A Cationic Micelle Complex Improves CD8+ T Cell Responses in Vaccination Against Unmodified Protein Antigen

Engineering customized nanovaccines for enhanced cancer immunotherapy

Nanovaccines have gathered significant attention for their potential to elicit tumor-specific immunological responses. Despite notable progress in tumor immunotherapy, nanovaccines still encounter considerable challenges such as low delivery efficiency, limited targeting ability, and suboptimal efficacy. With an aim of addressing these issues, engineering customized nanovaccines through modification or functionalization has emerged as a promising approach. These tailored nanovaccines not only enhance antigen presentation, but also effectively modulate immunosuppression within the tumor microenvironment. Specifically, they are distinguished by their diverse sizes, shapes, charges, structures, and unique physicochemical properties, along with targeting ligands. These features of nanovaccines facilitate lymph node accumulation and activation/regulation of immune cells. This overview of bespoke nanovaccines underscores their potential in both prophylactic and therapeutic applications, offering insights into their future development and role in cancer immunotherapy.

Cascade Reaction of "Mn2+ -Catechol" Triggered by H2 O2 to Integrate Firm Tumor Vessel Embolization and Hypoxic Response Relief

Transcatheter arterial embolization (TAE) therapy requires firm and long-term vessel embolization without recanalization. However, firm embolization usually leads to unanticipated hypoxic response which promotes tumor recurrence and metastasis. Herein, an injectable thermosensitive hydrogel containing catechol groups and Mn²⁺ (PNDM) has been developed to enhance embolization and inhibit hypoxic response utilizing augmented H₂ O₂ after TAE. This novel embolic agent converts H₂ O₂ into hydroxyl radicals via Mn²⁺ -dependent Fenton-like reaction, which are subsequently scavenged through a "catechol-quinone" transition to supress hypoxic responses. Quinone structure can not only make hydrogel internal structure more compact, but also enhance hydrogel adhesion to vessel wall. In vivo experiments confirm that the rabbit renal artery can be firmly embolized for 84 days. Studies in liver VX2 tumor-bearing rabbits demonstrate the PNDM-based TAE can promote tumor necrosis, inhibit angiogenesis and tumor metastasis, and greatly prolong rabbit survival. This strategy opens new sights in the TAE therapy for liver cancer. This article is protected by copyright. All rights reserved.

Nanotechnology-Based Approaches to Promote Lymph Node Targeted Delivery of Cancer Vaccines

Vaccines are a promising immunotherapy that awakens the human immune system to inhibit and eliminate cancer with fewer side effects compared with traditional radiotherapy and chemotherapy. Although cancer vaccines have shown some efficacy, there are still troublesome bottlenecks to expand their benefits in the clinic, including weak immune effects and limited therapeutic outcomes. In the past few years, in addition to neoantigen screening, a main branch of the efforts has been devoted to promoting the lymph nodes (LNs) targeting of cancer vaccines and the cross-presentation of antigens by dendritic cells (DCs), two cardinal stages in effective initiation of the immune response. Especially, nanomaterials have shown hopeful biomedical applications in the improvement of vaccine effectiveness. This Review briefly outlines the possible mechanisms by which nanoparticle properties affect LN targeting and antigen cross-presentation and then gives an overview of state-of-the-art advances in improving these biological outcomes with nanotechnology.

A Polylactide-Based Micellar Adjuvant Improves the Intensity and Quality of Immune Response

Micelles from amphiphilic polylactide-block-poly(N-acryloxysuccinimide-co-N-vinylpyrrolidone) (PLA-b-P(NAS-co-NVP)) block copolymers of 105 nm in size were characterized and evaluated in a vaccine context. The micelles were non-toxic in vitro (both in dendritic cells and HeLa cells). In vitro fluorescence experiments combined with in vivo fluorescence tomography imaging, through micelle loading with the DiR near infrared probe, suggested an efficient uptake of the micelles by the immune cells. The antigenic protein p24 of the HIV-1 was successfully coupled on the micelles using the reactive N-succinimidyl ester groups on the micelle corona, as shown by SDS-PAGE analyses. The antigenicity of the coupled antigen was preserved and even improved, as assessed by the immuno-enzymatic (ELISA) test. Then, the performances of the micelles in immunization were investigated and compared to different p24-coated PLA nanoparticles, as well as Alum and MF59 gold standards, following a standardized HIV-1 immunization protocol in mice. The humoral response intensity (IgG titers) was substantially similar between the PLA micelles and all other adjuvants over an extended time range (one year). More interestingly, this immune response induced by PLA micelles was qualitatively higher than the gold standards and PLA nanoparticles analogs, expressed through an increasing avidity index over time (>60% at day 365). Taken together, these results demonstrate the potential of such small-sized micellar systems for vaccine delivery.

A versatile photothermal vaccine based on acid-responsive glyco-nanoplatform for synergistic therapy of cancer

The race is on for therapeutic agents that stop cancer. An effective vaccine offers a safe and promising approach for cancer immunotherapy. However, substantial barriers to immunotherapy in cancer vaccines include the low immunogenicity of cancer antigens and the immunosuppression commonly present in solid tumors, resulting in significant challenges for developing a clinically effective cancer vaccine. Here, the state of the art of synergistic therapy, which includes the photothermal effect combined with immunotherapy, was investigated to target tumors. For the first time, indocyanine green (ICG, referred to as I), imiquimod (R837, referred to as R) and a foreign cytotoxic T lymphocyte antigen peptide (CTL-Ap, referred to as Ap) with the sequence of SIINFEKL from ovalbumin (OVA) were encapsulated by acetalated dextran (AcDEX) to form nanoparticles (NPs) averaging 92 nm in diameter as an immunogen. Administration of the resulting multifunctional vaccine I-R-Ap-AcDEX NPs enhanced antitumor cytotoxic T lymphocyte (CTL) immunotherapy. On the one hand, subcutaneous immunization of the NPs allows foreign Ap to enter the major histocompatibility complex class I (MHC-I) cross-presentation pathway of antigen-presenting cells, thereby presenting Ap and eliciting high levels of Ap-specific CTLs. On the other hand, intratumor/intravenous injections of the NPs allow foreign Ap to enter tumor cells and present Ap through the MHC-I cross-presentation pathway. Ap-specific CTLs can kill Ap-presented tumor cells. Furthermore, the NPs generated near-infrared laser triggered the photothermal killing of tumor cells. To our knowledge, this is the first report of AcDEX NPs in antitumor photothermal therapy. Strikingly, systemic administration of the I-R-Ap-AcDEX NPs combined with near-infrared laser irradiation allowed for complete protection to mice from the tumors when applied to two non-OVA tumor models. This quite impressive result displays the great promise of synergistic therapy by the vaccine I-R-Ap-AcDEX NPs, an approach that harnesses the photothermal effect to boost antitumor immunotherapy.

Polymeric nanoparticle vaccines to combat emerging and pandemic threats

Subunit vaccines are more advantageous than live attenuated vaccines in terms of safety and scale-up manufacture. However, this often comes as a trade-off to their efficacy. Over the years, polymeric nanoparticles have been developed to improve vaccine potency, by engineering their physicochemical properties to incorporate multiple immunological cues to mimic pathogenic microbes and viruses. This review covers recent advances in polymeric nanostructures developed toward particulate vaccines. It focuses on the impact of microbe mimicry (e.g. size, charge, hydrophobicity, and surface chemistry) on modulation of the nanoparticles’ delivery, trafficking, and targeting antigen-presenting cells to elicit potent humoral and cellular immune responses. This review also provides up-to-date progresses on rational designs of a wide variety of polymeric nanostructures that are loaded with antigens and immunostimulatory molecules, ranging from particles, micelles, nanogels, and polymersomes to advanced core-shell structures where polymeric particles are coated with lipids, cell membranes, or proteins.

Self-Assembly as a Molecular Strategy to Improve Immunotherapy

Immunotherapies harness an individual's immune system to battle diseases such as cancer and autoimmunity. During cancer, the immune system often fails to detect and destroy cancerous cells, whereas during autoimmune disease, the immune system mistakenly attacks self-tissue. Immunotherapies can help guide more effective responses in these settings, as evidenced by recent advances with monoclonal antibodies and adoptive cell therapies. However, despite the transformative gains of immunotherapies for patients, many therapies are not curative, work only for a small subset of patients, and lack specificity in distinguishing between healthy and diseased cells, which can cause severe side effects. From this perspective, self-assembled biomaterials are promising technologies that could help address some of the limitations facing immunotherapies. For example, self-assembly allows precision control over the combination and relative concentration of immune cues and directed cargo display densities. These capabilities support selectivity and potency that could decrease off-target effects and enable modular or personalized immunotherapies. The underlying forces driving self-assembly of most systems in aqueous solution result from hydrophobic interactions or charge polarity. In this Account, we highlight how these forces are being used to self-assemble immunotherapies for cancer and autoimmune disease.Hydrophobic interactions can create a range of intricate structures, including peptide nanofibers, nanogels, micelle-like particles, and in vivo assemblies with protein carriers. Certain nanofibers with hydrophobic domains uniquely benefit from the ability to elicit immune responses without additional stimulatory signals. This feature can reduce nonspecific inflammation but may also limit the nanofiber's application because of their inherent stimulatory properties. Micelle-like particles have been developed with the ability to incorporate a range of tumor-specific antigens for immunotherapies in mouse models of cancer. Key observations have revealed that both the total dose of antigen and display density of antigen per particle can impact immune response and efficacy of immunotherapies. These developments are promising benchmarks that could reveal design principles for engineering more specific and personalized immunotherapies.There has also been extensive work to develop platforms using electrostatic interactions to drive assembly of oppositely charged immune signals. These strategies benefit from the ability to tune biophysical interactions between components by altering the ratio of cationic to anionic charge during formulation, or the density of charge. Using a layer-by-layer assembly method, our lab developed hollow capsules composed entirely of immune signals for therapies in cancer and autoimmune disease models. This platform allowed for 100% of the immunotherapy to be composed of immune signals and completely prevents the onset of disease in a mouse model of multiple sclerosis. Layer-by-layer assembly has also been used to coat microneedle patches to target signals to immune cells in the dermal layer. As an alternative to layer-by-layer assembly, one step assembly can be achieved by mixing cationic and anionic components in solution. Additional approaches have created molecular structures that leverage hydrogen bonding for self-assembly. The creativity of engineered self-assembly has led to key insights that could benefit future immunotherapies and revealed aspects that require further study. The challenge now remains to utilize these insights to push development of new immunotherapeutics into clinical settings.

Chemical Strategies to Boost Cancer Vaccines

Personalized cancer vaccines (PCVs) are reinvigorating vaccine strategies in cancer immunotherapy. In contrast to adoptive T-cell therapy and checkpoint blockade, the PCV strategy modulates the innate and adaptive immune systems with broader activation to redeploy antitumor immunity with individualized tumor-specific antigens (neoantigens). Following a sequential scheme of tumor biopsy, mutation analysis, and epitope prediction, the administration of neoantigens with synthetic long peptide (SLP) or mRNA formulations dramatically improves the population and activity of antigen-specific CD4+ and CD8+ T cells. Despite the promising prospect of PCVs, there is still great potential for optimizing prevaccination procedures and vaccine potency. In particular, the arduous development of tumor-associated antigen (TAA)-based vaccines provides valuable experience and rational principles for augmenting vaccine potency which is expected to advance PCV through the design of adjuvants, delivery systems, and immunosuppressive tumor microenvironment (TME) reversion since current personalized vaccination simply admixes antigens with adjuvants. Considering the broader application of TAA-based vaccine design, these two strategies complement each other and can lead to both personalized and universal therapeutic methods. Chemical strategies provide vast opportunities for (1) exploring novel adjuvants, including synthetic molecules and materials with optimizable activity, (2) constructing efficient and precise delivery systems to avoid systemic diffusion, improve biosafety, target secondary lymphoid organs, and enhance antigen presentation, and (3) combining bioengineering methods to innovate improvements in conventional vaccination, "smartly" re-educate the TME, and modulate antitumor immunity. As chemical strategies have proven versatility, reliability, and universality in the design of T cell- and B cell-based antitumor vaccines, the union of such numerous chemical methods in vaccine construction is expected to provide new vigor and vitality in cancer treatment.

Nanomedicine-mediated alteration of the pharmacokinetic profile of small molecule cancer immunotherapeutics

The advent of immunotherapy is a game changer in cancer therapy with monoclonal antibody- and T cell-based therapeutics being the current flagships. Small molecule immunotherapeutics might offer advantages over the biological drugs in terms of complexity, tissue penetration, manufacturing cost, stability, and shelf life. However, small molecule drugs are prone to rapid systemic distribution, which might induce severe off-target side effects. Nanotechnology could aid in the formulation of the drug molecules to improve their delivery to specific immune cell subsets. In this review we summarize the current efforts in changing the pharmacokinetic profile of small molecule immunotherapeutics with a strong focus on Toll-like receptor agonists. In addition, we give our vision on limitations and future pathways in the route of nanomedicine to the clinical practice.

Antigen Delivery to Antigen-Presenting Cells for Adaptive Immune Response by Self-Assembled Anionic Polysaccharide Nanogel Vaccines

Although current vaccine technology induces sufficient antibody responses to prophylactically ward off viral infections, an anticancer vaccine that directs the patient's immune system to directly fight extant malignant cells will require inducing Th1 and cytotoxic T lymphocyte responses in addition to antibody-mediated activities. Thus, new mechanisms are necessary to deliver antigen to cells in the lymphatic system that will induce these responses. To this end, we have developed a cholesterol-bearing pullulan (CHP) self-assembly nanogel of less than 100 nm, which we have now further modified to be anionic by carboxyl group substitution. Overall, the nanogel-protected antigens during transport to the lymphatic system and converting the vehicle to an anionic charge improved interactions with antigen-presenting cells. We further show that these modified nanogels are a more efficient system for delivering antigen to antigen-presenting cells, particularly langerin-expressing cells, and that this induced significant adaptive immunity. Therefore, we think that this technology could be used to improve anticancer immunotherapies.

Self-assembled amphiphilic copolymers as dual delivery system for immunotherapy

Subunit vaccines using recombinant antigens appear as the privileged vaccination technology for safety reasons but still require the development of carriers/adjuvants ensuring optimal immunogenicity and efficacy. Micelles from self-assembled amphiphilic copolymers have recently emerged as highly relevant and promising candidates owing to their ease of preparation, low size (entering in lymphatic capillaries for reaching lymph nodes), size/surface tunability and chemical versatility enabling introduction of stimuli (e.g. pH) responsive features and biofunctionalization with dedicated molecules. In particular, research efforts have increasingly focused on dendritic cells (DCs) targeting and activation by co-delivering (with antigen) ligands of pattern recognition receptors (PRRs, e.g. toll-like receptors). Such strategy has appeared as one of the most effective for eliciting CD 8+ T-cell response, which is crucial in the eradication of tumors and numerous infectious diseases. In this short review, we highlight the recent advances in such micelle-based carriers in subunit vaccination and how their precise engineering can be a strong asset for guiding and controlling immune responses.

Engineering self-assembled materials to study and direct immune function

The immune system is an awe-inspiring control structure that maintains a delicate and constantly changing balance between pro-immune functions that fight infection and cancer, regulatory or suppressive functions involved in immune tolerance, and homeostatic resting states. These activities are determined by integrating signals in space and time; thus, improving control over the densities, combinations, and durations with which immune signals are delivered is a central goal to better combat infectious disease, cancer, and autoimmunity. Self-assembly presents a unique opportunity to synthesize materials with well-defined compositions and controlled physical arrangement of molecular building blocks. This review highlights strategies exploiting these capabilities to improve the understanding of how precisely-displayed cues interact with immune cells and tissues. We present work centered on fundamental properties that regulate the nature and magnitude of immune response, highlight pre-clinical and clinical applications of self-assembled technologies in vaccines, cancer, and autoimmunity, and describe some of the key manufacturing and regulatory hurdles facing these areas.

Macromolecular systems for vaccine delivery

Vaccines have helped considerably in eliminating some life-threatening infectious diseases in past two hundred years. Recently, human medicine has focused on vaccination against some of the world's most common infectious diseases (AIDS, malaria, tuberculosis, etc.), and vaccination is also gaining popularity in the treatment of cancer or autoimmune diseases. The major limitation of current vaccines lies in their poor ability to generate a sufficient level of protective antibodies and T cell responses against diseases such as HIV, malaria, tuberculosis and cancers. Among the promising vaccination systems that could improve the potency of weakly immunogenic vaccines belong macromolecular carriers (water soluble polymers, polymer particels, micelles, gels etc.) conjugated with antigens and immunistumulatory molecules. The size, architecture, and the composition of the high molecular-weight carrier can significantly improve the vaccine efficiency. This review includes the most recently developed (bio)polymer-based vaccines reported in the literature.

Biomaterials-Based Vaccination Strategies for the Induction of CD8+T Cell Responses

Natural and synthetic biomaterials are increasingly being used for the development of vaccines and immunotherapies as alternatives to traditional live-attenuated formulations due to their improved safety profiles and no risk of reversion to virulence. Polymeric materials in particular enjoy attention due to the ease of fabrication, control over physicochemical properties, and their wide range of immunogenicity. While the majority of studies focus on inducing protective antibody responses, in recent years, materials-based strategies for the delivery of antigens and immunomodulators to improve CD8⁺T cell immunity against infectious and non-infectious diseases have gained momentum. Notably, platforms based on polymeric nanoparticles, liposomes, micelles, virus-like particles, self-assembling peptides and peptidomimetics, and multilayer thin films show considerable promise in preclinical studies. In this Review, we first introduce the concepts of CD8⁺T cell activation, effector and memory functions, and cytotoxic activity, followed by vaccine design for eliciting robust and protective long-lived CD8⁺T cell immunity. We then discuss different materials-based vaccines developed in the past decade to elicit CD8⁺T cell responses based on molecular composition or fabrication methods and conclude with a summary and glimpse at the future trends in this area.