• Haplotypes of the porcine peroxisome proliferator-activated receptor delta gene are associated with backfat thickness.

      Meidtner, Karina; Schwarzenbacher, Hermann; Scharfe, Maren; Severitt, Simone; Blöcker, Helmut; Fries, Ruedi; Chair of Animal Breeding, Technical University of Munich, Hochfeldweg 1, 85354 Freising - Weihenstephan, Germany. karina.meidtner@tierzucht.tum.de (2009)
      BACKGROUND: Peroxisome proliferator-activated receptor delta belongs to the nuclear receptor superfamily of ligand-inducible transcription factors. It is a key regulator of lipid metabolism. The peroxisome proliferator-activated receptor delta gene (PPARD) has been assigned to a region on porcine chromosome 7, which harbours a quantitative trait locus for backfat. Thus, PPARD is considered a functional and positional candidate gene for backfat thickness. The purpose of this study was to test this candidate gene hypothesis in a cross of breeds that were highly divergent in lipid deposition characteristics. RESULTS: Screening for genetic variation in porcine PPARD revealed only silent mutations. Nevertheless, significant associations between PPARD haplotypes and backfat thickness were observed in the F2 generation of the Mangalitsa x Piétrain cross as well as a commercial German Landrace population. Haplotype 5 is associated with increased backfat in F2 Mangalitsa x Piétrain pigs, whereas haplotype 4 is associated with lower backfat thickness in the German Landrace population. Haplotype 4 and 5 carry the same alleles at all but one SNP. Interestingly, the opposite effects of PPARD haplotypes 4 and 5 on backfat thickness are reflected by opposite effects of these two haplotypes on PPAR-delta mRNA levels. Haplotype 4 significantly increases PPAR-delta mRNA levels, whereas haplotype 5 decreases mRNA levels of PPAR-delta. CONCLUSION: This study provides evidence for an association between PPARD and backfat thickness. The association is substantiated by mRNA quantification. Further studies are required to clarify, whether the observed associations are caused by PPARD or are the result of linkage disequilibrium with a causal variant in a neighbouring gene.
    • Potentiation of epithelial innate host responses by intercellular communication.

      Dolowschiak, Tamas; Chassin, Cécilia; Ben Mkaddem, Sanae; Fuchs, Thilo M; Weiss, Siegfried; Vandewalle, Alain; Hornef, Mathias W; Hannover Medical School, Hannover, Germany. (2010)
      The epithelium efficiently attracts immune cells upon infection despite the low number of pathogenic microbes and moderate levels of secreted chemokines per cell. Here we examined whether horizontal intercellular communication between cells may contribute to a coordinated response of the epithelium. Listeria monocytogenes infection, transfection, and microinjection of individual cells within a polarized intestinal epithelial cell layer were performed and activation was determined at the single cell level by fluorescence microscopy and flow cytometry. Surprisingly, chemokine production after L. monocytogenes infection was primarily observed in non-infected epithelial cells despite invasion-dependent cell activation. Whereas horizontal communication was independent of gap junction formation, cytokine secretion, ion fluxes, or nitric oxide synthesis, NADPH oxidase (Nox) 4-dependent oxygen radical formation was required and sufficient to induce indirect epithelial cell activation. This is the first report to describe epithelial cell-cell communication in response to innate immune activation. Epithelial communication facilitates a coordinated infectious host defence at the very early stage of microbial infection.
    • Type I Interferons Interfere with the Capacity of mRNA Lipoplex Vaccines to Elicit Cytolytic T Cell Responses.

      De Beuckelaer, Ans; Pollard, Charlotte; Van Lint, Sandra; Roose, Kenny; Van Hoecke, Lien; Naessens, Thomas; Udhayakumar, Vimal Kumar; Smet, Muriel; Sanders, Niek; Lienenklaus, Stefan; et al. (2016-11)
      Given their high potential to evoke cytolytic T cell responses, tumor antigen-encoding messenger RNA (mRNA) vaccines are now being intensively explored as therapeutic cancer vaccines. mRNA vaccines clearly benefit from wrapping the mRNA into nano-sized carriers such as lipoplexes that protect the mRNA from degradation and increase its uptake by dendritic cells in vivo. Nevertheless, the early innate host factors that regulate the induction of cytolytic T cells to mRNA lipoplex vaccines have remained unresolved. Here, we demonstrate that mRNA lipoplexes induce a potent type I interferon (IFN) response upon subcutaneous, intradermal and intranodal injection. Regardless of the route of immunization applied, these type I IFNs interfered with the generation of potent cytolytic T cell responses. Most importantly, blocking type I IFN signaling at the site of immunization through the use of an IFNAR blocking antibody greatly enhanced the prophylactic and therapeutic antitumor efficacy of mRNA lipoplexes in the highly aggressive B16 melanoma model. As type I IFN induction appears to be inherent to the mRNA itself rather than to unique properties of the mRNA lipoplex formulation, preventing type I IFN induction and/or IFNAR signaling at the site of immunization might constitute a widely applicable strategy to improve the potency of mRNA vaccination.