Effective induction of anti-tumor immune responses with oligomannose-coated liposome targeting to intraperitoneal phagocytic cells

Mannosylated Systems for Targeted Delivery of Antibacterial Drugs to Activated Macrophages

Macrophages are a promising target for drug delivery to influence macrophage-associated processes in the body, namely due to the presence of resistant microorganisms in macrophages. In this work, a series of mannosylated carriers based on mannan, polyethylenimine (PEI) and cyclodextrin (CD) was synthesized. The molecular architecture was studied using FTIR and ¹H NMR spectroscopy. The particle size, from small 10-50 nm to large 500 nm, depending on the type of carrier, is potentially applicable for the creation of various medicinal forms: intravenous, oral and inhalation. Non-specific capture by cells with a simultaneous increase in selectivity to CD206+ macrophages was achieved. ConA was used as a model mannose receptor, binding galactosylated (CD206 non-specific) carriers with constants of the order of 10⁴ M^-1 and mannosylated conjugates of 10⁶-10⁷ M^-1. The results of such primary "ConA-screening" of ligands are in a good agreement in terms of the comparative effectiveness of the interaction of ligands with the CD206+ macrophages: non-specific (up to 10%) absorption of highly charged and small particles; weakly specific uptake of galactosylated polymers (up to 50%); and high affine capture (more than 70-80%) of the ligands with grafted trimannoside was demonstrated using the cytometry method. Double and multi-complexes of antibacterials (moxifloxacin with its adjuvants from the class of terpenoids) were proposed as enhanced forms against resistant pathogens. In vivo pharmacokinetic experiments have shown that polymeric carriers significantly improve the efficiency of the antibiotic: the half-life of moxifloxacin is increased by 2-3 times in conjugate-loaded forms, bio-distribution to the lungs in the first hours after administration of the drug is noticeably greater, and, after 4 h of observation, free moxifloxacin was practically removed from the lungs of rats. Although, in polymer systems, its content is significant-1.2 µg/g. Moreover, the importance of the covalent crosslinking carrier with mannose label was demonstrated. Thus, this paper describes experimental, scientifically based methods of targeted drug delivery to macrophages to create enhanced medicinal forms.

Mannosylated Polymeric Ligands for Targeted Delivery of Antibacterials and Their Adjuvants to Macrophages for the Enhancement of the Drug Efficiency

Bacterial infections and especially resistant strains of pathogens localized in macrophages and granulomas are intractable diseases that pose a threat to millions of people. In this paper, the theoretical and experimental foundations for solving this problem are proposed due to two key aspects. The first is the use of a three-component polymer system for delivering fluoroquinolones to macrophages due to high-affinity interaction with mannose receptors (CD206). Cytometry assay determined that 95.5% macrophage-like cells were FITC-positive after adding high-affine to CD206 trimannoside conjugate HPCD-PEI1.8-triMan, and 61.7% were FITC-positive after adding medium-affine ligand with linear mannose label HPCD-PEI1.8-Man. The second aspect is the use of adjuvants, which are synergists for antibiotics. Using FTIR and NMR spectroscopy, it was shown that molecular containers, namely mannosylated polyethyleneimines (PEIs) and cyclodextrins (CDs), load moxifloxacin (MF) with dissociation constants of the order of 10⁻⁴–10⁻⁶ M; moreover, due to prolonged release and adsorption on the cell membrane, they enhance the effect of MF. Using CLSM, it was shown that eugenol (EG) increases the penetration of doxorubicin (Dox) into cells by an order of magnitude due to the creation of defects in the bacterial wall and the inhibition of efflux proteins. Fluorescence spectroscopy showed that 0.5% EG penetrates into bacteria and inhibits efflux proteins, which makes it possible to increase the maximum concentration of the antibiotic by 60% and maintain it for several hours until the pathogens are completely neutralized. Regulation of efflux is a possible way to overcome multiple drug resistance of both pathogens and cancer cells.

Importance of particle size of oligomannose-coated liposomes for induction of Th1 immunity

Oligomannose-coated liposomes (OMLs) comprised of dipalmitoylphosphatidylcholine, cholesterol and Man3-DPPE at a molar ratio of 1:1:0.1 and particle diameters of about 1000 nm can induce liposome-encased antigen-specific strong Th1 immunity. In this study, we evaluated the effect of particle sizes of OMLs on induction of Th1 immune responses in mice. Spleen cells obtained from mice immunized with antigen-encapsulating OMLs with 1000- and 800-nm diameters secreted remarkably high levels of IFN-γ upon in vitro stimulation. In addition, sera of mice that received these OMLs had significantly higher titers of antigen-specific IgG2a than those of IgG1, which are commonly associated with Th1 responses. In contrast, treatment with antigen-encapsulating OMLs with 400- and 200-nm diameters failed to induce IFN-γ secretion from spleen cells, although these OMLs did elicit elevation of antigen-specific IgGs. In addition, the titers of serum antigen-specific IgG2a were the same as those of IgG1 in mice that received 400-nm OMLs. Resident peritoneal mononuclear phagocytes (MNPs) treated with OMLs of diameter ≥ 600 nm secreted IL-12, which is essential for induction of Th1 immune responses, while those treated with OMLs of ≤ 400 nm failed to produce this cytokine. However, 400-nm OMLs did induce enhanced expression of MHC class II and costimulatory molecules on MNPs, similarly to OMLs of ≥ 600 nm. Taken together, these results strongly indicate that OMLs of diameter ≥ 600 nm are required to induce Th1 immune responses against OML-encased antigens, although OMLs of diameter ≤ 400 nm can activate MNPs.

Chemical synthesis and immunological evaluation of new generation multivalent anticancer vaccines based on a Tn antigen analogue

Tumor associated carbohydrate antigens (TACAs), such as the Tn antigen, have emerged as key targets for the development of synthetic anticancer vaccines. However, the induction of potent and functional immune responses has been challenging and, in most cases, unsuccessful. Herein, we report the design, synthesis and immunological evaluation in mice of Tn-based vaccine candidates with multivalent presentation of the Tn antigen (up to 16 copies), both in its native serine-linked display (Tn-Ser) and as an oxime-linked Tn analogue (Tn-oxime). The high valent vaccine prototypes were synthesized through a late-stage convergent assembly (Tn-Ser construct) and a versatile divergent strategy (Tn-oxime analogue), using chemoselective click-type chemistry. The hexadecavalent Tn-oxime construct induced robust, Tn-specific humoral and CD4⁺/CD8⁺ cellular responses, with antibodies able to bind the Tn antigen on the MCF7 cancer cell surface. The superior synthetic accessibility and immunological properties of this fully-synthetic vaccine prototype makes it a compelling candidate for further advancement towards safe and effective synthetic anticancer vaccines.

Immunological Functions of the Omentum

The omentum is a visceral adipose tissue with unique immune functions. Although it is primarily an adipose tissue, the omentum also contains lymphoid aggregates, called milky spots (MSs), that contribute to peritoneal immunity by collecting antigens, particulates, and pathogens from the peritoneal cavity and, depending on the stimuli, promoting a variety of immune responses, including inflammation, tolerance, or even fibrosis. Reciprocal interactions between cells in the MS and adipocytes regulate their immune and metabolic functions. Importantly, the omentum collects metastasizing tumor cells and supports tumor growth by immunological and metabolic mechanisms. Here we summarize our current knowledge about the development, organization, and function of the omentum in peritoneal immunity.

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.

Requirement of TLR4 signaling for the induction of a Th1 immune response elicited by oligomannose-coated liposomes

We have previously demonstrated that administration of oligomannose-coated liposomes (OMLs), in which an antigen is encased, induce antigen-specific Th1 immune responses and CTLs. In the present study, we showed that TLR4 signaling is required for the induction of specific immune responses following OML administration. In C3H/HeJ mice, which express a dysfunctional TLR4, the antigen-specific Th1 immune response could not be elicited following intraperitoneal administration of OVA-encased OMLs (OML/OVA). However, OML uptake by peritoneal cells, the subsequent production of IL-12 and the upregulation of co-stimulatory molecules and MHC class II on the cells in response to OML uptake occurred in C3H/HeJ mice to the same extent as in wild type C3H/HeN mice. In addition, peritoneal phagocytic cells from TLR4(-/-) mice that ingest OML/OVA can activate CD4(+) T cells from OT-II mice. On the other hand, the number of OML-ingesting peritoneal cells that migrated into mesenteric lymph nodes in C3H/HeJ mice was significantly less than that in C3H/HeN mice. Therefore, the chemotactic capability of OML-ingesting peritoneal phagocytes to the draining lymph nodes rather than the activation and maturation of the cells in response to OML uptake is impaired by lack of TLR4 signaling, and disorder of the Th1 immune response elicited by OMLs in mice, which lack TLR4 signaling, is due to the impairment of cell migration following OML uptake.

Development of M2BPGi: a novel fibrosis serum glyco-biomarker for chronic hepatitis/cirrhosis diagnostics

Many proteins in the living body are glycoproteins, which present glycans linked on their surface. Glycan structures reflect the degree of cell differentiation or canceration and are cell specific. These characteristics are advantageous in the development of various disease biomarkers. Glycoprotein-based biomarkers (glyco-biomarkers) are developed by utilizing the specific changes in the glycan structure on a glycoprotein secreted from the diseased cells of interest. Therefore, quantification of the altered glycan structures is the key to developing a new glyco-biomarker. Glycoscience is a relatively new area of molecular science, and recent advancement of glycotechnologies is remarkable. In the author's institute, new glycoscience technologies have been designed to be efficiently utilized for the development of new diagnostic agents. This paper introduces a strategy for glyco-biomarker development, which was successfully applied in the development of Wisteria floribunda agglutinin-positive Mac-2 binding protein M2BPGi, a liver fibrosis marker now commercially available for clinical use.

Microenvironment of tumor-draining lymph nodes: opportunities for liposome-based targeted therapy

The World Health Organization (WHO) recently reported that the total number of global cancer cases in 2013 reached 14 million, a 10% rise since 2008, while the total number of cancer deaths reached 8.2 million, a 5.2% increase since 2008. Metastasis is the major cause of death from cancer, accounting for 90% of all cancer related deaths. Tumor-draining lymph nodes (TDLN), the sentinel nodes, are the first organs of metastasis in several types of cancers. The extent of metastasis in the TDLN is often used in disease staging and prognosis evaluation in cancer patients. Here, we describe the microenvironment of the TDLN and review the recent literature on liposome-based therapies directed to immune cells within the TDLN with the intent to target cancer cells.

The role of the CCL22-CCR4 axis in the metastasis of gastric cancer cells into omental milky spots

Background

The omentum is one of the initial sites for peritoneal metastasis because it possesses milky spots that provide a microenvironment for cancer cells to readily migrate and grow into micrometastases. This study investigated the role of the CCL22-CCR4 axis in gastric cancer cells selectively infiltrating into milky spots.

Methods

Gastric cancer MFC cells labelled with DiI were injected intraperitoneally into strain 615 mice. The mice were euthanised at specified intervals and the omentum was excised for immunohistochemistry. The effects of CCL22 on the proliferation and migration of MFCs were assessed by MTT and trans-well assays. RT-PCR and Western blot analysis detected CCR4 mRNA and protein expression levels in MFCs. Immunohistochemistry was used to analyse CCL22 and CCR4 expression in the milky spot micrometastases.

Results

Two weeks after intraperitoneal injection, the milky spot areas were completely occupied by proliferating gastric cancer cells and cell cluster-type micrometastases were observed. In contrast, cancer cells formed single cell-type micrometastases in the non-milky spot areas. MFCs expressed CCR4, which was localised on the cell surface and or in the cytoplasm. Different concentrations of CCL22 significantly increased the proliferation ability of MFCs. Additionally, concentrations of CCL22 between 10–100 ng/ml significantly increased the migration of MFCs. Within omental milky spots, CCL22 was localised mainly on the cell surface and or in the cytoplasm. Within sections of omental milky spot micrometastases, CCR4 was recognised on or in gastric cancer cells, constituent cells milky spots, blood cells and blood endothelial cells.

Conclusions

Omental milky spots are a congenial microenvironment for peritoneal free gastric cancer cells to migrate, survive, and establish cell cluster-type metastases. The CCL22-CCR4 axis contributes to this selective infiltration process.

Unexpected and successful "one-step" formation of porous polymeric particles only by mixing organic solvent and water under "low-energy-input" conditions

We found that porous particles were unexpectedly obtained in a "one-step" manner only by mixing an organic solvent and water under "low-energy-input" (i.e., low-homogenization-rate) conditions. This phenomenon was attributable to the unexpected formation of the spontaneously formed water-in-oil (w/o) emulsions in the droplets of o/w emulsions. The unexpected formation resulted in the successful formation of water-in-oil-in-water (w/o/w) emulsions instead of o/w emulsions, although the mixed solution containing both an organic solvent and water were simply emulsified in the presence of block copolymers. The present study clarifies the effects of the various preparation conditions on the morphology of unexpected w/o/w emulsions and resulting particles. The porous particles are expected to be suitable drug carriers for pulmonary delivery. The results obtained in the present study show that a newly developed one-step emulsification can be a powerful and facile technique for preparing porous polymeric particles.

Comparison of the carbohydrate preference of SIGNR1 as a phagocytic receptor with the preference as an adhesion molecule

C-type lectin receptors expressed on cell surfaces of antigen-presenting cells can serve as not only cell adhesion molecules but also as phagocytic receptors, and therefore, are potentially useful for antigen targeting for vaccination. In the present study, we compared the carbohydrate preference of the C-type lectin SIGNR1 as a cell adhesion molecule with that of SIGNR1 as a phagocytic receptor, using a series of neoglycolipids (NGLs) and the mouse macrophage-like cells stably expressing SIGNR1. When SIGNR1-mediated cell adhesion was assessed based on the binding of the cells to NGL-coated solid phases, the order of degree of cell adhesion was Le(b)-≈Le(a)-≈Le(x)-≥Man5->Man3-≥α1-3Man2->α1-6Man2-DPPE. By contrast, when SIGNR1-mediated phagocytosis was assessed based on the uptake of NGL-coated liposomes, the order of phagocytosis of the liposomes by the cells was Le(a)-≈Man3->Man5-≈α1-3Man2->Le(x)->Le(b)->α1-6Man2-DPPE. Collectively, SIGNR1 mediates cell adhesion to Lewis blood group antigen-containing NGL-coated solid phases more preferably than those coated with terminal mannose-containing NGLs, but mediates the phagocytosis of the Man3-DPPE- and Le(a)-DPPE-coated liposomes most preferably among the tested NGLs. Thus, the subtle carbohydrate preference of SIGNR1 on the cell surface is altered depending on the function, and the preferable carbohydrate for phagocytosis elucidated using NGL-coated liposomes might be used as the appropriate targeting signals for antigen delivery.

Oligomannose-coated liposome as a novel adjuvant for the induction of cellular immune responses to control disease status

Professional phagocytic cells, such as dendritic cells, are mainly responsible for phagocytosis, antigen presentation, and cytokine secretion, which induce subsequent activation of T cell-mediated immunity. Thus, strategies that deliver antigens and stimulatory signals to the cells have significant implications for vaccine design. In this paper, we summarize the potential for liposomes coated with the neoglycolipids containing oligomannose residues (OMLs) as a novel adjuvant for induction of Th1 immune responses and CTLs specific for the encased antigen. OMLs preferentially take up peripheral phagocytic cells. In response to OML uptake, the cells secrete IL-12 selectively, enhance the expression of costimulatory molecules, and migrate into lymphoid tissues from peripheral tissues. OMLs also have the ability to deliver encapsulated protein antigens to the MHC class I and class II pathways to generate antigen-specific CTLs and Th1 cells, respectively, and lipid antigen to CD1d to activate NKT cells. Since administration of OML-based vaccines can eliminate an established tumor, inhibit elevation of the serum IgE level, and prevent progression of protozoan infections in several murine, human, and bovine models, OML-based vaccines have revealed their potential for clinical use in vaccination for a variety of diseases in which CTLs and/or Th1 cells act as effector cells.

Targeting C-type lectin receptors with multivalent carbohydrate ligands

C-type lectin receptors (CLRs) represent a large receptor family including collectins, selectins, lymphocyte lectins, and proteoglycans. CLRs share a structurally homologous carbohydrate-recognition domain (CRD) and often bind carbohydrates in a Ca²⁺-dependent manner. In innate immunity, CLRs serve as pattern recognition receptors (PRRs) and bind to the glycan structures of pathogens and also to self-antigens. In nature, the low affinity of CLR/carbohydrate interactions is overcome by multivalent ligand presentation at the surface of cells or pathogens. Thus, multivalency is a promising strategy for targeting CLR-expressing cells and, indeed, carbohydrate-based targeting approaches have been employed for a number of CLRs, including asialoglycoprotein receptor (ASGPR) in the liver, or DC-SIGN expressed by dendritic cells. Since CLR engagement not only mediates endocytosis but also influences intracellular signaling pathways, CLR targeting may allow for cell-specific drug delivery and also the modulation of cellular functions. Glyconanoparticles, glycodendrimers, and glycoliposomes were successfully used as tools for CLR-specific targeting. This review will discuss different approaches for multivalent CLR ligand presentation and aims to highlight how CLR targeting has been employed for cell specific drug delivery. Major emphasis is directed towards targeting of CLRs expressed by antigen-presenting cells to modulate immune responses.

Recent trends in multifunctional liposomal nanocarriers for enhanced tumor targeting

Liposomes are delivery systems that have been used to formulate a vast variety of therapeutic and imaging agents for the past several decades. They have significant advantages over their free forms in terms of pharmacokinetics, sensitivity for cancer diagnosis and therapeutic efficacy. The multifactorial nature of cancer and the complex physiology of the tumor microenvironment require the development of multifunctional nanocarriers. Multifunctional liposomal nanocarriers should combine long blood circulation to improve pharmacokinetics of the loaded agent and selective distribution to the tumor lesion relative to healthy tissues, remote-controlled or tumor stimuli-sensitive extravasation from blood at the tumor's vicinity, internalization motifs to move from tumor bounds and/or tumor intercellular space to the cytoplasm of cancer cells for effective tumor cell killing. This review will focus on current strategies used for cancer detection and therapy using liposomes with special attention to combination therapies.

Immunotoxicity derived from manipulating leukocytes with lipid-based nanoparticles

Lipid-based nanoparticles (LNPs) such as liposomes, micelles, and hybrid systems (e.g. lipid-polymer) are prominent delivery vehicles that already made an impact on the lives of millions around the globe. A common denominator of all these LNP-based platforms is to deliver drugs into specific tissues or cells in a pathological setting with minimal adverse effects on bystander cells. All these platforms must be compatible to the physiological environment and prevent undesirable interactions with the immune system. Avoiding immune stimulation or suppression is an important consideration when developing new strategies in drug and gene delivery, whereas in adjuvants for vaccine therapies, immune activation is desired. Therefore, profound understanding of how LNPs elicit immune responses is essential for the optimization of these systems for various biomedical applications. Herein, I describe general concepts of the immune system and the interaction of subsets of leukocytes with LNPs. Finally, I detail the different immune toxicities reported and propose ways to manipulate leukocytes' functions using LNPs.

Liposomes and nanotechnology in drug development: focus on oncotargets

Nanotechnology is the development of an engineered device at the atomic, molecular, and macromolecular level in the nanometer range. Advances in nanotechnology have proven beneficial in therapeutic fields such as drug-delivery and gene/protein delivery. Antigen delivery systems are important for inducing and modifying immune responses. In cellular immunity, cytotoxic T lymphocytes (CTLs) are important in the host defense against tumors. Key to the development of CTL-inducible vaccines is the ability to deliver antigens to antigen-presenting cells efficiently and to induce the subsequent activation of T cell-mediated immunity without adjuvants, as they can induce excessive inflammation leading to systemic febrile disease. Since expression and cloning methods for tumor-associated antigens have been reported, cancer vaccines that induce effective cell immunity may be promising therapeutic candidates, but Th2 cells are undesirable for use in cancer immunotherapy. Peptide vaccines have immunological and economic advantages as cancer vaccines because CTL epitope peptides from tumor-associated antigens have high antigen-specificity. However, cancer vaccines have had limited effectiveness in clinical responses due to the ability of cancer cells to “escape” from cancer immunity and a low efficiency of antigen-specific CTL induction due to immunogenic-free synthetic peptides. In contrast, carbohydrate-decorated particles such as carbohydrate-coated liposomes with encapsulated antigens might be more suitable as antigen delivery vehicles to antigen-presenting cells. Oligomannose-coated liposomes (OML) can eliminate established tumors in mouse cancer models. In addition, OMLs with an encased antigen can induce antigen-specific CTLs from peripheral blood mononuclear cells obtained from patients. Feasibility studies of OML-based vaccines have revealed their potential for clinical use as vaccines for diseases where CTLs act as effector cells. Furthermore, use of the hepatitis B core particle, in which tumor-antigen epitopes are set, has consistently been shown to induce strong CTL responses without the use of an adjuvant. Thus, nanoparticles may provide a new prophylactic strategy for infectious disease and therapeutic approaches for cancer via the induction of T-cell immunity.

Antigen delivery to macrophages using liposomal nanoparticles targeting sialoadhesin/CD169

Sialoadhesin (Sn, Siglec-1, CD169) is a member of the sialic acid binding Ig-like lectin (siglec) family expressed on macrophages. Its macrophage specific expression makes it an attractive target for delivering antigens to tissue macrophages via Sn-mediated endocytosis. Here we describe a novel approach for delivering antigens to macrophages using liposomal nanoparticles displaying high affinity glycan ligands of Sn. The Sn-targeted liposomes selectively bind to and are internalized by Sn-expressing cells, and accumulate intracellularly over time. Our results show that ligand decorated liposomes are specific for Sn, since they are taken up by bone marrow derived macrophages that are derived from wild type but not Sn(-/-) mice. Importantly, the Sn-targeted liposomes dramatically enhance the delivery of antigens to macrophages for presentation to and proliferation of antigen-specific T cells. Together, these data provide insights into the potential of cell-specific targeting and delivery of antigens to intracellular organelles of macrophages using Sn-ligand decorated liposomal nanoparticles.

[New treatment strategy for adult T-cell leukemia targeting for anti-tumor immunity and a longevity gene-encoded protein]

Adult T-cell leukemia-lymphoma (ATL) is an aggressive peripheral T-cell neoplasm with a poor prognosis, developing after long-term infection with human T-cell leukemia virus-1 (HTLV-1). Multiple factors (e.g., virus, host cells, epigenetic aberrations, and immune factors) have been implicated in the development of ATL, although the underlying mechanisms of leukemogenesis have not been fully elucidated. Despite recent progress in both chemotherapy and supportive care for hematological malignancies, the prognosis of ATL is still poor; overall survival at 3 years is only 24%. New strategies for the therapy and prophylaxis of ATL (e.g., vaccines and novel molecular target agents) are still required. This article reviews new strategy of ATL treatment targeted for HTLV-1-specific cytotoxic T-lymphocytes (CTLs) and SIRT1, a longevity gene-encoded protein. HTLV-1-specific CTLs play a critical role in the host immune response against HTLV-1. We have described here the decreased frequency and function of HTLV-1-specific CD8+ T cells in ATL patients and the efficient induction of the HTLV-1-specific CTLs response in human leukocyte antigen-A* 0201-transgenic mice by the HTLV-1/hepatitis B core chimeric particle and oligomannose-coated liposomes encapsulating HTLV-1 epitope without adjuvant, suggesting that the efficient antigen delivery system and CTL induction can be exploited to develop a prophylactic vaccine model against tumors and infectious diseases. Furthermore, our studies suggest that SIRT1, a longevity gene-encoded protein, is a crucial anti-apoptotic molecule in ATL cells, and that SIRT1 inhibitors may be useful therapeutic agents for leukemia, especially in patients with ATL. These studies targeted for anti-tumor immunity such as vaccine and SIRT1 may support the new prophylactic and therapeutic approach for ATL.

Altering the immune response with lipid-based nanoparticles

Lipid-based nanoparticles (LNPs) hold great promise as delivery vectors in the treatment of cancer, inflammation, and infections and are already used in clinical practice. Numerous strategies based on LNPs are being developed to carry drugs into specific target sites. The common denominator for all of these LNPs-based platforms is to improve the payloads' pharmacokinetics, biodistribution, stability and therapeutic benefit, and to reduce to minimal adverse effects. In addition, the delivery system must be biocompatible and non-toxic and avoid undesirable interactions with the immune system. In order to achieve optimal benefits from these delivery strategies, interactions with the immune system must be thoroughly investigated. This report will center on the interactions of LNPs with different subsets of leukocytes and will detail representative examples of suppression or activation of the immune system by these carriers. By understanding the interactions of LNPs with the innate and the adaptive arms of the immune system it might be possible to attain improved therapeutic benefits and to avoid immune toxicity.

Novel oligomannose liposome-DNA complex DNA vaccination efficiently evokes anti-HPV E6 and E7 CTL responses

The aim of this study was to establish an efficient human papilloma virus (HPV) type 16-targeting cancer immunotherapy. Persistent high-risk HPV infection causes cervical intra-epithelial neoplasia (CIN) and subsequent cervical carcinoma. HPV type16 (HPV16) is one of the common carcinogenic types and is found in about 50% of invasive cervical carcinomas. HPV16-derived viral proteins E6 and E7 are expressed in cancerous cells through the progression of the disease and have a role in carcinogenesis but are not expressed in normal cells. Thus, these proteins are regarded as ideal antigens for cervical carcinoma immunotherapy. In this study, we generated a novel HPV 16 E6 and E7 gene plasmid containing oligomannose liposomes (OML-HPV). We compared the cytotoxic T lymphocyte (CTL) induction efficiency of OML-HPV and that of standard liposome-HPV16 E6 and E7 DNA complex. HPV16 E6-specific CTLs could be generated from HPV 16-positive cervical carcinoma patient's peripheral blood mononuclear cells (PBMCs) by stimulating OML-HPV, but could not by stimulating standard liposome-HPV 16 E6, E7 DNA complex. Furthermore, we screened HLA-A24-restricted HPV16 E6- and E7-derived peptides, and found that one E6-derived peptide (E6 66-74) showed the highest immunogenicity with ELISPOT assay from 100% of HPV16-positive patients (4 out of 4). On the other hand, other E6- or E7-derived peptides, including E6 49-57, E6 82-90, E6 87-95, E6 98-106 and E7 83-93, showed less frequent reactivity. These results indicate that OML-HPV is a more effective approach than DNA vaccination using standard liposomes, and that a novel HLA-A24-restricted peptide, E6 66-74, might be a suitable target of cervical cancer immunotherapy.

Development of peritoneal macrophage along a dendritic cell lineage in response to uptake of oligomannose-coated liposomes

In this study, we investigate the potential of peritoneal macrophages to differentiate into dendritic cell (DCs) in response to preferential uptake of oligomannose-coated liposomes (OMLs). About 30% of peritoneal cells (PECs) preferentially took up OMLs that were administered into the peritoneal cavity. The OML-ingesting cells expressed CD11b and F4/80, but lacked CD11c expression, indicating that the OML-ingesting PECs with a CD11b(high)CD11c(-) phenotype are resident peritoneal macrophages. During in vitro cultivation, CD11c(+) cells arose among the PECs with ingested OMLs. CD11c(+) cells also developed among enriched peritoneal CD11b(high)CD11(-) cells from OML-treated mice, and the resulting CD11c(+) cells expressed co-stimulatory molecules and MHC class II. In addition, OML-ingesting CD11b(high)CD11c(+) cells were found in spleen after the enriched peritoneal macrophages with ingested OMLs were transplanted in the peritoneal cavity of mice. These results show that a fraction of peritoneal macrophages can differentiate into mature DCs following uptake of OMLs.

Oligomannose-coated liposomes efficiently induce human T-cell leukemia virus-1-specific cytotoxic T lymphocytes without adjuvant

Human T-cell leukemia virus-1 (HTLV-1) causes adult T-cell leukemia/lymphoma, which is an aggressive peripheral T-cell neoplasm. Insufficient T-cell response to HTLV-1 is a potential risk factor in adult T-cell leukemia/lymphoma. Efficient induction of antigen-specific cytotoxic T lymphocytes is important for immunological suppression of virus-infected cell proliferation and oncogenesis, but efficient induction of antigen-specific cytotoxic T lymphocytes has evaded strategies utilizing poorly immunogenic free synthetic peptides. Here, we examined the efficient induction of an HTLV-1-specific CD8+ T-cell response by oligomannose-coated liposomes (OMLs) encapsulating the human leukocyte antigen (HLA)-A*0201-restricted HTLV-1 Tax-epitope (OML/Tax). Immunization of HLA-A*0201 transgenic mice with OML/Tax induced an HTLV-1-specific gamma-interferon reaction, whereas immunization with epitope peptide alone induced no reaction. Upon exposure of dendritic cells to OML/Tax, the levels of CD86, major histocompatibility complex class I, HLA-A02 and major histocompatibility complex class II expression were increased. In addition, our results showed that HTLV-1-specific CD8+ T cells can be efficiently induced by OML/Tax from HTLV-1 carriers compared with epitope peptide alone, and these HTLV-1-specific CD8+ T cells were able to lyse cells presenting the peptide. These results suggest that OML/Tax is capable of inducing antigen-specific cellular immune responses without adjuvants and may be useful as an effective vaccine carrier for prophylaxis in tumors and infectious diseases by substituting the epitope peptide.

Liposomes modified by carbohydrate ligands can target B cells for the treatment of B-cell lymphomas

Evaluation of: Chen WC, Completo GC, Sigal DS, Crocker PR, Saven A, Paulson JC. In vivo targeting of B-cell lymphoma with glycan ligands of CD22. Blood 115(23), 4778-4786 (2010). A strategy has been developed to deliver selectively chemotherapeutic drugs to B cells by employing doxorubicin-loaded liposomes modified by a ligand for the B-cell-specific cell-surface protein CD22, also known as Siglec-2. The liposomes bound in a rapid and saturable manner to the human Burkitt lymphoma Daudi B-cell line and exhibited significantly higher cytotoxicity in vitro and in vivo compared with similar untargeted liposomes. The CD22-targeted liposome bound to B cells isolated from lymphoma patients and although binding was proportional to CD22 expression on the cell surface, low levels of expression on chronic lymphocytic leukemia cells were sufficient to effect cell neutralization. The glycan-based strategy for delivery of chemotherapeutic agents may provide a new strategy for the treatment of B-cell lymphomas.

Targeting with oligomannose-coated liposomes promotes maturation and splenic trafficking of dendritic cells in the peritoneal cavity

In previous studies, we have shown that oligomannose-coated liposomes (OMLs) have a strong adjuvant effect in inducing T-helper 1 (Th1) immune responses and cytotoxic T cells specific for the encased antigen. In the present study, we demonstrate that preferential uptake of OMLs by DCs and subsequent DC maturation and splenic trafficking may be correlated with the adjuvant effect of OMLs. About 3% of resting murine peritoneal cells are CD11b(dull)CD11c(+) cells, which express MHC class II and CD86, and about 30% are CD11b(high)CD11c(-) cells, which express F4/80 and CD14. This indicates that these cells are resident peritoneal DCs and monocytes/macrophages, respectively. Both types of cells rapidly took up OMLs in the peritoneal cavity, but only CD11b(dull)CD11c(+) cells produced interleukin (IL)-12 in response to OML uptake. IL-6 was not produced by either type of cells. The expression levels of CD205 and CCR7, which are markers of cell maturity in murine DCs, were upregulated in CD11b(dull)CD11c(+) cells obtained from OML-treated mice. In addition, CD11b(dull)CD11c(+) cells with ingested OMLs were found in the spleen 18 h after intraperitoneal administration of OMLs. These results indicate that OMLs can be used as a vehicle for delivery of antigens to DCs and as an adjuvant to promote DC maturation, activation, and trafficking into lymphoid organs, thereby eliciting a Th1 immune response.

Recent advancements in cytotoxic T lymphocyte generation methods using carbohydrate-coated liposomes

Both tumor-specific CD4⁺ and CD8⁺ T cells have been identified, and the latter is known as a major effector of adaptive antitumor immune responses. Optimal antitumor immune responses are considered to require the concomitant activation of both CD8⁺ and CD4⁺ T cells and the additional selective activation of CD4⁺ T cells with helper, but not regulatory function. As optimal antitumor immune responses are generated by the concomitant activation of both T cell types, it is necessary for vaccine methods involving cytotoxic T-lymphocytes (CTLs) generation to possess a mechanism whereby antigen presenting cells can present administrated exogenous antigens on not only Major histocompatibility complex (MHC) class II, but also MHC class I molecules.

Anti-allergic potential of oligomannose-coated liposome-entrapped Cry j 1 as immunotherapy for Japanese cedar pollinosis in mice

Administration of oligomannose-coated liposomes (OMLs) in mice can induce Th1 immune responses against antigens entrapped in the OMLs. In the present study, we investigated the anti-allergic effect of treatment with oligomannose-coated liposomes (OMLs) with entrapped Cry j 1, a major allergen of Japanese cedar pollen (Cry j 1/OMLs), in Balb/c mice sensitized with Cry j 1. Pretreatment of unsensitized mice with Cry j 1/OMLs repressed the elevation of total and allergen-specific IgE levels in sera elicited in response to subsequent sensitization with Cry j 1. Cry j 1-specific IgG1 in sera also decreased in Cry j 1/OML-treated mice, while the levels of Cry j 1-specific IgG2a in these mice significantly increased after sensitization with Cry j 1. In addition, Cry j 1/OML-treated mice showed high IFN-gamma production from spleen cells and low IL-4/IFN-gamma and IL-5/IFN-gamma ratios in response to in vitro stimulation with Cry j 1. These results indicate that allergen-specific Th1 immune responses predominate over Th2 responses and control IgE elevation in Cry j 1/OML-treated mice. The anti-allergic effect of Cry j 1/OML determined by suppression of serum IgE levels was also observed in Cry j 1-presensitized mice after challenge with antigen. Thus, Cry j 1/OMLs may be useful for immunotherapeutic control of allergic reactions to Japanese cedar pollinosis.

Recent developments in carbohydrate-decorated targeted drug/gene delivery

Targeted delivery of a drug or gene to its site of action has clear therapeutic advantages by maximizing its therapeutic efficiency and minimizing its systemic toxicity. Generally, targeted drug or gene delivery is performed by loading a macromolecular carrier with an appropriate drug or gene, and by targeting the drug/gene carrier to specific cell or tissue with the help of specific targeting ligand. The emergence of glycobiology, glycotechnology, and glycomics and their continual adaptation by pharmaceutical scientists have opened exciting avenue of medicinal applications of carbohydrates. Among them, the biocompatibility and specific receptor recognition ability confer the ability of carbohydrates as potential targeting ligands for targeted drug and gene delivery applications. This review summarizes recent progress of carbohydrate-decorated targeted drug/gene delivery applications.

In vivo targeting of B-cell lymphoma with glycan ligands of CD22

Antibody-mediated cell depletion therapy has proven to provide significant clinical benefit in treatment of lymphomas and leukemias, driving the development of improved therapies with novel mechanisms of cell killing. A current clinical target for B-cell lymphoma is CD22, a B-cell-specific member of the sialic acid binding Ig-like lectin (siglec) family that recognizes alpha2-6-linked sialylated glycans as ligands. Here, we describe a novel approach for targeting B lymphoma cells with doxorubicin-loaded liposomal nanoparticles displaying high-affinity glycan ligands of CD22. The targeted liposomes are actively bound and endocytosed by CD22 on B cells, and significantly extend life in a xenograft model of human B-cell lymphoma. Moreover, they bind and kill malignant B cells from peripheral blood samples obtained from patients with hairy cell leukemia, marginal zone lymphoma, and chronic lymphocytic leukemia. The results demonstrate the potential for using a carbohydrate recognition-based approach for efficiently targeting B cells in vivo that can offer improved treatment options for patients with B-cell malignancies.

Mucosal adjuvant activity of oligomannose-coated liposomes for nasal immunization

In the present study, we investigated the effectiveness of liposomes coated with a neoglycolipid consisting of mannotriose and dipalmitoylphosphatidylcholine (Man3-DPPE) as an adjuvant for induction of mucosal immunity. Immunization of BALB/c mice with ovalbumin (OVA)-encapsulated Man3-DPPE-coated liposomes (oligomannose-coated liposomes; OMLs) by a nasal route produced high levels of OVA-specific IgG and IgA antibodies in serum of immunized mice 1 week after the last nasal immunization, whereas no significant serum antibody responses were observed in mice that received OVA in uncoated liposomes or OVA alone. Seven weeks after the last nasal immunization, nasal challenge with an excess amount of OVA in mice that had received OVA/OMLs led to an anamnestic response to the antigen that resulted in 5- to 10-fold increases of antigen-specific serum IgG and IgA antibodies. Only mice immunized nasally with OML/OVA secreted antigen-specific secretory IgA in nasal washes and produced interferon-gamma secreting cells in nasopharyngeal-associated lymphoreticular tissue. Taken together, these results show that nasal administration of OMLs induces mucosal and systemic immunity that are specific for the entrapped antigen in the liposomes. Thus, liposomes coated with synthetic neoglycolipids might be useful as adjuvants for induction of mucosal immunity.

Immunization with oligomannose-coated liposome-entrapped dense granule protein 7 protects dams and offspring from Neospora caninum infection in mice

The present study demonstrates that the subcutaneous administration of Neospora caninum dense granule protein 7 (NcGRA7) entrapped in liposomes coated with mannotriose strongly induces the parasite-specific T-helper type 1 immune response and humoral antibody in mice. Although anti-NcGRA7 immunoglobulin G1 antibody production was induced in mice injected with NcGRA7 alone, the dams and offspring were never protected from N. caninum infection. The immunization of mice with liposome-entrapped NcGRA7 before pregnancy resulted in increased offspring survival and decreased the infection rates in the brains of dams after parasite infection at 6 to 9 days of gestation. In conclusion, oligomannose-coated liposome-entrapped NcGRA7 can be used as a new type of effective vaccine to control neosporosis.