The production of the oral mucosa of antiendomysial and anti-tissue-transglutaminase antibodies in patients with celiac disease: a review

Celiac disease (CD) is a lifelong, T cell—mediated enteropathy, triggered by the ingestion of gluten and related prolamins in genetically susceptible subjects, resulting in minor intestinal mucosal injury, including villous atrophy with crypt hyperplasia and intraepithelial lymphocytosis, and subsequent nutrient malabsorption. Although serological tests for antiendomysial (EMA) and anti—tissue transglutaminase (anti-tTG) autoantibodies are used to screen and follow up on patients with CD, diagnostic confirmation is still based on the histological examination of the small intestinal mucosa. Although the small intestinal mucosa is the main site of the gut involved in CD, other mucosal surfaces (such as gastric, rectal, ileal, and esophageal) belonging to the gastrointestinal tract and the gut-associated lymphoid tissue (GALT) can also be involved. A site that could be studied less invasively is the mouth, as it is the first part of the gastrointestinal system and a part of the GALT. Indeed, not only have various oral ailments been reported as possible atypical aspects of CD, but it has been also demonstrated that inflammatory changes occur after oral supramucosal application and a submucosal injection of gliadin into the oral mucosa of CD patients. However, to date, only two studies have assessed the capacity of the oral mucosa of untreated CD patients to EMA and anti-tTG antibodies. In this paper, we will review studies that evaluate the capacity of the oral mucosa to produce specific CD autoantibodies. Discrepancies in sensitivity from the two studies have revealed that biopsy is still not an adequate procedure for the routine diagnostic purposes of CD patients, and a more in-depth evaluation on a larger sample size with standardized collection and analysis methods is merited. However, the demonstration of immunological reactivity to the gluten ingestion of the oral mucosa of CD, in terms of IgA EMA and anti-tTG production, needs to be further evaluated in order to verify whether the oral mucosa is colonized by lymphocytes activated in the intestine or if gluten could stimulate naïve lymphocytes directly in the oral mucosa. This would have important implications for the pathogenesis, diagnosis, and treatment of CD.