Paul D. Bryson

PD-1/PD-L1 Blockade Can Enhance HIV-1 Gag-specific T Cell Immunity Elicited by Dendritic Cell-Directed Lentiviral Vaccines

Exhaustion of CD8(+) T cells and upregulation of programmed death 1 (PD-1), a negative regulator of T cell activation, are characteristic features of individuals chronically infected with human immunodeficiency virus type 1. In a previous study, we showed in mice that a dendritic cell-directed lentiviral vector (DCLV) system encoding the human immunodeficiency virus (HIV)-1 Gag protein was an efficient vaccine modality to induce a durable Gag-specific T cell immune response. In this study, we demonstrate that blocking of the PD-1/PD-1 ligand (PD-L) inhibitory signal via an anti-PD-L1 antibody generated an enhanced HIV-1 Gag-specific CD8(+) immune response following both a single round of DCLV immunization and a homologous prime/boost regimen. The prime/boost regimen combined with PD-L1 blockade generated very high levels of Gag-specific CD8(+) T cells comprising several valuable features: improved ability to produce multiple cytokines, responding to a broader range of Gag-derived epitopes, and long-lasting memory. This enhanced cellular immune response generated by DCLV immunization combined with anti-PD-L1 blockade correlated with improved viral control following challenge with Gag-expressing vaccinia virus. Taken together, our studies offer evidence to support the use of PD-1/PD-L1 blockade as an adjuvant modality to enhance antigen-specific immune responses elicited by T cell-based immunizations such as DCLV.

A Tetracycline-regulated Cell Line Produces High-titer Lentiviral Vectors that Specifically Target Dendritic Cells

Lentiviral vectors (LVs) are a powerful means of delivering genetic material to many types of cells. Because of safety concerns associated with these HIV-1 derived vectors, producing large quantities of LVs is challenging. In this paper, we report a method for producing high titers of self-inactivating LVs. We retrovirally transduce the tet-off stable producer cell line GPR to generate a cell line, GPRS, which can express all the viral components, including a dendritic cell-specific glycoprotein, SVGmu. Then, we use concatemeric DNA transfection to transfect the LV transfer plasmid encoding a reporter gene GFP in combination with a selectable marker. Several of the resulting clones can produce LV at a titer 10-fold greater than what we achieve with transient transfection. Plus, these viruses efficiently transduce dendritic cells in vitro and generate a strong T cell immune response to our reporter antigen. This method may be a good option for producing strong LV-based vaccines for clinical studies of cancer or infectious diseases.

Protonic doping of bis-thienylpolyenes and oligomers of poly (2,5-thienylenevinylene): comparison to oxidative chemical doping

Protonic doping of polymer oligomers containing thiophene end groups or repeat units yields predominantly bipolaronic charge states.

The Temperature Dependence of Electron Spin-Lattice Relaxation Data in Trans-Polyacetylene and the Evidence for a Soliton-Phonon Interaction

Abstract The temperature and frequency dependence of the electron spin-lattice relaxation rate Rj for the paramagnetic defects in pristine transpolyacetylene is analyzed in terms of a model in which the electron-electron dipolar interaction between spins is modulated by one-dimensional diffusion induced by phonon scattering of the spins. According to this model, at room temperatures R1 has a T1/2 temperature dependence; at low temperatures R1 has a T2 or T5/2 temperature dependence. R1 is described by a ω−1/2 frequency dependence. The model shows the symmetry between moving and stationary solitons scattered by phonons. The soliton wave function obtained from experimental ENDOR data is used to obtain analytical results. We discuss the possible temperature and frequency limitations of this model.

Breast cancer vaccines delivered by dendritic cell-targeted lentivectors induce potent antitumor immune responses and protect mice from mammary tumor growth

Breast cancer immunotherapy is a potent treatment option, with antibody therapies such as trastuzumab increasing 2-year survival rates by 50%. However, active immunotherapy through vaccination has generally been clinically ineffective. One potential means of improving vaccine therapy is by delivering breast cancer antigens to dendritic cells (DCs) for enhanced antigen presentation. To accomplish this in vivo, we pseudotyped lentiviral vector (LV) vaccines with a modified Sindbis Virus glycoprotein so that they could deliver genes encoding the breast cancer antigen alpha-lactalbumin (Lalba) or erb-b2 receptor tyrosine kinase 2 (ERBB2 or HER2) directly to resident DCs. We hypothesized that utilizing these DC-targeting lentiviral vectors asa breast cancer vaccine could lead to an improved immune response against self-antigens found in breast cancer tumors. Indeed, single injections of the vaccine vectors were able to amplify antigen-specific CD8T cells 4-6-fold over naïve mice, similar to the best published vaccine regimens. Immunization of these mice completely inhibited tumor growth in a foreign antigen environment (LV-ERBB2 in wildtype mice), and it reduced the rate of tumor growth in a self-antigen environment (LV-Lalba in wildtype or LV-ERBB2 in MMTV-huHER2 transgenic). These results show that a single injection with targeted lentiviral vectors can be an effective immunotherapy for breast cancer. Furthermore, they could be combined with other immunotherapeutic regimens to improve outcomes for patients with breast cancer.

Chapter 24 – Lentivector Vaccines

As a vector for gene delivery, lentiviruses based on HIV-1 are commonly used in the laboratory. These lentivectors benefit from the advantages of efficient transduction of nondividing cells, low natural antivector immunity, and a low potential for genotoxicity due to insertional mutagenesis. Numerous modifications of the lentivector have improved their safety profile and ability to elicit a strong immune response. In cancer therapy, lentivectors have been used to transduce dendritic cells with tumor-associated antigens ex vivo. When transferred back into mice, these vaccines generate a strong antigen-specific immune response, and they can slow the growth of tumors in several mouse models of human cancer. Antigen-carrying lentivectors can also be injected directly into mice, after which they also elicit a strong immune response and provide protection to tumor challenge. In the few clinical trials that have utilized lentivectors, no adverse effects from the lentivector have been observed. Future advances in the field will likely focus on improving the safety profile of these vectors and adapting them for large-scale clinical trials.

Abstract 2888: Dendritic cell-targeted lentiviral vector vaccines overcome tolerance to generate a protective T-cell immune response to breast cancer antigens ERBB2 and α-lactalbumin

Breast cancer immunotherapy is a potent treatment option, with antibody therapies such as trastuzumab increasing 2-year survival rates by 50%. In contrast, active immunotherapy through therapeutic vaccination has yet to be proven clinically effective for breast cancer. One potential means of improving vaccine therapy is by delivering breast cancer antigens to dendritic cells (DCs) for enhanced antigen presentation. To achieve this in vivo, we have pseudotyped lentiviral vector vaccines with a modified Sindbis Virus glycoprotein that targets the C-type lectin DC-SIGN, which is expressed on DCs. We hypothesized that utilizing these DC-targeting lentiviral vectors as a breast cancer vaccine could lead to an improved immune response against self antigens found in breast cancer tumors. Such an improved immune response may help to prevent or slow tumor growth in breast cancer models. To test these hypotheses, we have constructed lentiviral vectors encoding each of the breast cancer antigens, human Her2 (ERBB2) and mouse alpha-lactalbumin (Lalba). Single injections were able to amplify antigen-specific CD8 T cells to 1.6% of total CD8 T cells in BALB/cJ mice and 0.7% in transgenic ERBB2 mice. This compares favorably with recently published vector vaccines, which have elicited 0.9% and Citation Format: Paul D. Bryson, Xiaolu Han, Norman Truong, Pin Wang. Dendritic cell-targeted lentiviral vector vaccines overcome tolerance to generate a protective T-cell immune response to breast cancer antigens ERBB2 and α-lactalbumin. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2888. doi:10.1158/1538-7445.AM2014-2888

Competition between polaronic and bipolaronic charge states in the oxidative and protonic doping of model oligomers of poly(dialkoxyphenylene vinylene)

Quantitative ESR measurements on oxidatively and protonically doped model oligomers of poly(dialkoxyphenylene vinylene) indicate that bipolaronic charge states dominate both doping processes.