Common yeast may trigger celiac disease onset

Candida albicans growing in petri dish

Celiac disease is a serious autoimmune disorder in which gluten, found in wheat, rye, and barley, triggers an immune response that damages the absorption capabilities of the intestines. The AMI has covered this topic in a few previous blogs (click celiac disease tag below) in relation to autoimmune disorders and possible bacterial triggers. One contributing factor to the celiac disease response is due to the protein gliadin, which is found in gluten. Gliadin, along with transglutaminase (which is a human protein that binds to, and deaminates gliadin), trigger a T Cell response that leads to the inflammation and tissue damage.

The yeast Candida albicans is a common gut commensal that is linked to inflammatory bowel diseases and vaginal infections.  This yeast also binds with transglutaminase, using a protein called Hwp1, in an identical fashion as gliadin.  This results in the bacteria’s strong binding to the intestinal wall, where it triggers an autoimmune response to destroy the yeast.  

Researchers in France hypothesized that the similarity between gliadin's and C. albicans' binding to transglutaminase may result in a similarity in the body's response to these two things.  In essence, they suggested that gluten ‘tricks’ the body into an immune response because it 'looks' similar to C. albicans.  

In the study, recently published by Plos One, blood cultures from 87 adult patients with celiac disease and 41 patients with C. albicans infection were collected.  The scientists then isolated the body's natural antibody for Hwp1 and measured its response to both gliadin and Hwp1.  They discovered that gliadin also binds to Hwp1's antibody, meaning that it should elicit the same immune response as Hwp1.  Therefore, the body should mount an immune response for gluten that is characteristic of C. albicans infection, and this response could manifest itself as celiac disease.

The significance of this study is that it comes closer to finding a cause and prevention of celiac disease. The T cell immune response that results from transglutaminase binding to gliadin could initially be triggered by a C. albicans yeast infection. This may explain why some people only become gluten sensitive later in life - perhaps it only occurs after they have a C. albicans infection and the body builds up antibodies for this yeast. This is another example of how microbes found in healthy individuals can be harmful when homeostasis is not controlled. 

Treating celiac disease with bacteria?

Celiac disease is a condition that results in an individual's immune system attacking it’s own small intestine as a result of gluten consumption. Researchers at the University of Nebraska and the University of Alberta published a study in the Journal of Applied Microbiology that aimed to identify gastrointestinal bacteria that are able to break down gluten proteins, possibly opening the door for therapeutic interventions. To do this, they studied the gastrointestinal tract of pigs, as they are physiologically similar to humans.

The scientists found four strains from the Lactobacillus species that had the greatest ability to degrade gluten, L. amylovorus, L. johnsonii, L.ruminis, and L. salivarius. Pigs were fed a diet supplemented with 20% gluten for at least 16 weeks and samples of their gastrointestinal bacteria were collected. They found that the four bacterial strains were enriched, and these strains were capable of degrading specific molecules that have been linked to the immune response in celiac disease.

This study identified specific bacteria that could potentially be used to treat celiac disease. Other studies have also identified L. ruminis and L. amylovorous as bacteria that are primary degraders of gluten, making them prime candidates for therapeutic use. Currently, the only way for an individual with celiac disease to remain healthy is to avoid any product containing gluten. In the future, it may be possible for bacterial strains, possibly those identified in this study, to be introduced into the gut of a celiac disease patient through a probiotic or other method to allow for the digestion of gluten.