Article

Early effects of gliadin on enterocyte intracellular signalling involved in intestinal barrier function.

Department of Biomedical Sciences and Biotechnology, 2nd Pediatric Clinic, University of Cagliari, Cagliari, Italy.
Gut (Impact Factor: 10.73). 03/2003; 52(2):218-23. DOI: 10.1136/gut.52.2.218
Source: PubMed

ABSTRACT Despite the progress made in understanding the immunological aspects of the pathogenesis of coeliac disease (CD), the early steps that allow gliadin to cross the intestinal barrier are still largely unknown. The aim of this study was to establish whether gliadin activates a zonulin dependent enterocyte intracellular signalling pathway(s) leading to increased intestinal permeability.
The effect of gliadin on the enterocyte actin cytoskeleton was studied on rat intestinal epithelial (IEC-6) cell cultures by fluorescence microscopy and spectrofluorimetry. Zonulin concentration was measured on cell culture supernatants by enzyme linked immunosorbent assay. Transepithelial intestinal resistance (Rt) was measured on ex vivo intestinal tissues mounted in Ussing chambers.
Incubation of cells with gliadin led to a reversible protein kinase C (PKC) mediated actin polymerisation temporarily coincident with zonulin release. A significant reduction in Rt was observed after gliadin addition on rabbit intestinal mucosa mounted in Ussing chambers. Pretreatment with the zonulin inhibitor FZI/0 abolished the gliadin induced actin polymerisation and Rt reduction but not zonulin release.
Gliadin induces zonulin release in intestinal epithelial cells in vitro. Activation of the zonulin pathway by PKC mediated cytoskeleton reorganisation and tight junction opening leads to a rapid increase in intestinal permeability.

0 Bookmarks
 · 
71 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: To characterize the deregulation of epithelial tight junction genes and investigate its reversibility upon removal of dietary gluten in small intestinal mucosa in Celiac Disease. The expression level of 23 genes related to tight junctions were studied in biopsies from 16 Celiac Disease patients with active disease and compared to biopsies from the same patients taken after 2 years on gluten-free diet and to 16 non-celiac controls. Nine genes showed altered expression levels in active patients (CLDN2, PARD6A, ZAK, SYMPK, MYH14 and ACTB were upregulated, while MAGI1, TJP1 and PPP2R3A were downregulated). Alterations were reversible after two years on treatment, except for PPP2R3A, implicated in the negative control of cell growth and division. At the biological network level, important dysfunctions in several processes within the pathway were observed, including intestinal permeability, apico-basal polarity and cell proliferation. Our work confirms the involvement of tight junction genes related to permeability, polarity and cell proliferation in the epithelial destruction observed in CD. Coexpression patterns of several genes support the idea of a common regulatory mechanism that seems to be altered in active CD. In general, GFD normalization confirms the reversibility of the process, except for the constitutive downregulation of PPP2R3A suggestive of a genetic implication. Further studies in proteins and cells or tissues are necessary to confirm these findings.
    Journal of pediatric gastroenterology and nutrition 02/2014; · 2.18 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: A significant percentage of the general population report problems caused by wheat and/or gluten ingestion, even though they do not have celiac disease (CD) or wheat allergy (WA), because they test negative both for CD-specific serology and histopathology and for immunoglobulin E (IgE)-mediated assays. Most patients report both gastrointestinal and nongastrointestinal symptoms, and all report improvement of symptoms on a gluten-free diet. This clinical condition has been named non-celiac gluten sensitivity (NCGS). Aim: We attempt to define the current pathogenic, clinical, and diagnostic criteria of this "new" disease, to provide a practical view that might be useful to evaluate, diagnose, and manage NCGS patients. Methods: We reviewed the international literature through PubMed and Medline, using the search terms "wheat (hyper)sensitivity," "wheat allergy," "wheat intolerance," "gluten (hyper)sensitivity," and "gluten intolerance," and we discuss current knowledge about NCGS. Results: It has been demonstrated that patients suffering from NCGS are a heterogeneous group, composed of several subgroups, each characterized by different pathogenesis, clinical history, and, probably, clinical course. NCGS diagnosis can be reached only by excluding CD and WA. Recent evidence shows that a personal history of food allergy in infancy, coexistent atopy, positive for immunoglobulin G (IgG) antigliadin antibodies and flow cytometric basophil activation test, with wheat and duodenal and/or ileum-colon intraepithelial and lamina propria eosinophil counts, could be useful to identify NCGS patients. Conclusions: Future research should aim to identify reliable biomarkers for NCGS diagnosis and to better define the different NCGS subgroups. Key teaching points: • Most patients report both gastrointestinal and nongastrointestinal symptoms, and all agree that there is an improvement of symptoms on a gluten-free diet. • NCGS diagnosis can be reached only by excluding celiac disease and wheat allergy. • Patients suffering from NCGS are a heterogeneous group, composed of several subgroups, each characterized by different pathogenesis, clinical history, and, probably, clinical course. • A personal history of food allergy in infancy, coexistent atopy, positive IgG antigliadin antibodies (AGA) and flow cytometric basophil activation test, with wheat and duodenal and/or ileum-colon intraepithelial and lamina propria eosinophil counts, could be useful to identify NCGS patients. • Future research should aim to identify reliable biomarkers for NCGS diagnosis and to better define the different NCGS subgroup.
    Journal of the American College of Nutrition 02/2014; 33(1):39-54. · 1.74 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Many studies have investigated the aetiological roles of genetic and environmental factors in coeliac disease (CD) with the long-term goal of developing an effective primary prevention strategy. CD is a condition with dysregulated systemic and intestinal mucosal immune responses to dietary gluten proteins among genetically predisposed individuals. We recently described spring birth as a novel risk factor for CD in children. We believe that the association between season of birth and CD is due to seasonal differences in sunlight exposure and subsequent vitamin D status. Concomitant with global increases in CD prevalence, vitamin D deficiency also is increasingly recognized in children worldwide. Recent studies have shown that vitamin D deficiency can cause improper immune responses, abnormal intestinal mucosal integrity and impaired local defence to pathogenic microbial agents. In conjunction with other potential aetiological factors, we propose a hypothesis model of early-life vitamin D deficiency in the pathogenesis of childhood-onset CD.
    Public Health Nutrition 04/2014; 17(4):823-6. · 2.25 Impact Factor

Full-text (2 Sources)

View
20 Downloads
Available from
Jun 5, 2014