Generation of effector memory T cell-based mucosal and systemic immunity with pulmonary nanoparticle vaccination

Silica Nanocapsules with Different Sizes and Physicochemical Properties as Suitable Nanocarriers for Uptake in T-Cells

Introduction

Adoptive T-cell immunotherapy emerged as a powerful and promising cancer therapy, as the problem regarding the immuno-reaction between different donors and recipients can be avoided. However, this approach is challenging. After long cultivation and expansion under laboratory media conditions, T-cells are losing their viability and function due to immune checkpoint proteins, leading to decreased efficiency in killing cancer cells. Therefore, a new strategy to improve T-cell survival and function is needed. With the advantages of nanotechnology and the biocompatibility of silica-based material, silica nanocapsules (SiNCs) provide an ideal delivery system to transport therapeutic biomolecules to T-cells. Up to now, there is a lack of cellular uptake studies of nanocarriers towards T-cells.

Methods

We systematically studied the influence of various physicochemical properties such as sizes, core hydrophobicities, surface charges, and surface functionalities of SiNC for their impact on cellular uptake and toxicity in CD8⁺ T-cells by flow cytometry and confocal laser scanning microscopy. Cytokine secretion assay was performed using the enzyme-linked immunosorbent assay. To identify suitable uptake conditions for SiNCs into CD8⁺ T-cells, the impact of human serum in cell culture medium was also investigated.

Results

The major impact on cellular uptake and toxicity was found to be size- and dose-dependent. Smaller sizes of SiNCs than 100 nm caused significant toxicity to the cells. It was found that the formed protein corona reduced the toxicity of the SiNCs. However, it also inhibited their uptake.

Conclusion

Overall, we present a set of different criteria for a suitable design of nanocarriers and cell culture conditions, which need to be carefully considered for T-cell immunotherapy in vitro to facilitate uptake while avoiding toxicity.

Properties of rapamycin solid lipid nanoparticles for lymphatic access through the lungs & part I: the effect of size

Background: Lymphangioleiomyomatosis (LAM) is characterized by growth of smooth muscle-like cells in the lungs that spread to other organs via lymphatic vessels. Current oral rapamycin treatment is limited by low bioavailability of approximately 15%. Aim: The effect of inhaled rapamycin solid lipid nanoparticles (Rapa-SLNs) size on its penetration through the lymphatics. Method: Three Rapa-SLN formulations (200-1000 nm) were produced and assessed for particle characteristics and further for toxicity and performance in vitro. Results: Rapa-SLNs of 200 nm inhibited proliferation in TSC2-negative mouse embryonic fibroblast cells and penetrated the respiratory epithelium and lymphatic endothelium significantly faster compared with free rapamycin and larger Rapa-SLNs. Conclusion: Rapa-SLN approximately 200 nm allows efficient entry of rapamycin into the lymphatic system and is therefore a promising treatment for LAM patients.

Properties of rapamycin solid lipid nanoparticles for lymphatic access through the lungs & part II: the effect of nanoparticle charge

Aim: Lymphangioleiomyomatosis is characterized by smooth muscle-like cells in the lungs that spread to other organs via lymphatic vessels. Oral rapamycin is restricted by low bioavailability approximately 15%. The aim of the present study is to systematically investigate the effect of inhaled rapamycin solid lipid nanoparticles (Rapa-SLN) surface charge on efficacy and penetration into the lymphatics. Materials & methods: Rapa-SLN formulations with different charge: neutral, positive and negative, were produced and assessed for their physicochemical particle characteristics and efficacy in vitro. Results: Negative Rapa-SLNs were significantly faster at entering the lymphatic endothelium and more potent at inhibiting lymphanigiogenesis compared with neutral and positive Rapa-SLNs. Conclusion: Negative Rapa-SLNs showed efficient lymphatic access and should therefore be investigated further as a treatment for targeting extrapulmonary lymphangioleiomyomatosis.

Nanotechnology for COVID-19: Therapeutics and Vaccine Research

The current global health threat by the novel coronavirus disease 2019 (COVID-19) requires an urgent deployment of advanced therapeutic options available. The role of nanotechnology is highly relevant to counter this "virus" nano enemy. Nano intervention is discussed in terms of designing effective nanocarriers to counter the conventional limitations of antiviral and biological therapeutics. This strategy directs the safe and effective delivery of available therapeutic options using engineered nanocarriers, blocking the initial interactions of viral spike glycoprotein with host cell surface receptors, and disruption of virion construction. Controlling and eliminating the spread and reoccurrence of this pandemic demands a safe and effective vaccine strategy. Nanocarriers have potential to design risk-free and effective immunization strategies for severe acute respiratory syndrome coronavirus 2 vaccine candidates such as protein constructs and nucleic acids. We discuss recent as well as ongoing nanotechnology-based therapeutic and prophylactic strategies to fight against this pandemic, outlining the key areas for nanoscientists to step in.

Pulmonary surfactant-biomimetic nanoparticles potentiate heterosubtypic influenza immunity

Current influenza vaccines only confer protection against homologous viruses. We synthesized pulmonary surfactant (PS)-biomimetic liposomes encapsulating 2',3'-cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), an agonist of the interferon gene inducer STING (stimulator of interferon genes). The adjuvant (PS-GAMP) vigorously augmented influenza vaccine-induced humoral and CD8⁺ T cell immune responses in mice by simulating the early phase of viral infection without concomitant excess inflammation. Two days after intranasal immunization with PS-GAMP-adjuvanted H1N1 vaccine, strong cross-protection was elicited against distant H1N1 and heterosubtypic H3N2, H5N1, and H7N9 viruses for at least 6 months while maintaining lung-resident memory CD8⁺ T cells. Adjuvanticity was then validated in ferrets. When alveolar epithelial cells (AECs) lacked Sting or gap junctions were blocked, PS-GAMP-mediated adjuvanticity was substantially abrogated in vivo. Thus, AECs play a pivotal role in configuring heterosubtypic immunity.

Immunology-Guided Biomaterial Design for Mucosal Cancer Vaccines

Cancer of mucosal tissues is a major cause of worldwide mortality for which only palliative treatments are available for patients with late-stage disease. Engineered cancer vaccines offer a promising approach for inducing antitumor immunity. The route of vaccination plays a major role in dictating the migratory pattern of lymphocytes, and thus vaccine efficacy in mucosal tissues. Parenteral immunization, specifically subcutaneous and intramuscular, is the most common vaccination route. However, this induces marginal mucosal protection in the absence of tissue-specific imprinting signals. To circumvent this, the mucosal route can be utilized, however degradative mucosal barriers must be overcome. Hence, vaccine administration route and selection of materials able to surmount transport barriers are important considerations in mucosal cancer vaccine design. Here, an overview of mucosal immunity in the context of cancer and mucosal cancer clinical trials is provided. Key considerations are described regarding the design of biomaterial-based vaccines that will afford antitumor immune protection at mucosal surfaces, despite limited knowledge surrounding mucosal vaccination, particularly aided by biomaterials and mechanistic immune-material interactions. Finally, an outlook is given of how future biomaterial-based mucosal cancer vaccines will be shaped by new discoveries in mucosal vaccinology, tumor immunology, immuno-therapeutic screens, and material-immune system interplay.

Biomimetic Nanotechnology toward Personalized Vaccines

While traditional approaches for disease management in the era of modern medicine have saved countless lives and enhanced patient well-being, it is clear that there is significant room to improve upon the current status quo. For infectious diseases, the steady rise of antibiotic resistance has resulted in super pathogens that do not respond to most approved drugs. In the field of cancer treatment, the idea of a cure-all silver bullet has long been abandoned. As a result of the challenges facing current treatment and prevention paradigms in the clinic, there is an increasing push for personalized therapeutics, where plans for medical care are established on a patient-by-patient basis. Along these lines, vaccines, both against bacteria and tumors, are a clinical modality that could benefit significantly from personalization. Effective vaccination strategies could help to address many challenging disease conditions, but current vaccines are limited by factors such as a lack of potency and antigenic breadth. Recently, researchers have turned toward the use of biomimetic nanotechnology as a means of addressing these hurdles. Recent progress in the development of biomimetic nanovaccines for antibacterial and anticancer applications is discussed, with an emphasis on their potential for personalized medicine.

Inhibition of neutrophil elastase prevents neutrophil extracellular trap formation and rescues mice from endotoxic shock

Neutrophil elastase (NE) is a serine protease stored in the azurophilic granules of neutrophils and released into the extracellular milieu during inflammatory response or formation of neutrophil extracellular traps (NETs). Neutrophils release NETs to entrap pathogens by externalizing their cellular contents in a DNA framework decorated with anti-microbials and proteases, including NE. Importantly, excess NETs in tissues are implicated in numerous pathologies, including sepsis, rheumatoid arthritis, vasculitis, and cancer. However, it remains unknown how to effectively prevent NET formation. Here, we show that NE plays a major role during NET formation and that inhibition of NE is a promising approach for decreasing NET-mediated tissue injury. NE promoted NET formation by human neutrophils. Whereas sivelestat, a small molecule inhibitor of NE, inhibited the formation of NETs in vitro , administration of free sivelestat did not have any efficacy in a murine model of lipopolysaccharide-induced endotoxic shock. To improve the efficacy of sivelestat in vivo, we have developed a nanoparticle system for delivering sivelestat. We demonstrate that nanoparticle-mediated delivery of sivelestat effectively inhibited NET formation, decreased the clinical signs of lung injury, reduced NE and other proinflammatory cytokines in serum, and rescued animals against endotoxic shock. Collectively, our data demonstrates that NE signaling can initiate NET formation and that nanoparticle-mediated inhibition of NE improves drug efficacy for preventing NET formation.

Materials for Immunotherapy

Breakthroughs in materials engineering have accelerated the progress of immunotherapy in preclinical studies. The interplay of chemistry and materials has resulted in improved loading, targeting, and release of immunomodulatory agents. An overview of the materials that are used to enable or improve the success of immunotherapies in preclinical studies is presented, from immunosuppressive to proinflammatory strategies, with particular emphasis on technologies poised for clinical translation. The materials are organized based on their characteristic length scale, whereby the enabling feature of each technology is organized by the structure of that material. For example, the mechanisms by which i) nanoscale materials can improve targeting and infiltration of immunomodulatory payloads into tissues and cells, ii) microscale materials can facilitate cell-mediated transport and serve as artificial antigen-presenting cells, and iii) macroscale materials can form the basis of artificial microenvironments to promote cell infiltration and reprogramming are discussed. As a step toward establishing a set of design rules for future immunotherapies, materials that intrinsically activate or suppress the immune system are reviewed. Finally, a brief outlook on the trajectory of these systems and how they may be improved to address unsolved challenges in cancer, infectious diseases, and autoimmunity is presented.

Gut microbiota and cardiovascular disease: opportunities and challenges

Coronary artery disease (CAD) is the most common health problem worldwide and remains the leading cause of morbidity and mortality. Over the past decade, it has become clear that the inhabitants of our gut, the gut microbiota, play a vital role in human metabolism, immunity, and reactions to diseases, including CAD. Although correlations have been shown between CAD and the gut microbiota, demonstration of potential causal relationships is much more complex and challenging. In this review, we will discuss the potential direct and indirect causal roots between gut microbiota and CAD development via microbial metabolites and interaction with the immune system. Uncovering the causal relationship of gut microbiota and CAD development can lead to novel microbiome-based preventative and therapeutic interventions. However, an interdisciplinary approach is required to shed light on gut bacterial-mediated mechanisms (e.g., using advanced nanomedicine technologies and incorporation of demographic factors such as age, sex, and ethnicity) to enable efficacious and high-precision preventative and therapeutic strategies for CAD.

Integrating Biomaterials and Immunology to Improve Vaccines Against Infectious Diseases

Despite the success of vaccines in preventing many infectious diseases, effective vaccines against pathogens with ongoing challenges - such as HIV, malaria, and tuberculosis - remain unavailable. The emergence of new pathogen variants, the continued prevalence of existing pathogens, and the resurgence of yet other infectious agents motivate the need for new, interdisciplinary approaches to direct immune responses. Many current and candidate vaccines, for example, are poorly immunogenic, provide only transient protection, or create risks of regaining pathogenicity in certain immune-compromised conditions. Recent advances in biomaterials research are creating new potential to overcome these challenges through improved formulation, delivery, and control of immune signaling. At the same time, many of these materials systems - such as polymers, lipids, and self-assembly technologies - may achieve this goal while maintaining favorable safety profiles. This review highlights ways in which biomaterials can advance existing vaccines to safer, more efficacious technologies, and support new vaccines for pathogens that do not yet have vaccines. Biomaterials that have not yet been applied to vaccines for infectious disease are also discussed, and their potential in this area is highlighted.

Nanoparticles for mucosal vaccine delivery

Mucosal surfaces represent important routes of entry into the human body for the majority of pathogens, and they constitute unique sites for targeted vaccine delivery. Nanoparticle-based drug delivery systems are emerging technologies for delivering and improving the efficacy of mucosal vaccines. Recent studies have provided new insights into formulation and delivery aspects of importance for the design of safe and efficacious mucosal subunit vaccines based on nanoparticles. These include novel nanomaterials, their physicochemical properties and formulation approaches, nanoparticle interaction with immune cells in the mucosa, and mucosal immunization and delivery strategies. Here, we present recent progress in the application of nanoparticle-based approaches for mucosal vaccine delivery and discuss future research challenges and opportunities in the field.

Multilamellar Vaccine Particle Elicits Potent Immune Activation with Protein Antigens and Protects Mice against Ebola Virus Infection

Recent outbreaks of emerging infectious diseases, such as Ebola virus disease (EVD), highlight the urgent need to develop effective countermeasures, including prophylactic vaccines. Subunit proteins derived from pathogens provide a safe source of antigens for vaccination, but they are often limited by their low immunogenicity. We have developed a multilamellar vaccine particle (MVP) system composed of lipid-hyaluronic acid multi-cross-linked hybrid nanoparticles for vaccination with protein antigens and demonstrate their efficacy against Ebola virus (EBOV) exposure. MVPs efficiently accumulated in dendritic cells and promote antigen processing. Mice immunized with MVPs elicited robust and long-lasting antigen-specific CD8⁺ and CD4⁺ T cell immune responses as well as humoral immunity. A single-dose vaccination with MVPs delivering EBOV glycoprotein achieved an 80% protection rate against lethal EBOV infection. These results suggest that MVPs offer a promising platform for improving recombinant protein-based vaccine approaches.

Mucosal Immunization with a pH-Responsive Nanoparticle Vaccine Induces Protective CD8+ Lung-Resident Memory T Cells

Tissue-resident memory T cells (T_RM) patrol nonlymphoid organs and provide superior protection against pathogens that commonly infect mucosal and barrier tissues, such as the lungs, intestine, liver, and skin. Thus, there is a need for vaccine technologies that can induce a robust, protective T_RM response in these tissues. Nanoparticle (NP) vaccines offer important advantages over conventional vaccines; however, there has been minimal investigation into the design of NP-based vaccines for eliciting T_RM responses. Here, we describe a pH-responsive polymeric nanoparticle vaccine for generating antigen-specific CD8⁺ T_RM cells in the lungs. With a single intranasal dose, the NP vaccine elicited airway- and lung-resident CD8⁺ T_RM cells and protected against respiratory virus challenge in both sublethal (vaccinia) and lethal (influenza) infection models for up to 9 weeks after immunization. In elucidating the contribution of material properties to the resulting T_RM response, we found that the pH-responsive activity of the carrier was important, as a structurally analogous non-pH-responsive control carrier elicited significantly fewer lung-resident CD8⁺ T cells. We also demonstrated that dual-delivery of protein antigen and nucleic acid adjuvant on the same NP substantially enhanced the magnitude, functionality, and longevity of the antigen-specific CD8⁺ T_RM response in the lungs. Compared to administration of soluble antigen and adjuvant, the NP also mediated retention of vaccine cargo in pulmonary antigen-presenting cells (APCs), enhanced APC activation, and increased production of T_RM-related cytokines. Overall, these data suggest a promising vaccine platform technology for rapid generation of protective CD8⁺ T_RM cells in the lungs.

Polysaccharide Nanoparticles Can Efficiently Modulate the Immune Response against an HIV Peptide Antigen

The development of an effective HIV vaccine continues to be a major health challenge since, so far, only the RV144 trial has demonstrated a modest clinical efficacy. Recently, the targeting of the 12 highly conserved protease cleavage sites (PCS1-12) has been presented as a strategy seeking to hamper the maturation and infectivity of HIV. To pursue this line of research, and because peptide antigens have low immunogenicity, we have included these peptides in engineered nanoparticles, aiming at overcoming this limitation. More specifically, we investigated whether the covalent attachment of a PCS peptide (PCS5) to polysaccharide-based nanoparticles, and their coadministration with polyinosinic:polycytidylic acid (poly(I:C)), improved the generated immune response. To this end, PCS5 was first conjugated to two different polysaccharides (chitosan and hyaluronic acid) through either a stable or a cleavable bond and then associated with an oppositely charged polymer (dextran sulfate and chitosan) and poly(I:C) to form the nanoparticles. Nanoparticles associating PCS5 by ionic interactions were used in this study as the control formulation. In vivo, all nanosystems elicited high anti-PCS5 antibodies. Nanoparticles containing PCS5 conjugated and poly(I:C) seemed to induce the strongest activation of antigen-presenting cells. Interestingly, T cell activation presented different kinetics depending on the prototype. These findings show that both the nanoparticle composition and the conjugation of the HIV peptide antigen may play an important role in the generation of humoral and cellular responses.

Tailoring Nanomaterials for Targeting Tumor-Associated Macrophages

Advances in the field of nanotechnology together with an increase understanding of tumor immunology have paved the way for the development of more personalized cancer immuno-nanomedicines. Nanovehicles, due to their specific physicochemical properties, are emerging as key translational moieties in tackling tumor-promoting, M2-like tumor-associated macrophages (TAMs). Cancer immuno-nanomedicines target TAMs primarily by blocking M2-like TAM survival or affecting their signaling cascades, restricting macrophage recruitment to tumors and re-educating tumor-promoting M2-like TAMs to the tumoricidal, M1-like phenotype. Here, the TAM effector mechanisms and strategies for targeting TAMs are summarized, followed by a focus on the mechanistic considerations in the development of novel immuno-nanomedicines. Furthermore, imaging TAMs with nanoparticles so as to forecast a patient's clinical outcome, describing treatment options, and observing therapy responses is also discussed. At present, strategies that target TAMs are being investigated not only at the basic research level but also in early clinical trials. The significance of TAM-targeting biomaterials is highlighted, with the goal of facilitating future clinical translation.

Impact of Polymer-TLR-7/8 Agonist (Adjuvant) Morphology on the Potency and Mechanism of CD8 T Cell Induction

Small molecule Toll-like receptor-7 and -8 agonists (TLR-7/8a) can be used as vaccine adjuvants to induce CD8 T cell immunity but require formulations that prevent systemic toxicity and focus adjuvant activity in lymphoid tissues. Here, we covalently attached TLR-7/8a to polymers of varying composition, chain architecture and hydrodynamic behavior (∼300 nm submicrometer particles, ∼10 nm micelles and ∼4 nm flexible random coils) and evaluated how these parameters of polymer-TLR-7/8a conjugates impact adjuvant activity in vivo. Attachment of TLR-7/8a to any of the polymer compositions resulted in a nearly 10-fold reduction in systemic cytokines (toxicity). Moreover, both lymph node cytokine production and the magnitude of CD8 T cells induced against protein antigen increased with increasing polymer-TLR-7/8a hydrodynamic radius, with the submicrometer particle inducing the highest magnitude responses. Notably, CD8 T cell responses induced by polymer-TLR-7/8a were dependent on CCR2+ monocytes and IL-12, whereas responses by a small molecule TLR-7/8a that unexpectedly persisted in vaccine-site draining lymph nodes (T1/2 = 15 h) had less dependence on monocytes and IL-12 but required Type I IFNs. This study shows how modular properties of synthetic adjuvants can be chemically programmed to alter immunity in vivo through distinct immunological mechanisms.

Nanoparticles for Immune Stimulation Against Infection, Cancer, and Autoimmunity

Vaccination using nanocarrier-based delivery systems has recently emerged as a promising approach for meeting the continued challenge posed by infectious diseases and cancer. A diverse portfolio of nanocarriers of various sizes, compositions, and physical parameters have now been developed, and this diversity provides an opportunity for the rational design of vaccines that can mediate targeted delivery of various antigens and adjuvants or immune regulatory agents in ways unachievable with classical vaccination approaches. This flexibility allows control over the characteristics of vaccine-elicited immune responses such that they can be tailored to be effective in circumstances where classical vaccines have failed. Furthermore, the utility of nanocarrier-based immune modulation extends to the treatment of autoimmune disease where precisely targeted inhibition of immune responses is desirable. Clearly, the selection of appropriate nanocarriers, antigens, adjuvants, and other components underpins the efficacy of these nanoimmune interventions. Herein, we provide an overview of currently available nanocarriers of various types and their physical and pharmacological properties with the goal of providing a resource for researchers exploring nanomaterial-based approaches for immune modulation and identify some information gaps and unexplored questions to help guide future investigation.

Vaccine nanoparticles displaying recombinant Ebola virus glycoprotein for induction of potent antibody and polyfunctional T cell responses

The recent outbreaks of Ebolavirus (EBOV) in West Africa underscore the urgent need to develop an effective EBOV vaccine. Here, we report the development of synthetic nanoparticles as a safe and highly immunogenic platform for vaccination against EBOV. We show that a large recombinant EBOV antigen (rGP) can be incorporated in a configurational manner into lipid-based nanoparticles, termed interbilayer-crosslinked multilamellar vesicles (ICMVs). The epitopes and quaternary structure of rGP were properly maintained on the surfaces of ICMVs formed either with or without nickel nitrilotriacetic acid (NTA)-functionalized lipids. When administered in mice, rGP-ICMVs without NTA-lipids efficiently generated germinal center B cells and polyfunctional T cells while eliciting robust neutralizing antibody responses. This study suggests the potential of vaccine nanoparticles as a delivery platform for configurational, multivalent display of large subunit antigens and induction of neutralizing antibody and T cell responses.

Nanoscale Peptide Self-assemblies Boost BCG-primed Cellular Immunity Against Mycobacterium tuberculosis

Bacillus Calmette-Guerin (BCG) is the only vaccine against TB and has limited protection efficacy, which wanes past adolescence. Multifunctional CD8+ T cells (IFN-γ+/TNF-α+/IL-2+) are associated with lower reactivation risk and enhanced control of active Mtb infection. Since boosting with BCG is contraindicated, booster vaccines that augment T cell immunity in the lungs of BCG-vaccinated individuals are urgently needed. We developed a vaccination strategy based on self-assembling peptide nanofibers presenting Mtb-specific CD8+ or CD4+ T cell epitopes that induce high frequency and antigen-specific effector memory T cells producing IFN-γ and IL-2. Intranasal immunization with peptide nanofibers was well tolerated in mice leading to increased antigen-specific CD8+ T cell population in the lungs. Co-assembled nanofibers of CD8+ T cell epitopes and toll-like receptor 2 (TLR2) agonists induced a 8-fold expansion in multifunctional CD8+ T cell populations in the lungs of vaccinated mice. Aerosol challenge with Mtb in BCG-primed and nanofiber-boosted mice provided an additional 0.5-log CFU reduction in lung bacterial load and indicating enhanced protection compared to BCG alone. Together, these data suggest that heterologous prime-boost with BCG and peptide nanofiber vaccines induces cell mediated immunity in the lung, reduces bacterial burden, and is a potentially safer alternative for boosting BCG-primed immunity.

Poly(propylacrylic acid)-peptide nanoplexes as a platform for enhancing the immunogenicity of neoantigen cancer vaccines

Cancer vaccines targeting patient-specific tumor neoantigens have recently emerged as a promising component of the rapidly expanding immunotherapeutic armamentarium. However, neoantigenic peptides typically elicit weak CD8⁺ T cell responses, and so there is a need for universally applicable vaccine delivery strategies to enhance the immunogenicity of these peptides. Ideally, such vaccines could also be rapidly fabricated using chemically synthesized peptide antigens customized to an individual patient. Here, we describe a strategy for simple and rapid packaging of peptide antigens into pH-responsive nanoparticles with endosomal escape activity. Electrostatically-stabilized polyplex nanoparticles (nanoplexes) can be assembled instantaneously by mixing decalysine-modified antigenic peptides and poly(propylacrylic acid) (pPAA), a polyanion with pH-dependent, membrane destabilizing activity. These nanoplexes increase and prolong antigen uptake and presentation on MHC-I (major histocompatibility complex class I) molecules expressed by dendritic cells, resulting in enhanced activation of CD8⁺ T cells. Using an intranasal immunization route, nanoplex vaccines inhibit formation of lung metastases in a murine melanoma model. Additionally, nanoplex vaccines strongly synergize with the adjuvant α-galactosylceramide (α-GalCer) in stimulating robust CD8⁺ T cell responses, significantly increasing survival time in mice with established melanoma tumors. Collectively, these findings demonstrate that peptide/pPAA nanoplexes offer a facile and versatile platform for enhancing CD8⁺ T cell responses to peptide antigens, with potential to complement ongoing advancements in the development of neoantigen-targeted cancer vaccines.

Improving Vaccine and Immunotherapy Design Using Biomaterials

Polymers, lipids, scaffolds, microneedles, and other biomaterials are rapidly emerging as technologies to improve the efficacy of vaccines against infectious disease and immunotherapies for cancer, autoimmunity, and transplantation. New studies are also providing insight into the interactions between these materials and the immune system. This insight can be exploited for more efficient design of vaccines and immunotherapies. Here, we describe recent advances made possible through the unique features of biomaterials, as well as the important questions for further study.

Nanotherapeutics in oral and parenteral drug delivery: Key learnings and future outlooks as we think small

Nanotechnology ushered the field of medicine in to a new era. Miniaturization, increased surface area, and the unique physicochemical properties in the nano dimension were explored for new applications. Pharmaceutical industry picked up the technology and early success came fast for oral drug delivery through improvement in dissolution properties of the active molecules. Many products were launched using the nanocrystal technology on the oral side. Further development of polymeric nanoparticles led to wide spread research of nanocarriers for parenteral delivery. While considerable efforts have gone in the last two decades for testing nanoparticles for tumor targeting, delivery into tumors has remained challenging and suboptimal. Inadequate in vivo models that didn't accurately reflect the age and vascularity of human tumors, and inability to reproducibly target therapeutic drugs to the tissue of interest due to intrinsic biodistribution of the particles and hence side effects, limited the number of studies that advanced to the clinic. Our article addresses the questions commonly asked by scientific researchers in nanomedicine: "Has nanoparticle technology yielded on its initial promise that scientists predicted towards improving therapeutic index and avoid toxicity by delivering molecules to target tissues or was it more of wishful thinking that had several roadblocks?" We answer this question by linking the relevance of nanoparticles to cancer immunotherapy. The advent of immunotherapy has begun to show the potential applicability of nanoparticles in a different light, to target the immune system. In this approach, nanoparticles may positively influence the immune system rather than create the targeted "magic bullet". Utilizing the intrinsic properties of nanoparticles for immune targeting as opposed to targeting the tumor can bring about a positive difference due to the underlying complex cancer mechanisms that can potentially overlap with the heterogeneous biodistribution of nanoparticles towards improving the acquired and innate immune responses. In this review, we have followed the progress of nanotechnology in pharmaceutical applications with key insights from oral and parenteral drug delivery, and how to modify our thinking to better utilize nanoparticles for immuno-oncology. In contrast to conventional "local" tumor targeting by nanoparticles, we propose a new mechanism whereby nanoparticles trigger priming of the T cells towards tumor destruction. The heterogenous biodistribution of nanoparticles lends itself to stimulating immune cells systemically in a "global" manner and with the right therapeutic combinations will be able to trigger tumor antigens to continually activate, retain memory effects and destroy tumor cells.

Prospects for chimeric antigen receptor-modified T cell therapy for solid tumors

The potential for adoptive cell immunotherapy as a treatment against cancers has been demonstrated by the remarkable response in some patients with hematological malignancies using autologous T cells endowed with chimeric antigen receptors (CARs) specific for CD19. Clinical efficacy of CAR-T cell therapy for the treatment of solid tumors, however, is rare due to physical and biochemical factors. This review focuses on different aspects of multiple mechanisms of immunosuppression in solid tumors. We characterize the current state of CAR-modified T cell therapy and summarize the various strategies to combat the immunosuppressive microenvironment of solid tumors, with the aim of promoting T cell cytotoxicity and enhancing tumor cell eradication.

Nanoparticle anchoring targets immune agonists to tumors enabling anti-cancer immunity without systemic toxicity

Immunostimulatory agents such as agonistic anti-CD137 and interleukin (IL)−2 generate effective anti-tumor immunity but also elicit serious toxicities, hampering their clinical application. Here we show that combination therapy with anti-CD137 and an IL-2-Fc fusion achieves significant initial anti-tumor activity, but also lethal immunotoxicity deriving from stimulation of circulating leukocytes. To overcome this toxicity, we demonstrate that anchoring IL-2 and anti-CD137 on the surface of liposomes allows these immune agonists to rapidly accumulate in tumors while lowering systemic exposure. In multiple tumor models, immunoliposome delivery achieves anti-tumor activity equivalent to free IL-2/anti-CD137 but with the complete absence of systemic toxicity. Immunoliposomes stimulated tumor infiltration by cytotoxic lymphocytes, cytokine production, and granzyme expression, demonstrating equivalent immunostimulatory effects to the free drugs in the local tumor microenvironment. Thus, surface-anchored particle delivery may provide a general approach to exploit the potent stimulatory activity of immune agonists without debilitating systemic toxicities.

Immunostimulatory agents used in cancer treatment often elicit serious toxicities, limiting their clinical application. Here, the authors show that the use of liposomes to intravenously deliver surface-anchored IL-2 and anti-CD137 proteins enables anti-cancer immunity and reduces the toxic side effects.

Nanoparticle impact on innate immune cell pattern-recognition receptors and inflammasomes activation

Nanotechnology-based strategies can dramatically impact the treatment, prevention and diagnosis of a wide range of diseases. Despite the unprecedented success achieved with the use of nanomaterials to address unmet biomedical needs and their particular suitability for the effective application of a personalized medicine, the clinical translation of those nanoparticulate systems has still been impaired by the limited understanding on their interaction with complex biological systems. As a result, unexpected effects due to unpredicted interactions at biomaterial and biological interfaces have been underlying the biosafety concerns raised by the use of nanomaterials. This review explores the current knowledge on how nanoparticle (NP) physicochemical and surface properties determine their interactions with innate immune cells, with particular attention on the activation of pattern-recognition receptors and inflammasome. A critical perspective will additionally address the impact of biological systems on the effect of NP on immune cell activity at the molecular level. We will discuss how the understanding of the NP-innate immune cell interactions can significantly add into the clinical translation by guiding the design of nanomedicines with particular effect on targeted cells, thus improving their clinical efficacy while minimizing undesired but predictable toxicological effects.

Multivalent bi-specific nanobioconjugate engager for targeted cancer immunotherapy

Tumour-targeted immunotherapy offers the unique advantage of specific tumouricidal effects with reduced immune-associated toxicity. However, existing platforms suffer from low potency, inability to generate long-term immune memory and decreased activities against tumour-cell subpopulations with low targeting receptor levels. Here we adopted a modular design approach that uses colloidal nanoparticles as substrates to create a multivalent bi-specific nanobioconjugate engager (mBiNE) to promote selective, immune-mediated eradication of cancer cells. By simultaneously targeting the human epidermal growth factor receptor 2 (HER2) expressed by cancer cells and pro-phagocytosis signalling mediated by calreticulin, the mBiNE stimulated HER2-targeted phagocytosis and produced durable antitumour immune responses against HER2-expressing tumours. Interestingly, although the initial immune activation mediated by the mBiNE was receptor dependent, the subsequent antitumour immunity also generated protective effects against tumour-cell populations that lacked the HER2 receptor. Thus, the mBiNE represents a new targeted, nanomaterial-immunotherapy platform to stimulate innate and adaptive immunity and promote a universal antitumour response.

Turbocharging vaccines: emerging adjuvants for dendritic cell based therapeutic cancer vaccines

Development of therapeutic cancer vaccines has been hindered by the many pro-tumorigenic mechanisms at play in cancer patients that serve to suppress both antigen presenting cells and T cells. In face of these obstacles, cancer vaccines are most likely to promote anti-tumorigenic immune responses only when formulated with strong adjuvants, and in combination with new immune interventions designed to reverse immune suppression and exhaustion of T cells in the tumor microenvironment. Dendritic cells (DCs) are often termed 'nature's adjuvant' due to their exceptional capacity for initiating both innate and adaptive immune responses. Hence, the past decade has witnessed a flurry of activity in testing DC based immunotherapies for cancer intervention. In this review we will discuss advances in conventional adjuvants and provide insight into new adjuvants as they pertain to DC cancer therapy.

Nasal nanovaccines

Nasal administration of vaccines is convenient for the potential stimulation of mucosal and systemic immune protection. Moreover the easy accessibility of the intranasal route renders it optimal for pandemic vaccination. Nanoparticles have been identified as ideal delivery systems and adjuvants for vaccine application. Heterogeneous protocols have been used for animal studies. This complicates the understanding of the formulation influence on the immune response and the comparison of the different nanoparticles approaches developed. Moreover anatomical and immunological differences between rodents and humans provide an additional hurdle in the rational development of nasal nanovaccines. This review will give a comprehensive expertise of the state of the art in nasal nanovaccines in animals and humans focusing on the nanomaterial used.

Nanoparticle Vaccines Adopting Virus-like Features for Enhanced Immune Potentiation

Synthetic nanoparticles play an increasingly significant role in vaccine design and development as many nanoparticle vaccines show improved safety and efficacy over conventional formulations. These nanoformulations are structurally similar to viruses, which are nanoscale pathogenic organisms that have served as a key selective pressure driving the evolution of our immune system. As a result, mechanisms behind the benefits of nanoparticle vaccines can often find analogue to the interaction dynamics between the immune system and viruses. This review covers the advances in vaccine nanotechnology with a perspective on the advantages of virus mimicry towards immune potentiation. It provides an overview to the different types of nanomaterials utilized for nanoparticle vaccine development, including functionalization strategies that bestow nanoparticles with virus-like features. As understanding of human immunity and vaccine mechanisms continue to evolve, recognizing the fundamental semblance between synthetic nanoparticles and viruses may offer an explanation for the superiority of nanoparticle vaccines over conventional vaccines and may spur new design rationales for future vaccine research. These nanoformulations are poised to provide solutions towards pressing and emerging human diseases.

Biomaterial strategies for generating therapeutic immune responses

Biomaterials employed to raise therapeutic immune responses have become a complex and active field. Historically, vaccines have been developed primarily to fight infectious diseases, but recent years have seen the development of immunologically active biomaterials towards an expanding list of non-infectious diseases and conditions including inflammation, autoimmunity, wounds, cancer, and others. This review structures its discussion of these approaches around a progression from single-target strategies to those that engage increasingly complex and multifactorial immune responses. First, the targeting of specific individual cytokines is discussed, both in terms of delivering the cytokines or blocking agents, and in terms of active immunotherapies that raise neutralizing immune responses against such single cytokine targets. Next, non-biological complex drugs such as randomized polyamino acid copolymers are discussed in terms of their ability to raise multiple different therapeutic immune responses, particularly in the context of autoimmunity. Last, biologically derived matrices and materials are discussed in terms of their ability to raise complex immune responses in the context of tissue repair. Collectively, these examples reflect the tremendous diversity of existing approaches and the breadth of opportunities that remain for generating therapeutic immune responses using biomaterials.

Pulmonary Delivery of Virosome-Bound Antigen Enhances Antigen-Specific CD4+ T Cell Proliferation Compared to Liposome-Bound or Soluble Antigen

Pulmonary administration of biomimetic nanoparticles loaded with antigen may represent an effective strategy to directly modulate adaptive immune responses in the respiratory tract. Depending on the design, virosomes may not only serve as biomimetic antigen carriers but are also endowed with intrinsic immune-stimulatory properties. We designed fluorescently labeled influenza-derived virosomes and liposome controls coupled to the model antigen ovalbumin to investigate uptake, phenotype changes, and antigen processing by antigen-presenting cells exposed to such particles in different respiratory tract compartments. Both virosomes and liposomes were captured by pulmonary macrophages and dendritic cells alike and induced activation in particle-bearing cells by upregulation of costimulatory markers such as CD40, CD80, CD86, PD-L1, PD-L2, and ICOS-L. Though antigen processing and accumulation of both coupled and soluble antigen was similar between virosomes and liposomes, only ovalbumin-coupled virosomes generated a strong antigen-specific CD4⁺ T cell proliferation. Pulmonary administrated antigen-coupled virosomes therefore effectively induced adaptive immune responses and may be utilized in novel preventive or therapeutic approaches in the respiratory tract.

Nanoparticles for immune system targeting

Nanoparticles (NPs) are found in numerous applications used to modulate the immune system. They serve as drug delivery carriers or vaccine adjuvants and are utilized as therapeutics against a variety of diseases. NPs can be engineered to target distinct cellular components representing multiple pathways of immunity. The combination of NPs with immune system-targeting moieties has paved the way for improved targeted immune therapies. Here we provide an update of recent progress in this field.

Coordinating antigen cytosolic delivery and danger signaling to program potent cross-priming by micelle-based nanovaccine

Although re-activating cytotoxic T-cell (CTLs) response inside tumor tissues by checkpoint blockade has demonstrated great success in tumor immunotherapy, active induction of efficient endogenous CTL response by therapeutic vaccines has been largely hampered by inefficient cytosolic delivery of antigens and coordinated activation of dendritic cells (DCs) in lymph nodes. Here we show that polyethylene glycol-phosphatidylethanolamine (PEG-PE) micelles transform soluble peptides into α-helix to enable their efficient cytosolic delivery. The same PEG-PE micelles also serve as chaperon of TLR4 signaling to coordinate its adjuvant effect on the same DCs. Furthermore, these nanovaccines effectively target lymph node DCs. Thus, PEG-PE micelle vaccines program at multiple key aspects for inducing strong CTL responses and build up a foundation for combinational tumor therapy.

Designer vaccine nanodiscs for personalized cancer immunotherapy

Despite the tremendous potential of peptide-based cancer vaccines, their efficacy has been limited in humans. Recent innovations in tumour exome sequencing have signalled the new era of personalized immunotherapy with patient-specific neoantigens, but a general methodology for stimulating strong CD8α⁺ cytotoxic T-lymphocyte (CTL) responses remains lacking. Here we demonstrate that high-density lipoprotein-mimicking nanodiscs coupled with antigen (Ag) peptides and adjuvants can markedly improve Ag/adjuvant co-delivery to lymphoid organs and sustain Ag presentation on dendritic cells. Strikingly, nanodiscs elicited up to 47-fold greater frequencies of neoantigen-specific CTLs than soluble vaccines and even 31-fold greater than perhaps the strongest adjuvant in clinical trials (that is, CpG in Montanide). Moreover, multi-epitope vaccination generated broad-spectrum T-cell responses that potently inhibited tumour growth. Nanodiscs eliminated established MC-38 and B16F10 tumours when combined with anti-PD-1 and anti-CTLA-4 therapy. These findings represent a new powerful approach for cancer immunotherapy and suggest a general strategy for personalized nanomedicine.

Vaccine nanocarriers: Coupling intracellular pathways and cellular biodistribution to control CD4 vs CD8 T cell responses

Nanoparticle delivery systems are known to enhance the immune response to soluble antigens (Ags) and are thus a promising tool for the development of new vaccines. Our laboratory has engineered two different nanoparticulate systems in which Ag is either encapsulated within the core of polymersomes (PSs) or decorated onto the surface of nanoparticles (NPs). Previous studies showed that PSs are better at enhancing CD4 T cells and antibody titers, while NPs preferentially augment cytotoxic CD8 T cells. Herein, we demonstrate that the differential activation of T cell immunity reflects differences in the modes of intracellular trafficking and distinct biodistribution of the Ag in lymphoid organs, which are both driven by the properties of each nanocarrier. Furthermore, we found that Ags within PSs promoted better CD4 T cell activation and induced a higher frequency of CD4 T follicular helper (Tfh) cells. These differences correlated with changes in the frequency of germinal center B cells and plasma cell formation, which reflects the previously observed antibody titers. Our results show that PSs are a promising vector for the delivery of Ags for B cell vaccine development. This study demonstrates that nanocarrier design has a large impact on the quality of the induced adaptive immune response.

Vaccine nanoparticles for protection against HIV infection

The development of a successful vaccine against HIV is a major global challenge. Antiretroviral therapy is the standard treatment against HIV-1 infection. However, only 46% of the eligible people received the therapy in 2015. Furthermore, suboptimal adherence poses additional obstacles. Therefore, there is an urgent need for an HIV-1 vaccine. The most promising clinical trial to date is Phase III RV144, which for the first time demonstrated the feasibility of vaccine-mediated immune protection against HIV-1. Nevertheless, its 31% efficacy and limited durability underscore major hurdles. Here, we discuss recent progress in HIV-1 vaccine development with a special emphasis on nanovaccines, which are at the forefront of efforts to develop a successful HIV-1 vaccine.

Virosome-bound antigen enhances DC-dependent specific CD4+ T cell stimulation, inducing a Th1 and Treg profile in vitro

There is considerable interest to develop antigen-carriers for immune-modulatory clinical applications, but insufficient information is available on their effects on antigen-presenting cells. We employed virosomes coupled to ovalbumin (OVA) to study their interaction with murine bone marrow-derived dendritic cells (BMDCs) and modulation of downstream T cell responses. BMDCs were treated in vitro with virosomes or liposomes prior to determining BMDC phenotype, viability, and intracellular trafficking. Antigen-specific CD4⁺ T cell activation was measured by co-culture of BMDCs with DO11.10 CD4⁺ T cells. Compared to liposomes, virosomes were rapidly taken up. Neither nanocarrier type affected BMDC viability, nor did a moderate degree of activation differ for markers such as CD40, CD80, CD86. Virosome uptake occurred via clathrin-mediated endocytosis and phagocytosis, with co-localization in late endosomes. Only BMDCs treated with OVA-coupled virosomes induced enhanced OVA-specific CD4⁺ T cell proliferation. Antigen-coupled virosomes are endowed with an intrinsic ability to modulate DC-dependent adaptive immune responses.

Immunological Principles Guiding the Rational Design of Particles for Vaccine Delivery

Despite the immense public health successes of immunization over the past century, effective vaccines are still lacking for globally important pathogens such as human immunodeficiency virus, malaria, and tuberculosis. Exciting recent advances in immunology and biotechnology over the past few decades have facilitated a shift from empirical to rational vaccine design, opening possibilities for improved vaccines. Some of the most important advancements include (i) the purification of subunit antigens with high safety profiles, (ii) the identification of innate pattern recognition receptors (PRRs) and cognate agonists responsible for inducing immune responses, and (iii) developments in nano- and microparticle fabrication and characterization techniques. Advances in particle engineering now allow highly tunable physicochemical properties of particle-based vaccines, including composition, size, shape, surface characteristics, and degradability. Enhanced collaborative efforts between researchers in immunology and materials science are expected to rise to next-generation vaccines. This process will be significantly aided by a greater understanding of the immunological principles guiding vaccine antigenicity, immunogenicity, and efficacy. With specific emphasis on PRR-targeted adjuvants and particle physicochemical properties, this review aims to provide an overview of the current literature to guide and focus rational particle-based vaccine design efforts.

Eliciting Epitope-Specific CD8+ T Cell Response by Immunization with Microbial Protein Antigens Formulated with α-Galactosylceramide: Theory, Practice, and Protocols

CD8+ cytotoxic T lymphocytes confer protection against infectious diseases caused by viruses, bacteria, and parasites. Hence, significant efforts have been invested into devising ways to generate CD8+ T cell-targeted vaccines. Generation of microbe-free protein subunit vaccines requires a thorough knowledge of protective target antigens. Such antigens are proteolytically processed peptides presented by MHC class I molecules. To induce a robust antigen-specific CD8+ T cell response through vaccination, it is essential to formulate the antigen with an effective adjuvant. Here, we describe a versatile method for generating high-frequency antigen-specific CD8+ T cells through immunization of mice using the invariant natural killer T cell agonist α-galactosylceramide as the adjuvant.

Nanotechnology for protein delivery: Overview and perspectives

Protein-based therapeutics have made a significant impact in the treatment of a variety of important human diseases. However, given their intrinsically vulnerable structure and susceptibility to enzymatic degradation, many therapeutic proteins such as enzymes, growth factors, hormones, and cytokines suffer from poor physicochemical/biological stability and immunogenicity that may limit their potential benefits, and in some cases limit their utility. Furthermore, when protein therapeutics are developed for intracellular targets, their internalization and biological activity may be limited by inefficient membrane permeability and/or endosomal escape. Development of effective protein delivery strategies is therefore essential to further enhance therapeutic outcomes to enable widespread medical applications. This review discusses the advantages and limitations of marketed and developmental-stage protein delivery strategies, and provides a focused overview of recent advances in nanotechnology platforms for the systemic delivery of therapeutic proteins. In addition, we also highlight nanoparticle-mediated non-invasive administration approaches (e.g., oral, nasal, pulmonary, and transdermal routes) for protein delivery.

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.

A Distinct Lung-Interstitium-Resident Memory CD8(+) T Cell Subset Confers Enhanced Protection to Lower Respiratory Tract Infection

The nature and anatomic location of the protective memory CD8(+) T cell subset induced by intranasal vaccination remain poorly understood. We developed a vaccination model to assess the anatomic location of protective memory CD8(+) T cells and their role in lower airway infections. Memory CD8(+) T cells elicited by local intranasal, but not systemic, vaccination with an engineered non-replicative CD8(+) T cell-targeted antigen confer enhanced protection to a lethal respiratory viral challenge. This protection depends on a distinct CXCR3(LO) resident memory CD8(+) T (Trm) cell population that preferentially localizes to the pulmonary interstitium. Because they are positioned close to the mucosa, where infection occurs, interstitial Trm cells act before inflammation can recruit circulating memory CD8(+) T cells into the lung tissue. This results in a local protective immune response as early as 1 day post-infection. Hence, vaccine strategies that induce lung interstitial Trm cells may confer better protection against respiratory pathogens.

Engineering nanoparticles to overcome barriers to immunotherapy

Advances in immunotherapy have led to the development of a variety of promising therapeutics, including small molecules, proteins and peptides, monoclonal antibodies, and cellular therapies. Despite this wealth of new therapeutics, the efficacy of immunotherapy has been limited by challenges in targeted delivery and controlled release, that is, spatial and temporal control on delivery. Particulate carriers, especially nanoparticles have been widely studied in drug delivery and vaccine research and are being increasingly investigated as vehicles to deliver immunotherapies. Nanoparticle-mediated drug delivery could provide several benefits, including control of biodistribution and transport kinetics, the potential for site-specific targeting, immunogenicity, tracking capability using medical imaging, and multitherapeutic loading. There are also a unique set of challenges, which include nonspecific uptake by phagocytic cells, off-target biodistribution, permeation through tissue (transport limitation), nonspecific immune-activation, and poor control over intracellular localization. This review highlights the importance of understanding the relationship between a nanoparticle's size, shape, charge, ligand density and elasticity to its vascular transport, biodistribution, cellular internalization, and immunogenicity. For the design of an effective immunotherapy, we highlight the importance of selecting a nanoparticle's physical characteristics (e.g., size, shape, elasticity) and its surface functionalization (e.g., chemical or polymer modifications, targeting or tissue-penetrating peptides) with consideration of its reactivity to the targeted microenvironment (e.g., targeted cell types, use of stimuli-sensitive biomaterials, immunogenicity). Applications of this rational nanoparticle design process in vaccine development and cancer immunotherapy are discussed.