An immuno-diffusion assay to assess the protective antigen content of anthrax vaccine

Immunogenicity of a Fully Synthetic MUC1 Glycopeptide Antitumor Vaccine Enhanced by Poly(I:C) as a TLR3-Activating Adjuvant

Fully synthetic MUC1 glycopeptide antitumor vaccines have a precisely specified structure and induce a targeted immune response without suppression of the immune response when using an immunogenic carrier protein. However, tumor-associated aberrantly glycosylated MUC1 glycopeptides are endogenous structures, "self-antigens", that exhibit only low immunogenicity. To overcome this obstacle, a fully synthetic MUC1 glycopeptide antitumor vaccine was combined with poly(inosinic acid:cytidylic acid), poly(I:C), as a structurally defined Toll-like receptor 3 (TLR3)-activating adjuvant. This vaccine preparation elicited extraordinary titers of IgG antibodies which strongly bound human breast cancer cells expressing tumor-associated MUC1. Beside the humoral response, the poly(I:C) glycopeptide vaccine induced a pro-inflammatory environment, very important to overcome the immune-suppressive mechanisms, and elicited a strong cellular immune response crucial for tumor elimination.

Isolation of Exosomes for the Purpose of Protein Cargo Analysis with the Use of Mass Spectrometry

Exosomes are intercellular messengers with a high potential for diagnostic and therapeutic utility. It is believed that exosomes present in body fluids are responsible for providing signals which inhibit immune cells, interfere with antitumor immunity, and thus influence the response to treatment and its effect. One of the most interesting issues in exosome studies is proper addressing of their cargo composed of nucleic acids and proteins. Effective and selective isolation of extracellular vesicles and identification of proteins present in exosomes has turned out to be a challenging aspect of their exploration. Here we propose a novel approach that is based on isolation of exosomes by mini-size-exclusion chromatography which allows efficient, rapid, and reliable isolation of morphologically intact and functionally active exosomes without the need of ultracentrifugation. The purpose of this chapter is to describe a simple and high-throughput method to isolate, purify, and identify exosomal proteins using a mass spectrometry approach. The proposed protocol compiles the expertise of two research groups specialized in exosome research and in mass spectrometry-based proteomics. The protocol combines differential centrifugation followed by ultrafiltration, centrifugation-based filtration, and gel filtration on Sepharose 2B in order to obtain exosomal fractions characterized by only low contamination with albumin.

TLR-3 stimulation improves anti-tumor immunity elicited by dendritic cell exosome-based vaccines in a murine model of melanoma

Dendritic cell (DC)-derived exosomes (Dexo) contain the machinery necessary to activate potent antigen-specific immune responses. As promising cell-free immunogens, Dexo have been tested in previous clinical trials for cancer vaccine immunotherapy, yet resulted in limited therapeutic benefit. Here, we explore a novel Dexo vaccine formulation composed of Dexo purified from DCs loaded with antigens and matured with either the TLR-3 ligand poly(I:C), the TLR-4 ligand LPS or the TLR-9 ligand CpG-B. When poly(I:C) was used to produce exosomes together with ovalbumin (OVA), the resulting Dexo vaccine strongly stimulated OVA-specific CD8⁺ and CD4⁺ T cells to proliferate and acquire effector functions. When a B16F10 melanoma cell lysate was used to load DCs with tumor antigens during exosome production together with poly(I:C), we obtained a Dexo vaccine capable of inducing robust activation of melanoma-specific CD8⁺ T cells and the recruitment of cytotoxic CD8⁺ T cells, NK and NK-T cells to the tumor site, resulting in significantly reduced tumor growth and enhanced survival as compared to a Dexo vaccine formulation similar to the one previously tested on human patients. Our results indicate that poly(I:C) is a particularly favorable TLR agonist for DC maturation during antigen loading and exosome production for cancer immunotherapy.

Poly I:C inhibits cell proliferation and enhances the growth inhibitory effect of paclitaxel in oral sqaumous cell carcinoma

OBJECTIVE

Toll-like receptors (TLR) signaling has dual effect of promoting tumor progression and anti-cancer property. This study was designed to determine the effect of polyinosinic-polycytidilic acid (poly I:C), a TLR3 agonist, on the proliferation of oral cancer cells.

MATERIALS AND METHODS

Human oral squamous cell carcinoma cell lines, YD-10B and YD-8, were used. TLRs expression was examined by RT-PCR and IL-8 production by poly I:C was examined by ELISA. Cell proliferation was determined by MTT assay. Flow cytometry and Western blot analysis were performed to determine the molecular mechanism of poly I:C-induced cell death.

RESULTS

TLR3 was functionally expressed in YD-10B and YD-8 cells. Treatment of poly I:C inhibited the cell growth in a dose-dependent manner. Flow cytometry and Western blot analysis revealed that poly I:C induced apoptosis via a mitochondria-dependent pathway. In addition, combination treatment with poly I:C and paclitaxel more significantly inhibited cell proliferation compared with poly I:C or paclitaxel alone.

CONCLUSIONS

Poly I:C effectively inhibits oral cancer cell proliferation and can be considered as a candidate to improve the inhibitory effect of anti-cancer drugs.

Toll-like receptor-7 agonist administered subcutaneously in a prolonged dosing schedule in heavily pretreated recurrent breast, ovarian, and cervix cancers

BACKGROUND

The primary objective was to study the antitumor activity of prolonged subcutaneous dosing of systemic 852A, a Toll-like receptor-7 agonist (TLR-7), in recurrent breast, ovarian and cervix cancer. Secondary objectives included assessment of safety and immune system activation.

METHODS

Adults with recurrent breast, ovarian or cervix cancer failing multiple therapies received 0.6 mg/m(2) of 852A subcutaneously twice weekly for 12 weeks. Doses increased by 0.2 mg/m(2)/week to a maximum of 1.2 mg/m(2). Serum was collected to assess immune activation.

RESULTS

Fifteen patients enrolled: 10 ovarian, 2 cervix and 3 breast. Three completed all 24 injections. There were two grade 2 (decreased ejection fractions), nine grade 3 (1 cardiovascular, 1 anorexia, 3 dehydration, 2 infections, 2 renal) and two grade 4 (hepatic and troponin elevation) unanticipated toxicities. Cardiac toxicities included three cardiomyopathies (2 asymptomatic) and one stress-related non-ST elevated myocardial infarction. Five patients discontinued therapy due to possibly associated side effects. One who had stable disease (SD) following 24 doses received 17 additional doses. A cervix patient with SD following 24 doses received chemotherapy after progressing 3 months later, and remains disease free at 18 months. Immune activation, as evidenced by increased IP-10 and IL-1ra, was observed.

CONCLUSIONS

In this first human experience of a TLR-7 agonist delivered subcutaneously using a prolonged dosing schedule, 852A demonstrated sustained tolerability in some patients. Clinical benefit was modest, but immune activation was seen suggesting further study of antitumor applications is warranted. Because of cardiac toxicity; 852A should be used cautiously in heavily pretreated patients.

Membrane vesicles as conveyors of immune responses

In multicellular organisms, communication between cells mainly involves the secretion of proteins that then bind to receptors on neighbouring cells. But another mode of intercellular communication - the release of membrane vesicles - has recently become the subject of increasing interest. Membrane vesicles are complex structures composed of a lipid bilayer that contains transmembrane proteins and encloses soluble hydrophilic components derived from the cytosol of the donor cell. These vesicles have been shown to affect the physiology of neighbouring recipient cells in various ways, from inducing intracellular signalling following binding to receptors to conferring new properties after the acquisition of new receptors, enzymes or even genetic material from the vesicles. This Review focuses on the role of membrane vesicles, in particular exosomes, in the communication between immune cells, and between tumour and immune cells.

Review: cancer immunotherapy by exosome-based vaccines

Exosomes (EXOs) are nanometer-sized membrane vesicles secreted from epithelial and hematopoietic cells. They display a spectrum of molecules involved in immune responses and signal transductions. Previous studies showed that tumor antigen-loaded dendritic cell (DC)- and tumor cell-derived EXOs (Dexo and Texo) induce tumor antigen-specific CD8(+) cytotoxic T-lymphocyte responses and antitumor immunity in experimental animal models and human clinical trials. This review will present the main biologic features of Dexo and Texo as cell-free cancer vaccines with emphasis on their immunostimulatory properties and their potential efficacy in cancer immunotherapy.

mRNA-based cancer vaccine: prevention of B16 melanoma progression and metastasis by systemic injection of MART1 mRNA histidylated lipopolyplexes

Immunization with mRNA encoding tumor antigen is an emerging vaccine strategy for cancer. In this paper, we demonstrate that mice receiving systemic injections of MART1 mRNA histidylated lipopolyplexes were specifically and significantly protected against B16F10 melanoma tumor progression. The originality of this work concerns the use of a new tumor antigen mRNA formulation as vaccine, which allows an efficient protection against the growth of a highly aggressive tumor model after its delivery by intravenous route. Synthetic melanoma-associated antigen MART1 mRNA was formulated with a polyethylene glycol (PEG)ylated derivative of histidylated polylysine and L-histidine-(N,N-di-n-hexadecylamine)ethylamide liposomes (termed histidylated lipopolyplexes). Lipopolyplexes comprised mRNA/polymer complexes encapsulated by liposomes. The tumor protective effect was induced with MART1 mRNA carrying a poly(A) tail length of 100 adenosines at an optimal dose of 12.5 microg per mouse. MART1 mRNA lipopolyplexes elicited a cellular immune response characterized by the production of interferon-gamma and the induction of cytotoxic T lymphocytes. Finally, the anti-B16 response was enhanced using a formulation containing both MART1 mRNA and MART1-LAMP1 mRNA encoding the antigen targeted to the major histocompatibility complex class II compartments by the lysosomal sorting signal of LAMP1 protein. Our results provide a basis for the development of mRNA histidylated lipopolyplexes for cancer vaccine.

Production and characterization of neutralizing monoclonal antibodies that recognize an epitope in domain 2 of Bacillus anthracis protective antigen

Antibodies against the protective antigen (PA) of Bacillus anthracis play a key role in response to infection by this important pathogen. The aim of this study was to produce and characterize monoclonal antibodies (mAbs) specific for PA and to identify novel neutralizing epitopes. Three murine mAbs with high specificity and nanomolar affinity for B. anthracis recombinant protective antigen (rPA) were produced and characterized. Western immunoblot analysis, coupled with epitope mapping using overlapping synthetic peptides, revealed that these mAbs recognize a linear epitope within domain 2 of rPA. Neutralization assays demonstrate that these mAbs effectively neutralize lethal toxin in vitro.

Bacillus anthracis: toxicology, epidemiology and current rapid-detection methods

B. anthracis, the causative agent for anthrax, has been well studied for over 150 years. Due to the genetic similarities among various Bacillus species, as well as its existence in both a spore form and a vegetative state, the detection and specific identification of B. anthracis have been proven to require complex techniques and/or laborious methods. With the heightened interest in the organism as a potential biological threat agent, a large number of interesting detection technologies have recently been developed, including methods involving immunological and nucleic acid-based assay formats. The technologies range from culture-based methods to portable Total Analysis Systems based on real-time PCR. This review with 170 references provides a brief background on the toxicology and epidemiology of B. anthracis, discusses challenges associated with its detection related to genetic similarities to other species, and reviews immunological and, with greater emphasis, nucleic acid-based detection systems.