A scaffold vaccine to promote tumor antigen cross-presentation via sustained toll-like receptor-2(TLR2)activation

Cancer vaccination holds great promise for cancer treatment,but its effectiveness is hindered by suboptimal activation of CD8+cytotoxic T lymphocytes,which are potent effectors to mediate anti-tumor immune responses.A possible solution is to switch antigen-presenting cells to present tumor antigens via the major histocompatibility complex class I(MHC-I)to CD8+T cells-a process known as cross-presentation.To achieve this goal,we develop a three-dimensional(3D)scaffold vaccine to promote antigen cross-presentation by persisted toll-like receptor-2(TLR2)activation after one injection.This vaccine comprises polysaccharide frameworks that“hook”TLR2 agonist(acGM)via tunable hydrophobic interactions and forms a 3D macroporous scaffold via click chemistry upon subcutaneous injection.Its retention-and-release of acGM enables sustained TLR2 activation in abundantly recruited dendritic cells in situ,inducing intracellular production of reactive oxygen species(ROS)in optimal kinetics that crucially promotes efficient antigen cross-presentation.The scaffold loaded with model antigen ovalbumin(OVA)or tumor specific antigen can generate potent immune responses against lung metastasis in B16-OVA-innoculated wild-type mice or spontaneous colorectal cancer in transgenic ApcMin/+mice,respectively.Notably,it requires neither additional adjuvants nor external stimulation to function and can be adjusted to accommodate different antigens.The developed scaffold vaccine may represent a new,competent tool for next-generation personalized cancer vaccination.

STING-activating dendritic cell-targeted nanovaccines that evoke potent antigen cross-presentation for cancer immunotherapy

Recently,nanovaccine-based immunotherapy has been robustly investigated due to its potential in governing the immune response and generating long-term protective immunity.However,the presentation of a tumor peptide-major histocompatibility complex to T lymphocytes is still a challenge that needs to be addressed for eliciting potent antitumor immunity.Type 1 conventional dendritic cell(cDC1)subset is of particular interest due to its pivotal contribution in the cross-presentation of exogenous antigens to CD8+T cells.Here,the DC-derived nanovaccine(denoted as Si9GM)selectively targets cDC1s with marginal loss of premature antigen release for effective stimulator of interferon genes(STING)-mediated antigen cross-presentation.Bone marrow dendritic cell(BMDC)-derived membranes,conjugated to cDC1-specific antibody(αCLEC9A)and binding to tumor peptide(OVA257-264),are coated onto dendrimer-like polyethylenimine(PEI)-grafted silica nanoparticles.Distinct molecular weight-cargos(αCLEC9A-OVA257-264 conjugates and 2′3′-cGAMP STING agonists)are loaded in hierarchical center-radial pores that enables lysosome escape for potent antigen-cross presentation and activates interferon type I,respectively.Impressively,Si9GM vaccination leads to the upregulation of cytotoxic T cells,a reduction in tumor regulatory T cells(Tregs),M1/M2 macrophage polarization,and immune response that synergizes with αPD-1 immune checkpoint blockade.This nanovaccine fulfills a dual role for both direct T cell activation as an artificial antigen-presenting cell and DC subset maturation,indicating its utility in clinical therapy and precision medicine.

A rationally designed cancer vaccine based on NIR-II fluorescence image-guided light-triggered remote control of antigen cross-presentation and autophagy

Cancer vaccines represent a promising immunotherapeutic treatment modality.The promotion of cross-presentation of extracellular tumor-associated antigens on the major histocompatibility complex(MHC) class I molecules and dendritic cell maturation at the appropriate time and place is crucial for cancer vaccines to prime cytolytic T cell response with reduced side effects.Current vaccination strategies,however,are not able to achieve the spatiotemporal control of antigen cross-presentation.Here,we report a liposomal vaccine loading the second near-infrared window(NIR-II,1000—1700 nm) fluorophore BPBBT with an efficient photothermal conversion effect that offers an NIR-light-triggered endolysosomal escape under the imaging guidance.The NIR-II image-guided vaccination strategy specifically controls the cytosolic delivery of antigens for cross-presentation in the draining lymph nodes(DLNs).Moreover,the photothermally induced endolysosomal rupture initiates autophagy.We also find that the adjuvant simvastatin acts as an autophagy activator through inhibiting the PI3K/AKT/m TOR pathway.The light-induced autophagy in the DLNs together with simvastatin treatment cooperatively increase MHC class II expression by activating autophagy machinery for dendritic cell maturation.This study presents a paradigm of NIR-II image-guided light-triggered vaccination.The approach for remote control of antigen cross-presentation and autophagy represents a new strategy for vaccine development.

p38α has an important role in antigen cross-presentation by dendritic cells

The role of the p38 signaling pathway in the innate and adaptive immune responses has been well documented,especially in inflammatory cytokine production by dendritic cells(DCs).However,whether the p38 signaling pathway affects the important antigen(Ag)presentation function of DCs remains largely unknown.In this study,we reported that the deletion of p38αresulted in an impaired cross-presentation ability of CD8^(+) conventional DCs(cDCs)and a reduction in the direct presentation ability of CD8−cDCs ex vivo.Further study revealed that p38αhad a crucial role in Ag processing by CD8^(+) cDCs but did not affect the Ag uptake or co-stimulation of T cells.Moreover,p38αdeficiency led to reduced cross-priming of T cells in vivo.The production of the IL-12p40 and IL-12p70 cytokines by p38α-deficient cDCs was also significantly reduced.Our study identified a new role for p38αin modulating the important antigen cross-presentation function of DCs.

Langerin-mediated internalization of a modified peptide routes antigens to early endosomes and enhances cross-presentation by human Langerhans cells

The potential of the skin immune system to generate immune responses is well established, and the skin is actively exploited as a vaccination site. Human skin contains several antigen-presenting cell subsets with specialized functions. In particular, the capacity to cross-present exogenous antigens to CD8^＋ T cells is of interest for the design of effective immunotherapies against viruses or cancer. Here, we show that primary human Langerhans cells （LCs） were able to cross-present a synthetic long peptide （SLP） to CD8^＋ T cells. In addition, modification of this SLP using antibodies against the receptor langerin, but not dectin-1, further enhanced the cross-presenting capacity of LCs through routing of internalized antigens to less proteolytic early endosome antigen 1 ^＋ early endosomes. The potency of LCs to enhance CD8^＋ T-cell responses could be further increased through activation of LCs with the toll-like receptor 3 ligand polyinosinic：polycytidylic acid （phC）. Altogether, the data provide evidence that human LCs are able to cross-present antigens after langerin-mediated internalization. Furthermore, the potential for antigen modification to target LCs specifically provides a rationale for generating effective anti-tumor or anti-viral cytotoxic T lymphocyte responses.

MHC Class I Assembly Function and Intracellular Transport Routes for Hepatitis B Virus Antigen Cross-presentation by Heat Shock Protein gp96

Background:During hepatitis B virus(HBV)infection,virus-infected hepatocytes directly cross-present viral antigens and regulate T cell response within the liver microenvironment.However,little is known regarding the regulatory pathways involved in viral antigen presentation in HBV-infected hepatocytes.This study investigated the underlying mechanism of antigen assembly and the HBV antigen-presenting function of major histocompatibility complex(MHC)class I molecules using heat shock protein gp96.Methods:First,western blotting,flow cytometry,co-immuno precipitation,GST pull-down,and confocal microscopic assays were performed to determine whether endogenous gp96 affects MHC-I levels via an antigen presentation pathway.Second,the B3Z assay and an AAV/HBV-infected hepatocyte-specific gp96-deficient mouse model were used to determine whether gp96 knockout functionally impaired peptide cross-presentation and produced a weakened antiviral cytotoxic T cell(CTL)response both in vivo and in vitro.Finally,confocal microscopic analysis and the B3Z assay were employed to show that exogenous gp96-associated peptide was present in MHC-I molecules via the endoplasmic reticulum(ER)-Golgi secretory pathway.Results:Compared with the control,gp96 knockdown significantly reduced the cell surface levels of MHC-I by approximately 75%(P<0.01).Endogenous gp96 interacts with MHC-I and is involved in antigen presentation.Moreover,a weakened antiviral CTL response(34%compared to control mice)has been observed in hepatocyte-specific gp96-deficient mice following HBV infection.gp96 directed exogenous antigen to the ER,and the exogenous gp96-chaperoned peptide was endosome-and proteasome-dependent but not transporter associated with antigen processing dependent.Conclusions:Cellular gp96 promotes the assembly and antigen presentation of MHC class I molecules.In addition,extracellular gp96 served as a natural adjuvant to induce a CTL response in a concerted and regulated manner within different cellular compartments.Our results elucidate the mechanism of assembly of MHC class I molecules by gp96,which may be beneficial for the design of immunotherapy and vaccines.

Dual-responsive nanovaccine for cytosolic delivery of antigens to boost cellular immune responses and cancer immunotherapy

Cancer vaccine contributing to the success of the treatment and prevention of tumors has attracted a huge attention as a strategy for tumor immunotherapy in recent years.A major challenge of cancer vaccine is to target cytosols of dendritic cells(DCs)in the lymph nodes(LNs)to enhance efficiency of antigen cross-presentation,which elicits high levels of cytotoxic T-lymphocytes to destruct tumor cells.Here,we address this issue by conjugating ovalbumin(OVA)to PEG-PCL using disulfide bond(-ss-),and the degradable pH-responsive polymer-PEI-PCL as delivery carrier.In addition,the mol ratio of PEG-PCL to PEI-PCL in the mixed micelles was tailored to deliver the OVA to LNs.Subsequently,CpG ODN_(1826),a TLR-9 agonist,was further introduced into a mixed micelle of 30nm or less as a unique tumor vaccine.Importantly,the results demonstrated the mixed micelles with 1:1mol of PCL-PEG and PCL-PEI can effectively migrate to distal LNs where antigen were efficiently captured by DCs,meanwhile,OVA was modified to the surface of mixed micelles via disulfide bonds(-ss-)for promotion efficiency of antigen cross-presentation.More surprisingly,combination of tumor vaccine with anti-PD-1,the therapy of ectopic melanoma(B16-OVA)and lung metastasis melanoma(B16-OVA)is excellent therapeutic effect.Taken together,our works offers a novel strategy for the cytosol delivery of antigens to achieve potent cancer immunotherapy.

Simultaneous enhancement of cellular and humoral immunity by the lymph node-targeted cholesterolized TLR7 agonist liposomes

Toll-like receptor(TLR)agonists,as promising adjuvants and immunotherapeutic agents,have the potential to enhance immune responses and modulate antigen-dependent T-cell immune memory through activation of distinct signaling pathways.However,their clinical application is hindered by uncontrolled systemic inflammatory reactions.Therefore,it is imperative to create a vaccine adjuvant for TLR receptors that ensures both safety and efficacy.In this study,we designed lymph node-targeted cholesterolized TLR7 agonist cationic liposomes(1V209-Cho-Lip^(+))to mitigate undesired side effects.Co-delivery of the model antigen OVA and cholesterolized TLR7 agonist facilitated DC maturation through TLR activation while ensuring optimal presentation of the antigen to CD8^(+)T cells.The main aim of the present study is to evaluate the adjuvant effectiveness of 1V209-Cho-Lip^(+)in tumor vaccines.Following immunization with 1V209-Cho-Lip^(+)+OVA,we observed a pronounced"depot effect"and enhanced trafficking to secondary lymphoid organs.Prophylactic vaccination with 1V209-Cho-Lip^(+)^(+)OVA significantly delays tumor development,prolongs mouse survival,and establishes durable immunity against tumor recurrence.Additionally,1V209-Cho-Lip^(+)+OVA,while used therapeutic tumor vaccine,has demonstrated its efficacy in inhibiting tumor progression,and when combined with anti-PD-1,it further enhances antitumor effects.Therefore,the co-delivery of antigen and lymph node-targeted cholesterolized TLR7 agonist shows great promise as a cancer vaccine.

An antigen self-assembled and dendritic cell-targeted nanovaccine for enhanced immunity against cancer

The rise of nanotechnology has opened new horizons for cancer immunotherapy.However,most nano vaccines fabricated with nanomaterials suffer from carrier-related concerns,including low drug loading capacity,unpredictable metabolism,and potential systemic toxicity,which bring obstacles for their clinical translation.Herein,we developed an antigen self-assembled nanovaccine,which was resulted from a simple acryloyl modification of the antigen to induce self-assembly.Furthermore,a dendritic cell targeting head mannose monomer and a mevalonate pathway inhibitor zoledronic acid(Zol)were integrated or absorbed onto the nanoparticles(denoted as MEAO-Z)to intensify the immune response.The synthesized nano vaccine with a diameter of around 70 nm showed successful lymph node transportation,high dendritic cell internalization,promoted costimulatory molecule expression,and preferable antigen cross-presentation.In virtue of the above superiorities,MEAO-Z induced remarkably higher titers of serum antibody,stronger cytotoxic T lymphocyte immune responses and IFN-γsecretion than free antigen and adjuvants.In vivo,MEAO-Z significantly suppressed EG7-OVA tumor groth and prolonged the survival time of tumor-bearing mice.These results indicated the translation promise of our self-assembled nano vaccine for immune potentiation and cancer immunotherapy.

mmunological functions of liver sinusoida endothelial cells

Liver sinusoidal endothelial cells （LSECs） line the liver sinusoids and separate passenger leukocytes in the sinusoidal lumen from hepatocytes. LSECs further act as a platform for adhesion of various liver-resident immune cell populations such as Kupffer cells, innate lymphoid cells or liver dendritic cells. In addition to having an extraordinary scavenger function, LSECs possess potent immune functions, serving as sentinel cells to detect microbial infection through pattern recognition receptor activation and as antigen （cross）-presenting cells. LSECs cross-prime naive CD8 T cells, causing their rapid differentiation into memory T cells that relocate to secondary lymphoid tissues and provide protection when they re-encounter the antigen during microbial infection. Cross-presentation of viral antigens by LSECs derived from infected hepatocytes triggers local activation of effector CD8 T cells and thereby assures hepatic immune surveillance. The immune function of LSECs complements conventional immune-activating mechanisms to accommodate optimal immune surveillance against infectious microorganisms while preserving the integrity of the liver as a metabolic organ.

Dendritic cells in cancer immunology

The clinical success of immune checkpoint therapy(ICT)has produced explosive growth in tumor immunology research because ICT was discovered through basic studies of immune regulation.Much of the current translational efforts are aimed at enhancing ICT by identifying therapeutic targets that synergize with CTLA4 or PD1/PD-L1 blockade and are solidly developed on the basis of currently accepted principles.Expanding these principles through continuous basic research may help broaden translational efforts.With this mindset,we focused this review on three threads of basic research directly relating to mechanisms underlying ICT.Specifically,this review covers three aspects of dendritic cell(DC)biology connected with antitumor immune responses but are not specifically oriented toward therapeutic use.First,we review recent advances in the development of the cDC1 subset of DCs,identifying important features distinguishing these cells from other types of DCs.Second,we review the antigen-processing pathway called cross-presentation,which was discovered in the mid-1970s and remains an enigma.This pathway serves an essential in vivo function unique to cDC1s and may be both a physiologic bottleneck and therapeutic target.Finally,we review the longstanding field of helper cells and the related area of DC licensing,in which CD4 T cells influence the strength or quality of CD8 T cell responses.Each topic is connected with ICT in some manner but is also a fundamental aspect of cell-mediated immunity directed toward intracellular pathogens.

Engineering cancer vaccines using stimuli-responsive biomaterials

Cancer vaccines aimed at expanding the pool or increasing the activity of tumor-specific T cells against malignancies is an important immunotherapy modality that has been extensively pursued in the past decades. However, the clinical efficacy of cancer vaccines remains modest in comparison to other immunotherapies, such as checkpoint blockade and adoptive T cell therapy. This unsatisfactory performance is likely due to the suboptimal selection of tumor antigens for vaccine and inefficient delivery platform. Recently, vaccines designed to target cancer neoantigens have shown marked promise in both preclinical and early clinical studies. However, enormous challenges need to be overcome to develop a highly efficient and safe delivery strategy for targeting cancer vaccines to professional antigen-presenting cells and eliciting optimized immune response against cancers. To meet these challenges, biomaterials, particularly biomaterials that are designed to respond to certain environmental stimuli, termed as stimuli-responsive biomaterials, are being actively developed to precisely manipulate the trafficking and release of cancer vaccines in vivo for enhanced therapeutic efficacy and safety. In this mini review, we provide a brief overview of the recent advances in applying stimuli-responsive biomaterials in enhancing non-cellular cancer vaccines while focusing on the chemistry and material design with varied responsiveness. We also discuss the present challenges and opportunities in the field and provide a perspective for future directions.

Trinity immune enhancing nanoparticles for boosting antitumor immune responses of immunogenic chemotherapy

Certain chemo drugs have been reported to potentially induce tumor-specific immune recognition by triggering immunogenic cell death(ICD),which provides a promising alternative way for cancer immunotherapy.However,the immunogenic effects of such treatments are still weak and robust systemic antitumor immune responses are rarely seen when these agents were used alone.Herein,we proposed a trinity immune enhancing nanoparticles(TIENs)for boosting antitumor immune responses of chemo agents.The TIENs was constructed with Food and Drug Administration(FDA)approved polylactic acid(PLA),canonical proton-sponging cationic polymer polyethyleneimine(PEI),and Toll-like receptor 9(TLR9)agonist cytosine phosphate guanine oligodeoxynucleotide(CpG-ODN).In in vitro studies,the TIENs was proved to(1)promote antigen capturing,(2)antigen-presenting cells(APCs)activation,and(3)antigen cross-presentation.In in vivo studies,intratumorally injected TIENs greatly enhanced antitumor effect and robust immune responses of oxaliplatin and doxorubicin in murine CT26 and 4T1 tumor models,respectively.Furthermore,after decoration with a detachable shielding,the TIENs was proved to be effective in promoting the antitumor effects of chemo agents after intravenous injection.The combination of TIENs with clinically widely used chemo agents should be meaningful in boosting effective antitumor immune responses and cancer therapy.

Trans-presentation of interleukin-15 by interleukin-15 receptor alpha is dispensable for the pathogenesis of autoimmune type 1 diabetes

Interleukin-15(IL-15)is a pro-inflammatory cytokine that is required for the survival and activation of memory CD8^(+)T cells,natural killer(NK)cells,innate lymphoid cells,macrophages and dendritic cells.IL-15 is implicated in the pathogenesis of various autoimmune diseases such as rheumatoid arthritis,inflammatory bowel disease,psoriasis and autoimmune type 1 diabetes(T1D).IL-15 receptor(IL-15R)consists of a specificαchain,theβchain that is shared with IL-2R and the commonγchain.IL-15 is unique in the manner in which it binds and signals through its receptor subunits.IL-15 that is complexed with IL-15Rαbinds to theβγreceptor complex present on the responding cell to mediate its biological effects through a process referred to as trans-presentation.The trans-presented IL-15 is essential to mediate the biological effects on T lymphocytes and NK cells.Here we show that IL-15,but not IL-15Rα,is required for the development of spontaneous and virus-induced T1D,viral clearance and for antigen cross-presentation to CD8^(+)T lymphocytes.Our findings provide insight into the complexities of IL-15 signalling in the initiation and maintenance of CD8^(+)T cell-mediated immune responses.

Programmed nanoparticle-loaded microparticles for effective antigen/adjuvant delivery

A microscale vaccine containing SiO_(2)nanoparticles loaded in CaC〇3 microparticles was constructed using the co-precipitation method.The antigen ovalbumin(OVA)was covalently conjugated with SiO_(2)nanoparticles,and these nanoparticles and CpG were co-encapsulated into CaCO_(3)microparticles,generating a vaccine with a size of approximately 5.2μm.Scanning electron microscopy(SEM),energy-dispersive X-ray(EDX),elemental mapping,and Fourier transform infrared(FTIR)analyses confirmed the successful preparation of the microscale vaccine;the vaccine had good storage stability without sustained antigen release,and negligible cytotoxicity to dendritic cells(DCs)and macrophages.Compared to SiO_(2)nanoparticles,the microscale vaccine can significantly improve antigen/adjuvant uptake.DCs internalized the entire microscale vaccine into lysosomes via macropinocytosis,and an increase in antigen endo/lysosomal escape was observed by confocal User scanning microscopy(CLSM).Specifically,DCs pulsed with the vaccine were fully mature,expressing high levels of costimulatory molecules(CD40,CD80,and CD86),MHCⅡ,and MHCⅠand secreting high levels of proinflammatory cytokines(IL-12,TNF-α,IL-1β,and IL-6).In addition,the vaccine had good in vivo biocompatibility,could protect the antigen from rapid degradation,and increased the retention time in lymph nodes.SiO_(2)nanoparticles-in-CaCO_(3)microparticles were an excellent carrier for antigen and adjuvant delivery.Hopefully,this study can provide some information on the design of microscale carriers for vaccine delivery systems.