary protein gluten, which can lead to inflammation of the intestines, causing abdominal pain and diarrhea. Just what causes the condition isn't fully understood, but it's believed to be the result of a mix of mostly genetic factors. Now, researchers have found that a common virus, introduced to the body at just the right stage of development, could set the stage for the disease – and vaccinating against that virus could help prevent it from ever taking hold.
Going gluten-free is trendy at the moment (even if it might be raising your risk of Type 2 diabetes), but for those living with celiac disease, that kind of strict diet is the only effective treatment. In these cases, gluten causes the immune system to overreact and try to fight off the protein, sending antibodies to the intestines and causing inflammation and the other unpleasant symptoms. A supplement currently in the works binds to gluten in the stomach to stop it irritating the bowel, but this new study, from scientists at the University of Pittsburgh and the University of Chicago, could lead to a vaccine.
Reovirus is a relatively common bug, although it's thought to be mostly harmless. For this study, the researchers found that reoviruses in the intestine can trigger the immune system's reaction to gluten, and while it's unlikely to be the only factor at play in developing the disease, it could help tip the scales in that direction. In tests on mice, one strain of human reovirus was found to trigger gluten intolerance and the related intestinal inflammation.
"We have been studying reovirus for some time, and we were surprised by the discovery of a potential link between reovirus and celiac disease," says Terence Dermody, an author of the study. "We are now in a position to precisely define the viral factors responsible for the induction of the autoimmune response."
Although one strain did cause the condition, the researchers found that related reoviruses induced immunity without causing the disease itself. That was backed up by the discovery that celiac patients tended to have higher levels of reovirus antibodies, indicating that they were probably infected with the virus in the past. Since it takes time for the human immune system to develop, young children are particularly vulnerable to infection, and if a reovirus infection happens to coincide with the first exposure to gluten in a child who's genetically predisposed to celiac, it could cause a perfect storm of gluten intolerance.
"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," says Bana Jabri, senior author of the study. "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."
But before any such vaccine can be developed, the researchers say that there's still plenty of work to do in unravelling the interactions between all the various factors.
"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," says Jabri. "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."
The research was published in the journal Science.
Source: University of Pittsburgh