Increase in T-cell subsets of oral mucosa: a late immune response in patients with treated coeliac disease?

Oral Mucosa as a Potential Site for Diagnosis and Treatment of Allergic and Autoimmune Diseases

Most prevalent food allergies during early childhood are caused by foods with a high allergenic protein content, such as milk, egg, nuts, or fish. In older subjects, some respiratory allergies progressively lead to food-induced allergic reactions, which can be severe, such as urticaria or asthma. Oral mucosa remodeling has been recently proven to be a feature of severe allergic phenotypes and autoimmune diseases. This remodeling process includes epithelial barrier disruption and the release of inflammatory signals. Although little is known about the immune processes taking place in the oral mucosa, there are a few reports describing the oral mucosa-associated immune system. In this review, we will provide an overview of the recent knowledge about the role of the oral mucosa in food-induced allergic reactions, as well as in severe respiratory allergies or food-induced autoimmune diseases, such as celiac disease.

Celiac Disease Causes Epithelial Disruption and Regulatory T Cell Recruitment in the Oral Mucosa

Celiac disease (CD) is a chronic autoimmune disease characterized by an immune-triggered enteropathy upon gluten intake. The only current treatment available is lifelong Gluten Free Diet (GFD). Several extraintestinal manifestations have been described in CD, some affecting the oral mucosa. Thus, we hypothesized that oral mucosa could potentially be a target for novel biomarkers and an administration route for CD treatment. Six de novo diagnosed and seven CD patients under GFD for at least 1 year were recruited. Non-celiac subjects (n = 8) were recruited as control group. Two biopsies of the cheek lining were taken from each subject for mRNA analysis and immunohistochemical characterization. We observed a significant decrease in the expression of epithelial junction proteins in all CD patients, indicating that oral mucosa barrier integrity is compromised. FoxP3+ population was greatly increased in CD patients, suggesting that Tregs are recruited to the damaged mucosa, even after avoidance of gluten. Amphiregulin mRNA levels from Peripheral Blood Mononuclear Cells (PBMCs) and epithelial damage in the oral mucosa correlated with Treg infiltration in all the experimental groups, suggesting that recruited Tregs might display a “repair” phenotype. Based on these results, we propose that oral mucosa is altered in CD and, as such, might have diagnostic potential. Furthermore, due to its tolerogenic nature, it could be an important target for oral immunotherapy.

Salivary proline-rich proteins and gluten: Do structural similarities suggest a role in celiac disease?

PURPOSE

Gluten proteins, the culprits in celiac disease (CD), show striking similarities in primary structure with human salivary proline-rich proteins (PRPs). Both are enriched in proline and glutamine residues that often occur consecutively in their sequences. We investigated potential differences in the spectrum of salivary PRPs in health and CD.

EXPERIMENTAL DESIGN

Stimulated salivary secretions were collected from CD patients, patients with refractory CD, patients with gastrointestinal complaints but no CD, and healthy controls. PRP isoforms/peptides were characterized by anionic and SDS-PAGE, PCR, and LC-ESI-MS.

RESULTS

The gene frequencies of the acidic PRP isoforms PIF, Db, Pa, PRP1, and PRP2 did not differ between groups. At the protein level, PRPs peptides showed minor group differences, but these could not differentiate the CD and/or refractory CDs groups from the controls.

CONCLUSIONS AND CLINICAL RELEVANCE

This extensive study established that salivary PRPs, despite similarity to gluten proteins, show no apparent correlation with CD and thus will not serve as diagnostic markers for the disease. The structural basis for the tolerance to the gluten-like PRP proteins in CD is worthy of further exploration and may lead to the development of gluten-like analogs lacking immunogenicity that could be used therapeutically.

HLA-DQB1 Haplotypes and their Relation to Oral Signs Linked to Celiac Disease Diagnosis

Objectives:

Celiac disease (CD) is an autoimmune disorder that can be divided into typical and atypical forms. Atypical forms can show extraintestinal manifestations among which oral signs are very frequent. Considering that the pathogenesis of CD is related to a positivity to specific HLA-DQB1 haplotypes, we tested whether the presence of the HLA-DQB1*02 allele could be a hypothetical cause of the development of oral manifestations.

Subjects and Methods:

For this study was been examined the oral condition of 98 Sardinian patients, all affected by CD and all on a gluten-free diet for at least 1 year. Then was been determined each patient’s HLA-DQB1 haplotype and compared these results with clinical information.

Results:

The statistical analysis evidenced that the absence of the HLA-DQB1*02 allele predisposes to oral manifestations such as dental enamel defects (DED) and recurrent aphthous stomatitis (RAS) (Pvalue=5.98x10^-05, OR = 0.23, CI: (0.10 - 0.45) per each copy of the HLA allele).

Conclusions:

These results showed that the presence of the HLA-DQB1*02 allele influences the development of oral signs in a dose-dependent manner and also how the HLA haplotype connected to oral signs could have a fundamental role for the diagnosis of atypical forms of CD.

Association between reduced copy-number at T-cell receptor gamma (TCRgamma) and childhood allergic asthma: A possible role for somatic mosaicism

Asthma is a chronic inflammatory disease of the lungs which affects more than 6.5 million American children. A family-based genome-wide association study of copy-number variation identified an association between decreased copy-number at TCRgamma and childhood allergic asthma. TCRgamma encodes the T-cell receptor gamma glycoprotein, a cell-surface protein found on T-cells and involved in cell-mediated immunity. Using quantitative real-time PCR, we sought to determine if copy-number variation at TCRalpha, TCRbeta or TCRgamma was associated with childhood allergic asthma in an independent cohort of 94 cases and 455 controls using DNA from buccal swabs. Copy-number variation at these loci is well-known, but appears to be dominated by somatic mutations. Genotyping results indicated that copy-number variants at these genes are largely somatic mutations, as inheritance did not show Mendelian consistency. In these mosaic cell populations, copy-number was significantly reduced among asthmatic children at TCRgamma (p=0.0199), but was not associated at TCRalpha or TCRbeta (p=0.7972 and 0.8585, respectively). These findings support the association between reduced copy-number at TCRgamma and childhood allergic asthma. Further work is needed to resolve whether reduced copy-number at TCRgamma predisposes individuals to asthma, or whether deletion of this gene is a somatic response to the disease.

Orally Based Diagnosis of Celiac Disease: Current Perspectives

Celiac disease (CD) is a lifelong immune-mediated disorder caused by the ingestion of wheat gluten in genetically susceptible persons. Most cases of CD are atypical and remain undiagnosed, which exposes the individuals to the risk of life-threatening complications. Serologic endomysial and tissue transglutaminase antibody tests are used to screen at-risk individuals, although a firm diagnosis requires demonstration of characteristic histopathologic findings in the small-intestinal mucosa. A gluten challenge, with a repeat biopsy to demonstrate recurrence of histopathologic changes in the intestinal mucosa after the re-introduction of gluten, is considered for those persons in whom diagnosis remains in doubt. In this paper, we review studies that evaluated: (1) the possibility of using oral mucosa for the initial diagnosis of CD or for local gluten challenge; and (2) the possibility of using salivary CD-associated antibodies as screening tests. Our review shows that orally based diagnosis of CD is attractive and promising, although additional evaluations with standardized collection and analysis methods are needed. There is some evidence of a dissociation between systemic and oral mucosal immune responses in CD. The hypothesis that gluten could stimulate naïve lymphocytes directly in the oral cavity would have important implications for the understanding, diagnosis, and management of CD.

Detection of anti-endomysial and anti-tissue transglutaminase autoantibodies in media following culture of oral biopsies from patients with untreated coeliac disease

BACKGROUND AND AIMS

Coeliac disease is an autoimmune disorder characterised by high levels of anti-endomysial and anti-tissue transglutaminase autoantibodies in sera and media of cultured intestinal mucosa biopsies from affected patients. In this study, we wished to investigate whether anti-endomysial and anti-tissue transglutaminase antibodies can also be detected in culture media of oral mucosa specimens, and whether the mouth can be used as an area of immunological testing for coeliac disease.

METHODS

Small intestine and cheek biopsy samples taken from 16 patients with active coeliac disease and from 11 controls were cultured in vitro for 48 h at 37 degrees C in presence of medium alone. Anti-endomysial and anti-tissue transglutaminase were detected in sera and in supernatants of these cultured biopsy samples by indirect immunofluorescence and enzyme immunoassay (EIA), respectively.

RESULTS

Anti-endomysial and anti-tissue transglutaminase were positive in sera of 15/16 coeliac disease patients. Culture media of intestinal mucosa samples from 14/16 coeliac disease patients were anti-endomysial positive, while the same antibodies were positive in supernatants of cultured oral mucosa samples from 15/16 coeliac disease patients. Anti-tissue transglutaminase were positive in both intestinal and oral culture media of 15/16 coeliac disease patients. Neither anti-endomysial nor anti-tissue transglutaminase were found in sera or in culture supernatants of both intestinal and oral biopsy samples from 11 controls.

CONCLUSIONS

Our study suggests a new immunological site to detect the pathognomonic autoantibodies of coeliac disease and confirms that the mouth is involved in this illness.