Intestinal Microbiota Modulates Gluten-Induced Immunopathology in Humanized Mice

Celiac disease (CD) is an immune-mediated enteropathy triggered by gluten in genetically susceptible individuals. The recent increase in CD incidence suggests that additional environmental factors, such as intestinal microbiota alterations, are involved in its pathogenesis. However, there is no direct evidence of modulation of gluten-induced immunopathology by the microbiota. We investigated whether specific microbiota compositions influence immune responses to gluten in mice expressing the human DQ8 gene, which confers moderate CD genetic susceptibility. Germ-free mice, clean specific-pathogen-free (SPF) mice colonized with a microbiota devoid of opportunistic pathogens and Proteobacteria, and conventional SPF mice that harbor a complex microbiota that includes opportunistic pathogens were used. Clean SPF mice had attenuated responses to gluten compared to germ-free and conventional SPF mice. Germ-free mice developed increased intraepithelial lymphocytes, markers of intraepithelial lymphocyte cytotoxicity, gliadin-specific antibodies, and a proinflammatory gliadin-specific T-cell response. Antibiotic treatment, leading to Proteobacteria expansion, further enhanced gluten-induced immunopathology in conventional SPF mice. Protection against gluten-induced immunopathology in clean SPF mice was reversed after supplementation with a member of the Proteobacteria phylum, an enteroadherent Escherichia coli isolated from a CD patient. The intestinal microbiota can both positively and negatively modulate gluten-induced immunopathology in mice. In subjects with moderate genetic susceptibility, intestinal microbiota changes may be a factor that increases CD risk.Facultad de Ciencias Exacta

Transient elastography in autoimmune hepatitis: Timing determines the impact of inflammation and fibrosis

Background & Aims: There is an unmet need for the non-invasive monitoring of fibrosis progression in patients with autoimmune hepatitis (AIH). The aim of this study was to assess the diagnostic performance of transient elastography in patients with AIH and to investigate the impact of disease activity on its diagnostic accuracy. Methods: Optimal cut-offs were defined in a prospective pilot study (n = 34) and the diagnostic performance of transient elastography validated in an independent second cohort (n = 60). To explore the impact of disease activity on liver stiffness, patients were stratified according to biochemical response and the time interval between start of immunosuppression and transient elastography. Results: Liver stiffness strongly correlated with histological fibrosis stage (pilot study: rho = 0.611, p <0.001; validation cohort: rho = 0.777, p <0.0001). ROC curves defined an area under the receiver operating curve of 0.95 for diagnosing cirrhosis at the optimal cut-off of 16 kPa. The performance of transient elastography was impaired when patients were analysed in whom transient elastography was performed within 3 months from start of treatment. In this setting, liver stiffness correlated with histological grading (rho = 0.558, p = 0.001), but not with staging. In contrast, using the cut-off of 16 kPa, the accuracy for diagnosing cirrhosis was excellent in patients treated for 6 months or longer (area under the receiver operating curve 1.0). Conclusions: Liver inflammation has a major impact on liver stiffness in the first months of AIH treatment. However, transient elastography has an excellent diagnostic accuracy for separating severe from non-severe fibrosis after 6 months of immunosuppressive treatment. Lay summary: Transient elastography is a special ultrasound scan, which assesses liver stiffness as a surrogate marker for liver fibrosis/scarring. Transient elastography has been shown to be a reliable non-invasive method to assess liver fibrosis in various chronic liver diseases, it takes less than 5 min and has a high patient acceptance. The current study validated for the first time this technique in a large cohort of patients with autoimmune hepatitis (AIH) and demonstrates that it is a reliable tool to detect liver fibrosis in treated AIH. For the monitoring of potential disease progression under treatment, the validation of liver stiffness as non-invasive marker of liver fibrosis will greatly improve patient care in autoimmune hepatitis. (C) 2016 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved

Intestinal microbiota modulates gluten-induced immunopathology in humanized mice

Celiac disease (CD) is an immune-mediated enteropathy triggered by gluten in genetically susceptible individuals. The recent increase in CD incidence suggests that additional environmental factors, such as intestinal microbiota alterations, are involved in its pathogenesis. However, there is no direct evidence of modulation of gluten-induced immunopathology by the microbiota. We investigated whether specific microbiota compositions influence immune responses to gluten in mice expressing the human DQ8 gene, which confers moderate CD genetic susceptibility. Germ-free mice, clean specific-pathogen-free (SPF) mice colonized with a microbiota devoid of opportunistic pathogens and Proteobacteria, and conventional SPF mice that harbor a complex microbiota that includes opportunistic pathogens were used. Clean SPF mice had attenuated responses to gluten compared to germ-free and conventional SPF mice. Germ-free mice developed increased intraepithelial lymphocytes, markers of intraepithelial lymphocyte cytotoxicity, gliadin-specific antibodies, and a proinflammatory gliadin-specific T-cell response. Antibiotic treatment, leading to Proteobacteria expansion, further enhanced gluten-induced immunopathology in conventional SPF mice. Protection against gluten-induced immunopathology in clean SPF mice was reversed after supplementation with a member of the Proteobacteria phylum, an enteroadherent Escherichia coli isolated from a CD patient. The intestinal microbiota can both positively and negatively modulate gluten-induced immunopathology in mice. In subjects with moderate genetic susceptibility, intestinal microbiota changes may be a factor that increases CD risk.Fil: Galipeau, Heather J.. McMaster University; CanadáFil: McCarville, Justin L.. McMaster University; CanadáFil: Huebener, Sina. Columbia University Medical Center; Estados UnidosFil: Litwin, Owen. McMaster University; CanadáFil: Meisel, Marlies. University of Chicago; Estados UnidosFil: Jabri, Bana. University of Chicago; Estados UnidosFil: Sanz, Yolanda. Consejo Superior de Investigaciones Científicas. Instituto de Agroquímica y Tecnología de Alimentos; EspañaFil: Murray, Joseph A.. Mayo Clinic College of Medicine and Science; Estados UnidosFil: Jordana, Manel. McMaster University; CanadáFil: Alaedini, Armin. Columbia University Medical Center; Estados UnidosFil: Chirdo, Fernando Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Estudios Inmunológicos y Fisiopatológicos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Estudios Inmunológicos y Fisiopatológicos; ArgentinaFil: Verdu, Elena F.. McMaster University; Canad

Specific Nongluten Proteins of Wheat Are Novel Target Antigens in Celiac Disease Humoral Response

While the antigenic specificity and pathogenic relevance of immunologic reactivity to gluten in celiac disease have been extensively researched, the immune response to nongluten proteins of wheat has not been characterized. We aimed to investigate the level and molecular specificity of antibody response to wheat nongluten proteins in celiac disease. Serum samples from patients and controls were screened for IgG and IgA antibody reactivity to a nongluten protein extract from the wheat cultivar <i>Triticum aestivum</i> Butte 86. Antibodies were further analyzed for reactivity to specific nongluten proteins by two-dimensional gel electrophoresis and immunoblotting. Immunoreactive molecules were identified by tandem mass spectrometry. Compared with healthy controls, patients exhibited significantly higher levels of antibody reactivity to nongluten proteins. The main immunoreactive nongluten antibody target proteins were identified as serpins, purinins, α-amylase/protease inhibitors, globulins, and farinins. Assessment of reactivity toward purified recombinant proteins further confirmed the presence of antibody response to specific antigens. The results demonstrate that, in addition to the well-recognized immune reaction to gluten, celiac disease is associated with a robust humoral response directed at a specific subset of the nongluten proteins of wheat