Coeliac disease (CD) is a malabsorptive enteropathy resulting from intolerance to gluten. Environmental factors and the microbiota are suggested to have critical roles in the onset of CD. The CD71 IgA receptor on epithelial cells is responsible for abnormal retrotranscytosis of IgA-gluten peptide complexes from the intestinal lumen into the lamina propria, inducing intestinal inflammation. However, understanding the role of gluten in the CD physiopathology has been hindered by the absence of relevant animal models. Here, we generated a mouse model for CD to study the factors controlling its pathogenesis as well as to investigate the influence of oral delivery of probiotics on disease development. Gluten sensitivity was established by feeding three generations of BALB/c mice a gluten-free diet (GÀ) followed by gluten challenge (G þ ) for 30 days. The G þ mice developed villous atrophy, crypt hyperplasia and infiltration of T cells and macrophages in the small intestine. Inflammation was associated with an overexpression of CD71 on the apical side of enterocytes and an increase of plasma cells producing IgA, which colocalised with the CD71. Moreover, IgA colocalised with the transglutaminase 2 (TG2), the production of which was increased in the lamina propria of G þ mice. These mice displayed increased production of cyclooxygenase-2 (COX-2), pro-inflammatory cytokines and IL-15, as well as anti-gliadin and anti-TG2 autoantibodies. The commensal flora-isolated presumptive probiotic Saccharomyces boulardii KK1 strain hydrolysed the 28-kDa a-gliadin fraction, and its oral delivery in G þ mice improved enteropathy development in association with decrease of epithelial cell CD71 expression and local cytokine production. In conclusion, the G þ BALB/c mouse represents a new mouse model for human CD based on histopathological features and expression of common biomarkers. The selected probiotic treatment reversing disease development will allow the study of the role of probiotics as a new therapeutic approach of CD.
Aims: To validate the use of the air pouch system to predict and examine early immune responses induced by the presumptive probiotics Lactobacillus paracasei subsp. paracasei B112, DC205, DC215 and DC412 strains in the gut mucosa. Methods and Results: Only the DC412 strain interacted strongly with the cells forming the air pouch lining tissue and induced early innate immune responses such as polymorphonuclear (PMN) cell recruitment, phagocytosis and tumour necrosis factor alpha (TNF‐α) production that equal the respective responses induced by the probiotic Lactobacillus acidophilus NCFB 1748. The strains exhibiting strong immunoregulatory activity in the air pouch also interacted strongly with the gut‐associated lymphoid tissue (GALT). The strain DC412 exerts its effect on the intestine through stimulation of Toll‐like receptor (TLR)2/TLR4‐mediated signalling events leading to secretion of a certain profile of cytokines in which gamma interferon (IFN‐γ), TNF‐α, interleukin (IL)‐6 and IL‐10 are included. The probiotic Lact. acidophilus NCFB 1748 induces the same cytokine profile in addition to IL‐12B, and this response is potentially mediated by the synergy of TLR2 and TLR9. Conclusion: The strain DC412 possesses the in vitro and in vivo characteristics of a probiotic micro‐organism. Significance and Impact of the Study: The dorsal mouse or rat air pouch may be used as an alternative and rapid method for the initial discrimination and selection of potential probiotic Lactobacillus strains.
Aims: To determine the immunostimulatory activity of 15 presumptive probiotic yeast strains in the dorsal air pouch system in comparison with their activity in the gut mucosa. Methods and Results: Presumptive probiotic yeast strains previously isolated from human gastrointestinal tract and Feta cheese were further characterized genotypically and biochemically. The Saccharomyces cerevisiae 982, Saccharomyces boulardii KK1 and Kluyveromyces lactis 630 strains exhibited in the air pouch increased polymorphonuclear cell influx and phagocytic activity as well as cytokine production with similar potency as the probiotics Ultra levure S. boulardii and Lactobacillus acidophilus NCFB 1748. Oral administration of these strains in mice results in differential activation of small intestine immune responses concerning IgA and cytokine production as well as Toll‐like receptor expression. Conclusion: Besides the Saccharomyces strains 982 and KK1, the K. lactis 630 strain could also be considered as a candidate probiotic. Significance and Impact of the Study: The air pouch model may be used as an alternative and rapid method for the discrimination and selection of potential probiotic yeast strains.
Aims: In this study we analysed urban, hospital wastewater and pig faeces samples to investigate the presence of vancomycin‐resistant Enterococcus faecium strains (VREF) and to determine potential links among the strains originating from the above sources and VREF strains causing clinical infections. Methods and Results: Urban, hospital wastewater and pig faeces exhibited high VREF prevalence of 52%, 87% and 85%, respectively. Pulsed field gel electrophoresis (PFGE) clustering of VREF genotypes as well as discriminant analysis of antibiotic resistance patterns of VREF strains revealed their source specificity while strains isolated from hospitalized humans were genetically distinct. Conclusions: PFGE genotypes and antimicrobial resistance patterns in VREF isolates are distinguishable by each sample origin. The observed high genetic diversity of VREF suggests horizontal transfer of genetic elements among VREF. Phenotypic and genotypic data indicate that VREF isolates of hospital‐treated wastewater might pass to the urban wastewater system. Significance and Impact of the Study: This study provides information to understand the origin and the mechanism of circulation of vancomycin resistance in food animals and wastewater treatment plants for minimizing the risk of transmission of VRE in human population.
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