• Influence of infection route and virulence factors on colonization of solid tumors by Salmonella enterica serovar Typhimurium.

      Crull, Katja; Bumann, Dirk; Weiss, Siegfried; Dept. Molecular Immunology, Helmholtz Centre for infection research, Inhoffenstr. 7, D38124 Braunschweig, Germany. (2011-06)
      Administration of facultative anaerobic bacteria such as Salmonella enterica serovar Typhimurium as anticancer treatment holds a great therapeutic potential. Here, we tested different routes of application of S. typhimurium with regard to tumor colonization and therapeutic efficacy. No differences between intravenous and intraperitoneal infection were observed, often leading to a complete tumor clearance. In contrast, after oral application, tumor colonization was inefficient and delayed. No therapeutic effect was observed under such conditions. We also showed that tumor invasion and colonization were independent of functional Salmonella pathogenicity island (SPI) 1 and SPI 2. Furthermore, tumor invasion and colonization did not require bacterial motility or chemotactic responsiveness. The distribution of the bacteria within the tumor was independent of such functions.
    • 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; Saelens, Xavier; Weiss, Siegfried; Vanham, Guido; Grooten, Johan; De Koker, Stefaan; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (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.