Duodenal mucosa of untreated celiac disease patients has altered expression of the GAS6 and PROS1 and the negative regulator tyrosine kinase TAM receptors subfamily.

Celiac disease (CD) is an immune-driven disease characterized by tissue damage in the small intestine of genetically-susceptible individuals. We evaluated here a crucial immune regulatory pathway involving TYRO3, AXL, and MERTK (TAM) receptors and their ligands PROS1 and GAS6 in duodenal biopsies of controls and CD patients. We found increased GAS6 expression associated with downregulation of PROS1 and variable TAM receptors levels in duodenum tissue of CD patients. Interestingly, CD3+ lymphocytes, CD68+, CD11c+ myeloid and epithelial cells, showed differential expressions of TAM components comparing CD vs controls. Principal component analysis revealed a clear segregation of two groups of CD patients based on TAM components and IFN signaling. In vitro validation demonstrated that monocytes, T lymphocytes and epithelial cells upregulated TAM components in response to IFN stimulation. Our findings highlight a dysregulated TAM axis in CD related to IFN signaling and contribute to a deeper understanding of the pathophysiology of CD.

IL-1ß blockade prevents cell death and mucosal damage of the small intestine in a model of sterile inflammation.

The intestinal mucosa is covered by a layer of epithelial cells that is constantly challenged by commensal, opportunistic, and pathogenic microorganisms, their components, and harmful compounds. Any inflammatory response to these materials must be tightly controlled to limit tissue damage and restore the integrity of the mucosal barrier. We have shown previously that production of IL-1ß via activation of the inflammasome can lead to mucosal damage in the small intestinal pathology that occurs after intragastric administration of a gluten derived peptide, p31-43. Here we show that specific inhibition of caspase-1 or NLRP3 abolishes the damage induced by p31-43, and that antibody-mediated blocking of IL-1ß inhibits the both the histological changes and the induction of apoptosis and caspase-3 activation driven by p31-43. Understanding the role of IL-1ß in sterile inflammation may help to understand chronic inflammatory pathological processes, and design new intervention strategies.

Programmed Cell Death in the Small Intestine: Implications for the Pathogenesis of Celiac Disease.

The small intestine has a high rate of cell turnover under homeostatic conditions, and this increases further in response to infection or damage. Epithelial cells mostly die by apoptosis, but recent studies indicate that this may also involve pro-inflammatory pathways of programmed cell death, such as pyroptosis and necroptosis. Celiac disease (CD), the most prevalent immune-based enteropathy, is caused by loss of oral tolerance to peptides derived from wheat, rye, and barley in genetically predisposed individuals. Although cytotoxic cells and gluten-specific CD4+ Th1 cells are the central players in the pathology, inflammatory pathways induced by cell death may participate in driving and sustaining the disease through the release of alarmins. In this review, we summarize the recent literature addressing the role of programmed cell death pathways in the small intestine, describing how these mechanisms may contribute to CD and discussing their potential implications.

p31-43 Gliadin Peptide Forms Oligomers and Induces NLRP3 Inflammasome/Caspase 1- Dependent Mucosal Damage in Small Intestine.

Celiac disease (CD) is a chronic enteropathy elicited by a Th1 response to gluten peptides in the small intestine of genetically susceptible individuals. However, it remains unclear what drives the induction of inflammatory responses of this kind against harmless antigens in food. In a recent work, we have shown that the p31-43 peptide (p31-43) from α-gliadin can induce an innate immune response in the intestine and that this may initiate pathological adaptive immunity. The receptors and mechanisms responsible for the induction of innate immunity by p31-43 are unknown and here we present evidence that this may reflect conformational changes in the peptide that allow it to activate the NLRP3 inflammasome. Administration of p31-43, but not scrambled or inverted peptides, to normal mice induced enteropathy in the proximal small intestine, associated with increased production of type I interferon and mature IL-1ß. P31-43 showed a sequence-specific spontaneous ability to form structured oligomers and aggregates in vitro and induced activation of the ASC speck complex. In parallel, the enteropathy induced by p31-43 in vivo did not occur in the absence of NLRP3 or caspase 1 and was inhibited by administration of the caspase 1 inhibitor Ac-YVAD-cmk. Collectively, these findings show that p31-43 gliadin has an intrinsic propensity to form oligomers which trigger the NLRP3 inflammasome and that this pathway is required for intestinal inflammation and pathology when p31-43 is administered orally to mice. This innate activation of the inflammasome may have important implications in the initial stages of CD pathogenesis.

In vitro presentation of gliadin-derived peptides by different cell lines.

BACKGROUND: Gliadin peptide presentation and T-cell activation are critical events in the pathogenesis of celiac disease. Several studies have been performed to identify the toxic gliadin peptides but the complexity of the antigenic fraction makes this analysis difficult. In this work, an in vitro model for the analysis of gliadin peptide presentation is studied. METHODS: The human cell lines U937 and THP-1 (monocytic), DUCAF and VAVY (immortalised B cells) and HT-29 and Caco-2 (intestinal epithelial cells) were incubated with biotin-labelled gliadin (bG). FITC-labelled streptavidin was used to detect biotinylated peptides at the cell surface by flow cytometry. RESULTS: All cell lines tested showed a fluorescence signal derived from bG, that was highest when cells were stimulated with IFN-gamma for 48 h. Time course experiments performed using THP-1 cells showed that after 4-h incubation, almost a maximal signal can be reached. THP-1 cells incubated at 4 degrees C or after paraformaldehyde fixation showed a substantial signal reduction, suggesting that metabolic activity was necessary for the detection of the maximal fluorescence signal at the cell surface. The presence of HLA class II-bound biotinylated peptides was observed in cell lysates of THP-1 cells incubated with bG. CONCLUSIONS: In all cell lines tested, a specific biotin-peptide-derived signal was observed. This was increased after IFN-gamma treatment and decreased after fixation or incubation at low temperature. The signal was higher in monocytic and B-cell lines than in the epithelial cell lines. The use of this procedure could be a useful tool to study the in vitro processing and presentation of naturally gliadin-derived peptides.

Desarrollo de un ELISA de alta detectabilidad y especificidad para la cuantificación de gliadinas en alimentos destinados a enfermos celíacos / Development of a quantitative ELISA to determination of gladins in food aimed to coeliac patients

La enfermedad celíaca (EC) es una enfermedad gastrointestinal crónica de muy alta incidencia en nuestro país. Se estima que puede afectar 1 de cada 300 habitantes. En individuos susceptibles, la patología es provocada por la ingestión de mínimas cantidades de prolaminas de los cereales: trigo, triticale, cebada y centeno. Su único tratamiento es una estricta dieta libre de dichas proteínas. La Organización Mundial de la Salud (OMS) establece que un alimento puede ser considerado como apto para consumo por enfermos celíacos sólo si su contenido de gluten es inferior a 1 mg/100 g de producto seco. La detección precisa de estas proteínas requiere entonces de métodos de alta detectabilidad y especificidad para discriminar entre las proteínas nocivas y las de otros vegetales frecuentemente usados como reemplazo en la formulación de los alimentos para estos pacientes. En este trabajo, se muestra el desarrollo de un ELISA con anticuerpos policlonales, para la cuantificación de gliadinas en alimentos destinados a enfermos celíacos. Se empleó un diseño de ELISA competitivo secuencial con un antisuero obtenido en conejos que detecta selectivamente las prolaminas tóxicas. Este inmunoensayo presenta un nivel de detección de 0,1 mg de gluten/100 g de producto y cumple con los niveles de detectabilidad aconsejados por la OMS. Mediante el ELISA descripto se han analizado una gran variedad de muestras comerciales, pudiendo cuantificar las prolaminas incluso en alimentos que sufrieron tratamientos térmicos durante su fabricación (AU)

Desarrollo de un ELISA de alta detectabilidad y especificidad para la cuantificación de gliadinas en alimentos destinados a enfermos celíacos / Development of a quantitative ELISA to determination of gladins in food aimed to coeliac patients

La enfermedad celíaca (EC) es una enfermedad gastrointestinal crónica de muy alta incidencia en nuestro país. Se estima que puede afectar 1 de cada 300 habitantes. En individuos susceptibles, la patología es provocada por la ingestión de mínimas cantidades de prolaminas de los cereales: trigo, triticale, cebada y centeno. Su único tratamiento es una estricta dieta libre de dichas proteínas. La Organización Mundial de la Salud (OMS) establece que un alimento puede ser considerado como apto para consumo por enfermos celíacos sólo si su contenido de gluten es inferior a 1 mg/100 g de producto seco. La detección precisa de estas proteínas requiere entonces de métodos de alta detectabilidad y especificidad para discriminar entre las proteínas nocivas y las de otros vegetales frecuentemente usados como reemplazo en la formulación de los alimentos para estos pacientes. En este trabajo, se muestra el desarrollo de un ELISA con anticuerpos policlonales, para la cuantificación de gliadinas en alimentos destinados a enfermos celíacos. Se empleó un diseño de ELISA competitivo secuencial con un antisuero obtenido en conejos que detecta selectivamente las prolaminas tóxicas. Este inmunoensayo presenta un nivel de detección de 0,1 mg de gluten/100 g de producto y cumple con los niveles de detectabilidad aconsejados por la OMS. Mediante el ELISA descripto se han analizado una gran variedad de muestras comerciales, pudiendo cuantificar las prolaminas incluso en alimentos que sufrieron tratamientos térmicos durante su fabricación