Magnitude of Therapeutic STING Activation Determines CD8 T Cell-Mediated Anti-tumor Immunity.

Intratumoral (IT) STING activation results in tumor regression in preclinical models, yet factors dictating the balance between innate and adaptive anti-tumor immunity are unclear. Here, clinical candidate STING agonist ADU-S100 (S100) is used in an IT dosing regimen optimized for adaptive immunity to uncover requirements for a T cell-driven response compatible with checkpoint inhibitors (CPIs). In contrast to high-dose tumor ablative regimens that result in systemic S100 distribution, low-dose immunogenic regimens induce local activation of tumor-specific CD8 effector T cells that are responsible for durable anti-tumor immunity and can be enhanced with CPIs.

Recombinant promotes tumor rejection by CD8 T cell-dependent remodeling of the tumor microenvironment.

Agents that remodel the tumor microenvironment (TME), prime functional tumor-specific T cells, and block inhibitory signaling pathways are essential components of effective immunotherapy. We are evaluating live-attenuated, double-deleted expressing tumor antigens (LADD-Ag) in the clinic. Here we show in numerous mouse models that while treatment with nonrecombinant LADD induced some changes in the TME, no antitumor efficacy was observed, even when combined with immune checkpoint blockade.

TNFα and Radioresistant Stromal Cells Are Essential for Therapeutic Efficacy of Cyclic Dinucleotide STING Agonists in Nonimmunogenic Tumors.

The cGAS-STING cytosolic DNA sensing pathway may play an integral role in the initiation of antitumor immune responses. Studies evaluating the immunogenicity of various cyclic dinucleotide (CDN) STING agonists administered by intratumoral (i.t.

A structure-function approach to optimizing TLR4 ligands for human vaccines.

Adjuvants are combined with vaccine antigens to enhance and modify immune responses, and have historically been primarily crude, undefined entities. Introducing toll-like receptor (TLR) ligands has led to a new generation of adjuvants, with TLR4 ligands being the most extensively used in human vaccines. The TLR4 crystal structures demonstrate extensive contact with their ligands and provide clues as to how they discriminate a broad array of molecules and activate or attenuate innate, as well as adaptive, responses resulting from these interactions.

IL-18 and Subcapsular Lymph Node Macrophages are Essential for Enhanced B Cell Responses with TLR4 Agonist Adjuvants.

Designing modern vaccine adjuvants depends on understanding the cellular and molecular events that connect innate and adaptive immune responses. The synthetic TLR4 agonist glycopyranosyl lipid adjuvant (GLA) formulated in a squalene-in-water emulsion (GLA-SE) augments both cellular and humoral immune responses to vaccine Ags. This adjuvant is currently included in several vaccines undergoing clinical evaluation including those for tuberculosis, leishmaniasis, and influenza.

Analysis of the Innate Response to Adjuvants: Characterization of the Draining Lymph Node by Fluorescence-Activated Cell Sorting.

A clear index for a response to adjuvants is a change in the cellular composition of lymph nodes draining the site of adjuvant injection (Didierlaurent et al., J Immunol 183:6186-6197, 2009; Caproni et al., J Immunol 188:3088-98, 2012; Desbien et al.

Antigen presentation by B cells guides programing of memory CD4 T-cell responses to a TLR4-agonist containing vaccine in mice.

The contribution of B cells to immunity against many infectious diseases is unquestionably important and well characterized. Here, we sought to determine the role of B cells in the induction of T-helper 1 (T 1) CD4 T cells upon vaccination with a tuberculosis (TB) antigen combined with a TLR4 agonist. We used B-cell deficient mice (μMT ), tetramer-positive CD4 T cells, markers of memory "precursor" effector cells (MPECs), and T-cell adoptive transfers and demonstrated that the early antigen-specific cytokine-producing T 1 responses are unaffected in the absence of B cells, however MPEC induction is strongly impaired resulting in a deficiency of the memory T 1 response in μMT mice.

The TLR4 Agonist Vaccine Adjuvant, GLA-SE, Requires Canonical and Atypical Mechanisms of Action for TH1 Induction.

The Toll-like receptor 4 agonist glucopyranosyl lipid adjuvant formulated in a stable emulsion (GLA-SE) promotes strong TH1 and balanced IgG1/IgG2 responses to protein vaccine antigens. This enhanced immunity is sufficient to provide protection against many diseases including tuberculosis and leishmaniasis. To better characterize the adjuvant action it is important to understand how the different cytokines and transcription factors contribute to the initiation of immunity.

Squalene emulsion potentiates the adjuvant activity of the TLR4 agonist, GLA, via inflammatory caspases, IL-18, and IFN-γ.

The synthetic TLR4 agonist glucopyranosyl lipid adjuvant (GLA) is a potent Th1-response-inducing adjuvant when formulated in a squalene oil-in-water emulsion (SE). While the innate signals triggered by TLR4 engagement are well studied, the contribution of SE remains unclear. To better understand the effect of SE on the adjuvant properties of GLA-SE, we compared the innate and adaptive immune responses elicited by immunization with different formulations: GLA without oil, SE alone or the combination, GLA-SE, in mice.

Elimination of the cold-chain dependence of a nanoemulsion adjuvanted vaccine against tuberculosis by lyophilization.

Next-generation rationally-designed vaccine adjuvants represent a significant breakthrough to enable development of vaccines against challenging diseases including tuberculosis, HIV, and malaria. New vaccine candidates often require maintenance of a cold-chain process to ensure long-term stability and separate vials to enable bedside mixing of antigen and adjuvant. This presents a significant financial and technological barrier to worldwide implementation of such vaccines.

TLR4 ligand formulation causes distinct effects on antigen-specific cell-mediated and humoral immune responses.

The formulation of TLR ligands and other immunomodulators has a critical effect on their vaccine adjuvant activity. In this work, the synthetic TLR4 ligand GLA was formulated with three distinct vaccine delivery system platforms (aqueous suspension, liposome, or oil-in-water emulsion). The effect of the different formulations on the adaptive immune response to protein subunit vaccines was evaluated in the context of a recombinant malaria antigen, Plasmodium berghei circumsporozoite protein (PbCSP).

Development of a high density hemagglutinin protein microarray to determine the breadth of influenza antibody responses.

We have developed an influenza hemagglutinin protein microarray to assess humoral recognition of diverse influenza strains induced by vaccination and infection. Each array consists of controls and 127 hemagglutinin antigens from 60 viruses, spotted in replicates to generate a single array of 1296 spots. Six arrays are configured on a single slide, which in the following analysis was probed simultaneously with 2 isotype-specific fluorescent secondary antibodies yielding over 15,000 data points per slide.

MyD88 and TRIF synergistic interaction is required for TH1-cell polarization with a synthetic TLR4 agonist adjuvant.

Glucopyranosyl lipid adjuvant-stable emulsion (GLA-SE) is a synthetic adjuvant TLR4 agonist that promotes potent poly-functional T(H)1 responses. Different TLR4 agonists may preferentially signal via MyD88 or TIR-domain-containing adapter inducing IFN-beta (TRIF) to exert adjuvant effects; however, the contribution of MyD88 and TRIF signaling to the induction of polyclonal T(H)1 responses by TLR4 agonist adjuvants has not been studied in vivo. To determine whether GLA-SE preferentially signals through MyD88 or TRIF, we evaluated the immune response against a candidate tuberculosis (TB) vaccine Ag following immunization of mice lacking either signaling adapter compared with that of wild-type mice.

The Epstein-Barr virus Bcl-2 homolog, BHRF1, blocks apoptosis by binding to a limited amount of Bim.

Current knowledge suggests that the balance between life and death within a cell can be controlled by the stable engagement of Bcl-2-related proapoptotic proteins such as Bak, Bax, and Bim by survival proteins such as Bcl-2. BHRF1 is a prosurvival molecule from Epstein-Barr virus that has a high degree of homology to Bcl-2. To understand how BHRF1 blocks apoptosis, BHRF1 and mutants of BHRF1 were expressed in primary cells and an IL-2-dependent T cell line.

Impaired viral entry cannot explain reduced CD4+ T cell susceptibility to HIV type 1 in certain highly exposed individuals.

Rare individuals report repeated unprotected HIV-1 sexual exposures, yet remain seronegative for years. We investigated the possibility that reduced in vitro CD4(+) T cell susceptibility to HIV-1 infection protects such highly exposed seronegative (ES) individuals. Susceptibility to three R5-tropic HIV-1 isolates, regardless of inoculating dose, was remarkably similar between 81 ES and 33 low-risk controls.