Synthesis and Detection of BODIPY-, Biotin-, and 19 F- Labeled Single-Entity Dendritic Heparan Sulfate Mimetics

Heparin and heparan sulfate (HS) are naturally occurring mammalian glycosaminoglycans, and their synthetic and semi-synthetic mimetics have attracted significant interest as potential therapeutics. However, understanding the mechanism of action by which HS, heparin, and HS mimetics have a biological effect is difficult due to their highly charged nature, broad protein interactomes, and variable structures. To address this, a library of novel single-entity dendritic mimetics conjugated to BODIPY, Fluorine-19 (19 F), and biotin was synthesized for imaging and localization studies. The novel dendritic scaffold allowed for the conjugation of labeling moieties without reducing the number of sulfated capping groups, thereby better mimicking the multivalent nature of HS-protein interactions. The 19 F labeled mimetics were assessed in phantom studies and were detected at concentrations as low as 5 mM. Flow cytometric studies using a fluorescently labeled mimetic showed that the compound associated with immune cells from tumors more readily than splenic counterparts and was directed to endosomal-lysosomal compartments within immune cells and cancer cells. Furthermore, the fluorescently labeled mimetic entered the central nervous system and was detectable in brain-infiltrating immune cells 24 hours after treatment. Here, we report the enabling methodology for rapidly preparing various labeled HS mimetics and molecular probes with diverse potential therapeutic applications.

Late-stage MC38 tumours recapitulate features of human colorectal cancer - implications for appropriate timepoint selection in preclinical studies

Anti-tumour T cell responses play a crucial role in controlling the progression of colorectal cancer (CRC), making this disease a promising candidate for immunotherapy. However, responses to immune-targeted therapies are currently limited to subpopulations of patients and specific types of cancer. Clinical studies have therefore focussed on identifying biomarkers that predict immunotherapy responses and elucidating the immunological landscapes of different cancers. Meanwhile, our understanding of how preclinical tumour models resemble human disease has fallen behind, despite their crucial role in immune-targeted drug development. A deeper understanding of these models is therefore needed to improve the development of immunotherapies and the translation of findings made in these systems. MC38 colon adenocarcinoma is a widely used preclinical model, yet how it recapitulates human colorectal cancer remains poorly defined. This study investigated the tumour-T cell immune landscape of MC38 tumours using histology, immunohistochemistry, and flow cytometry. We demonstrate that early-stage tumours exhibit a nascent TME, lacking important immune-resistance mechanisms of clinical interest, while late-stage tumours exhibit a mature TME resembling human tumours, with desmoplasia, T cell exhaustion, and T cell exclusion. Consequently, these findings clarify appropriate timepoint selection in the MC38 model when investigating both immunotherapies and mechanisms that contribute to immunotherapy resistance. Overall, this study provides a valuable resource that will enable appropriate application of the MC38 model and expedite the development and clinical translation of new immunotherapies.

Effect of carrier molecular weight on physicochemical properties and the in vitro immune-stimulatory activity of the CpG-dextran conjugates

The effect of dextran molecular weight on the in vitro physicochemical and immune properties of cytosine-phosphate-guanine (CpG) oligodeoxynucleotide-amino-dextran conjugates is investigated. CpG-1668 was conjugated at the 3'-end to amino-dextran of differing molecular weight (20, 40, 70 or 110-kDa) via a stable bis-aryl hydrazone linkage. Conjugate formation was confirmed by agarose gel electrophoresis and dynamic light scattering measured the size and surface charge of conjugates. Uptake and immune-stimulatory activity of CpG-dextran by antigen-presenting cells was evaluated by flow cytometry and confocal microscopy. Degradation by DNase I was monitored by loss of the fluorescent signal from labelled CpG and changes in size and zeta potential. Hydrazone bond formation (UV 354 nm) showed on average four CpG molecules conjugated per polymer. CpG-dextran prepared from 20 or 40-kDa dextran had a size of 17 nm while 70 or 110-kDa was 30 nm. CpG-dextran was preferentially taken up by dendritic cells, followed by macrophages and then B-cells. Only the 20-kDa dextran conjugate significantly enhanced uptake by bone-marrow derived dendritic cells (BMDCs) compared to free CpG. Confocal microscopy showed that CpG and CpG-dextran accumulates in the endo-lysosomal compartment of BMDCs at 24 h. All conjugates upregulated activation markers (CD40, CD80 or CD86) of BMDCs to a similar level as for free CpG. CpG-dextran 40-kDa produced highest levels of cytokines (TNF-α, IL-6, and IL-12p70) secreted by BMDCs. Enzymatic protection assays showed that the conjugate made from dextran 20-kDa provided no protection for CpG while the higher molecular weight conjugates reduced degradation by DNase I. The 40-kDa dextran conjugate produced the greatest in vitro immune activity, this was due to the conjugate being relatively small in size for cell uptake while sufficiently large enough to protect CpG from nuclease attack. These in vitro studies identify the need to consider the molecular weight of the carrier in bioconjugate design.

3D living dressing improves healing and modulates immune response in a thermal injury model

Thermal injury trauma can induce a state of immunosuppression causing wounds to become chronic in nature. Stem-cell based therapies represent a promising new approach to treat such wounds due to their capacity to self-renew and their multi-lineage potential. Mesenchymal stem cells (MSCs) are known to secrete endogenous factors that stimulate wound healing by promoting angiogenesis, extracellular matrix (ECM) remodeling, skin re-generation, and by dampening down inflammation. MSC delivery in a biomaterial construct can augment their wound healing capacity by concentrating cells at the burn site and upregulating trophic factor secretion. The work presented is the first to evaluate repair in an in vitro raft thermal injury model using a regenerative, dual cell delivery 3D core/shell (c/s) "living dressing" construct. This previously characterized 3D c/s bioprinted construct, that delivers both MSCs and endothelial cells, was used to treat an in vitro 3D raft skin thermal injury wound model. The mesenchymal stromal cell line (T0523) was encapsulated within a gelatin-based shell bioink, and human um-bilical vein endothelial cells (HUVECs) within a chitosan-based core bioink to biofabricate a living dressing for enhanced thermal injury repair and regeneration. We hypothesized that the cell-laden c/s tissue engineered con-struct (TEC) would strengthen the wound's proangiogenic, anti-inflammatory, and skin regeneration potential. An in vitro thermal injury in a 3D raft skin model showed a slight delay in wound closure in the presence of the c/s TEC but was augmented by corresponding increases in the release of wound healing factors, EGF, MMP-9, TGF-α, PDGF; a decrease in pro-inflammatory factor IL-6, and evidence of neovascularization. Impact statement C/s 3D bioprinted living dressings were used to heal an in vitro thermal injury wound in a 3D raft skin model. The MSC/HUVEC-laden 3D TEC when compared to the untreated control resulted in a slight de-lay in wound closure along with corresponding increases in the secretion of wound healing factors EGF, MMP-9, TGF-α, PDGF; a decrease in pro-inflammatory factor IL-6, and promotion of neovascularization. The present work is the first to evaluate repair and corresponding cytokine response in an in vitro 3D raft thermal injury model using a "living dressing" construct.

Synthesis of novel glycolipid mimetics of heparan sulfate and their application in colorectal cancer treatment in a mouse model

Heparan sulfate (HS) is a highly sulfated natural carbohydrate that plays crucial roles in cancer, inflammation, and angiogenesis. Heparanase (HPSE) is the sole HS degrading endoglycosidase that cleaves HS at structure‐dependent sites along the polysaccharide chain. Overexpression of HPSE by cancer cells correlates with increased tumor size and enhanced metastasis. Previously we have shown that a tetramer HS mimetic is a potent HPSE inhibitor displaying remarkable anticancer activity in vivo. Building on that work, we report the synthesis and testing of a novel library of single entity trimer glycolipid mimetics that effectively inhibit HPSE at low nanomolar concentrations. A lipophilic arm was introduced to assess whether an improvement of pharmacokinetics and plasma residence time would offset the reduction in charge and multivalency. Preclinical tests in a mouse syngeneic model showed effective tumor growth inhibition by the tetramer but not the trimer glycomimetic.

Obesity Has a Systemic Effect on Immune Cells in Naïve and Cancer-Bearing Mice

Obesity is a major risk factor for developing cancer, with obesity-induced immune changes and inflammation in breast (BC) and colorectal cancer (CRC) providing a potential link between the two. This study investigates systemic effects of obesity on adaptive and innate immune cells in healthy and tumour-bearing mice. Immune cells from lean and obese mice were phenotyped prior to implantation of either BC (C57mg and EO771.LMB) or CRC (MC38) cells as tumour models. Tumour growth rate, tumour-infiltrating lymphocytes (TIL) and peripheral blood immune cell populations were compared between obese and lean mice. In vitro studies showed that naïve obese mice had higher levels of myeloid cells in the bone marrow and bone marrow-derived dendritic cells expressed lower levels of activation markers compared to cells from their lean counterparts. In the tumour setting, BC tumours grew faster in obese mice than in lean mice and lower numbers of TILs as well as higher frequency of exhausted T cells were observed. Data from peripheral blood showed lower levels of myeloid cells in tumour-bearing obese mice. This study highlights that systemic changes to the immune system are relevant for tumour burden and provides a potential mechanism behind the effects of obesity on cancer development and progression in patients.

Molecular monitoring of glioblastoma's immunogenicity using a combination of Raman spectroscopy and chemometrics

Raman spectroscopy (RS) has been used as a powerful diagnostic and non-invasive tool in cancer diagnosis as well as in discrimination of cancer and immune cells. In this study RS in combination with chemometrics was applied to cellular Raman spectral data to distinguish the phenotype of T-cells and monocytes after incubation with media conditioned by glioblastoma stem-cells (GSCs) showing different molecular background. For this purpose, genetic modulations of epithelial-to-mesenchymal transition (EMT) process and expression of immunomodulator CD73 were introduced. Principal component analysis of the Raman spectral data showed that T-cells and monocytes incubated with tumour-conditioned media (TCMs) of GSCs with inhibited EMT activator ZEB1 or CD73 formed distinct clusters compared to controls highlighting their differences. Further discriminatory analysis performed using linear discriminant analysis (LDA) and support vector machine classification (SVM), yielded sensitivities and specificities of over 70 and 67% respectively upon validation against an independent test set. Supporting those results, flow cytometric analysis was performed to test the influence of TCMs on cytokine profile of T-cells and monocytes. We found that ZEB1 and CD73 influence T-cell and monocyte phenotype and promote monocyte differentiation into a population of mixed pro- and anti-tumorigenic macrophages (MΦs) and dendritic cells (DCs) respectively. In conclusion, Raman spectroscopy in combination with chemometrics enabled tracking T-cells and monocytes.

Data on the uptake of CpG-loaded amino-dextran nanoparticles by antigen-presenting cells

Cytosine-phosphate-guanine (CpG) oligonucleotides are commonly-used vaccine adjuvants to promote the activation of antigen-presenting cells (APCs). To mount an effective immune response, CpG needs to be internalized and bind to its endosomal Toll-like receptor 9 (TLR-9) inside the APCs. Using flow cytometry and fluorescence microscopy, this article presents the cellular uptake data of the amino-dextran nanoparticle (aDNP) and aDNP loaded with CpG immobilized on its surface by either electrostatic adsorption or covalent conjugation. The uptake of fluorescently-labelled aDNPs by murine splenic dendritic cells and macrophages was determined by flow cytometry and uptake by murine bone-marrow-derived dendritic cells was evaluated by fluorescence microscopy. The data presented in this paper correlates with the in vitro immune-stimulatory activity observed for the two different CpG loading methods in the research article “Nanoparticle system based on amino-dextran as a drug delivery vehicle: immune-stimulatory CpG-oligonucleotide loading and delivery” (Nguyen et al., 2020) [1]. The data provide experimental evidence for a better understanding how the nanoparticle surface loading method of CpG influences the uptake of these nanoparticles by antigen-presenting cells as a step guide in the design of more effective vaccine formulations.

Alterations to Placental Glucocorticoid Receptor Expression with Alcohol Consumption

Maternal alcohol consumption during pregnancy results in elevated vulnerability to intrauterine growth restriction, preterm birth, miscarriage, and stillbirth. Many of the detrimental effects of fetal alcohol exposure may be mediated through placental dysfunction; however, the exact mechanisms remain unknown. Here, we aimed to determine the effect of maternal alcohol exposure prior to and during early pregnancy on placental glucocorticoid receptor (GR) isoforms, associated GR regulated genes, and infant outcomes. Participants carrying singleton fetuses (n = 113) were recruited during early pregnancy. Amount and type of alcohol consumed over the last 12 months were obtained at 18 weeks of gestation. The level of drinking was separated into none (0 g/day), low (< 10 g/day), moderate (10-100 g/day), and heavy (> 100 g/day). At delivery, placental weight, infant sex, birthweight, and head circumference were recorded. Placental GR isoforms and genes involved in downstream signalling pathways were quantified. The majority of women (70.8%) consumed alcohol. Of these, most consumed low (48.8%) or moderate (37.5%) amounts. Placental weight was unaffected by alcohol consumption, but infants born to heavy drinkers tended to be lighter at birth. In female, but not male, placentae, maternal alcohol consumption resulted in increased GRαC and decreased GRαD1 cytoplasmic expression. In both female and male placentae, a dampened inflammatory response was evident with maternal alcohol consumption, involving downregulated IL6R and upregulated POU2F2 gene expression, respectively. Maternal alcohol consumption in the months prior to, and/or during early, pregnancy alters placental GR isoform and expression of some inflammatory genes in a sex-specific manner.

Nanoparticle System Based on Amino-Dextran as a Drug Delivery Vehicle: Immune-Stimulatory CpG-Oligonucleotide Loading and Delivery

The aim of this study is to prepare and characterize an amino-dextran nanoparticle (aDNP) platform and investigate two loading strategies for unmethylated cytosine-phosphate-guanine (CpG) oligonucleotide. aDNP was prepared by desolvation of amino-dextran followed by the chemical crosslinking of amino groups. Size, surface charge, and surface morphology of aDNP was determined by dynamic light scattering and transmission electron microscopy. CpG was either loaded onto aDNP by adsorption (CpG-adsorbed-aDNP) or conjugated to aDNP (CpG-conjugated-aDNP). In vitro cytokine production by bone marrow-derived dendritic cells (BMDCs) was measured by flow cytometry. aDNPs size and zeta potential could be controlled to produce uniform particles in the size range of 50 to 300 nm, surface charge of −16.5 to +14 mV, and were spherical in shape. Formulation control parameters investigated included the anti-solvent, water-to-anti-solvent ratio, level of amine functionality of dextran, and the molar ratio of glutaraldehyde to amine. aDNP could be lyophilized without additional cryoprotectant. Unloaded cationic aDNP (+13 mV) showed acceptable in vitro hemolysis. Unloaded and CpG-loaded aDNPs showed no cytotoxicity on BMDCs. CpG-loaded nanoparticles stimulated cytokine production by BMDCs, the level of cytokine production was higher for CpG-conjugated-aDNP compared to CpG-absorbed-aDNP. aDNP is a promising new drug delivery platform as its offers versatility in loading and tuning of particle properties.

Oncolytic virus-derived type I interferon restricts CAR T cell therapy

The application of adoptive T cell therapies, including those using chimeric antigen receptor (CAR)-modified T cells, to solid tumors requires combinatorial strategies to overcome immune suppression associated with the tumor microenvironment. Here we test whether the inflammatory nature of oncolytic viruses and their ability to remodel the tumor microenvironment may help to recruit and potentiate the functionality of CAR T cells. Contrary to our hypothesis, VSVmIFNβ infection is associated with attrition of murine EGFRvIII CAR T cells in a B16EGFRvIII model, despite inducing a robust proinflammatory shift in the chemokine profile. Mechanistically, type I interferon (IFN) expressed following infection promotes apoptosis, activation, and inhibitory receptor expression, and interferon-insensitive CAR T cells enable combinatorial therapy with VSVmIFNβ. Our study uncovers an unexpected mechanism of therapeutic interference, and prompts further investigation into the interaction between CAR T cells and oncolytic viruses to optimize combination therapy.

The Effects of Obesity on Anti-Cancer Immunity and Cancer Immunotherapy

Cancer is one of the leading causes of morbidity and mortality worldwide. Traditional treatments include surgery, chemotherapy and radiation therapy, and more recently targeted therapies including immunotherapy are becoming routine care for some cancers. Immunotherapy aims to upregulate the patient's own immune system, enabling it to destroy cancerous cells. Obesity is a metabolic disorder characterized by significant weight that is an important contributor to many different diseases, including cancers. Obesity impacts the immune system and causes, among other things, a state of chronic low-grade inflammation. This is hypothesized to impact the efficacy of the immunotherapies. This review discusses the effects of obesity on the immune system and cancer immunotherapy, including the current evidence on the effect of obesity on immune checkpoint blockade, something which currently published reviews on this topic have not delved into. Data from several studies show that even though obesity causes a state of chronic low-grade inflammation with reductions in effector immune populations, it has a beneficial effect on patient survival following anti-PD-1/PD-L1 and anti-CTLA-4 treatment. However, research in this field is just emerging and further work is needed to expand our understanding of which cancer patients are likely to benefit from immunotherapy.

The Delta-Subunit Selective GABA A Receptor Modulator, DS2, Improves Stroke Recovery via an Anti-inflammatory Mechanism

Inflammatory processes are known to contribute to tissue damage in the central nervous system (CNS) across a broad range of neurological conditions, including stroke. Gamma amino butyric acid (GABA), the main inhibitory neurotransmitter in the CNS, has been implicated in modulating peripheral immune responses by acting on GABA _A receptors on antigen-presenting cells and lymphocytes. Here, we investigated the effects and mechanism of action of the delta-selective compound, DS2, to improve stroke recovery and modulate inflammation. We report a decrease in nuclear factor (NF)-κB activation in innate immune cells over a concentration range in vitro. Following a photochemically induced motor cortex stroke, treatment with DS2 at 0.1 mg/kg from 1 h post-stroke significantly decreased circulating tumor necrosis factor (TNF)-α, interleukin (IL)-17, and IL-6 levels, reduced infarct size and improved motor function in mice. Free brain concentrations of DS2 were found to be lower than needed for robust modulation of central GABA _A receptors and were not affected by the presence and absence of elacridar, an inhibitor of both P-glycoprotein and breast cancer resistance protein (BCRP). Finally, as DS2 appears to dampen peripheral immune activation and only shows limited brain exposure, we assessed the role of DS2 to promote functional recovery after stroke when administered from 3-days after the stroke. Treatment with DS2 from 3-days post-stroke improved motor function on the grid-walking, but not on the cylinder task. These data highlight the need to further develop subunit-selective compounds to better understand change in GABA receptor signaling pathways both centrally and peripherally. Importantly, we show that GABA compounds such as DS2 that only shows limited brain exposure can still afford significant protection and promote functional recovery most likely via modulation of peripheral immune cells and could be given as an adjunct treatment.

Data on the uptake of reducible antigen-adjuvant conjugates by dendritic cells

This article contains the uptake data of two reducible antigen-adjuvant conjugates with different sensitivities to the extracellular and intracellular reductive environment. Using a linker with different redox sensitivity the adjuvant cytosine-phosphate-guanine (CpG) was conjugated to the fluorescently labeled model tumour antigen ovalbumin (OVA). The uptake of the conjugates by dendritic cells in a total splenocyte culture was determined using flow cytometry. The data presented in this paper supports the finding in the research article “Intracellular cleavable CpG oligodeoxynucleotide – antigen conjugate enhances anti-tumour immunity” (Kramer et al., 2016) [1].

Abstract P4-06-20: Delivering tumour antigens survivin and mucin-1 on virus-like particles for breast cancer immunotherapy

Breast cancer is the most frequently diagnosed cancer in women worldwide. Although there are a variety of treatment options available, breast cancer is a difficult disease to treat and many patients experience recurrence following treatment. We have previously shown that tumour antigens delivered on virus-like particles (VLP) induce a targeted anti-cancer immune response. In this study we investigated whether combining the two tumour antigens survivin and mucin 1 as vaccine targets can induce a superior anti-cancer immune response for breast cancer immunotherapy. VLP were designed to recombinantly express the murine survivin epitope. Following expression of Survivin-VLP, aberrantly glycosylated mucin 1 (MUC1) peptide was conjugated onto the Survivin-VLP using intracellular cleavable bis-arylhydrazone linking strategy. Western Blot analysis and electron microscopy confirmed Survivin-VLP expression and UV absorption confirmed conjugation of the MUC1 peptide to the Survivin-VLP. C57mg.MUC1 breast cancer cells were injected into the mammary fat pad of C57Bl/6 and MUC1 transgenic mice. Once tumours were palpable, mice were vaccinated with the Survivin-MUC1-VLP and controls of DPBS, VLP without antigen or VLP delivering either survivin or MUC1 antigen. Tumour growth and mouse survival were monitored for 80 days. Mice vaccinated with Survivin-MU1-VLP delivering both antigens showed enhanced survival (D78) compared to mice vaccinated with VLP delivering only one of the antigens (D66) and controls (D53). Delivery of two tumour antigens induced an enhanced anti-tumour immune response compared to delivery of single tumour antigens. The induction of multiple immune responses against different tumour antigens may apply additional evolutionary pressure upon tumours, prolonging the ability for tumours to develop resistance, or escape through the proliferation of a resistant subpopulation. The use of VLP for the delivery of multiple antigens and adjuvants represents a promising approach to improve cancer immunotherapy for breast cancer.

Citation Format: Kramer K, Braeden D, Young VL, Walker GF, Ward VK, Young SL. Delivering tumour antigens survivin and mucin-1 on virus-like particles for breast cancer immunotherapy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-06-20.

Virus-like particle vaccines: immunology and formulation for clinical translation

INTRODUCTION

Virus-like particle (VLP) vaccines face significant challenges in their translation from laboratory models, to routine clinical administration. While some VLP vaccines thrive and are readily adopted into the vaccination schedule, others are restrained by regulatory obstacles, proprietary limitations, or finding their niche amongst the crowded vaccine market. Often the necessity to supplant an existing vaccination regimen possesses an immediate obstacle for the development of a VLP vaccine, despite any preclinical advantages identified over the competition. Novelty, adaptability and formulation compatibility may prove invaluable in helping place VLP vaccines at the forefront of vaccination technology.

AREAS COVERED

The purpose of this review is to outline the diversity of VLP vaccines, VLP-specific immune responses, and to explore how modern formulation and delivery techniques can enhance the clinical relevance and overall success of VLP vaccines.

EXPERT COMMENTARY

The role of formation science, with an emphasis on the diversity of immune responses induced by VLP, is underrepresented amongst clinical trials for VLP vaccines. Harnessing such diversity, particularly through the use of combinations of select excipients and adjuvants, will be paramount in the development of VLP vaccines.

MIS416 as a siRNA Delivery System with the Ability to Target Antigen-Presenting Cells

MIS416 is a microparticulate formulation derived from propionibacterium acnes cell wall skeletons with intrinsic adjuvant activity. Conjugates of MIS416-SS-peptide containing a disulfide linkage facilitate the cytoplasmic delivery and release of peptides in antigen-presenting cells (APCs). We hypothesized that MIS416-siRNA (small interfering RNA) conjugates, containing a disulfide linkage between MIS416 and the siRNA, would allow cytoplasmic release of siRNA in APCs. MIS416-SS-siStat3 conjugates added to cell culture medium of monolayers of DCs in culture flasks successfully targeted Stat3 mRNA in DCs in vitro without transfection, downregulating Stat3 mRNA and protein levels. These results suggest that MIS416-SS-siRNA conjugates can be used as a novel siRNA delivery system for the knockdown of mRNA levels in APCs.

Multi-target chimaeric VLP as a therapeutic vaccine in a model of colorectal cancer

Background

Colorectal cancer is responsible for almost 700,000 deaths annually worldwide. Therapeutic vaccination is a promising alternative to conventional treatment for colorectal cancer, using vaccines to induce targeted immune responses against tumour-associated antigens. In this study, we have developed chimaeric virus-like particles (VLP), a form of non-infectious non-replicative subunit vaccine consisting of rabbit haemorrhagic disease virus (RHDV) VP60 capsid proteins containing recombinantly inserted epitopes from murine topoisomerase IIα and survivin. These vaccines were developed in mono- (T.VP60, S.VP60) and multi-target (TS.VP60) forms, aiming to elucidate the potential benefits from multi-target vaccination.

Methods

Chimaeric RHDV VLP were developed by recombinantly inserting immune epitopes at the N-terminus of VP60. Vaccines were tested against a murine model of colorectal cancer by establishing MC38-OVA tumours subcutaneously. Unmethylated CpG DNA oligonucleotides (CpGs) were used as a vaccine adjuvant. Statistical tests employed included the Mantel-Cox log-rank test, ANOVA and unpaired t-tests depending on the data analysed, with a post hoc Bonferroni adjustment for multiple measures.

Results

Chimaeric RHDV VLP were found to form a composite particle in the presence of CpGs. Overall survival was significantly improved amongst mice bearing MC38-OVA tumours following vaccination with T.VP60 (60%, 9/15), S.VP60 (60%, 9/15) or TS.VP60 (73%, 11/15). TS.VP60 significantly prolonged the vaccine-induced remission period in comparison to each mono-therapy.

Conclusions

Chimaeric VLP containing multiple epitopes were found to confer an advantage for therapeutic vaccination in a model of colorectal cancer based on the prolongation of remission prior to tumour escape.

Electronic supplementary material

The online version of this article (doi:10.1186/s40425-017-0270-1) contains supplementary material, which is available to authorized users.

Combining dendritic cells and B cells for presentation of oxidised tumour antigens to CD8+ T cells

The dendritic cell (DC) is the foremost antigen-presenting cell (APC) for ex vivo expansion of tumour-specific patient T cells. Despite marked responses in some patients following reinfusion of DC-activated autologous or HLA-matched donor T cells, overall response rates remain modest in solid tumours. Furthermore, most studies aim to generate immune responses against defined tumour-associated antigens (TAA), however, meta-analysis reveals that those approaches have less clinical success than those using whole tumour cells or their components. Tumour lysate (TL) is used as a source of tumour antigen in clinical trials and potentially represents the full range of TAAs in an undefined state. Little is known about how different APCs cooperate to present TL antigens. We examined the effect of oxidised whole-cell lysate (ox-L) versus soluble fraction freeze-thaw lysate (s-L) on bone marrow-derived DCs and macrophages, and magnetic bead-isolated splenic B cells. The APCs were used individually, or in combination, to prime T cells. CD8⁺ T cells produced interferon (IFN)-γ in response to both s-L and ox-L, but only proliferated in response to ox-L. IFN-γ production and proliferation was enhanced by priming with the DC+B cell combination. Compared to DC alone, a trend toward greater interleukin (IL)-12 production was observed when DC+B cell were loaded with s-L and ox-L antigens. CD8⁺ T-cell specific lysis in vivo was greatest in ox-L-primed groups and DC+B cell priming significantly increased in vivo cytotoxicity compared to DC alone. These improved T-cell responses with two APCs and stressed cell lysate has implications for APC-based adoptive cell therapies.

Comparative Study of 5'- and 3'-Linked CpG-Antigen Conjugates for the Induction of Cellular Immune Responses

Conjugation of CpG to an antigen induces a stronger immune response compared to that of the mixture. This study compares the in vitro immunostimulatory activity of CpG conjugated via either its 5' or 3' end to the model antigen ovalbumin (OVA). CpG modified with an amine at either the 5' or 3' end was conjugated to OVA via a stable bis-aryl hydrazone bond. Similar levels of CpG conjugation to OVA were observed for both conjugates on the basis of the absorbance at 360 nm for the formation of the bis-aryl hydrazone bond, which determined 2.8 ± 0.3 CpGs linked per OVA. Both the 5' and 3' CpG-OVA conjugates had similar size-exclusion chromatography elution profiles. The immunostimulatory properties of the conjugates were determined by dendritic cells (DCs) and T-cells isolated from mice. The activation of DCs was determined by the upregulation of activation markers CD86 and CD40. T-cells were co-cultured with stimulated DCs, and the immunogenicity was determined by measuring T-cell proliferation and interferon γ production. Both the CpG 5'- and 3'-linked conjugates induced the same level (p > 0.5) of DC activation markers, which were significantly higher than those of the untreated control. Similarly, T-cell assays showed no significant difference (p > 0.5) between the 5' and 3' conjugates with respect to T-cell proliferation and interferon γ production. The 5' and 3' conjugates induced T-cell activation significantly higher than the mixture of CpG and OVA. This study showed that the end at which CpG is conjugated to an antigen has no influence on the generation of a T-cell-based immune response in vitro.

Intracellular Cleavable CpG Oligodeoxynucleotide-Antigen Conjugate Enhances Anti-tumor Immunity

Conjugation of a vaccine adjuvant to an antigen enhances anti-tumor immune responses. Direct chemical conjugation, however, may limit their processing by the antigen-presenting cell for immune stimulation. To test this hypothesis, antigen-adjuvant conjugates were designed to be cleaved by an intracellular trigger to release antigen and adjuvant from each other. The different reductive environment inside and outside antigen-presenting cells was used as a trigger for targeted intracellular release. Two redox-responsive disulphide linkers were used to conjugate the model antigen ovalbumin to CpG. In vitro stability assays with the reductant glutathione showed that one conjugate (SS) was cleaved by glutathione concentrations of the extra- and intracellular compartments. A second conjugate (HYN-SS) was only cleaved at the higher intracellular glutathione concentration. In vitro cell culture studies showed that high T cell responses were generated by the HYN-SS and the stable conjugate HYN. The SS conjugate induced a lower T cell response similar to a mixture of CpG and ovalbumin. An in vivo therapeutic tumor trial demonstrated a superior survival rate of 9/10 for mice vaccinated with HYN-SS conjugate compared to HYN (6/10), SS (2/10), and the mixture (2/10). This intracellular cleavable conjugation strategy represents a promising approach to improve cancer immunotherapy of soluble vaccines.

cAMP-Response Element-Binding 3-Like Protein 1 (CREB3L1) is Required for Decidualization and its Expression is Decreased in Women with Endometriosis

Endometriosis is a major cause of infertility and pelvic pain, affecting more than 10% of reproductive-aged women. Progesterone resistance has been observed in the endometrium of women with this disease, as evidenced by alterations in progesterone-responsive gene and protein expression. cAMPResponse Element-Binding 3-like protein 1 (Creb3l1) has previously been identified as a progesterone receptor (PR) target gene in mouse uterus via high density DNA microarray analysis. However, CREB3L1 function has not been studied in the context of endometriosis and uterine biology. In this study, we validated progesterone (P4) regulation of Creb3l1 in the uteri of wild-type and progesterone receptor knockout (PRKO) mice. Furthermore, we observed that CREB3L1 expression was significantly higher in secretory phase human endometrium compared to proliferative phase and that CREB3L1 expression was significantly decreased in the endometrium of women with endometriosis. Lastly, by transfecting CREB3L1 siRNA into cultured human endometrial stromal cells (hESCs) prior to hormonal induction of in vitro decidualization, we showed that CREB3L1 is required for the decidualization process. Interestingly, phosphorylation of ERK1/2, critical factor for decidualization, was also significantly reduced in CREB3L1-silenced hESCs. It is known that hESCs from patients with endometriosis show impaired decidualization and that dysregulation of the P4-PR signaling axis is linked to a variety of endometrial diseases including infertility and endometriosis. Therefore, these results suggest that CREB3L1 is required for decidualization in mice and humans and may be linked to the pathogenesis of endometriosis in a P4-dependent manner.

Bridging Small Molecules to Modified Bacterial Microparticles Using a Disulphide Linkage: MIS416 as a Cargo Delivery System

MIS416 is an intact minimal cell wall skeleton derived from Proprionibacterium acnes that is phagocytosed by antigen presenting cells, including dendritic cells (DCs). This property allows MIS416 to be exploited as a vehicle for the delivery of peptide antigens or other molecules (for example, nucleic acids) to DCs. We previously showed that covalent (non-cleavable) conjugation of OVA, a model antigen derived from ovalbumin, to MIS416 enhanced immune responses in DCs in vivo, compared to unconjugated MIS416 and OVA. Intracellular trafficking promotes the lysosomal degradation of MIS416, leading to the destruction of MIS416 plus the associated cargos conjugated to MIS416. However, lysosomal degradation of cargo may not be desired for some MIS416 conjugates. Here we have investigated whether a cleavable linkage could facilitate release of the cargo in the cytoplasm of DCs to avoid lysosomal degradation. DCs were treated in vitro with disulfide-containing conjugates, and as hypothesised faster release of SIINFEKL peptide in the cytoplasm of DCs was observed with the inclusion of a disulfide bond between MIS416 and cargo. The inclusion of a cleavable disulfide bond in the conjugates did not significantly alter the amount of SIINFEKL antigens presented on MHC I molecules on DCs as compared with conjugates without a disulfide bond. However, the conjugates containing disulfide-linkages performed either slightly better (p<0.05) than, or the same as conjugates without a disulfide bond with respect to in vitro OT-1 T-cell proliferation induced by the presentation of SIINFEKL antigens on DCs, or DC activation studies, respectively. However, disulfide-containing conjugates were less effective than conjugates without a disulfide bond in in vivo cytotoxicity assays. In conclusion, inclusion of a disulfide bond in MIS416-peptide conjugates was associated with efficient release of peptides in the cytoplasm of DCs, an important consideration for MIS416-mediated delivery of degradation-sensitive cargoes. However, treatment of DCs with disulfide-containing conjugates did not significantly alter the presentation of peptide antigens on MHC class I molecules to T-cells, or greatly enhance antigen-associated T-cell proliferation in vitro.

Altered expression of microRNA-451 in eutopic endometrium of baboons (Papio anubis) with endometriosis

STUDY QUESTION

Are microRNAs (miRs) altered in the eutopic endometrium (EuE) of baboons following the induction of endometriosis?

SUMMARY ANSWER

Induction of endometriosis causes significant changes in the expression of eight miRs, including miR-451, in the baboon endometrium as early as 3 months following induction of the disease.

WHAT IS KNOWN ALREADY

Endometriosis is one of the most common gynecological disorders and causes chronic pelvic pain and infertility in women of reproductive age. Altered expression of miRs has been reported in women and has been suggested to play an important role in the pathophysiology of several gynecological disorders including endometriosis.

STUDY DESIGN, SIZE, DURATION

EuE was obtained from the same group of baboons before and 3 months after the induction of endometriosis. The altered expression of miR-451 was validated in the eutopic and ectopic endometrium of additional baboons between 3 and 15 months following disease induction. Timed endometrial biopsies from women with and without endometriosis were also used to validate the expression of miR-451.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Total RNA was extracted from EuE samples before and after the induction of endometriosis, and miRNA expression was analyzed using a 8 × 15 K miR microarray. Microarray signal data were preprocessed by AgiMiRna software, and an empirical Bayes model was used to estimate the changes. The present study focused on quantitative RT-PCR validation of the microarray data, specifically on miR-451 and its target genes in both baboons (n = 3) and women [control (n = 7) and endometriosis (n = 19)]. Descriptive and correlative analysis of miR-451 and target gene expression was conducted using in situ hybridization and immunohistochemistry, while functional analysis utilized an in vitro 3' untranslated region (UTR) luciferase assay and overexpression of miR-451 in human endometrial and endometriotic cell lines.

MAIN RESULTS AND THE ROLE OF CHANCE

Induction of endometriosis results in the altered expression of miR-451, -141, -29c, -21, -424, -19b, -200a and -181a in the baboon endometrium. In the baboon, induction of endometriosis significantly decreased the expression of miR-451 at 3 months (P < 0.001), which was also associated with increased expression of its target gene YWHAZ (14.3.3ζ). A similar significant (P < 0.0001) decrease in miR-451 expression was observed in women with endometriosis. The 3' UTR luciferase assay confirmed the regulation of YWHAZ expression by miR-451. Furthermore, overexpression of miR-451 in 12Z cells (immortalized human endometriotic epithelial cell line) led to the decreased expression of its target YWHAZ and this was correlated with decreased cell proliferation.

LIMITATIONS, REASONS FOR CAUTION

The study focused only on miR-451 and one of its targets, namely YWHAZ. A single miR could target number of genes and a single gene could also be regulated by number of miRs; hence, it is possible that other miRs and their regulated genes may contribute to the pathophysiology of endometriosis.

WIDER IMPLICATIONS OF THE FINDINGS

Our data suggest that the presence of ectopic lesions in baboon causes changes in EuE miR expression as early as 3 months postinduction of the disease, and some of these changes may persist throughout the course of the disease. We propose that the marked down-regulation of miR-451 in both baboons and women with endometriosis increases the expression of multiple target genes. Increased expression of one of the target genes, YWHAZ, increases proliferation, likely contributing to the pathophysiology of the disease.

Characterization of GAB1 expression over the menstrual cycle in women with and without polycystic ovarian syndrome provides a new insight into its pathophysiology

CONTEXT

In a previous microarray analysis, GRB2-associated binding protein 1 (GAB1), a docking protein closely related to the insulin receptor substrate, was down-regulated in endometrium of women with polycystic ovary syndrome (PCOS).

OBJECTIVE

The objective of the study was to characterize the cyclic expression of endometrial GAB1 in vivo in normal women and those with PCOS as well as investigate the possible mechanisms of endometrial regulation of GAB1 expression and action in vitro.

DESIGN

This was an experimental and case-control study.

SETTING

The study was conducted at a tertiary university hospital.

PATIENTS

Normal proven fertile women (controls; n = 31) and women with PCOS (cases; n = 26) participated in the study.

INTERVENTIONS

INTERVENTIONS included timed endometrial biopsies at different phases of the menstrual cycle. Ishikawa cells were cultured with β-estradiol (E2), medroxyprogesterone acetate, and E2 + medroxyprogesterone acetate. Transfection of small interfering RNA for GAB1 in Ishikawa cells incubated with or without insulin.

MAIN OUTCOME MEASURES

GAB1 mRNA expression in Ishikawa cells and in endometrium of cases and controls was measured. Protein expression of phosphorylated MAPK by Western blot was also measured. Immunohistochemical localization and expression of phosphorylated GAB1 in endometrium was also measured, using a digital histological score.

RESULTS

In endometrial tissue, GAB1 mRNA was reduced in the proliferative phase of PCOS women, compared with controls (P = .003; ANOVA). When all the phases of the menstrual cycle were grouped, GAB1 protein expression was reduced in endometrium of PCOS women (P < .0001; Student t test). E2 increases GAB1 mRNA expression in Ishikawa cells (P = .001; ANOVA). Phosphorylated MAPK is reduced in cells transfected with small interfering RNA for GAB1 (P = .008; ANOVA) and incubated with insulin.

CONCLUSIONS

GAB1 mRNA expression is positively modulated by E2. Endometrial GAB1 protein and mRNA expression are reduced in women with PCOS, suggesting that the endometrium of PCOS women have a defect in insulin signaling due to GAB1 down-regulation.

Mannosylation of virus-like particles enhances internalization by antigen presenting cells

Internalization of peptides by antigen presenting cells is crucial for the initiation of the adaptive immune response. Mannosylation has been demonstrated to enhance antigen uptake through mannose receptors, leading to improved immune responses. In this study we test the effect of surface mannosylation of protein-based virus-like particles (VLP) derived from Rabbit hemorrhagic disease virus (RHDV) on uptake by murine and human antigen presenting cells. A monomannoside and a novel dimannoside were synthesized and successfully conjugated to RHDV VLP capsid protein, providing approximately 270 mannose groups on the surface of each virus particle. VLP conjugated to the mannoside or dimannoside exhibited significantly enhanced binding and internalization by murine dendritic cells, macrophages and B cells as well as human dendritic cells and macrophages. This uptake was inhibited by the inclusion of mannan as a specific inhibitor of mannose specific uptake, demonstrating that mannosylation of VLP targets mannose receptor-based uptake. Consistent with mannose receptor-based uptake, partial retargeting of the intracellular processing of RHDV VLP was observed, confirming that mannosylation of VLP provides both enhanced uptake and modified processing of associated antigens.

Expression of the transmembrane mucins, MUC1, MUC4 and MUC16, in normal endometrium and in endometriosis

STUDY QUESTION

Are the transmembrane mucins, MUC1, MUC4 and MUC16, differentially expressed in endometriosis compared with normal endometrium?

SUMMARY ANSWER

This study revealed that transmembrane mucin expression does not vary significantly in normal endometrium during the menstrual cycle and is not altered in endometriosis relative to the epithelial marker, cytokeratin-18 (KRT18).

WHAT IS KNOWN ALREADY

Increased serum levels of the transmembrane mucin fragments MUC1, MUC4 and MUC16 that normally dominate the apical surface of simple epithelia are found in several pathological conditions, including endometriosis. Altered mucin expression in gynecologic diseases may promote infertility or endometrial pathologies.

STUDY DESIGN, SIZE, DURATION

This was a laboratory-based study of samples from 12 endometriosis patients as well as non-endometriosis control samples obtained from 31 patients.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Total RNA was isolated from endometrial biopsies of ectopic and eutopic endometrium from women with endometriosis and control patients from different stages of the menstrual cycle. Quantitative (q)-RT-PCR analyses were performed for the mucins, MUC1, MUC4 and MUC16, relative to the epithelial marker, cytokeratin-18 (KRT18), or β-actin (ACTB). Frozen sections from endometrial biopsies of proliferative and mid-secretory stage women with endometriosis were immunostained for MUC1, MUC4 and MUC16.

MAIN RESULTS AND THE ROLE OF CHANCE

qRT-PCR analyses of MUC1 and MUC16 mRNA revealed that these mucins do not vary significantly during the menstrual cycle nor are they altered in women with endometriosis relative to the epithelial marker, KRT18. MUC4 mRNA is expressed at very low levels relative to MUC1 and MUC16 under all conditions. There was little difference in MUC1 and MUC16 expression between eutopic endometrial and ectopic endometriotic tissues. MUC4 expression also was not significantly higher in the ectopic endometriotic tissues. Immunostaining for all three mucins reveals robust expression of MUC1 and MUC16 at the apical surfaces of endometrial epithelia, but little to no staining for MUC4.

LIMITATIONS, REASONS FOR CAUTION

qRT-PCR analysis was the main method used for mucin detection. Additional studies with stage III-IV endometriotic tissue would be useful to determine if changes in MUC1 and MUC16 expression occur, or if MUC4 expression increases, at later stages of endometriosis.

WIDER IMPLICATIONS OF THE FINDINGS

We report a comprehensive comparative profile of the major transmembrane mucins, MUC1, MUC4 and MUC16, relative to the epithelial marker, KRT18, in normal cycling endometrium and in endometriosis, and indicate constitutive expression. Previous studies have profiled the expression of individual mucins relative to β-actin and indicate accumulation in the luteal phase. Thus, these differences in interpretation appear to reflect the increased epithelial content of endometrium during the luteal phase.

STUDY FUNDING

This study was supported by: NIH R01HD29963 to D.D.C.; NIH U54HD007495 to S.M.H.; and NIH R01HD067721 to S.L.Y. and B.A.L. The authors have no competing interests to declare.

Obesity during pregnancy disrupts placental morphology, cell proliferation, and inflammation in a sex-specific manner across gestation in the mouse

It is well-accepted that maternal obesity affects fetal development to elevate the risk of offspring disease, but how this happens is unclear. Understanding placental alterations during gestation as a consequence of maternal obesity is critical to understanding the impact of maternal obesity on fetal programming. Here, we used histological criteria, flow cytometry, quantitative PCR, and multiplex cytokine assays to examine changes in cell proliferation and inflammation in the placenta during gestation in a mouse model of maternal high-fat diet-induced obesity. We focused on mouse mid- to late gestation (approximately human late first and third trimester) because previous literature has indicated that this is when important regulators of metabolism, including that of the brain and endocrine pancreas, are forming. These studies were undertaken in order to understand how maternal obesity changes the placenta during this period, which might suggest a causal link to later-life metabolic dysfunction. We found that labyrinth thickness and cell proliferation were decreased at both pregnancy stages in obese compared to normal weight pregnancies. Inflammation was also altered in late pregnancy with increased macrophage activation and elevated cytokine gene expression in the placenta as well as increased abundance of some cytokines in the fetal circulation in obese compared to normal weight pregnancies. These changes in macrophage activation and cytokine gene expression were of greater magnitude and significance in placentas accompanying male fetuses. These data provide insight into placental changes in obesity and identify potential links between placental inflammation and programming of offspring disease by maternal obesity.

Resveratrol and endometrium: a closer look at an active ingredient of red wine using in vivo and in vitro models

Resveratrol is a natural phytoestrogen with antiproliferative properties present in red wine, grapes, and berries. Published reports on the effects of resveratrol in human endometrial function are limited. The objective of this study was to investigate the expression of estrogen receptor α (ESR1), Ki-67 (a proliferative marker), aryl hydrocarbon receptor (AhR), and members of the cytochrome P450 superfamily of enzymes (CYP1A1 and CYP1B1) in an in vitro and vivo assay. Alkaline phosphatase assay of estrogenicity was used to compare estrogen activity of different concentrations of resveratrol to estradiol (E2) and diethylstilbestrol (DES), using Ishikawa cell culture. Immunohistochemical expression of ESR1 and Ki67, and reverse transcriptase polymerase chain reaction of AhR, CYP1A1, and CYP1B1 were analyzed from xenograft implants of human endometrial tissue in ovariectomized immunodeficient RAG-2-γ(c) mice, after 30 days of treatment with subcutaneous pellets of E2, E2 plus progesterone (P4), or E2 plus resveratrol (6, 30, or 60 mg) for 30 days. Compared to E2, resveratrol acted as an agonist and antagonist of estrogen in low and high concentrations, respectively, when combined with E2. Xenografts of human endometrial tissues in RAG-2 mice exhibited reduced expression of ESR1 and proliferative activity (Ki67) with 60 mg of resveratrol. This study suggests that resveratrol, at high doses, has the potential benefit to reduce proliferation of human endometrium through ESR1.

Potent antietumor immunity in mice induced by vaccination with an ovine atadenovirus vector

Identification of adenoviral isolates of nonhuman origin has fostered development of vectors with potential to overcome preexisting immunity in the human population that may affect clinical applications. Ovine adenoviral isolate, OAdV287 (OAdV7), the prototype of the genus Atadenovirus, has been previously characterized as a gene delivery vector although the receptor(s) used for infection remain to be identified. Here, we report the first use of recombinant OAdV7 as a vaccine for inducing an antitumor immune response in a mouse model. Treatment of murine BMDC with OAdV7 vectors expressing ovalbumin (OVA) resulted in upregulation of costimulatory markers and production of IL-12. Splenocytes isolated from immunized mice responded to antigen restimulation in vitro by proliferation and production of IFNγ. In vivo cytotoxicity assays revealed efficient killing of antigenic peptide-pulsed target cells 1 week after immunization, with an average killing efficiency of 75%. In mice inoculated with B16-OVA tumor cells immunization with OAdV7-OVA retarded and essentially prevented tumor growth in prophylactic and therapeutic tumor trials, respectively. Generation of a robust memory response was confirmed on tumor rechallenge in the prophylactic model. Therefore, OAdV7 is a novel vector with potential for further development of tumor vaccines.

Environmental strains of Mycobacterium avium interfere with immune responses associated with Mycobacterium bovis BCG vaccination

Prior exposure of a vaccinee to certain species of environmental mycobacteria can prime the immune system against common mycobacterial antigens, which can in turn reduce the subsequent efficacy of live attenuated mycobacterial vaccines (such as Mycobacterium bovis BCG), in both human and livestock vaccination programs. In this study, two strains of Mycobacterium avium, both isolated from New Zealand livestock, were investigated to determine their growth characteristics and effects on the immune system in murine models. Markedly different effects on the immune system were observed; an IS901-negative strain (WAg 207) induced significant up-regulation of cell surface activation markers (major histocompatibility complex II, CD80, and CD86) on in vitro-derived dendritic cells and induced the release of proinflammatory monokines (interleukin-1beta [IL-1beta], IL-6, and tumor necrosis factor alpha) in dendritic cell-macrophage cocultures following direct in vitro contact of cells with bacteria. In contrast, an IS901-positive strain (WAg 206) had none of these effects. When mice were exposed to M. avium via oral infection prior to BCG parenteral immunization, both strains were shown to be capable of decreasing subsequent antigen-stimulated gamma interferon secretion by splenic lymphocytes, although this effect was more significant for strain WAg 206. Both strains also induced a mycobacterial antigen-specific serological response in M. avium-sensitized and BCG-immunized mice; this response was greater in WAg 206-sensitized mice, and there was a predominance of immunoglobulin G1 antibody. The down-regulation of IFN-gamma responses and the up-regulation of antibody responses are characteristic of a switch to a type 2 immune response. The different results may be linked to the inherent growth characteristics of the two strains, since WAg 206 was shown to grow slowly in murine macrophages in vitro and to cause a persistent systemic infection following infection in vivo, while WAg 207 grew fast and did not persist in mice. The implications of these findings for BCG vaccination protocols are discussed.

Transcutaneous vaccination with virus-like particles

Virus-like particles (VLP) are inert, empty capsids of viruses, which contain no DNA/RNA from the virus itself. However they retain the structure of a virus and they can be engineered to have antigens attached. We have constructed VLP, derived from Rabbit hemorrhagic disease virus, and shown they are highly immunogenic. We tested the capacity of these engineered VLP to induce immune responses when they are administered to mice via the transcutaneous route. This route of vaccination is important, in order to generate mucosal protection. Our data showed that VLP are taken up by dendritic cells (DC), antigen-presenting cells that are essential to initiate acquired immune responses. The VLP induced an increase in expression of CD40, CD80 and CD86 but required an adjuvant, CpG DNA oligo-deoxy nucleotides (ODN) motifs, to enhance these responses. In vivo testing has also shown that the VLP, when wiped on to the skin in conjunction with immunostimulatory CpG, induce Ag-specific immune responses, typified by high levels of IFN-gamma and IgG1.

Identification, characterization, and evolution of a primate beta-defensin gene cluster

Defensins are members of a large diverse family of cationic antimicrobial peptides that share a signature pattern consisting of six conserved cysteine residues. Defensins have a wide variety of functions and their disruption has been implicated in various human diseases. Here we report the characterization of DEFB119-DEFB123, five genes in the human beta-defensin cluster locus on chromosome 20q11.1. The genomic structures of DEFB121 and DEFB122 were determined in silico. Sequences of the five macaque orthologs were obtained and expression patterns of the genes were analyzed in humans and macaque by semiquantitative reverse transcription polymerase chain reaction. Expression was restricted to the male reproductive tract. The genes in this cluster are differentially regulated by androgens. Evolutionary analyses suggest that this cluster originated by a series of duplication events and by positive selection. The evolutionary forces driving the proliferation and diversification of these defensins may be related to reproductive specialization and/or the host-parasite coevolutionary process.

Proteomic analysis of melanoma-derived exosomes by two-dimensional polyacrylamide gel electrophoresis and mass spectrometry

Exosomes are 40-100 nm vesicles released by numerous cell types and are thought to have a variety of roles depending on their origin. Exosomes derived from antigen presenting cells have been shown to be capable of initiating immune responses in vivo and eradicating established tumours in murine models. Tumour-derived exosomes can be utilised as a source of tumour antigen for cross-priming to T-cells and are thus of interest for use in anti-tumour immunotherapy. Further exploration into the protein composition of exosomes may increase our understanding of their potential roles in vivo and this study has examined the proteome of exosomes purified from cell supernatants of the melanoma cell lines MeWo and SK-MEL-28. The vesicular nature and size (30-100 nm) of the purified exosomes was confirmed by electron microscopy and sucrose density gradient centrifugation. Western blotting demonstrated the absence of calnexin and cytochrome c, verifying the purity of the exosome preparations, as well as enrichment of MHC class I and the tumour-associated antigens Mart-1 and Mel-CAM. The two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) protein profiles of exosomes from the two cell lines were highly comparable and strikingly different from the profiles of the total cell lysates. Mass spectrometric sequencing identified proteins present in 49 protein spots in the exosome lysates. Several of these have been identified previously in exosomes but some are novel, including p120 catenin, radixin, and immunoglobulin superfamily member 8 (PGRL). Proteins present in whole-cell lysates that were significantly reduced or excluded from exosomes were also identified and included several mitochondrial and lysosomal proteins, again confirming the proposed endosomal origin of exosomes. This study presents a starting point for future more in-depth protein studies of tumour-derived exosomes which will aid the understanding of their biogenesis and targeting for use in anti-tumour immunotherapy protocols.

Cytokine-modifiedMycobacterium smegmatis as a novel anticancer immunotherapy

Intravesical administration of live M. bovis BCG organisms for carcinoma in situ of the urinary bladder is the most successful immunotherapy for solid malignancy. Nevertheless BCG-therapy is associated with significant toxicity and is ineffective in 30-40% of cases. Recently it has been proposed that cytokine-modified mycobacteria may give greater efficacy. As any immunotherapy involving administration of live BCG organisms (wild-type or recombinant) is likely to have associated toxicity (notably in the immunocompromised), we examined the anti-tumour potential of the closely related nonpathogenic organism, Mycobacterium smegmatis, and a TNFalpha gene-modified recombinant M. smegmatis. When wild-type M. smegmatis were delivered to immunocompetent C57Bl/6 mice bearing the transplantable MB49 bladder tumour, efficacy comparable to live BCG was observed with 10-20% long-term survival. However, this effect was lost in both Nude and Beige mice, lacking functional T and NK cells, respectively. Recombinant M. smegmatis secreting TNFalpha, however, gave a 70% durable tumour-free survival. Lymphocytes from draining lymph-nodes and spleens of these mice exhibited pronounced IFNgamma production to mycobacterial-antigen and tumour-lysate, indicating a bias towards cell-mediated immunity. This was further supported by histopathological examination of the tumour site, which revealed significantly increased numbers of CD3+ lymphocytes in animals receiving the recombinant vaccine, but not in those receiving wild-type bacteria. Importantly, tumour rejection following M. smegmatis/TNFalpha was independent of T lymphocytes, as athymic Nude mice efficiently eradicated MB49 tumours. In contrast, the therapeutic efficacy of M. smegmatis/TNFalpha was reduced in animals deficient in NK cytolytic function, suggesting a role for NK-cells in initial tumour destruction. Furthermore the absence of NK-function in Beige mice did not prevent the establishment of tumour-protective memory. No toxicity was observed with wild-type or recombinant M. smegmatis in immunocompetent, T-deficient or NK-deficient models. We demonstrate for the first time that recombinant mycobacteria expressing mammalian cytokines have markedly increased anti-tumour properties. The lack of toxicity suggests that M. smegmatis is a "safe" vehicle for use in immunocompromised patients.

Bifidobacterial species differentially affect expression of cell surface markers and cytokines of dendritic cells harvested from cord blood

The gut microbiota may be important in the postnatal development of the immune system and hence may influence the prevalence of atopic diseases. Bifidobacteria are the most numerous bacteria in the guts of infants, and the presence or absence of certain species could be important in determining the geographic incidence of atopic diseases. We compared the fecal populations of bifidobacteria from children aged 25 to 35 days in Ghana (which has a low prevalence of atopy), New Zealand, and the United Kingdom (high-prevalence countries). Natal origin influenced the detection of bifidobacterial species in that fecal samples from Ghana almost all contained Bifidobacterium infantis whereas those of the other children did not. Choosing species on the basis of our bacteriological results, we tested bifidobacterial preparations for their effects on cell surface markers and cytokine production by dendritic cells harvested from cord blood. Species-specific effects on the expression of the dendritic-cell activation marker CD83 and the production of interleukin-10 (IL-10) were observed. Whereas CD83 expression was increased and IL-10 production was induced by Bifidobacterium bifidum, Bifidobacterium longum, and Bifidobacterium pseudocatenulatum, B. infantis failed to produce these effects. We concluded that B. infantis does not trigger the activation of dendritic cells to the degree necessary to initiate an immune response but that B. bifidum, B. longum, and B. pseudocatenulatum induce a Th2-driven immune response. A hypothesis is presented to link our observations to the prevalence of atopic diseases in different countries.

IL-2-secreting recombinant bacillus Calmette Guerin can overcome a Type 2 immune response and corticosteroid-induced immunosuppression to elicit a Type 1 immune response

The efficacy of bacillus Calmette Guerin (BCG) as a vaccine against tuberculosis is adversely affected by both genetic and environmental factors on the immune system. In this study we have demonstrated that a recombinant BCG (rBCG) secreting biologically active IL-2 has the ability to induce a T(h)1 profile in both immunocompromised and in IL-4 transgenic (Tg) mice. Dexamethasone (DXM) was administered orally to mice prior to vaccination with either rBCG or normal BCG (nBCG). Six weeks post-vaccination with rBCG, splenocytes from DXM-treated mice exhibited a strong antigen-specific proliferative response, while also secreting large amounts of IFN-gamma and low levels of IgG1. The opposite profile occurred when DXM-treated mice were vaccinated with nBCG. Splenocytes from these mice showed no significant proliferation and produced a cytokine profile associated with a T(h)2 immune response, in addition to exhibiting high levels of serum IgG1. In the IL-4 Tg model, mice vaccinated with rBCG again produced a strong T(h)1 immune response, exhibiting a high antigen-specific IFN-gamma:IL-4 ratio and a concomitantly high IgG2a:IgG1 ratio. IL-4 Tg mice vaccinated with nBCG produced the opposite profile. These findings suggest that BCG can be made more robust by incorporating immunopotentiating cytokines into the vaccine.

Utilization of umbilical cords to assess in utero exposure to persistent pesticides and polychlorinated biphenyls

In support of a study to relate developmental and cognitive effects with prenatal exposure to selected environmental toxicants, we developed and applied an analytical method to determine the concentration of two persistent pesticides, hexachlorobenzene (HCB) and p,p'-dichlorodiphenyldichloroethylene (DDE), and 32 specific polychlorinated biphenyl (PCB) congeners in 316 umbilical cords taken in 1986-1987 from women of the Faroe Islands. The analytical method consisted of homogenization of the cords, partitioning, microsilica gel column chromatography for clean-up, and dual-column capillary gas chromatography (DB-5 and DB-1701) with electron capture detection. Several quality control parameters were followed to monitor the performance of the method. Important criteria used before reporting unknown data were the recovery of in vitro-spiked analytes from a bovine umbilical cord (BUC) and the percentage lipid obtained for a Certified Reference Material (CRM)-350 of mackerel oil (MO). Recoveries of analytes that had been spiked at two concentration ranges (0.26-0.95 ng/g whole weight; 0.35-2.42 ng/g whole weight) into bovine cords ranged from 38.5% to 158% and from 50.4% to 145%, respectively, with a median recovery of 77.7%. Measurement of the percentage lipid for CRM-350 ranged from 73.8% to 107% with a median lipid value of 96.0%. The most prevalent analytes detected (%) in unknown umbilical cords were HCB (100), DDE (100), Ballschmiter/Zell PCBs 153 (100), 138 (98), 180 (98), 170 (93), 118 (88), 187 (86), and 146 (83), with corresponding median concentrations (ng/g whole weight) of 0.17, 1.19, 0.38, 0.30, 0.17, 0.11, 0.12, 0.09, and 0.07, respectively. Total PCB--sum of all measurable PCB congeners--had a median concentration of 1.37 ng/g whole weight. The analytes, which were very low in lipid content were also quantified on a lipid-adjusted basis, which provided an analytical challenge in these umbilical cord samples. The gravimetrically measured lipids in the human specimens ranged from 0.01% to 1.43% (median of 0.18%). In the pooled BUCs, our lipid measurements varied from 0.05% to 0.33% with a median value of 0.13%. The utility of using the umbilical cord as a matrix to assess in utero exposure to persistent environmental pollutants, compared with the use of umbilical cord blood or mother's blood, is worthy of debate.

Incorporation of biotinylated SP-A into rat lung surfactant layer, type II cells, and clara cells

The goal of this study was to compare the functions of Clara and type II cells during alveolar clearance and recycling of surfactant protein (SP) A, a secretory product of both cell types. We examined the incorporation of instilled biotinylated SP-A (bSP-A) into rat lung type II and Clara cells as a measure of clearance and recycling of the protein. Ultrastructural localization of bSP-A was accomplished by an electron-microscopic immunogold technique at 7, 30, and 120 min after intratracheal instillation. Localization of bSP-A was quantitatively evaluated within extracellular surfactant components (lipid-rich forms: myelin figures, vesicles, and tubular myelin; and lipid-poor hypophase) and in compartments of type II and Clara cells. bSP-A was incorporated into myelinic and vesicular forms of extracellular surfactant, but tubular myelin and hypophase had little bSP-A. Lamellar bodies of type II cells demonstrated a significant time-dependent increase in their incorporation of bSP-A. There was a concentration of bSP-A in the secretory granules and mitochondria of Clara cells, but no Clara cell compartment showed a pattern of time-dependent change in immunolabeling. Our immunolabeling data demonstrated a time-dependent movement of exogenous SP-A from extracellular components into type II cells and their secretory granules. Clara cells did not demonstrate a time-dependent incorporation of bSP-A into their secretory granules during the period of this study. If Clara cells recycle SP-A, they must reach a steady state very quickly or very slowly.

Ontogeny and localization of TGF-beta type I receptor expression during lung development

Transforming growth factor (TGF)-beta is a family of multifunctional cytokines controlling cell growth, differentiation, and extracellular matrix deposition in the lung. The biological effects of TGF-beta are mediated by type I (TbetaR-I) and II (TbetaR-II) receptors. Our previous studies show that the expression of TbetaR-II is highly regulated in a spatial and temporal fashion during lung development. In the present studies, we investigated the temporal-spatial pattern and cellular expression of TbetaR-I during lung development. The expression level of TbetaR-I mRNA in rat lung at different embryonic and postnatal stages was analyzed by Northern blotting. TbetaR-I mRNA was expressed in fetal rat lungs in early development and then decreased as development proceeded. The localization of TbetaR-I in fetal and postnatal rat lung tissues was investigated by using in situ hybridization performed with an antisense RNA probe. TbetaR-I mRNA was present in the mesenchyme and epithelium of gestational day 14 rat lungs. An intense TbetaR-I signal was observed in the epithelial lining of the developing bronchi. In gestational day 16 lungs, the expression of TbetaR-I mRNA was increased in the mesenchymal tissue. The epithelium in both the distal and proximal bronchioles showed a similar level of TbetaR-I expression. In postnatal lungs, TbetaR-I mRNA was detected in parenchymal tissues and blood vessels. We further studied the expression of TbetaR-I in cultured rat lung cells. TbetaR-I was expressed by cultured rat lung fibroblasts, microvascular endothelial cells, and alveolar epithelial cells. These studies demonstrate a differential regulation and localization of TbetaR-I that is different from that of TbetaR-II during lung development. TbetaR-I, TbetaR-II, and TGF-beta isoforms exhibit distinct but overlapping patterns of expression during lung development. This implies a distinct role for TbetaR-I in mediating TGF-beta signal transduction during lung development.

Targeting early events in T cell activation to construct improved vaccines

Live, attenuated vaccines currently offer the best protection against virulent pathogens. Recent advances in Immunology and Molecular Biology provide an opportunity to design vaccines that will be more effective and safer than existing ones. Immunologists are rapidly developing the capacity to identify and construct the minimal immunogenic units from pathogens. The molecular signals required to fully activate antigen presenting cells (APCs) and responder T cells are becoming apparent. Improved vaccine delivery systems are being designed which will mimic the actions of pathogens in vivo. These vaccines will incorporate protective epitopes fused to immunoregulatory cytokines in chimeric proteins. They will be encapsulated in formulations which allow for the slow release of these chimeric proteins thereby inducing the memory T cells required for long-lived immunity. These vaccine formulations will target receptors present on the most active APCs. Here we discuss how these advances will allow us to rationally construct "virtual pathogens" which will provide improved protection against new and old microbial foes.

Regulation of signal transducers and activators of transcription (STATs) by effectors of adipogenesis: coordinate regulation of STATs 1, 5A, and 5B with peroxisome proliferator-activated receptor-gamma and C/AAAT enhancer binding protein-alpha

We have recently demonstrated that three signal transducers and activators of transcription (STAT) family members are induced during adipocyte differentiation (Stephens et al., J. Biol. Chem. 271 (1996) 10441-10444). Since STATs 1, 5A, and 5B are induced during adipocyte differentiation, we have examined the ability of these proteins to be regulated by components of the differentiation cocktail. In addition, we have examined the effects of potent effectors of differentiation on STAT protein expression during adipogenesis. A negative effector, tumor necrosis factor-alpha (TNFalpha), and a positive effector, a thiazolidinedione, were used in these experiments. Our results demonstrate that the expression of STATs 1, 5A, and 5B is not dramatically influenced by individual components of the differentiation cocktail. However, the expression of these three STAT family members tightly correlates with lipid accumulation. Moreover, the expression of STATs 1, 5A, and 5B, but not STATs 3 and 6, are regulated in an identical fashion to both C/AAAT enhancer binding proteins alpha and peroxisome proliferator-activated receptor-gamma by TNFalpha and a thiazolidinedione. Furthermore, the expression of adipocyte-expressed JAK kinases are unaffected by effectors of differentiation. These findings suggest that three STAT family members may play a role in the regulation of adipocyte gene expression.

Dietary NaC1 during pregnancy and lactation: effect on brain angiotensin II receptors and behavior

Female rats were fed diets containing either a basal (0.12%), mid- (1%) or high (3%) level of NaCl during pregnancy and lactation. Plasma aldosterone was elevated approximately 5- and 15-fold in dams fed basal compared with either the mid- or high-NaCl diets at the end of both pregnancy and lactation (Postnatal Day 21), respectively. Dams fed basal diet and killed at the end of lactation had a higher density of angiotensin II receptors in the organum vasculosum laminae terminalis, paraventricular hypothalamus, and median preoptic nucleus than did rats fed either mid- or high-NaCl diets. Other dams, treated identically, were returned to rodent chow (approximately 0.2% NaCl) at the end of lactation for intake tests during the next week. Dams that had received basal diet did not differ from mid-NaCl and high-NaCl groups in sodium appetite induced by either acute sodium depletion or mineralocorticoid administration but showed the lowest spontaneous intake of NaCl solution.

Tyloxapol confers durable protection against hyperoxic lung injury in the rat

We tested the hypothesis that the nonlipid components of Exosurf, tyloxapol (TY), and cetyl alcohol (CA), protect against hyperoxic lung injury by induction of the animals' endogenous antioxidant defenses. Adult rats were intratracheally instilled with escalating doses of TY and CA (n = 20) or TY alone (n = 32) and immediately exposed to 100% oxygen. Intratracheal instillation of TY alone or in combination with CA protected against lethal hyperoxic injury in the rat in a dose-dependent fashion. To assess the effects of timing, rats were instilled with TY plus CA 24 hours before (n = 6) and 24 hours after (n = 6) exposure to 100% oxygen, with time to death determined. Rats were also instilled with TY alone at 0 hour (n = 6), 48 hours (n = 3), 96 hours (n = 3), and 186 hours (n = 4) prior to exposure to 100% oxygen. Lungs were assayed for superoxide dismutase, glutathione peroxidase, and catalase activities. Finally, the pharmacokinetics of TY in the rat lung were determined by instilling radiolabelled TY intratracheally. TY has a prolonged half-life in the rat lung, and protection against lethal hyperoxic injury was achieved by a single intratracheal dose delivered up to 186 hours prior to injury. Antioxidant enzymes were not induced in protected animals. We conclude that TY provides durable protection against hyperoxic lung injury without induction of antioxidant enzymes. It is present in the lung for sufficient duration to invoke a direct mechanism of protection, possibly as a radical scavenger. These findings raise the prospect of a therapeutic application for TY as prophylaxis in patients at risk for oxygen toxicity and adult respiratory distress syndrome.

Mechanical ventilation of rat lung: effect on surfactant forms

Mechanical ventilation of the lung could affect surfactant turnover by alteration of its secretion, recycling, and degradation. In vitro studies of surfactant subfractions recoverable from lavage fluid have led to predictions about surfactant physiology in vivo that include morphological transformations. We used electron microscopy to study in situ lipid forms in alveoli of rat lungs after two ventilation strategies [15 min at pressures (cmH(2)O) of 20/0 or 20/10]. In control animals, 4% of the lipid profile area in the surface lining layer was myelin figures (MF), 14% was tubular myelin, 37% was vesicular forms (VF), and the remainder (45%) was hypophase. Compared with controls, the length-normalized sum of the lipid forms and the hypophase was two times as great in the lungs of the 20/0 group. MF were threefold higher in the 20/0 group and fivefold higher in the 20/10 group. VF doubled after ventilation at 20/0, but VF were the same as control after ventilation at 20/10. The results showed that a ventilation pattern of 20/0 compared with that of 20/10 group was associated with a significantly larger VF, suggesting an increased net production of these surfactant forms during a large tidal volume breathing pattern. These morphological results are consistent with published results using physical methods of fractionating lung lavage.

Intrahippocampal infusions of a metabotropic glutamate receptor antagonist block the memory of context-specific but not tone-specific conditioned fear

The role of metabotropic glutamate receptors (mGluRs) in the acquisition of learning and memory using fear conditioning as a behavioral model was examined. The mGluR antagonist (R, S)-alpha-methyl-4-carboxyphenylglycine (MCPG) was infused into the hippocampus 30 min before fear conditioning, and freezing was measured during both acquisition and retention tests. The results show that pretraining antagonism of MCPG-sensitive mGluRs in the hippocampus impaired context-specific memory for an aversive event during testing. The memory for tone-specific fear, however, remained intact despite pretraining infusion of MCPG. Treating rats with MCPG did not affect context- or tone-specific fear during acquisition. Results suggest that mGluR activation may play an important role in hippocampally mediated memory consolidation.