Intestinal epithelium, intraepithelial lymphocytes and the gut microbiota-Key players in the pathogenesis of celiac disease

Celiac disease(CD) is a chronic immune-mediated disorder triggered by the ingestion of gluten in genetically predisposed individuals. Before activating the immune system, gluten peptides are transferred by the epithelial barrier to the mucosal lamina propria, where they are deamidated by intestinal tissue transglutaminase 2. As a result, they strongly bind to human leucocyte antigens(HLAs), especially HLA-DQ2 and HLA-DQ8, expressed on antigen-presenting cells. This induces an inflammatory response, which results in small bowel enteropathy. Although gluten is the main external trigger activating both innate and adaptive(specific) immunity, its presence in the intestinal lumen does not fully explain CD pathogenesis. It has been hypothesized that an early disruption of the gut barrier in genetically susceptible individuals, which would result in an increased intestinal permeability, could precede the onset of gluten-induced immune events. The intestinal barrier is a complex functional structure, whose functioning is dependent on intestinal microbiotahomeostasis, epithelial layer integrity, and the gutassociated lymphoid tissue with its intraepithelial lymphocytes(IELs). The aim of this paper was to review the current literature and summarize the role of the gut microbiota, epithelial cells and their intercellular junctions, and IELs in CD development.

Clinical utility of quantitative multi-antibody Polycheck immunoassays in the diagnosis of coeliac disease

AIM:To evaluate the clinical utility of multi-antibody strategies in the diagnosis of coeliac disease(CD),the new quantitative Polycheck immunoassays were analysed.METHODS:Polycheck Celiac Panels(PCPs)are immunoenzyme screening assays for the quantitative measurement of coeliac-specific immunoglobulin class G(Ig G)or class A(Ig A)in serum.Lines of relevant antigens are coated together with five Ig G or Ig A standard lines used for the standard curve as positive control.PCP IgA consists of human recombinant human tissue transglutaminase(t TG)and deamidated gliadin peptides(DGP)as targets to detect Ig A antibodies.PCP IgG consists of t TG,DGP and IF(intrinsic factor)antigens to detect antibodies in Ig G class.PCPs were performed on 50 CD patients,including 6 cases with selective Ig A deficiency,and 50 non-coeliac controls.CD diagnosis was performed according to the ESPGHAN recommendations:The presence of specific anti-t TG-Ig A or anti-DGP-Ig G(in the case of Ig A deficiency)antibodies,typical histopathological changes in duodenal mucosa described in Marsh-Oberhüber classification as at least grade 2.The diagnosis of the majority of the control subjects was functional gastrointestinal disorders.The PCP results were compared with reference EliA Celikey.RESULTS:The usage of PCPs led to the correct identification of all CD patients.In our study,PCPs showed 100%agreement with the histopathological results.PCP IgA test showed a 98%concordance and correlated positively(R=0.651,P=0.0014)with Eli A Celikey test.The highest specificity and positive predictive value(both 100%)were observed for the detection of Polycheck anti-t TG-Ig A antibodies.The highest sensitivity and negative predictive value(both 100%)were achieved by Polycheck anti-DGPIg G antibody detection.The best performance(98%sensitivity and negative predictive value,100%specificity and positive predictive value,diagnostic accuracy-AU ROC 99%)was observed for the strategy of using both PCP IgA and IgG and determining positive outcomes of the test with two or more coeliac-specific antibodies detected.The majority of coeliac patients had multiple antibodies.All four antibodies were detected in 7(14%)cases,19 children(38%)were positive for three antibodies and 23(46%)were positive for two antibodies.CONCLUSION:The present study showed that detection of coeliac-specific antibodies with multi-antibody PCPs is effective and efficacious in the diagnosis of CD.

Colonization of germ-free mice with a mixture of three lactobacillus strains enhances the integrity of gut mucosa and ameliorates allergic sensitization

Increasing numbers of clinical trials and animal experiments have shown that probiotic bacteria are promising tools for allergy prevention. Here, we analyzed the immunomodulatory properties of three selected lactobacillus strains and the impact of their mixture on allergic sensitization to Bet v I using a gnotobiotic mouse model. We showed that Lactobacillus （L.） rhamnosus LOCK0900, L. rhamnosus LOCK0908 and L. casei LOCK0919 are recognized via Toll-like receptor 2 （TLR2） and nucleotide-binding oligomerization domain-containing protein 2 （NOD2） receptors and stimulate bone marrow-derived dendritic cells to produce cytokines in species- and strain-dependent manners. Colonization of germ-free （GF） mice with a mixture of all three strains （Lmix） improved the intestinal barrier by strengthening the apical junctional complexes of enterocytes and restoring the structures of microfilaments extending into the terminal web. Mice colonized with Lmix and sensitized to the Bet v I allergen showed significantly lower levels of allergen-specific IgE, IgG 1 and IgG2a and an elevated total IgA level in the sera and intestinal lavages as well as an increased transforming growth factor （TGF）-β level compared with the sensitized GF mice. Splenocytes and mesenteric lymph node cells from the Lmix-colonized mice showed the significant upregulation of TGF-β after in vitro stimulation with Bet v 1. Our results show that Lmix colonization improved the gut epithelial barrier and reduced allergic sensitization to Bet v 1. Furthermore, these findings were accompanied by the increased production of circulating and secretory IgA and the regulatory cytokine TGF-β. Thus, this mixture of three lactobacillus strains shows potential for use in the prevention of increased gut permeability and the onset of allergies in humans,