Mannose receptor-mediated uptake of antigens strongly enhances HLA class II-restricted antigen presentation by cultured dendritic cells

Current status of mannose receptor-targeted drug delivery for improved anti-HIV therapy

In the pursuit of achieving better therapeutic outcomes in the treatment of HIV, innovative drug delivery strategies have been extensively explored. Mannose receptors, which are primarily found on macrophages and dendritic cells, offer promising targets for drug delivery due to their involvement in HIV pathogenesis. This review article comprehensively evaluates recent drug delivery system advancements targeting the mannose receptor. We have systematically described recent developments in creating and utilizing drug delivery platforms, including nanoparticles, liposomes, micelles, noisomes, dendrimers, and other nanocarrier systems targeted at the mannose receptor. These strategies aim to enhance drug delivery specificity, bioavailability, and therapeutic efficacy while decreasing off-target effects and systemic toxicity. Furthermore, the article delves into how mannose receptors and HIV interact, highlighting the potential for exploiting this interaction to enhance drug delivery to infected cells. The review covers essential topics, such as the rational design of nanocarriers for mannose receptor recognition, the impact of physicochemical properties on drug delivery performance, and how targeted delivery affects the pharmacokinetics and pharmacodynamics of anti-HIV agents. The challenges of these novel strategies, including immunogenicity, stability, and scalability, and future research directions in this rapidly growing area are discussed. The knowledge synthesis presented in this review underscores the potential of mannose receptor-based targeted drug delivery as a promising avenue for advancing HIV treatment. By leveraging the unique properties of mannose receptors, researchers can design drug delivery systems that cater to individual needs, overcome existing limitations, and create more effective and patient-friendly treatments in the ongoing fight against HIV/AIDS.

Synthetically mannosylated antigens induce antigen-specific humoral tolerance and reduce anti-drug antibody responses to immunogenic biologics

Immunogenic biologics trigger an anti-drug antibody (ADA) response in patients that reduces efficacy and increases adverse reactions. Our laboratory has shown that targeting protein antigen to the liver microenvironment can reduce antigen-specific T cell responses; herein, we present a strategy to increase delivery of otherwise immunogenic biologics to the liver via conjugation to a synthetic mannose polymer, p(Man). This delivery leads to reduced antigen-specific T follicular helper cell and B cell responses resulting in diminished ADA production, which is maintained throughout subsequent administrations of the native biologic. We find that p(Man)-antigen treatment impairs the ADA response against recombinant uricase, a highly immunogenic biologic, without a dependence on hapten immunodominance or control by T regulatory cells. We identify increased T cell receptor signaling and increased apoptosis and exhaustion in T cells as effects of p(Man)-antigen treatment via transcriptomic analyses. This modular platform may enhance tolerance to biologics, enabling long-term solutions for an ever-increasing healthcare problem.

Lipopeptides development in cosmetics and pharmaceutical applications: A comprehensive review

Lipopeptides are surface active, natural products of bacteria, fungi and green-blue algae origin, having diverse structures and functionalities. In analogy, a number of chemical synthesis techniques generated new designer lipopeptides with desirable features and functions. Lipopetides are self-assembly guided, supramolecular compounds which have the capacity of high-density presentation of the functional epitopes at the surface of the nanostructures. This feature contributes to their successful application in several industry sectors, including food, feed, personal care, and pharmaceutics. In this comprehensive review, the novel class of ribosomally synthesized lipopeptides is introduced alongside the more commonly occuring non-ribosomal lipopeptides. We highlight key representatives of the most researched as well as recently described lipopeptide families, with emphasis on structural features, self-assembly and associated functions. The common biological, chemical and hybrid production routes of lipopeptides, including prominent analogues and derivatives are also discussed. Furthermore, genetic engineering strategies aimed at increasing lipopeptide yields, diversity and biological activity are summarized and exemplified. With respect to application, this work mainly details the potential of lipopeptides in personal care and cosmetics industry as cleansing agents, moisturizer, anti-aging/anti-wrinkling, skin whitening and preservative agents as well as the pharmaceutical industry as anitimicrobial agents, vaccines, immunotherapy, and cancer drugs. Given that this review addresses human applications, we conclude on the topic of safety of lipopeptide formulations and their sustainable production.

Synthetically mannosylated antigens induce antigen-specific humoral tolerance and reduce anti-drug antibody responses to immunogenic biologics

Immunogenic biologics trigger an anti-drug antibody (ADA) response in patients, which reduces efficacy and increases adverse reactions. Our laboratory has previously shown that targeting protein antigen to the liver microenvironment can reduce antigen-specific T cell responses; herein, we present a strategy to increase delivery of otherwise immunogenic biologics to the liver via conjugation to a synthetic mannose polymer (p(Man)). This delivery leads to reduced antigen-specific T follicular helper cell and B cell responses resulting in diminished ADA production, which is maintained throughout subsequent administrations of the native biologic. We found that p(Man)-antigen treatment impairs the ADA response against recombinant uricase, a highly immunogenic biologic, without a dependence on hapten immunodominance or control by Tregs. We identify increased TCR signaling and increased apoptosis and exhaustion in T cells as effects of p(Man)-antigen treatment via transcriptomic analyses. This modular platform may enhance tolerance to biologics, enabling long-term solutions for an ever-increasing healthcare problem.

Immunomodulatory glycomedicine: Introducing next generation cancer glycovaccines

Cancer remains a leading cause of death worldwide due to the lack of safer and more effective therapies. Cancer vaccines developed from neoantigens are an emerging strategy to promote protective and therapeutic anti-cancer immune responses. Advances in glycomics and glycoproteomics have unveiled several cancer-specific glycosignatures, holding tremendous potential to foster effective cancer glycovaccines. However, the immunosuppressive nature of tumours poses a major obstacle to vaccine-based immunotherapy. Chemical modification of tumour associated glycans, conjugation with immunogenic carriers and administration in combination with potent immune adjuvants constitute emerging strategies to address this bottleneck. Moreover, novel vaccine vehicles have been optimized to enhance immune responses against otherwise poorly immunogenic cancer epitopes. Nanovehicles have shown increased affinity for antigen presenting cells (APCs) in lymph nodes and tumours, while reducing treatment toxicity. Designs exploiting glycans recognized by APCs have further enhanced the delivery of antigenic payloads, improving glycovaccine's capacity to elicit innate and acquired immune responses. These solutions show potential to reduce tumour burden, while generating immunological memory. Building on this rationale, we provide a comprehensive overview on emerging cancer glycovaccines, emphasizing the potential of nanotechnology in this context. A roadmap towards clinical implementation is also delivered foreseeing advances in glycan-based immunomodulatory cancer medicine.

Recent advances in antigen targeting to antigen-presenting cells in veterinary medicine

Advances in antigen targeting in veterinary medicine have gained traction over the years as an alternative approach for diseases that remain a challenge for traditional vaccines. In addition to the nature of the immunogen, antigen-targeting success relies heavily on the chosen receptor for its direct influence on the elicited response that will ensue after antigen uptake. Different approaches using antibodies, natural or synthetic ligands, fused proteins, and DNA vaccines have been explored in various veterinary species, with pigs, cattle, sheep, and poultry as the most frequent models. Antigen-presenting cells can be targeted using a generic approach, such as broadly expressed receptors such as MHC-II, CD80/86, CD40, CD83, etc., or focused on specific cell populations such as dendritic cells or macrophages (Langerin, DC-SIGN, XCR1, DC peptides, sialoadhesin, mannose receptors, etc.) with contrasting results. Interestingly, DC peptides show high specificity to DCs, boosting activation, stimulating cellular and humoral responses, and a higher rate of clinical protection. Likewise, MHC-II targeting shows consistent results in enhancing both immune responses; an example of this strategy of targeting is the approved vaccine against the bovine viral diarrhea virus in South America. This significant milestone opens the door to continuing efforts toward antigen-targeting vaccines to benefit animal health. This review discusses the recent advances in antigen targeting to antigen-presenting cells in veterinary medicine, with a special interest in pigs, sheep, cattle, poultry, and dogs.

Pulmonary Delivery of Recombinant Human Bleomycin Hydrolase Using Mannose-Modified Hierarchically Porous UiO-66 for Preventing Bleomycin-Induced Pulmonary Fibrosis

Bleomycins (BLMs) are widely used in clinics as antitumor agents. However, BLM-based chemotherapies often accompany severe pulmonary fibrosis (PF). Human bleomycin hydrolase is a cysteine protease that can convert BLMs into inactive deamido-BLMs. In this study, mannose-modified hierarchically porous UiO-66 (MHP-UiO-66) nanoparticles (NPs) were used to encapsulate the recombinant human bleomycin hydrolase (rhBLMH). When rhBLMH@MHP-UiO-66 was intratracheally instilled into the lungs, the NPs were transported into the epithelial cells, and rhBLMH prevented the lungs from PF during BLM-based chemotherapies. Encapsulation of rhBLMH in the MHP-UiO-66 NPs protects the enzyme from proteolysis in physiological conditions and enhances cellular uptake. In addition, the MHP-UiO-66 NPs significantly enhance the pulmonary accumulation of intratracheally instilled rhBLMH, thus providing more efficient protection of the lungs against BLMs during the chemotherapies.

Mannosylated engineered trichosanthin-legumain protein vaccine hydrogel for breast cancer immunotherapy

The development of cancer vaccines based on tumor-associated antigens is hurdled by lack of an efficient adjuvant and insufficient efficacy. To improve the efficacy of vaccines, a genetically-engineered method was employed in this work to achieve the codelivery of antigen and adjuvant to enhance immune responses. Trichosanthin is a plant-derived protein that possesses cancer immune stimulation function. A genetically engineered protein vaccine composed of trichosanthin (adjuvant) and legumain domain (a peptidic antigen) was constructed, which was further chemically modified with mannose for targeting dendritic cells (DCs). The method is facile and ready for scaling up for massive production. Such a "two-in-one" vaccine is advantageous for codelivery for augmenting the immune responses. The vaccine inhibited the tumors by triggering a robust cytotoxic T lymphocyte response in the orthotopic-breast-tumor mice. Furthermore, the vaccine was loaded into the temperature-sensitive hydrogel based on Pluronic F127 for implanting use in the post-surgical site. The sustained-released vaccine from the hydrogel inhibited not only the tumor recurrence but also the lung metastases of breast cancer. These findings demonstrated that it was a safe and effective vaccination for breast cancer immunotherapy in a prophylactical and therapeutical manner for remodeling the tumor immune microenvironment and arresting tumor growth.

Antigen targeting to dendritic cells: Still a place in future immunotherapy?

The hallmark of DCs is their potent and outstanding capacity to activate naive resting T cells. As such, DCs are the sentinels of the immune system and instrumental for the induction of immune responses. This is one of the reasons, why DCs became the focus of immunotherapeutical strategies to fight infections, cancer, and autoimmunity. Besides the exploration of adoptive DC-therapy for which DCs are generated from monocytes or purified in large numbers from the blood, alternative approaches were developed such as antigen targeting of DCs. The idea behind this strategy is that DCs resident in patients' lymphoid organs or peripheral tissues can be directly loaded with antigens in situ. The proof of principle came from mouse models; subsequent translational studies confirmed the potential of this therapy. The first clinical trials demonstrated feasibility and the induction of T-cell immunity in patients. This review will cover: (i) the historical aspects of antigen targeting, (ii) briefly summarize the biology of DCs and the immunological functions upon which this concept rests, (iii) give an overview on attempts to target DC receptors with antibodies or (glycosylated) ligands, and finally, (iv) discuss the translation of antigen targeting into clinical therapy.

Maturation of circulating Ly6ChiCCR2+ monocytes by mannan-MOG induces antigen-specific tolerance and reverses autoimmune encephalomyelitis

Autoimmune diseases affecting the CNS not only overcome immune privilege mechanisms that protect neural tissues but also peripheral immune tolerance mechanisms towards self. Together with antigen-specific T cells, myeloid cells are main effector cells in CNS autoimmune diseases such as multiple sclerosis, but the relative contributions of blood-derived monocytes and the tissue resident macrophages to pathology and repair is incompletely understood. Through the study of oxidized mannan-conjugated myelin oligodendrocyte glycoprotein 35-55 (OM-MOG), we show that peripheral maturation of Ly6C^hiCCR2⁺ monocytes to Ly6C^hiMHCII⁺PD-L1⁺ cells is sufficient to reverse spinal cord inflammation and demyelination in MOG-induced autoimmune encephalomyelitis. Soluble intradermal OM-MOG drains directly to the skin draining lymph node to be sequestered by subcapsular sinus macrophages, activates Ly6C^hiCCR2⁺ monocytes to produce MHC class II and PD-L1, prevents immune cell trafficking to spinal cord, and reverses established lesions. We previously showed that protection by OM-peptides is antigen specific. Here, using a neutralizing anti-PD-L1 antibody in vivo and dendritic cell-specific Pdl1 knockout mice, we further demonstrate that PD-L1 in non-dendritic cells is essential for the therapeutic effects of OM-MOG. These results show that maturation of circulating Ly6C^hiCCR2⁺ monocytes by OM-myelin peptides represents a novel mechanism of immune tolerance that reverses autoimmune encephalomyelitis.

Immunostimulatory Polymers as Adjuvants, Immunotherapies, and Delivery Systems

Activating innate immunity in a controlled manner is necessary for the development of next-generation therapeutics. Adjuvants, or molecules that modulate the immune response, are critical components of vaccines and immunotherapies. While small molecules and biologics dominate the adjuvant market, emerging evidence supports the use of immunostimulatory polymers in therapeutics. Such polymers can stabilize and deliver cargo while stimulating the immune system by functioning as pattern recognition receptor (PRR) agonists. At the same time, in designing polymers that engage the immune system, it is important to consider any unintended initiation of an immune response that results in adverse immune-related events. Here, we highlight biologically derived and synthetic polymer scaffolds, as well as polymer–adjuvant systems and stimuli-responsive polymers loaded with adjuvants, that can invoke an immune response. We present synthetic considerations for the design of such immunostimulatory polymers, outline methods to target their delivery, and discuss their application in therapeutics. Finally, we conclude with our opinions on the design of next-generation immunostimulatory polymers, new applications of immunostimulatory polymers, and the development of improved preclinical immunocompatibility tests for new polymers.

Mucosal immunity of mannose-modified chitosan microspheres loaded with the nontyepable Haemophilus influenzae outer membrane protein P6 in BALB/c mice

Nontypeable Haemophilus influenzae (NTHi) is a common opportunistic pathogen that colonizes the nasopharynx. NTHi infections result in enormous global morbidity in two clinical settings: otitis media in children and acute exacerbation of chronic obstructive pulmonary disease (COPD) in adults. Thus, there is an urgent need to design and develop effective vaccines to prevent morbidity and reduce antibiotic use. The NTHi outer membrane protein P6, a potential vaccine candidate, is highly conserved and effectively induces protective immunity. Here, to enhance mucosal immune responses, P6-loaded mannose-modified chitosan (MC) microspheres (P6-MCMs) were developed for mucosal delivery. MC (18.75%) was synthesized by the reductive amination reaction method using sodium cyanoborohydride (NaBH₃CN), and P6-MCMs with an average size of 590.4±16.2 nm were successfully prepared via the tripolyphosphate (TPP) ionotropic gelation process. After intranasal immunization with P6-MCMs, evaluation of humoral immune responses indicated that P6-MCMs enhance both systemic and mucosal immune responses. Evaluation of cellular immune responses indicated that P6-MCMs enhance cellular immunity and trigger a mixed Th1/Th2-type immune response. Importantly, P6-MCMs also trigger a Th17-type immune response. They are effective in promoting lymphocyte proliferation and differentiation without toxicity in vitro. The results also demonstrate that P6-MCMs can effectively induce MHC class I- and II-restricted cross-presentation, promoting CD4⁺-mediated Th immune responses and CD8⁺-mediated cytotoxic T lymphocyte (CTL) immune responses. Evaluation of protective immunity indicated that immunization with P6-MCMs can reduce inflammation in the nasal mucosa and the lung and prevent NTHi infection. In conclusion, MCMs are a promising adjuvant-delivery system for vaccines against NTHi.

Controlled Decoration of [60]Fullerene with Polymannan Analogues and Amino Acid Derivatives through Malondiamide-Based Linkers

In the last few years, nanomaterials based on fullerene have begun to be considered promising tools in the development of efficient adjuvant/delivery systems for vaccination, thanks to their several advantages such as biocompatibility, size, and easy preparation and modification. In this work we reported the chemoenzymatic synthesis of natural polymannan analogues (di- and tri-mannan oligosaccharides characterized by α1,6man and/or α1,2man motifs) endowed with an anomeric propargyl group. These sugar derivatives were submitted to 1,3 Huisgen dipolar cycloaddition with a malondiamide-based chain equipped with two azido terminal groups. The obtained sugar-modified malondiamide derivatives were used to functionalize the surface of Buckminster fullerene (C₆₀) in a highly controlled fashion, and yields (11–41%) higher than those so far reported by employing analogue linkers. The same strategy has been exploited to obtain C₆₀ endowed with natural and unnatural amino acid derivatives. Finally, the first double functionalization of fullerene with both sugar- and amino acid-modified malondiamide chains was successfully performed, paving the way to the possible derivatization of fullerenes with immunogenic sugars and more complex antigenic peptides.

Feasibility of using monocyte-derived dendritic cells obtained from cryopreserved cells for DC-based vaccines

The study of the effect of cryopreservation on the functionality of monocyte-derived dendritic cells (MDDCs) and dendritic cells (DCs) is essential for their use in different clinical applications such as DCs-based vaccines. Its full maturation and its optimal functionality are crucial for DCs based immunotherapy. In this study, we compared MDDCs derived from fresh and cryopreserved PBMCs in the aspects of phenotype and its effect on T cells at the level of proliferation and cytokine secretion. We pulsed MDDCs obtained from fresh and cryopreserved PBMCs with two different stimuli, CEF and SEA, and the expression maturation markers and cytokine secretion were analyzed. Our results showed that the cryopreservation had no effects in the phenotype of the MDDCs obtained, cell viability, maturation markers expression and/or cytokines secretion, independently whether MDDCs had been generated from fresh or cryopreserved PBMCs. Thus, this study suggests that the use of cryopreserved cells is a good method to keep the cells before use in immunotherapy, avoiding the variability within same individual due to severe blood draws. Even so, the interpretation and comparison of different results should be done considering the different cryopreservation techniques and assays, and their effects on PBMCs, specifically on MDDC and DC cells.

C-type lectin receptors MR and DC-SIGN are involved in recognition of hemocyanins, shaping their immunostimulatory effects on human dendritic cells

Hemocyanins are used as immunomodulators in clinical applications because they induce a strong Th1-biased cell-mediated immunity, which has beneficial effects. They are multiligand glycosylated molecules with abundant and complex mannose-rich structures. It remains unclear whether these structures influence hemocyanin-induced immunostimulatory processes in human APCs. We have previously shown that hemocyanin glycans from Concholepas concholepas (CCH), Fissurella latimarginata (FLH), and Megathura crenulata (KLH), participate in their immune recognition and immunogenicity in mice, interacting with murine C-type lectin receptors (CLRs). Here, we studied the interactions of these hemocyanins with two major mannose-binding CLRs on monocyte-derived human DCs: MR (mannose receptor) and DC-SIGN (DC-specific ICAM-3-grabbing nonintegrin). Diverse analyses showed that hemocyanins are internalized by a mannose-sensitive mechanism. This process was calcium dependent. Moreover, hemocyanins colocalized with MR and DC-SIGN, and were partly internalized through clathrin-mediated endocytosis. The hemocyanin-mediated proinflammatory cytokine response was impaired when using deglycosylated FLH and KLH compared to CCH. We further showed that hemocyanins bind to human MR and DC-SIGN in a carbohydrate-dependent manner with affinity constants in the physiological concentration range. Overall, we showed that these three clinically valuable hemocyanins interact with human mannose-sensitive CLRs, initiating an immune response and promoting a Th1 cell-driving potential.

Investigation of a new tumor-associated glycosylated antigen as target for dendritic cell vaccination in pancreatic cancer

Glycoproteins, as valuable targets for dendritic cell (DC)-vaccination in cancers, remain an open question. Glycosylated structures, which are aberrantly modified during cancerisation, impact positively or negatively on glycoprotein immunogenicity. Here is presented an oncofetal glycovariant of bile-salt-dependent-lipase, expressed on human tumoral pancreas and efficiently processed by DC's, inducing T-lymphocyte activation.

Nanocarriers targeting adipose macrophages increase glucocorticoid anti-inflammatory potency to ameliorate metabolic dysfunction

Obesity is associated with systemic inflammation due to macrophage accumulation in adipose tissue (AT). AT macrophages are, therefore, a target for therapeutics to modulate inflammation and prevent comorbidities. Because inflammatory processes have pleiotropic effects throughout the body and are intertwined with metabolic axes, systemic anti-inflammatory therapies are often harmful. We report that targeting AT macrophages using dextran nanocarriers radically alters the pharmacology of anti-inflammatory glucocorticoids, uncoupling the metabolic axis in obese mice. Following a single treatment, expression of inflammatory mediators and markers of inflammatory macrophages decreased with a nearly 20-fold higher potency compared with free drug. As a result, long-term treatment resulted in potent fat mobilization, AT reduction, weight loss, improved glucose tolerance, and altered AT gene expression profiles that led to elevated liver stress. Two weeks after treatment ceased, gene expression of inflammatory mediators in AT remained lower than obese controls, while gene expression related to metabolic function improved. These data demonstrate that nanocarriers show potential for amelioration of obesity-related AT inflammation and metabolic dysfunction, highlighting an important opportunity for nanomedicine to impact chronic metabolic disorders with complex and poorly understood etiology.

Modulation of Macrophages M1/M2 Polarization Using Carbohydrate-Functionalized Polymeric Nanoparticles

Exploiting surface endocytosis receptors using carbohydrate-conjugated nanocarriers brings outstanding approaches to an efficient delivery towards a specific target. Macrophages are cells of innate immunity found throughout the body. Plasticity of macrophages is evidenced by alterations in phenotypic polarization in response to stimuli, and is associated with changes in effector molecules, receptor expression, and cytokine profile. M1-polarized macrophages are involved in pro-inflammatory responses while M2 macrophages are capable of anti-inflammatory response and tissue repair. Modulation of macrophages’ activation state is an effective approach for several disease therapies, mediated by carbohydrate-coated nanocarriers. In this review, polymeric nanocarriers targeting macrophages are described in terms of production methods and conjugation strategies, highlighting the role of mannose receptor in the polarization of macrophages, and targeting approaches for infectious diseases, cancer immunotherapy, and prevention. Translation of this nanomedicine approach still requires further elucidation of the interaction mechanism between nanocarriers and macrophages towards clinical applications.

miR-223-3p Inhibits Antigen Endocytosis and Presentation and Promotes the Tolerogenic Potential of Dendritic Cells through Targeting Mannose Receptor Signaling and Rhob

Background

The role of miR-223-3p in dendritic cells (DCs) is unknown. This study is aimed at investigating the effect of miR-223-3p on the antigen uptake and presentation capacities of DCs and the underlying molecular mechanism.

Methods

FITC-OVA antigen uptake and cell surface markers in bone marrow-derived DCs (BMDCs) were analyzed by flow cytometry. BMDCs were transfected with the miR-223-3p mimic or inhibitor. Cytokine levels were determined by ELISA. CD4+ T cell differentiation was determined by mixed lymphocyte culture assay.

Results

OVA treatment significantly downregulated miR-223-3p in BMDCs. The miR-223-3p mimic significantly inhibited OVA-induced antigen uptake and surface expression of MHC-II on BMDCs (P < 0.01). The miR-223-3p mimic increased TGF-β1 production in OVA-treated DCs (P < 0.01). Mixed lymphocyte reaction showed that the miR-223-3p mimic significantly promoted Treg cell differentiation. In addition, the miR-223-3p mimic significantly upregulated CD103 in DCs, indicating the promotion of tolerogenic DCs. The miR-223-3p mimic downregulated Rhob protein in OVA-induced DCs. Rhob knockdown significantly suppressed the ability of FITC-OVA endocytosis (P < 0.01) and surface MHC-II molecule expression (P < 0.01) in BMDCs, promoting promoted Treg cell differentiation. Mannose receptor (MR) knockdown significantly upregulated miR-223-3p, downregulated Rhob protein in OVA-treated DCs, inhibited the FITC-OVA endocytosis and surface MHC-II expression in BMDCs, and promoted Treg cell differentiation (all P < 0.01).

Conclusion

These data suggest that miR-223-3p has an inhibitory effect on the antigen uptake and presentation capacities of BMDCs and promotes Treg cell differentiation, which is, at least partially, through targeting MR signaling and Rhob.

Ex vivo-generated dendritic cell-based vaccines in melanoma: the role of nanoparticulate delivery systems

Melanoma is a poor immunogenic cancer and many treatment strategies have been used to enhance specific or nonspecific immunity against it. Dendritic cell (DC)-based cancer vaccine is the most effective therapies that have been used so far. Meanwhile, the efficacy of DC-based immunotherapy relies on critical factors relating to DCs such as the state of maturation and proper delivery of antigens. In this regard, the use of nanoparticulate delivery systems for effective delivery of antigen to ex vivo-generated DC-based vaccines that also poses adjuvanticity would be an ideal approach. In this review article, we attempt to summarize the role of different types of nanoparticulate antigen delivery systems used in the development of ex vivo-generated DC-based vaccines against melanoma and describe their adjuvanticity in mediation of DC maturation, cytoplasmic presentation of antigens to MHC class I molecules, which led to potent antigen-specific immune responses. As were represented, cationic liposomes were the most used approach, which suggest its potential applicability as delivery systems for further experiments in combination with either adjuvants or monoclonal antibodies.

Dendritic Cells in Anticancer Vaccination: Rationale for Ex Vivo Loading or In Vivo Targeting

Dendritic cells (DCs) have shown great potential as a component or target in the landscape of cancer immunotherapy. Different in vivo and ex vivo strategies of DC vaccine generation with different outcomes have been proposed. Numerous clinical trials have demonstrated their efficacy and safety in cancer patients. However, there is no consensus regarding which DC-based vaccine generation method is preferable. A problem of result comparison between trials in which different DC-loading or -targeting approaches have been applied remains. The employment of different DC generation and maturation methods, antigens and administration routes from trial to trial also limits the objective comparison of DC vaccines. In the present review, we discuss different methods of DC vaccine generation. We conclude that standardized trial designs, treatment settings and outcome assessment criteria will help to determine which DC vaccine generation approach should be applied in certain cancer cases. This will result in a reduction in alternatives in the selection of preferable DC-based vaccine tactics in patient. Moreover, it has become clear that the application of a DC vaccine alone is not sufficient and combination immunotherapy with recent advances, such as immune checkpoint inhibitors, should be employed to achieve a better clinical response and outcome.

HBs antigen and mannose loading on the surface of iron oxide nanoparticles in order to immuno-targeting: fabrication, characterization, cellular and humoral immunoassay

Mannosylation of nanovaccine is an appropriate strategy for targeting the mannose receptors on DCs. Here, HBsAg and mannose loaded on the surface of iron oxide nanoparticles to increases HBsAg vaccine potency. Nanoparticles are made by co-precipitation method and bonded to the HBsAg and mannose by chemical bonding. The physicochemical properties of nano-vaccines, their toxicity and antigenicity were determined. The synthesized nano-vaccine showed spherical shape with a mean particle size of 60 nm, a zeta potential of -44 mV, an antigen-binding efficiency of around 100% and for mannose 78%. In vitro release of nanoparticles exhibited about 30% at the first day and about 60% until the third day. SDSPAGE analysis confirmed structural integrity of HBsAg loaded on nanoparticles. The HBsAg-loaded LCMNP and MLCMNP nanoparticles had no toxic effects on HEK293 cell line. The quantification of the intracellular Fe by ICP-OES as a criterion of nano-vaccine uptake revealed mannose intensify uptake of MLCMNP. In addition, mannose in the structure of MLCMNP improved IL-6, TNF-α and IFN-γ (>16 fold) cytokines genes expression by macrophage/dendritic cells after exposure in 12 h. Immunization of experimental mice (subcutaneously, two times with 2-week intervals) with 5 µg of HBsAg loaded on MLCMNP nanoparticles increased specific total IgG and IgG2a/IgG1 ratio. In addition, TNF-α, IL-12, IL-2 and IL-4 cytokines in mannosylated nano-vaccine increased versus nano-vaccine group while lymphocyte proliferation and IFN-γ responses in the targeted nano-vaccine group show a tiny increase versus the nano-vaccine group. The results show that mannosylated nano-vaccine promotes higher level of cellular and humoural immune responses against HBsAg nano-vaccine.

Engineering mannosylated nanogels with membrane-disrupting properties

In this work, mannosylated core-cross-linked nanogels are designed that contain cationic moieties in their core.

The Elusive Anti-Candida Vaccine: Lessons From the Past and Opportunities for the Future

Candidemia is a bloodstream fungal infection caused by Candida species and is most commonly observed in hospitalized patients. Even with proper antifungal drug treatment, mortality rates remain high at 40–50%. Therefore, prophylactic or preemptive antifungal medications are currently recommended in order to prevent infections in high-risk patients. Moreover, the majority of women experience at least one episode of vulvovaginal candidiasis (VVC) throughout their lifetime and many of them suffer from recurrent VVC (RVVC) with frequent relapses for the rest of their lives. While there currently exists no definitive cure, the only available treatment for RVVC is again represented by antifungal drug therapy. However, due to the limited number of existing antifungal drugs, their associated side effects and the increasing occurrence of drug resistance, other approaches are greatly needed. An obvious prevention measure for candidemia or RVVC relapse would be to immunize at-risk patients with a vaccine effective against Candida infections. In spite of the advanced and proven techniques successfully applied to the development of antibacterial or antiviral vaccines, however, no antifungal vaccine is still available on the market. In this review, we first summarize various efforts to date in the development of anti-Candida vaccines, highlighting advantages and disadvantages of each strategy. We next unfold and discuss general hurdles encountered along these efforts, such as the existence of large genomic variation and phenotypic plasticity across Candida strains and species, and the difficulty in mounting protective immune responses in immunocompromised or immunosuppressed patients. Lastly, we review the concept of “trained immunity” and discuss how induction of this rapid and nonspecific immune response may potentially open new and alternative preventive strategies against opportunistic infections by Candida species and potentially other pathogens.

N-glycosylation converts non-glycoproteins into mannose receptor ligands and reveals antigen-specific T cell responses in vivo

N-glycosylation is generally accepted to enhance the immunogenicity of antigens because of two main reasons. First, the attachment of glycans enables recognition by endocytic receptors like the mannose receptor (MR) and hence increased uptake by dendritic cells (DCs). Second, foreign glycans are postulated to be immunostimulatory and their recognition could induce DC activation. However, a direct comparison between the immunogenicity of N-glycosylated vs. de-glycosylated proteins in vivo and a direct effect of N-glycosylated antigens on the intrinsic capacity of DCs to activate T cells have not been assessed so far.To analyze whether enforced N-glycosylation is a suited strategy to enhance the immunogenicity of non-glycosylated antigens for vaccination studies, we targeted non-glycoproteins towards the MR by introduction of artificial N-glycosylation using the methylotrophic yeast Komagataella phaffii (previously termed Pichia pastoris). We could demonstrate that the introduction of a single N-X-S/T motif was sufficient for efficient MR-binding and internalization. However, addition of N-glycosylated proteins neither influenced DC maturation nor their general capacity to activate T cells, pointing out that enforced N-glycosylation does not increase the immunogenicity of the antigen per se. Additionally, increased antigen-specific cytotoxic T cell responses in vivo after injection of N-glycosylated compared to de-glycosylated proteins were observed but this effect strongly depended on the epitope tested. A beneficial effect of N-glycosylation on antibody production could not be detected, which might be due to MR-cross-linking on DCs and to concomitant differences in IL-6 production by CD4+ T cells.These observations point out that the effect of N-glycosylation on antigen immunogenicity can vary between different antigens and therefore might have important implications for the development of vaccines using K. phaffii.

A Synthetic MUC1 Anticancer Vaccine Containing Mannose Ligands for Targeting Macrophages and Dendritic Cells

A MUC1 anticancer vaccine equipped with covalently linked divalent mannose ligands was found to improve the antigen uptake and presentation by targeting mannose-receptor-positive macrophages and dendritic cells. It induced much stronger specific IgG immune responses in mice than the non-mannosylated reference vaccine. Mannose coupling also led to increased numbers of macrophages, dendritic cells, and CD4⁺ T cells in the local lymph organs. Comparison of di- and tetravalent mannose ligands revealed an increased binding of the tetravalent version, suggesting that higher valency improves binding to the mannose receptor. The mannose-coupled vaccine and the non-mannosylated reference vaccine induced IgG antibodies that exhibited similar binding to human breast tumor cells.

Involvement of PKA signalling in anti-inflammatory effects of chitosan oligosaccharides in IPEC-J2 porcine epithelial cells

Weaning is characterized by intestinal inflammation, which is a big challenge in pig industry. Control of intestinal inflammation is important for improvement of growth performance and health. Therefore, the study was focused on the anti-inflammatory activity of low-molecular-weight chitosan oligosaccharide (LCOS) in a porcine small intestinal epithelial cell line (IPEC-J2). The results showed that TNF-α, as inflammation inducer, significantly upregulated the mRNA expression of IL-8 and MCP-1. Afterwards, LCOS significantly attenuated mRNA expression of IL-8 and MCP-1 induced by TNF-α in the cells. Mannose (MAN), as ligand of mannose receptor, had no effect on the anti-inflammatory activity of LCOS, which suggested that mannose receptor may not involve in the anti-inflammatory activity of LCOS in IPEC-J2 cells. Interestingly, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide 2HCl hydrate (H89), as PKA (protein kinase A)-specific inhibitor, reversed the mRNA expression of IL-8 when co-cultured with LCOS. Furthermore, LCOS concentration dependent downregulated the mRNA expression of claudin-1 compared with TNF-α treatment. However, the trans-epithelial electric resistance (TEER) was not affected by LCOS when co-cultured with TNF-α in 3 hr. In conclusion, LCOS have a potent anti-inflammatory activity, and as a feed additives, may be useful for the inhibition of inflammatory process in weaning period of pigs with intestinal inflammation occurring.

The study of H. pylori putative candidate factors for single- and multi-component vaccine development

Helicobacter pylori has grown to colonize inside the stomach of nearly half of the world's population, turning into the most prevalent infections in the universe. Medical care failures noticeably confirm the need for a vaccine to hinder or deal with H. pylori. This review is planned to discuss the most known factors as a vaccine candidate, including single (AhpC, BG, CagA, KatA, Fla, Hsp, HWC, Lpp, LPS, NAP, OMP, OMV, SOD, Tpx, Urease, VacA) and multi-component vaccines. Many promising results in the field of single and multivalent vaccine can be seen, but there is no satisfactory outcome and neither a prophylactic nor a therapeutic vaccine to treat or eradicate the infection in human has been acquired. Hence, selecting suitable antigen is an important factor as an appropriate adjuvant. Taken all together, the development of efficient anti-H. pylori vaccines relies on the fully understanding of the interactions between H. pylori and its host immune system. Therefore, more work should be done on epitope mapping, analysis of molecular structure, and determination of the antigen determinant region as well due to design a vaccine, preferably a multi-component vaccine to elicit specific CD4 T-cell responses that are required for H. pylori vaccine efficacy.

Mannose-coated gadolinium liposomes for improved magnetic resonance imaging in acute pancreatitis

Background

Acute pancreatitis (AP) is an acute inflammatory condition of the pancreas. The symptoms, treatment, and prognosis of mild and severe AP are different, and severe AP is a potentially life-threatening disease with a high incidence of complications and high mortality rate. Thus, it is urgent to develop an effective approach to reliably discriminate between mild and severe AP.

Methods

We have developed novel gadolinium-diethylenetriaminepentaacetic (Gd-DTPA)-loaded mannosylated liposomes (named thereafter M-Gd-NL) that preferably target macrophages in AP. The targeting ability of M-Gd-NL toward macrophages in AP and its ability to discriminate between mild and severe AP were evaluated.

Results

The liposomes were of desired particle size (~100 nm), Gd-DTPA encapsulation efficiency (~85%), and stability. M-Gd-NL and non-targeted Gd-DTPA-loaded liposomes (Gd-NL) exhibited increased relaxivity compared with Gd-DTPA. Compared with Gd-NL and Gd-DTPA, M-Gd-NL showed increased uptake in macrophages, resulting in increased T₁ imaging ability both in vitro (macrophage cell line) and in vivo (severe AP model). Importantly, M-Gd-NL had the ability to discriminate between mild and severe AP, as reflected by a significantly higher T₁ magnetic resonance imaging signal in severe AP than in mild AP. M-Gd-NL did not show severe organ toxicity in rats.

Conclusion

Our data suggest that M-Gd-NL had enhanced magnetic resonance imaging ability by targeting macrophages in AP and good ability to discriminate between mild and severe AP. We believe that M-Gd-NL could shed new light on the diagnosis of AP in the near future.

A semi-synthetic whole parasite vaccine designed to protect against blood stage malaria

Although attenuated malaria parasitized red blood cells (pRBCs) are promising vaccine candidates, their application in humans may be restricted for ethical and regulatory reasons. Therefore, we developed an organic microparticle-based delivery platform as a whole parasite malaria-antigen carrier to mimic pRBCs. Killed blood stage parasites were encapsulated within liposomes that are targeted to antigen presenting cells (APCs). Mannosylated lipid core peptides (MLCPs) were used as targeting ligands for the liposome-encapsulated parasite antigens. MLCP-liposomes, but not unmannosylated liposomes, were taken-up efficiently by APCs which then significantly upregulated expression of MHC-ll and costimulatory molecules, CD80 and CD86. Two such vaccines using rodent model systems were constructed - one with Plasmodium chabaudi and the other with P. yoelii. MLCP-liposome vaccines were able to control the parasite burden and extended the survival of mice. Thus, we have demonstrated an alternative delivery system to attenuated pRBCs with similar vaccine efficacy and added clinical advantages. Such liposomes are promising candidates for a human malaria vaccine.

STATEMENT OF SIGNIFICANCE

Attenuated whole parasite-based vaccines, by incorporating all parasite antigens, are very promising candidates, but issues relating to production, storage and safety concerns are significantly slowing their development. We therefore developed a semi-synthetic whole parasite malaria vaccine that is easily manufactured and stored. Two such prototype vaccines (a P. chabaudi and a P. yoelii vaccine) have been constructed. They are non-infectious, highly immunogenic and give good protection profiles. This semi-synthetic delivery platform is an exciting strategy to accelerate the development of a licensed malaria vaccine. Moreover, this strategy can be potentially applied to a wide range of pathogens.

Uptake of HLA Alloantigens via CD89 and CD206 Does Not Enhance Antigen Presentation by Indirect Allorecognition

In organ transplantation, alloantigens are taken up by antigen presenting cells and presented via the indirect pathway to T-cells which in turn can induce allograft rejection. Monitoring of these T-cells is of major importance; however no reliable assay is available to routinely monitor indirect allorecognition. Recently we showed that HLA monomers can be successfully used to monitor indirect allorecognition. Targeting antigens to endocytic receptors on antigen presenting cells may further enhance the presentation of antigens via HLA class II and improve the efficiency of this assay. In the current study we explored targeting of HLA monomers to either CD89 expressing monocytes or mannose receptor expressing dendritic cells. Monomer-antibody complexes were generated using biotin-labeled monomers and avidin labeling of the antibodies. We demonstrate that targeting the complexes to these receptors resulted in a dose-dependent HLA class II mediated presentation to a T-cell clone. The immune-complexes were efficiently taken up and presented to T-cells. However, the level of T-cell reactivity was similar to that when only exogenous antigen was added. We conclude that HLA-A2 monomers targeted for presentation through CD89 on monocytes or mannose receptor on dendritic cells lead to proper antigen presentation but do not enhance indirect allorecognition via HLA-DR.

Synthesis of Mannosylated Lipopeptides with Receptor Targeting Properties

Present on the surface of antigen presenting cells (APCs), the mannose receptor (MR) has long been recognized as a front-line receptor in pathogen recognition. During the past decade many attempts have been made to target this receptor for applications including vaccine and drug development. In the present study, a library of vaccine constructs comprising fluorescently labeled mannosylated lipid-dendrimers that contained the ovalbumin CD4(+) epitope, OVA(323-339), as the model peptide antigen were synthesized using fluorenylmethyloxycarbonyl (Fmoc) solid phase peptide synthesis (SPPS). The vaccine constructs were designed with an alanine spacer between the O-linked mannose moieties to investigate the impact of distance between the mannose units on receptor-mediated uptake and/or binding in APCs. Uptake studies performed on F4/80(+) and CD11c(+) cells showed significant uptake and/or binding for lipopeptides containing mannose, and also the lipopeptide without mannose when compared to the control peptides (peptide with no lipid and peptide with no mannose and no lipid). Furthermore, mannan inhibition assays demonstrated that uptake of the mannosylated and lipidated peptides was receptor mediated. To address the specificity of receptor uptake, surface plasmon resonance studies were performed using biacore technology and confirmed high affinity of the mannosylated and lipidated vaccine constructs toward the MR. These studies confirm that both mannose and lipid moieties play significant roles in receptor-mediated uptake on APCs, potentially facilitating vaccine development.

Glycomaterials for immunomodulation, immunotherapy, and infection prophylaxis

Synthetic carbohydrate-modified materials that can engage the innate and adaptive immune systems are receiving increasing interest to confer protection against onset of future disease, such as pathogen infection, as well as to treat established diseases, such as autoimmunity and cancer.

N-Glycosylation of Cholera Toxin B Subunit: Serendipity for Novel Plant-Made Vaccines?

The non-toxic B subunit of cholera toxin (CTB) has attracted considerable interests from vaccinologists due to strong mucosal immunomodulatory effects and potential utility as a vaccine scaffold for heterologous antigens. Along with other conventional protein expression systems, various plant species have been used as production hosts for CTB and its fusion proteins. However, it has recently become clear that the protein is N-glycosylated within the endoplasmic reticulum of plant cells-a eukaryotic post-translational modification that is not present in native CTB. While functionally active aglycosylated variants have been successfully engineered to circumvent potential safety and regulatory issues related to glycosylation, this modification may actually provide advantageous characteristics to the protein as a vaccine platform. Based on data from our recent studies, I discuss the unique features of N-glycosylated CTB produced in plants for the development of novel vaccines.

Oxidation by neutrophils-derived HOCl increases immunogenicity of proteins by converting them into ligands of several endocytic receptors involved in antigen uptake by dendritic cells and macrophages

The initiation of adaptive immune responses to protein antigens has to be preceded by their uptake by antigen presenting cells and intracellular proteolytic processing. Paradoxically, endocytic receptors involved in antigen uptake do not bind the majority of proteins, which may be the main reason why purified proteins stimulate at most weak immune responses. A shared feature of different types of adjuvants, capable of boosting immunogenicity of protein vaccines, is their ability to induce acute inflammation, characterized by early influx of activated neutrophils. Neutrophils are also rapidly recruited to sites of tissue injury or infection. These cells are the source of potent oxidants, including hypochlorous acid (HOCl), causing oxidation of proteins present in inflammatory foci. We demonstrate that oxidation of proteins by endogenous, neutrophils-derived HOCl increases their immunogenicity. Upon oxidation, different, randomly chosen simple proteins (yeast alcohol dehydrogenase, human and bovine serum albumin) and glycoproteins (human apo-transferrin, ovalbumin) gain the ability to bind with high affinity to several endocytic receptors on antigen presenting cells, which seems to be the major mechanism of their increased immunogenicity. The mannose receptor (CD206), scavenger receptors A (CD204) and CD36 were responsible for the uptake and presentation of HOCl-modified proteins by murine dendritic cells and macrophages. Other scavenger receptors, SREC-I and LOX-1, as well as RAGE were also able to bind HOCl-modified proteins, but they did not contribute significantly to these ligands uptake by dendritic cells because they were either not expressed or exhibited preference for more heavily oxidised proteins. Our results indicate that oxidation by neutrophils-derived HOCl may be a physiological mechanism of conferring immunogenicity on proteins which in their native forms do not bind to endocytic receptors. This mechanism might enable the immune system to detect infections caused by pathogens not recognized by pattern recognition receptors.

The Consequences of Multiple Simultaneous C-Type Lectin-Ligand Interactions: DCIR Alters the Endo-Lysosomal Routing of DC-SIGN

Antigen-presenting cells (APCs) are equipped with multiple receptors to allow proper pathogen recognition and capture. C-type lectin receptors (CLRs) recognize glycan structures on pathogens and endogenous glycoproteins for internalization and antigen processing and presentation. Often, the glycan specificity of these receptors is overlapping and/or pathogens are decorated with ligands for multiple CLRs, posing the question whether interference or cooperativity within the CLR family exists. Here, we used imaging flow cytometry to investigate the internalization properties of four different CLRs [mannose receptor, DC-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN), macrophage galactose-type lectin, and dendritic cell immunoreceptor (DCIR)] on different APCs, as well as their intracellular routing. Although the internalization score of the investigated CLRs was similar on monocytes, macrophages, and dendritic cells (DCs), DCIR internalization rates were lower compared to the other CLRs. Upon triggering, DCIR routed to intracellular compartments outside of the classical endo-lysosomal pathway, resulting in poor CD4(+) T-cell stimulation. Although DC maturation reduced CLR expression levels, it did not affect their internalization rates. Although CLR internalization appeared to be independently regulated, DC-SIGN routing was affected when DCIR was triggered simultaneously. In conclusion, our results provide new insights for the design of DC-based immunotherapeutic strategies and suggest that DCIR is an inferior target in this respect.

Glycodendropeptides stimulate dendritic cell maturation and T cell proliferation: a potential influenza A virus immunotherapy

A GDP displaying the NP_366–374 influenza A virus epitope induces an immunostimulatory effect, emerging as a potential flu vaccine.

Mannan-conjugated myelin peptides prime non-pathogenic Th1 and Th17 cells and ameliorate experimental autoimmune encephalomyelitis

Antigen presenting cells (APC) are critical for regulating immune responses. We tested mannan-peptide conjugates for targeting myelin peptides to APC to induce T cell tolerance and resistance to experimental autoimmune encephalomyelitis (EAE). Myelin peptides conjugated to mannan in oxidized (OM) or reduced (RM) forms protected mice against EAE in prophylactic and therapeutic protocols, with OM-conjugated peptides giving best results. Protection was peptide-specific and associated with reduced antigen-specific T cell proliferation, but not alterations in Th1, Th17 and Treg cell differentiation or T cell apoptosis compared to EAE controls. Bone marrow-derived dendritic cells (DC) loaded with OM-MOG showed up-regulated expression of co-stimulatory molecules, reduced PD-L1 expression and enhanced CD40-inducible IL-12 and IL-23 production compared to MOG DC, features consistent with immunogenic DC. OM-MOG induced active T cell tolerance because i.d. administration or passive transfer of OM-MOG DC suppressed ongoing EAE, while OM-MOG-vaccinated mice did not reduce the proliferation of transferred MOG-specific T cells. As in vivo, MOG-specific T cells cultured with OM-MOG DC showed reduced proliferation and equal Th1 and Th17 cell differentiation compared to those with MOG DC, but surprisingly cytokine production was unresponsive to CD40 engagement. Impaired effector T cell function was further evidenced in spinal cord sections from OM-MOG-vaccinated EAE mice, where markedly reduced numbers of CD3(+) T cells were present, restricted to leptomeninges and exceptional parenchymal lesions. Our results show that mannan-conjugated myelin peptides protect mice against EAE through the expansion of antigen-specific Th1 and Th17 cells with impaired proliferation responses and APC-induced co-stimulatory signals that are required for licensing them to become fully pathogenic T cells.

Enhanced cross-presentation and improved CD8+ T cell responses after mannosylation of synthetic long peptides in mice

The use of synthetic long peptides (SLP) has been proven to be a promising approach to induce adaptive immune responses in vaccination strategies. Here, we analyzed whether the efficiency to activate cytotoxic T cells by SLP-based vaccinations can be increased by conjugating SLPs to mannose residues. We could demonstrate that mannosylation of SLPs results in increased internalization by the mannose receptor (MR) on murine antigen-presenting cells. MR-mediated internalization targeted the mannosylated SLPs into early endosomes, from where they were cross-presented very efficiently compared to non-mannosylated SLPs. The influence of SLP mannosylation was specific for cross-presentation, as no influence on MHC II-restricted presentation was observed. Additionally, we showed that vaccination of mice with mannosylated SLPs containing epitopes from either ovalbumin or HPV E7 resulted in enhanced proliferation and activation of antigen-specific CD8⁺ T cells. These findings demonstrate that mannosylation of SLPs augments the induction of a cytotoxic T cell response in vitro and in vivo and might be a promising approach to induce cytotoxic T cell responses in e.g. cancer therapy and anti-viral immunity.

Mannosylation of virus-like particles enhances internalization by antigen presenting cells

Internalization of peptides by antigen presenting cells is crucial for the initiation of the adaptive immune response. Mannosylation has been demonstrated to enhance antigen uptake through mannose receptors, leading to improved immune responses. In this study we test the effect of surface mannosylation of protein-based virus-like particles (VLP) derived from Rabbit hemorrhagic disease virus (RHDV) on uptake by murine and human antigen presenting cells. A monomannoside and a novel dimannoside were synthesized and successfully conjugated to RHDV VLP capsid protein, providing approximately 270 mannose groups on the surface of each virus particle. VLP conjugated to the mannoside or dimannoside exhibited significantly enhanced binding and internalization by murine dendritic cells, macrophages and B cells as well as human dendritic cells and macrophages. This uptake was inhibited by the inclusion of mannan as a specific inhibitor of mannose specific uptake, demonstrating that mannosylation of VLP targets mannose receptor-based uptake. Consistent with mannose receptor-based uptake, partial retargeting of the intracellular processing of RHDV VLP was observed, confirming that mannosylation of VLP provides both enhanced uptake and modified processing of associated antigens.

Dendritic cell immunotherapy: clinical outcomes

The use of tumour-associated antigens for cancer immunotherapy studies is exacerbated by tolerance to these self-antigens. Tolerance may be broken by using ex vivo monocyte-derived dendritic cells (DCs) pulsed with self-antigens. Targeting tumour-associated antigens directly to DCs in vivo is an alternative and simpler strategy. The identification of cell surface receptors on DCs, and targeting antigens to DC receptors, has become a popular approach for inducing effective immune responses against cancer antigens. Many years ago, we demonstrated that targeting the mannose receptor on macrophages using the carbohydrate mannan to DCs led to appropriate immune responses and tumour protection in animal models. We conducted Phase I, I/II and II, clinical trials demonstrating the effectiveness of oxidised mannan-MUC1 in patients with adenocarcinomas. Here we summarise DC targeting approaches and their efficacy in human clinical trials.

Carboxymethylation enhances the maturation-inducing activity in dendritic cells of polysaccharide from the seeds of Plantago asiatica L

Carboxymethylation is a well-known modification process for polysaccharides. To evaluate the biological availability of carboxymethyl, polysaccharide from the seeds of Plantago asiatica L. (PLCP) was carboxymethylated (CM-PLCP) and the immunomodulatory activities of five CM-PLCPs of gradient degree of substitution (DS) from 0.40 to 0.62 were determined on dendritic cells (DCs) in vitro. Compared with DCs treated with PLCP, DCs treated with CM-PLCP of DS0.50, DS0.55, DS0.62, as well as CD86 and CD80, expressed higher levels of MHCII, CD86 and CD80 surface molecules. In addition, the secretion of IL-12p70 and the mRNA of CCR7 and CXCR4 chemokines were increased, while the endocytosis activities were inhibited. Correspondingly, stronger mixed lymphocyte reactions were induced by the DCs treated with the CM-PLCPs. The results showed that carboxymethylation modification of relevant high DS can enhance the DC maturation-inducing function of PLCP, indicating the potential application of carboxymethylated polysaccharide as an immunotherapeutic adjuvant.

Improvement of spinal non-viral IL-10 gene delivery by D-mannose as a transgene adjuvant to control chronic neuropathic pain

BACKGROUND

Peri-spinal subarachnoid (intrathecal; i.t.) injection of non-viral naked plasmid DNA encoding the anti-inflammatory cytokine, IL-10 (pDNA-IL-10) suppresses chronic neuropathic pain in animal models. However, two sequential i.t. pDNA injections are required within a discrete 5 to 72-hour period for prolonged efficacy. Previous reports identified phagocytic immune cells present in the peri-spinal milieu surrounding the i.t injection site that may play a role in transgene uptake resulting in subsequent IL-10 transgene expression.

METHODS

In the present study, we aimed to examine whether factors known to induce pro-phagocytic anti-inflammatory properties of immune cells improve i.t. IL-10 transgene uptake using reduced naked pDNA-IL-10 doses previously determined ineffective. Both the synthetic glucocorticoid, dexamethasone, and the hexose sugar, D-mannose, were factors examined that could optimize i.t. pDNA-IL-10 uptake leading to enduring suppression of neuropathic pain as assessed by light touch sensitivity of the rat hindpaw (allodynia).

RESULTS

Compared to dexamethasone, i.t. mannose pretreatment significantly and dose-dependently prolonged pDNA-IL-10 pain suppressive effects, reduced spinal IL-1β and enhanced spinal and dorsal root ganglia IL-10 immunoreactivity. Macrophages exposed to D-mannose revealed reduced proinflammatory TNF-α, IL-1β, and nitric oxide, and increased IL-10 protein release, while IL-4 revealed no improvement in transgene uptake. Separately, D-mannose dramatically increased pDNA-derived IL-10 protein release in culture supernatants. Lastly, a single i.t. co-injection of mannose with a 25-fold lower pDNA-IL-10 dose produced prolonged pain suppression in neuropathic rats.

CONCLUSIONS

Peri-spinal treatment with D-mannose may optimize naked pDNA-IL-10 transgene uptake for suppression of allodynia, and is a novel approach to tune spinal immune cells toward pro-phagocytic phenotype for improved non-viral gene therapy.