Designing the optimal vaccine: the importance of cytokines and dendritic cells

Immunostimulatory nanoparticles delivering cytokines as a novel cancer nanoadjuvant to empower glioblastoma immunotherapy

Glioblastoma (GBM) stands as a highly aggressive and deadly malignant primary brain tumor with a median survival time of under 15 months upon disease diagnosis. While immunotherapies have shown promising results in solid cancers, brain cancers are still unresponsive to immunotherapy due to immunological dysfunction and the presence of a blood-brain barrier. Interleukin-12 (IL-12) emerges as a potent cytokine in fostering anti-tumor immunity by triggering interferon-gamma production in T and natural killer cells and changing macrophages to a tumoricidal phenotype. However, systemic administration of IL-12 toxicity in clinical trials often leads to significant toxicity, posing a critical hurdle. To overcome this major drawback, we have formulated a novel nanoadjuvant composed of immunostimulatory nanoparticles (ISN) loaded with IL-12 to decrease IL-12 toxicity and enhance the immune response by macrophages and GBM cancer cells. Our in vitro results reveal that ISN substantially increase the production of pro-inflammatory cytokines in GBM cancer cells (e.g. 2.6 × increase in IL-8 expression compared to free IL-12) and macrophages (e.g. 2 × increase in TNF-α expression and 6 × increase in IL-6 expression compared to the free IL-12). These findings suggest a potential modulation of the tumor microenvironment. Additionally, our study demonstrates the effective intracellular delivery of IL-12 by ISN, triggering alterations in the levels of pro-inflammatory cytokines at both transcriptional and protein expression levels. These results highlight the promise of the nanoadjuvant as a prospective platform for resharing the GBM microenvironment and empowering immunotherapy.

Immunostimulant plant proteins: Potential candidates as vaccine adjuvants

The COVID-19 pandemic is shaking up global scientific structures toward addressing antibiotic resistance threats and indicates an urgent need to develop more cost-effective vaccines. Vaccine adjuvants play a crucial role in boosting immunogenicity and improving vaccine efficacy. The toxicity and adversity of most adjuvant formulations are the major human immunization problems, especially in routine pediatric and immunocompromised patients. The present review focused on preclinical studies of immunoadjuvant plant proteins in use with antiparasitic, antifungal, and antiviral vaccines. Moreover, this report outlines the current perspective of immunostimulant plant protein candidates that can be used by researchers in developing new generations of vaccine-adjuvants. Future clinical studies are required to substantiate the plant proteins' safety and applicability as a vaccine adjuvant in pharmaceutical manufacturing.

Human lymph node immune dynamics as driver of vaccine efficacy: an understudied aspect of immune responses

INTRODUCTION

During the last century, changes in hygiene, sanitation, and the advent of childhood vaccination have resulted in profound reductions in mortality from infectious diseases. Despite this success, infectious diseases remain an enigmatic public health threat, where effective vaccines for influenza, human immunodeficiency virus (HIV), tuberculosis, and malaria, among others remain elusive.

AREA COVERED

In addition to the immune evasion tactics employed by complex pathogens, our understanding of immunopathogenesis and the development of effective vaccines is also complexified by the inherent variability of human immune responses. Lymph nodes (LNs) are the anatomical sites where B cell responses develop. An important, but understudied component of immune response complexity is variation in LN immune dynamics and in particular variation in germinal center follicular helper T cells (Tfh) and B cells which can be impacted by genetic variation, aging, the microbiome and chronic infection.

EXPERT OPINION

This review describes the contribution of genetic variation, aging, microbiome and chronic infection on LN immune dynamics and associated Tfh responses and offers perspective on how inclusion of LN immune subset and cytoarchitecture analyses, along with peripheral blood biomarkers can supplement systems vaccinology or immunology approaches for the development of vaccines or other interventions to prevent infectious diseases.

Oxidative Stress Compromises Lymphocyte Function in Neonatal Dairy Calves

Dairy calves are unable to mount an effective immune response during their first weeks of life, which contributes to increased disease susceptibility during this period. Oxidative stress (OS) diminishes the immune cell capabilities of humans and adult cows, and dairy calves also experience OS during their first month of life. However, the impact that OS may have on neonatal calf immunity remains unexplored. Thus, we aimed to evaluate the impact of OS on newborn calf lymphocyte functions. For this, we conducted two experiments. First, we assessed the association of OS status throughout the first month of age and the circulating concentrations of the cytokines interferon-gamma (IFN-γ) and interleukin (IL) 4, as well as the expression of cytokine-encoding genes IFNG, IL2, IL4, and IL10 in peripheral mononuclear blood cells (PBMCs) of 12 calves. Subsequently, we isolated PBMCs from another 6 neonatal calves to investigate in vitro the effect of OS on immune responses in terms of activation of lymphocytes, cytokine expression, and antibody production following stimulation with phorbol 12-myristate 13-acetate or bovine herpesvirus-1. The results were compared statistically through mixed models. Calves exposed to high OS status in their first month of age showed higher concentrations of IL-4 and expression of IL4 and IL10 and lower concentrations of IFN-γ and expression of IFNG and IL2 than calves exposed to lower OS. In vitro, OS reduced lymphocyte activation, production of antibodies, and protein and gene expression of key cytokines. Collectively, our results demonstrate that OS can compromise some immune responses of newborn calves. Hence, further studies are needed to explore the mechanisms of how OS affects the different lymphocyte subsets and the potential of ameliorating OS in newborn calves as a strategy to augment the functional capacity of calf immune cells, as well as enhance calves’ resistance to infections.

In Vivo Antitumor Effect against Murine Cells of CT26 Colon Cancer and EL4 Lymphoma by Autologous Whole Tumor Dead Cells

Active immunotherapy against cancer is based on immune system stimulation, triggering efficient and long-lasting antigen-specific immune responses. Immunization strategies using whole dead cells from tumor tissue, containing specific antigens inside, have become a promising approach, providing efficient lymphocyte activation through dendritic cells (DCs). In this work, we generate whole dead tumor cells from CT26, E.G7, and EL4 live tumor cells as antigen sources, which termed immunogenic cell bodies (ICBs), generated by a simple and cost-efficient starvation-protocol, in order to determine whether are capable of inducing a transversal anticancer response regardless of the tumor type, in a similar way to what we describe previously with B16 melanoma. We evaluated the anticancer effects of immunization with doses of ICBs in syngeneic murine tumor models. Our results showed that mice's immunization with ICBs-E.G7 and ICBs-CT26 generate 18% and 25% of tumor-free animals, respectively. On the other hand, all carrying tumor-animals and immunized with ICBs, including ICBs-EL4, showed a significant delay in their growth compared to not immunized animals. These effects relate to DCs maturation, cytokine production, increase in CD4+T-bet+ and CD4+ROR-γt+ population, and decrease of T regulatory lymphocytes in the spleen. Altogether, our data suggest that whole dead tumor cell-based cancer immunotherapy generated by a simple starvation protocol is a promising way to develop complementary, innovative, and affordable antitumor therapies in a broad spectrum of tumors.

Evaluation of immuno-modulating effect of recombinant heat shock protein 40 of Brucella abortus in mice

The present study was aimed to evaluate the immuno-modulatory effect of Brucella-specific recombinant HSP40 (rDnaJ) when co-immunized with Brucella rOmp22 in mice. For this, dnaJ of Brucella abortus was cloned, expressed in E. coli, and purified to homogeneity using Ni-NTA agarose columns. Three groups of mice (n = 6 in each group) were used in the study. The control group was immunized with rOmp22 alone, while group 1 mice were injected subcutaneously with rOmp22 along with conventional adjuvants (FCA, FIA), and group 2 mice with rOmp22 mixed with rDnaJ. IgG isotype (IgG1 and IgG2a) response to rOmp22 immunization was evaluated by enzyme-linked immunosorbent assay which was found to be directed towards the cell-mediated arm of immune system (CMI) in group 2 mice in which rOmp22 was co-immunized with rDnaJ. Expression profiling of IL-4 and IL-12 was checked in all the groups by qRT PCR. IL12 mRNA was up-regulated to a greater extent in group2 mice, suggesting that the CMI arm of immune system was stimulated. Hence, it was concluded that CMI response against rOmp22 is stimulated to a greater extent in mice when co-immunized with Brucella rDnaJ.

Transendothelial migration (TEM) of in vitro generated dendritic cell vaccine in cancer immunotherapy

Many efforts have been made to improve the efficacy of dendritic cell (DC) vaccines in DC-based cancer immunotherapy. One of these efforts is to deliver a DC vaccine more efficiently to the regional lymph nodes (rLNs) to induce stronger anti-tumor immunity. Together with chemotaxis, transendothelial migration (TEM) is believed to be a critical and indispensable step for DC vaccine migration to the rLNs after administration. However, the mechanism underlying the in vitro-generated DC TEM in DC-based cancer immunotherapy has been largely unknown. Currently, junctional adhesion molecules (JAMs) were found to play an important role in the TEM of in vitro generated DC vaccines. This paper reviews the TEM of DC vaccines and TEM-associated JAM molecules.

Dendritic cells as cancer therapeutics

The ability of immune therapies to control cancer has recently generated intense interest. This therapeutic outcome is reliant on T cell recognition of tumour cells. The natural function of dendritic cells (DC) is to generate adaptive responses, by presenting antigen to T cells, hence they are a logical target to generate specific anti-tumour immunity. Our understanding of the biology of DC is expanding, and they are now known to be a family of related subsets with variable features and function. Most clinical experience to date with DC vaccination has been using monocyte-derived DC vaccines. There is now growing experience with alternative blood-derived DC derived vaccines, as well as with multiple forms of tumour antigen and its loading, a wide range of adjuvants and different modes of vaccine delivery. Key insights from pre-clinical studies, and lessons learned from early clinical testing drive progress towards improved vaccines. The potential to fortify responses with other modalities of immunotherapy makes clinically effective "second generation" DC vaccination strategies a priority for cancer immune therapists.

Carbohydrate-based vaccines for oncotherapy

Cancer is still one of the most serious threats to human worldwide. Aberrant patterns of glycosylation on the surface of cancer cells, which are correlated with various cancer development stages, can differentiate the abnormal tissues from the healthy ones. Therefore, tumor-associated carbohydrate antigens (TACAs) represent the desired targets for cancer immunotherapy. However, these carbohydrate antigens may not able to evoke powerful immune response to combat with cancer for their poor immunogenicity and immunotolerance. Different approaches have been developed to address these problems. In this review, we want to summarize the latest advances in TACAs based anticancer vaccines.

Attenuated Streptococcus pneumoniae vaccine candidate SPY1 promotes dendritic cell activation and drives a Th1/Th17 response

Streptococcus pneumoniae is one of the causative agent of pneumonia, meningitis, otitis media and sepsis. Vaccination is an effective strategy to combat S. pneumoniae invasion. We previously reported that SPY1, a novel attenuated vaccine candidate against S. pneumoniae, induces a protective immune response against pneumococcal infection in mice. However, underlying mechanisms have yet to be fully illustrated. To explore the mechanism of innate and adaptive immunities induced by SPY1. In this study, bone marrow-derived dendritic cells (DCs) of mice were infected with SPY1 and its parental wild-type strain D39, SPY1-infected DCs were co-cultured with homologous CD4+T cells or adoptive transfer to C57BL/6 mice. Results showed that SPY1 promoted DCs maturation with increased levels of surface molecules such as CD40, CD86, and MHC II, and upregulated the expression of proinflammatory cytokines, including TNF-α, IL-6, IL-12p40, IL-12p70 and IL-23. By contrast, D39 did not efficiently induce DCs activation and maturation. SPY1 could also activate MAPK and NF-κB signaling pathways in DC, but D39 unlikely affected this pathways. SPY1 treated DCs also induced Th1 and Th17 responses in vitro and in vivo. Our results supported the potential of SPY1 as a novel attenuated pneumococcus vaccine, because SPY1-activated DCs exhibit fully matured phenotype, initiated an adaptive immune response, and orchestrated Th1 and Th17 responses.

Native cellulose nanofibrills induce immune tolerance in vitro by acting on dendritic cells

Cellulose nanofibrills (CNFs) are attractive biocompatible, natural nanomaterials for wide biomedical applications. However, the immunological mechanisms of CNFs have been poorly investigated. Considering that dendritic cells (DCs) are the key immune regulatory cells in response to nanomaterials, our aim was to investigate the immunological mechanisms of CNFs in a model of DC-mediated immune response. We found that non-toxic concentrations of CNFs impaired the differentiation, and subsequent maturation of human monocyte-derived (mo)-DCs. In a co-culture with CD4⁺T cells, CNF-treated mo-DCs possessed a weaker allostimulatory and T helper (Th)1 and Th17 polarizing capacity, but a stronger capacity to induce Th2 cells and CD4⁺CD25^hiFoxP3^hi regulatory T cells. This correlated with an increased immunoglobulin-like transcript-4 and indolamine dioxygenase-1 expression by CNF-treated mo-DCs, following the partial internalization of CNFs and the accumulation of CD209 and actin bundles at the place of contacts with CNFs. Cumulatively, we showed that CNFs are able to induce an active immune tolerance by inducing tolerogenic DCs, which could be beneficial for the application of CNFs in wound healing and chronic inflammation therapies.

Triggering of NF-κB in cytokine-matured human DCs generates superior DCs for T-cell priming in cancer immunotherapy

Understanding the signaling that governs the immunogenicity of human dendritic cells (DCs) is a prerequisite for improving DC-based therapeutic vaccination strategies, in which the ability of DCs to induce robust and lasting Ag-specific CTL responses is of critical importance. Cytokine-matured DCs are regularly used, but to induce memory-type CTLs, they require additional activation stimuli, such as CD4+ T-cell help or TLR activation. One common denominator of these stimuli is the activation of NF-κB. Here, we show that human monocyte-derived, cytokine cocktail-matured DCs transfected with constitutively active mutants of IκB kinases (caIKKs) by mRNA electroporation, further upregulated maturation markers, and secreted enhanced amounts of cytokines, including IL-12p70, which was produced for more than 48 h after transfection. Most importantly, cytotoxic T cells induced by caIKK-transfected DCs combined high CD27 expression, indicating a more memory-like phenotype, and a markedly enhanced secondary expandability with a high lytic capacity. In contrast, CTLs primed and expanded with unmodified cytokine cocktail-matured DCs did not maintain their proliferative capacity upon repetitive stimulations. We hypothesize that "designer" DCs expressing constitutively active IκB kinases will prove highly immunogenic also in vivo and possibly emerge as a new strategy to improve the clinical efficacy of therapeutic vaccinations against cancer and other chronic diseases.

Enhancement of antibody production against rabies virus by uridine 5'-triphosphate in mice

Extracellular nucleotides such as adenosine 5'-triphospate (ATP) and uridine 5'-triphosphate (UTP) interact with P2 purinergic receptors on the surface of phagocytic cells and induce various physiological reactions. In this study, the production of antibody in mice immunized with an inactivated rabies vaccine containing these nucleotides was investigated. Injection of inactivated rabies vaccine with UTP, but not with ATP, induced significantly higher serum antibody production in mice. The enhancement of antibody production by UTP was inhibited by an anti-P2Y4 receptor antibody. In an air pouch experiment, UTP treatment increased the number of monocytes and macrophages infiltrating the pouch and up-regulated the gene expression of IL-4 and IL-13 in the regional lymph nodes. These results suggested that UTP admixed with rabies vaccine activates Th2 cells and induces a humoral immune response. Furthermore, the survival rate of mice immunized with a rabies vaccine admixed with UTP before rabies virus challenge was slightly higher than that of control mice. In conclusion, UTP can act as a vaccine adjuvant to enhance antibody production against the rabies virus in mice.

Dendritic cells and the maintenance of self-tolerance

Dendritic cells (DC) play important roles in the initiation of immune responses and in the maintenance of self-tolerance. We have been studying the role of DC in the pathogenesis of type 1 diabetes and exploring the ability of specific DC subsets to prevent diabetes in non-obese diabetic (NOD) mice. DC presenting low doses of antigen are capable of inducing and expanding T-regulatory (Treg) cells that have potent suppressive function. We review here our recent findings in this area and highlight the ability of semi-mature therapeutic DC to induce Treg expansion in the absence of exogenous antigen. We discuss how the presentation of endogenous self-antigen by DC may represent a natural mechanism for peripheral self-tolerance that can be harnessed to prevent autoimmunity.