What intracellular receptors are involved in recognition of S. Typhimurium in mouse intestinal epithelial cells ?

National audienc

Gene expression profile of enterocytes purified from two lines of chicken during the <em>Salmonella</em> carrier state

National audienc

Inoculation of four commensal bacteria in chicken has an impact on the gut microbiota composition, Salmonella colonisation and the immune response

International audienceAim: Many studies have revealed the importance of heterogeneous shedding levels in the context of infectious diseases. Individual hosts that excrete higher levels of pathogens (so-called super-shedders) are key targets for control strategies. However, the mechanisms associated with the emergence of super-shedders remain largely unknown. The development of a new infection model for chickens reared in isolator, where animal reinfections are greatly reduced, has allowed us to demonstrate that two main Salmonella Enteritidis shedding phenotypes can emerge within the same chicken genetic background. These phenotypes were designated as super- and low-shedder on the levels of Salmonella faecal excretion and caecal colonization. Methods and results: In this project, we analysed the parameters that could be responsible for these phenotypes, namely: 1- the modification of the virulence of the Salmonella strain during the asymptomatic carrier state ; 2- the faecal and caecal microbiota composition ; 3- the immune status of chicks measured in kinetic in blood. We also analysed the impact on these parameters of four commensal bacteria inoculated before infection. Conclusions: The data obtained showed the protective effect of the four commensal bacteria on Salmonella excretion and their major impact on gut microbiota composition and immune response

Susceptibility to Salmonella carrier-state: A possible Th2 response in susceptible chicks

Infection of chicken with Salmonella may lead to a carrier-state characterized by the persistence of bacteria in the ceca for a long period of time and result in their excretion in feces. This excretion is the source of contamination of their congeners and food. During infection, enterocytes are the primary target cells for Salmonella, the producers of soluble factors which launch immune response and cells which are reciprocally responsive to surrounding immune cells. This study used microarrays to compare the gene expression profile during carrier-state of enterocytes purified from infected and control chicks which are either resistant or susceptible to Salmonella Enteritidis carrier-state. In total, we identified 271 genes significantly differentially expressed with an absolute fold change greater than 1.5. A global analysis determined interaction networks between differentially regulated genes. Using an a priori approach, our analyses focused on differentially expressed genes which were transcriptionally linked to cytokines playing a major role in the fate of the immune response. The expression of genes transcriptionally linked to type I interferon and TGF-beta was down-regulated in infected chicks from both lines. Gene expression linked to the Th1 axis suggests the latter is inhibited in both lines. Finally, the expression of genes linked to IL-4, IL-5 and IL-13 indicates that susceptibility to carrier-state could be associated with a Th2 bias. Overall, these results highlight that the response to Salmonella during the acute phase and carrier-state is different and that enterocytes play a central role in this response. (C) 2014 Elsevier B.V. All rights reserved

Analysis of MHC polymorphism in a histocompatible B19 chicken line: role of Rfp-Y locus

International audienc

Identifying potential biomarkers to improve production in pigs

International audienc

Epithelial cell invasion by salmonella typhimurium induces modulation of genes controlled by aryl hydrocarbon receptor signaling and involved in extracellular matrix biogenesis

International audienceSalmonella is the only bacterium able to enter a host cell by the two known mechanisms: trigger and zipper. The trigger mechanism relies on the injection of bacterial effectors into the host cell through the Salmonella type III secretion system 1. In the zipper mechanism, mediated by the invasins Rck and PagN, the bacterium takes advantage of a cellular receptor for invasion. This study describes the transcriptomic reprogramming of the IEC-6 intestinal epithelial cell line to Salmonella Typhimurium strains that invaded cells by a trigger, a zipper, or both mechanisms. Using S. Typhimurium strains invalidated for one or other entry mechanism, we have shown that IEC-6 cells could support both entries. Comparison of the gene expression profiles of exposed cells showed that irrespective of the mechanism used for entry, the transcriptomic reprogramming of the cell was nearly the same. On the other hand, when gene expression was compared between cells unexposed or exposed to the bacterium, the transcriptomic reprogramming of exposed cells was significantly different. It is particularly interesting to note the modulation of expression of numerous target genes of the aryl hydrocarbon receptor showing that this transcription factor was activated by S. Typhimurium infection. Numerous genes associated with the extracellular matrix were also modified. This was confirmed at the protein level by western-blotting showing a dramatic modification in some extracellular matrix proteins. Analysis of a selected set of modulated genes showed that the expression of the majority of these genes was modulated during the intracellular life of S. Typhimurium

Epithelial cell invasion by salmonella typhimurium induces modulation of genes controlled by aryl hydrocarbon receptor signaling and involved in extracellular matrix biogenesis

ABSTRACTSalmonella is the only bacterium able to enter a host cell by the two known mechanisms: trigger and zipper. The trigger mechanism relies on the injection of bacterial effectors into the host cell through the Salmonella type III secretion system 1. In the zipper mechanism, mediated by the invasins Rck and PagN, the bacterium takes advantage of a cellular receptor for invasion. This study describes the transcriptomic reprogramming of the IEC-6 intestinal epithelial cell line to Salmonella Typhimurium strains that invaded cells by a trigger, a zipper, or both mechanisms. Using S. Typhimurium strains invalidated for one or other entry mechanism, we have shown that IEC-6 cells could support both entries. Comparison of the gene expression profiles of exposed cells showed that irrespective of the mechanism used for entry, the transcriptomic reprogramming of the cell was nearly the same. On the other hand, when gene expression was compared between cells unexposed or exposed to the bacterium, the transcriptomic reprogramming of exposed cells was significantly different. It is particularly interesting to note the modulation of expression of numerous target genes of the aryl hydrocarbon receptor showing that this transcription factor was activated by S. Typhimurium infection. Numerous genes associated with the extracellular matrix were also modified. This was confirmed at the protein level by western-blotting showing a dramatic modification in some extracellular matrix proteins. Analysis of a selected set of modulated genes showed that the expression of the majority of these genes was modulated during the intracellular life of S. Typhimurium

Identification of genes which are associated with production diseases in pigs and chickens

Production disease in pigs and chickens is caused by a variety of different pathogens, mainly enteric and respiratory, which may result in significant economic losses. Other factors such as stress, poor husbandry and nutrition can also contribute to an animal’s susceptibility to disease. Molecular biomarkers of production disease could be of value by improving diagnosis and risk analysis to determine best practice with an impact on increased economic output and animal welfare. Over 480 chicken tissue samples from countries including Belgium, Spain and the UK, and over 115 pig samples from Belgium, Spain, France and Ireland were available. Samples included lung, intestine, mesenteric and tracheobronchic lymph node, bone, cartilage and sciatic nerve. Two types of software were used to analyse the microarray data; Genespring was used for statistical analysis and visualisation of transcriptomic data and Cytoscape was used to visualise molecular interaction networks between genes. Results indicated that panels of genes may identify a broad spectrum of infectious disease in chickens, whereas combinations of upregulated genes may be used as biomarkers of specific pathogens such as Escherichia coli or Eimeria. Pigs from two lines (RFI high and low) were kept in dirty environments which had the same bedding and clean environments which had fresh bedding. A greater difference was observed in the number of genes differentially expressed in the RFI high pigs than RFI low pigs. Pathway analysis from both chicken and pig experiments indicated that many networks were affected including those involved in regulating the immune-system. Whilst a large number of studies have been carried out in human medicine, further work is needed to identify molecular biomarkers in veterinary medicine and in particular those associated with production disease in the pig and poultry livestock industry