Synthesis of surfactant-free electrostatically stabilized gold nanoparticles by plasma-induced liquid chemistry

Plasma-induced non-equilibrium liquid chemistry is used to synthesize gold nanoparticles (AuNPs) without using any reducing or capping agents. The morphology and optical properties of the synthesized AuNPs are characterized by transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy. Plasma processing parameters affect the particle shape and size and the rate of the AuNP synthesis process. Particles of different shapes (e.g. spherical, triangular, hexagonal, pentagonal, etc) are synthesized in aqueous solutions. In particular, the size of the AuNPs can be tuned from 5 nm to several hundred nanometres by varying the initial gold precursor (HAuCl4) concentration from 2.5 μM to 1 mM. In order to reveal details of the basic plasma-liquid interactions that lead to AuNP synthesis, we have measured the solution pH, conductivity and hydrogen peroxide (H2O2) concentration of the liquid after plasma processing, and conclude that H2O2 plays the role of the reducing agent which converts Au(+3) ions to Au(0) atoms, leading to nucleation growth of the AuNPs.

Taming dendritic cells with TIM-3: another immunosuppressive strategy used by tumors

Evaluation of: Chiba S, Baghdadi M, Akiba H et al. Tumor-infiltrating DCs suppress nucleic acid-mediated innate immune responses through interactions between the receptor TIM-3 and the alarmin HMGB1. Nat. Immunol. 13, 832-842 (2012). The identification of TIM-3 expression on tumor-associated dendritic cells (TADCs) provides insight into another aspect of tumor-mediated immunosuppression. The role of TIM-3 has been well characterized on tumor-infiltrating T cells; however, its role on TADCs was not previously known. The current paper demonstrated that TIM-3 was predominantly expressed by TADCs and its interaction with the nuclear protein HMGB1 suppressed nucleic acid-mediated activation of an effective antitumor immune response. The authors were able to show that TIM-3 interaction with HMGB1 prevented the localization of nucleic acids into endosomal vesicles. Furthermore, chemotherapy was found to be more effective in anti-TIM-3 monoclonal antibody-treated mice or mice depleted of all DCs, which indicated that a significant role is played by TADCs in inhibiting tumor regression. Taken together, these findings identify TIM-3 as a potential target for inducing antitumor immunity in conjunction with DNA vaccines and/or immunogenic chemotherapy in clinical settings.

Increased B7-1 (CD80) expression reduces overall tumorigenicity and metastatic potential of the murine pancreatic cancer cell model Pan02 (P2085)

Pancreatic cancer is both difficult to detect and harbors survival rates as low as 5%, thus heightening the need for better and new therapies. Several molecules have been investigated to increase the immunogenicity of tumor cells including the costimulatory molecule B7-1. The murine pancreatic cancer cell line, Pan02, expresses low, endogenous levels of B7-1; however, the role of B7-1 in pancreatic cancer progression has not yet been elucidated. We hypothesized that increased cell surface expression of B7-1 in the Pan02 model would decrease tumor growth and metastasis. To test this, Pan02 cells were transfected with mB7-1 (Pan02-mB7-1). Flow cytometry analysis confirmed a 40-fold increase in B7-1 cell surface expression in transfected cells compared to WT. In order to assess the in vivo effects of increased B7-1 expression, C57BL/6 mice, were challenged with Pan02-mB7-1 and Pan02-WT cells. We observed that B7-1 transfected Pan02 cells showed an overall decrease in tumor kinetics compared to mice challenged with Pan02-WT. In addition, increased cell surface B7-1 expression prevented metastasis to the lung in tumor positive C57BL-6 mice. More interestingly, Pan02 cells that metastasized to the lung (Pan02-RG-M-Lung) from WT challenged mice showed lower B7-1 expression by flow cytometry compared to Pan02-WT cells. Taken together, increased cell surface B7-1 expression is successful in inhibiting tumor growth and preventing metastasis in the murine pancreatic cancer model.

GPI-GM-CSF protein transferred onto H5 influenza VLPs remains stably expressed and functionally active (P6168)

Pathogenic H5N1, a lipid-enveloped influenza virus, is a pandemic threat. The use of virus-like particles (VLPs) as an alternative to current influenza vaccines is highly promising. VLPs are similar in structure to their live viral counterparts but do not contain viral genome that is required for replication; hence VLPs provide for a safe and immunogenic vaccine. Although the particulate nature of VLPs allows them to be highly immunogenic, the need for protection against heterotypic viruses still remains. Therefore, inclusion of immunostimulatory molecules (ISMs) onto the VLP surface can help to induce cross-protection against strains and provide for stronger immunity. We were able to show that GPI-anchored-GM-CSF can incorporate stably onto H5 influenza VLP surfaces after a simple and quick protein transfer method. This method allows for the incorporation of the GPI-anchor onto the surface of lipid-bilayered VLPs within a matter of hours and allows for the incorporation of multiple GPI-ISMs in a concentration-dependent manner. Furthermore, protein transferred VLPs were functional in leading to bone marrow derived cell proliferation compared to unmodified VLPs, and incorporated GM-CSF was as functional as equal concentrations of commercially available recombinant soluble GM-CSF. Therefore, VLPs expressing GPI-GM-CSF could lead to enhanced immunogenicity and antiviral immune responses compared to unmodified VLPs.