Th cells promote CTL survival and memory via acquired pMHC-I and endogenous IL-2 and CD40L signaling and by modulating apoptosis-controlling pathways

Immuno-informatics study identifies conserved T cell epitopes in non-structural proteins of Bluetongue virus serotypes: formulation of a computationally optimized next-generation broad-spectrum multi-epitope vaccine

Introduction

Bluetongue (BT) poses a significant threat to the livestock industry, affecting various animal species and resulting in substantial economic losses. The existence of numerous BT virus (BTV) serotypes has hindered control efforts, highlighting the need for broad-spectrum vaccines.

Methodology

In this study, we evaluated the conserved amino acid sequences within key non-structural (NS) proteins of BTV and identified numerous highly conserved murine- and bovine-specific MHC class I-restricted (MHC-I) CD8+ and MHC-II-restricted CD4+ epitopes. We then screened these conserved epitopes for antigenicity, allergenicity, toxicity, and solubility. Using these epitopes, we developed in silico-based broad-spectrum multiepitope vaccines with Toll-like receptor (TLR-4) agonists. The predicted proinflammatory cytokine response was assessed in silico using the C-IMMSIM server. Structural modeling and refinement were achieved using Robetta and GalaxyWEB servers. Finally, we assessed the stability of the docking complexes through extensive 100-nanosecond molecular dynamics simulations before considering the vaccines for codon optimization and in silico cloning.

Results

We found many epitopes that meet these criteria within NS1 and NS2 proteins and developed in silico broad-spectrum vaccines. The immune simulation studies revealed that these vaccines induce high levels of IFN-γ and IL-2 in the vaccinated groups. Protein-protein docking analysis demonstrated promising epitopes with strong binding affinities to TLR-4. The docked complexes were stable, with minimal Root Mean Square Deviation and Root Mean Square Fluctuation values. Finally, the in silico-cloned plasmids have high % of GC content with > 0.8 codon adaptation index, suggesting they are suitable for expressing the protein vaccines in prokaryotic system.

Discussion

These next-generation vaccine designs are promising and warrant further investigation in wet lab experiments to assess their immunogenicity, safety, and efficacy for practical application in livestock. Our findings offer a robust framework for developing a comprehensive, broad-spectrum vaccine, potentially revolutionizing BT control and prevention strategies in the livestock industry.

An ultrasound-driven immune-boosting molecular machine for systemic tumor suppression

Exploring facile and effective therapeutic modalities for synergistically controlling primary tumor and metastasis remains a pressing clinical need. Sonodynamic therapy (SDT) offers the possibility of noninvasively eradicating local solid tumors, but lacks antimetastatic activity because of its limited ability in generating systemic antitumor effect. Here, we exploited a previously unidentified ultrasound-driven “molecular machine,” DYSP-C34 (C34 for short), with multiple attractive features, emerging from preferential tumor accumulation, potent ultrasound-triggered cytotoxicity, and intrinsic immune-boosting capacity. Driven by the ultrasound, C34 functioned not only as a tumor cell killing reagent but also as an immune booster that could potentiate robust adaptive antitumor immunity by directly stimulating dendritic cells, resulting in the eradication of the primary solid tumor along with the inhibition of metastasis. This molecular machine, C34, rendered great promise to achieve systemic treatment against cancer via unimolecule-mediated SDT.

Nanovaccine-Based Strategies to Overcome Challenges in the Whole Vaccination Cascade for Tumor Immunotherapy

Nanovaccine-based immunotherapy (NBI) has received greater attention recently for its potential to prime tumor-specific immunity and establish a long-term immune memory that prevents tumor recurrence. Despite encouraging results in the recent studies, there are still numerous challenges to be tackled for eliciting potent antitumor immunity using NBI strategies. Based on the principles that govern immune response, here it is proposed that these challenges need to be addressed at the five critical cascading events: Loading tumor-specific antigens by nanoscale drug delivery systems (L); Draining tumor antigens to lymph nodes (D); Internalization by dendritic cells (DCs) (I); Maturation of DCs by costimulatory signaling (M); and Presenting tumor-peptide-major histocompatibility complexes to T cells (P) (LDIMP cascade in short). This review provides a detailed and objective overview of emerging NBI strategies to improve the efficacy of nanovaccines in each step of the LDIMP cascade. It is concluded that the balance between each step must be optimized by delicate designing and modification of nanovaccines and by combining with complementary approaches to provide a synergistic immunity in the fight against cancer.

Modes of Communication between T Cells and Relevance for Immune Responses

T cells are essential mediators of the adaptive immune system, which constantly patrol the body in search for invading pathogens. During an infection, T cells that recognise the pathogen are recruited, expand and differentiate into subtypes tailored to the infection. In addition, they differentiate into subsets required for short and long-term control of the pathogen, i.e., effector or memory. T cells have a remarkable degree of plasticity and heterogeneity in their response, however, their overall response to a given infection is consistent and robust. Much research has focused on how individual T cells are activated and programmed. However, in order to achieve a critical level of population-wide reproducibility and robustness, neighbouring cells and surrounding tissues have to provide or amplify relevant signals to tune the overall response accordingly. The characteristics of the immune response-stochastic on the individual cell level, robust on the global level-necessitate coordinated responses on a system-wide level, which facilitates the control of pathogens, while maintaining self-tolerance. This global coordination can only be achieved by constant cellular communication between responding cells, and faults in this intercellular crosstalk can potentially lead to immunopathology or autoimmunity. In this review, we will discuss how T cells mount a global, collective response, by describing the modes of T cell-T cell (T-T) communication they use and highlighting their physiological relevance in programming and controlling the T cell response.

Intracellular Pathogens: Host Immunity and Microbial Persistence Strategies

Infectious diseases caused by pathogens including viruses, bacteria, fungi, and parasites are ranked as the second leading cause of death worldwide by the World Health Organization. Despite tremendous improvements in global public health since 1950, a number of challenges remain to either prevent or eradicate infectious diseases. Many pathogens can cause acute infections that are effectively cleared by the host immunity, but a subcategory of these pathogens called "intracellular pathogens" can establish persistent and sometimes lifelong infections. Several of these intracellular pathogens manage to evade the host immune monitoring and cause disease by replicating inside the host cells. These pathogens have evolved diverse immune escape strategies and overcome immune responses by residing and multiplying inside host immune cells, primarily macrophages. While these intracellular pathogens that cause persistent infections are phylogenetically diverse and engage in diverse immune evasion and persistence strategies, they share common pathogen type-specific mechanisms during host-pathogen interaction inside host cells. Likewise, the host immune system is also equipped with a diverse range of effector functions to fight against the establishment of pathogen persistence and subsequent host damage. This article provides an overview of the immune effector functions used by the host to counter pathogens and various persistence strategies used by intracellular pathogens to counter host immunity, which enables their extended period of colonization in the host. The improved understanding of persistent intracellular pathogen-derived infections will contribute to develop improved disease diagnostics, therapeutics, and prophylactics.

Multiple effects of CD40-CD40L axis in immunity against infection and cancer

CD8⁺ cytotoxic T lymphocyte (CTL) protects against infection and cancer cells. Understanding the mechanisms involved in generation and maintenance of effective CTL responses is essential for improving disease therapy and vaccine protocols. During CTL responses, immune cells encounter several tightly regulated signaling pathways; therefore, in such a dynamic process, proper integration of critical signals is necessary to orchestrate an effective immune response. In this review, we have focused on CD40-CD40L interactions (a key signal) in the regulation of dendritic cell (DC)-T cell (CD4⁺ T and CD8⁺ T) cross-talk, rescuing CTL exhaustion, and converting DC tolerization. We have also highlighted the knowledge gap and future directions to design immunotherapies.

Novel exosome-targeted T-cell-based vaccine counteracts T-cell anergy and converts CTL exhaustion in chronic infection via CD40L signaling through the mTORC1 pathway

CD8⁺ cytotoxic T lymphocyte (CTL) exhaustion is a chief issue for ineffective virus elimination in chronic infectious diseases. We generated novel ovalbumin (OVA)-specific OVA-Texo and HIV-specific Gag-Texo vaccines inducing therapeutic immunity. To assess their therapeutic effect in chronic infection, we developed a new chronic infection model by i.v. infecting C57BL/6 mice with the OVA-expressing adenovirus AdVova. During chronic AdVova infection, mouse CTLs were found to express the inhibitory molecules programmed cell-death protein-1 (PD-1) and lymphocyte-activation gene-3 (LAG-3) and to be functionally exhausted, showing a significant deficiency in T-cell proliferation, IFN-γ production and cytolytic effects. Naive CD8⁺ T cells upregulated inhibitory PD-ligand 1 (PD-L1), B- and T-lymphocyte attenuator and T-cell anergy-associated molecules (Grail and Itch) while down-regulating the proliferative response upon stimulation in mice with chronic infection. Remarkably, the OVA-Texo vaccine counteracted T-cell anergy and converted CTL exhaustion. The latter was associated with (i) the upregulation of a marker for CTL functionality, diacetylated histone-H3 (diAcH3), (ii) a fourfold increase in CTLs, occurring independent of host DCs or CD4⁺ T cells, and (iii) the restoration of CTL IFN-γ production and cytotoxicity. In vivo OVA-Texo-stimulated CTLs upregulated the activities of the mTORC1 pathway-related molecules Akt, S6, eIF4E and T-bet, and treatment of the CTLs with an mTORC1 inhibitor, rapamycin, significantly reduced the OVA-Texo-induced increase in CTLs. Interestingly, OVA-Texo-mediated CD40L signaling played a critical role in the observed immunological effects. Importantly, the Gag-Texo vaccine induced Gag-specific therapeutic immunity in chronic infection. Therefore, this study should have a serious impact on the development of new therapeutic vaccines for human immunodeficiency virus (HIV-1) infection.

Simulated Microgravity Promotes Cell Apoptosis Through Suppressing Uev1A/TICAM/TRAF/NF-κB-Regulated Anti-Apoptosis and p53/PCNA- and ATM/ATR-Chk1/2-Controlled DNA-Damage Response Pathways

Microgravity has been known to induce cell death. However, its underlying mechanism is less studied. In this study, BL6-10 melanoma cells were cultured in flasks under simulated microgravity (SMG). We examined cell apoptosis, and assessed expression of genes associated with apoptosis and genes regulating apoptosis in cells under SMG. We demonstrate that SMG induces cell morphological changes and microtubule alterations by confocal microscopy, and enhances apoptosis by flow cytometry, which was associated with up- and down-regulation of pro-apoptotic and anti-apoptotic genes, respectively. Moreover, up- and down-regulation of pro-apoptotic (Caspases 3, 7, 8) and anti-apoptotic (Bcl2 and Bnip3) molecules was confirmed by Western blotting analysis. Western blot analysis also indicates that SMG causes inhibition of an apoptosis suppressor, pNF-κB-p65, which is complemented by the predominant localization of NF-κB-p65 in the cytoplasm. SMG also reduces expression of molecules regulating the NF-κB pathway including Uev1A, TICAM, TRAF2, and TRAF6. Interestingly, 10 DNA repair genes are down-regulated in cells exposed to SMG, among which down-regulation of Parp, Ercc8, Rad23, Rad51, and Ku70 was confirmed by Western blotting analysis. In addition, we demonstrate a significant inhibition of molecules involved in the DNA-damage response, such as p53, PCNA, ATM/ATR, and Chk1/2. Taken together, our work reveals that SMG promotes the apoptotic response through a combined modulation of the Uev1A/TICAM/TRAF/NF-κB-regulated apoptosis and the p53/PCNA- and ATM/ATR-Chk1/2-controlled DNA-damage response pathways. Thus, our investigation provides novel information, which may help us to determine the cause of negative alterations in human physiology occurring at spaceflight environment. J. Cell. Biochem. 117: 2138-2148, 2016. © 2016 Wiley Periodicals, Inc.

Transgenic 4-1BBL-engineered vaccine stimulates potent Gag-specific therapeutic and long-term immunity via increased priming of CD44(+)CD62L(high) IL-7R(+) CTLs with up- and downregulation of anti- and pro-apoptosis genes

Human immunodeficiency virus type-1 (HIV-1)-specific dendritic cell (DC) vaccines have been used in clinical trials. However, they have been found to only induce some degree of immune responses in these studies. We previously demonstrated that the HIV-1 Gag-specific Gag-Texo vaccine stimulated Gag-specific effector CD8(+) cytotoxic T lymphocyte (CTL) responses, leading to completely protective, but very limited, therapeutic immunity. In this study, we constructed a recombinant adenoviral vector, adenovirus (AdV)4-1BBL, which expressed mouse 4-1BB ligand (4-1BBL), and generated transgenic 4-1BBL-engineered OVA-Texo/4-1BBL and Gag-Texo/4-1BBL vaccines by transfecting ovalbumin (OVA)-Texo and Gag-Texo cells with AdV4-1BBL, respectively. We demonstrate that the OVA-specific OVA-Texo/4-1BBL vaccine stimulates more efficient OVA-specific CTL responses (3.26%) compared to OVA-Texo-activated responses (1.98%) in wild-type C57BL/6 mice and the control OVA-Texo/Null vaccine without transgenic 4-1BBL expression, leading to enhanced therapeutic immunity against 6-day established OVA-expressing B16 melanoma BL6-10OVA cells. OVA-Texo/4-1BBL-stimulated CTLs, which have a CD44(+)CD62L(high) IL-7R(+) phenotype, are likely memory CTL precursors, demonstrating prolonged survival and enhanced differentiation into memory CTLs with functional recall responses and long-term immunity against BL6-10OVA melanoma. In addition, we demonstrate that OVA-Texo/4-1BBL-stimulated CTLs up- and downregulate the expression of anti-apoptosis (Bcl2l10, Naip1, Nol3, Pak7 and Tnfrsf11b) and pro-apoptosis (Casp12, Trp63 and Trp73) genes, respectively, by RT(2) Profiler PCR array analysis. Importantly, the Gag-specific Gag-Texo/4-1BBL vaccine also stimulates more efficient Gag-specific therapeutic and long-term immunity against HLA-A2/Gag-expressing B16 melanoma BL6-10Gag/A2 cells than the control Gag-Texo/Null vaccine in transgenic HLA-A2 mice. Taken together, our novel Gag-Texo/4-1BBL vaccine, which is capable of stimulating potent Gag-specific therapeutic and long-term immunity, may represent a new immunotherapeutic vaccine for controlling HIV-1 infection.

Co-expression of tumor antigen and interleukin-2 from an adenoviral vector augments the efficiency of therapeutic tumor vaccination

We have previously shown that for the majority of antigens, adenoviral vaccines expressing the target antigen fused to the MHC associated invariant chain (Ii) induce an accelerated, augmented, and prolonged transgene-specific CD8(+) T-cell response. Here we describe a new adenoviral vaccine vector approach where the target antigen fused to Ii is expressed from the adenoviral E1 region and IL-2 is expressed from the E3 region. Immunization of mice with this new vector construct resulted in an augmented primary effector CD8(+) T-cell response. Furthermore, in a melanoma model we observed significantly prolonged tumor control in vaccinated wild type (WT) mice. The improved tumor control required antigen-specific cells, since no tumor control was observed, unless the melanoma cells expressed the vaccine targeted antigen. We also tested our new vaccine in immunodeficient (CD80/86 deficient) mice. Following vaccination with the IL-2 expressing construct, these mice were able to raise a delayed but substantial CD8(+) T-cell response, and to control melanoma growth nearly as efficaciously as similarly vaccinated WT mice. Taken together, these results demonstrate that current vaccine vectors can be improved and even tailored to meet specific demands: in the context of therapeutic vaccination, the capacity to promote an augmented effector T-cell response.

A purified recombinant lipopeptide as adjuvant for cancer immunotherapy

Synthetic lipopeptides have been widely used as vaccine adjuvants to enhance immune responses. The present study demonstrated that the tryptic N-terminal fragment of the lipoprotein rlipo-D1E3 (lipo-Nter) induces superior antitumor effects compared to a synthetic lipopeptide. The lipo-Nter was purified and formulated with protein or peptide vaccines to determine if lipo-Nter could be used as a novel adjuvant and could induce antitumor immunity in a cervical cancer model. Purified lipo-Nter activated the maturation of bone marrow-derived dendritic cells (BM-DCs), leading to the secretion of TNF-α through TLR2/6 but not TLR1/2. A recombinant mutant HPV16 E7 (rE7m) protein was mixed with lipo-Nter to immunize the mice; the anti-E7 antibody titers were increased, and the T helper cells were skewed toward the Th1 fate (increased IL-2 and decreased IL-5 secretion). Single-dose injection of rE7m and lipo-Nter inhibited tumor growth, but the injection of rE7m alone did not. Accordingly, lipo-Nter also enhanced the antitumor immunity of the E7-derived peptide but not the synthetic lipopeptide (Pam3CSK4). We demonstrated that the lipo-Nter of a bacterial-derived recombinant lipoprotein is a novel adjuvant that could be used for the development of a new generation of vaccines.