Dectin-1 targeting delivery of TNF-α antisense ODNs complexed with β-1,3-glucan protects mice from LPS-induced hepatitis

Antisense oligonucleotide is a promising intervention for liver diseases

As the body's critical metabolic organ, the liver plays an essential role in maintaining proper body homeostasis. However, as people's living standards have improved and the number of unhealthy lifestyles has increased, the liver has become overburdened. These have made liver disease one of the leading causes of death worldwide. Under the influence of adverse factors, liver disease progresses from simple steatosis to hepatitis, to liver fibrosis, and finally to cirrhosis and cancer, followed by increased mortality. Until now, there has been a lack of accepted effective treatments for liver disease. Based on current research, antisense oligonucleotide (ASO), as an alternative intervention for liver diseases, is expected to be an effective treatment due to its high efficiency, low toxicity, low dosage, strong specificity, and additional positive characteristics. In this review, we will first introduce the design, modification, delivery, and the mechanisms of ASO, and then summarize the application of ASO in liver disease treatment, including in non-alcoholic fatty liver disease (NAFLD), hepatitis, liver fibrosis, and liver cancer. Finally, we discuss challenges and perspectives on the transfer of ASO drugs into clinical use. This review provides a current and comprehensive understanding of the integrative and systematic functions of ASO for its use in liver disease.

Oligonucleotide delivery to antigen presenting cells by using schizophyllan

Schizophyllan (SPG), a member of the β-glucan family, can form novel complexes with homo-polynucleotides such as poly(dA) through hydrogen bonding between two main chain glucoses and the one nucleotide base. Dectin-1, one of the major receptors for β-glucans, is known to be expressed on antigen presenting cells (APCs) such as macrophages and dendritic cells. This suggests that the above-mentioned complexes could deliver bound functional oligonucleotides (ODNs) including antisense (AS)-ODNs, small interfering RNA, and CpG-ODNs to the APCs. Analysis using a quartz crystal microbalance revealed that a complex consisting of SPG and dA₆₀ with a phosphorothioate backbone was recognized by recombinant Dectin-1 protein. Treatment with this complex containing an AS-ODN for tumor necrosis factor alpha protected mice against lipopolysaccharide-induced hepatitis at a very low AS-ODN dose. Moreover, immunization with CpG-ODN/SPG complex and antigenic proteins induced potent antigen specific immune responses. The present review also represents peptide delivery by conjugation with dA₆₀ and the preparation of a nanogel using DNA-DNA hybridization. These findings indicate that the delivery of a specific ODN using β-glucans could be used for treating various diseases caused by APCs and for activating antigen specific immune responses.

Binding assay of human Dectin-1 variants to DNA/β-glucan complex for active-targeting delivery of antisense DNA

The lectin Dectin-1 is a good target for β-glucan-mediated drug delivery. Although many murine studies of Dectin-1 have been performed, its human analog has not been studied well in terms of being a drug delivery target. We thus analyzed human Dectin-1 cDNA obtained from chronic myelogenous leukemia-derived cells, CML-1, and confirmed the findings of previous studies that there are many isoforms of human Dectin-1 due to exon skipping, although murine Dectin-1 has only two forms. When we transfected the Dectin-1 gene into a non-Dectin-1-expressing cell line and examined cellular uptake of the antisense DNA/β-glucan complex, we confirmed that expression of the target gene was effectively suppressed through β-glucan/Dectin-1-mediated uptake. The present results suggest that the β-glucan complex would be an effective tool to deliver antisense oligonucleotide (AS-ODN) to Dectin-1-expressing cells not only for mice but also for humans.

Beta-d-glucan-based drug delivery system and its potential application in targeting tumor associated macrophages

Use of polysaccharides as carriers in drug delivery system is a hot topic, especially those with specific recognition of immune cells, enabling them to be applied in targeting delivery system. β-d-glucans are naturally occurring non-digestible polysaccharides with immunomodulatory activities that have attracted increasing attention to serve as therapeutic agents or immune-adjuvants. Being able to be specifically recognized by immune cells like macrophages, β-d-glucans can be developed as promising carriers for targeting delivery with stability, biocompatibility and specificity when applied in immunotherapy. Targeting tumor associated macrophages (TAMs) is an emerging strategy for cancer immunotherapy since it exerts anti-cancer effects based on modulating body immunity in tumor microenvironment (TME). This new strategy does not require high concentration of drugs to kill cancer cells directly and lessen tumor recurrence by creating unique immune memory for malignant cells. In this review, construction strategies of polysaccharide-based drug delivery system of three types of β-d-glucan including non-yeast and yeast β-d-glucans as well as hyper-branched β-d-glucan are discussed with reference to their branching characteristics and conformation. The applications of these β-d-glucans as nano-carrier for drug delivery targeting TAMs are also discussed.

Induction of potent cell growth inhibition by schizophyllan/K-ras antisense complex in combination with gemcitabine

Antisense oligonucleotides (AS-ODNs) specifically hybridize with target mRNAs, resulting in interference with the splicing mechanism or the regulation of protein translation. In our previous reports, we demonstrated that β-glucan schizophyllan (SPG) can form a complex with AS-ODNs attached with oligo deoxyadenosine dA₄₀ (AS-ODN-dA₄₀/SPG), and that this complex can be recognized by β-glucan receptor Dectin-1 on antigen presenting cells and lung cancer cells. In many types of cancer cell, activating K-ras mutations related to malignancy are frequently observed. In this study, we first designed 78 AS-ODNs for K-ras to optimize the sequence for highly efficient gene suppression. The selected AS-ODN (K-AS07) having dA₄₀ made a complex with SPG. The resultant complex (K-AS07-dA₄₀/SPG) showed an effect of silencing the ras gene in the cells (PC9: human adenocarcinoma differentiated from lung tissue) expressing Dectin-1, leading to the suppression of cell growth. Furthermore, the cytotoxic effect was enhanced when used in combination with the anticancer drug gemcitabine. Gemcitabine, a derivative of cytidine, was shown to interact with dA₄₀ in a sequence-dependent manner. This interaction did not appear to be so strong, with the gemcitabine being released from the complex after internalization into the cells. SPG and the dA₄₀ part of K-AS07-dA₄₀ play roles in carriers for K-AS07 and gemcitabine, respectively, resulting in a strong cytotoxic effect. This combination effect is a novel feature of the AS-ODN-dA₄₀/SPG complexes. These results could facilitate the clinical application of these complexes for cancer treatment.

Carbohydrate Conjugates in Vaccine Developments

Vaccines are powerful tools that can activate the immune system for protection against various diseases. As carbohydrates can play important roles in immune recognition, they have been widely applied in vaccine development. Carbohydrate antigens have been investigated in vaccines against various pathogenic microbes and cancer. Polysaccharides such as dextran and β-glucan can serve as smart vaccine carriers for efficient antigen delivery to immune cells. Some glycolipids, such as galactosylceramide and monophosphoryl lipid A, are strong immune stimulators, which have been studied as vaccine adjuvants. In this review, we focus on the current advances in applying carbohydrates as vaccine delivery carriers and adjuvants. We will discuss the examples that involve chemical modifications of the carbohydrates for effective antigen delivery, as well as covalent antigen-carbohydrate conjugates for enhanced immune responses.

A β-glucan from Grifola frondosa effectively delivers therapeutic oligonucleotide into cells via dectin-1 receptor and attenuates TNFα gene expression

Grifola frondosa is an edible and medicinal mushroom with great nutritional values and bioactivities. In the present study, a soluble homogeneous β-glucan, GFPS, with high molecular mass of 5.42 × 10⁶ Da was purified from the fruit bodies of Grifola frondosa using 5% cold NaOH. The structure of GFPS was determined with FT-IR, NMR, and monosaccharide composition analysis, and was identified to be a β-D-(1-3)-linked glucan backbone with a single β-D-(1-6)-linked glucopyranosyl residue branched at C-6 on every third residue. Our results indicated that GFPS had a triple helical structure and could form complex with polydeoxyadenylic acid (poly[A]). Further studies demonstrated that GFPS could interact with poly[A] moiety of a designed antisense oligonucleotide (ASO) targeting the primary transcript of proinflammatory cytokine TNFα (TNFα-A60). This GFPS-based complex could incorporate TNFα-A60 into the macrophage cells via dectin-1 receptor and attenuate lipopolysaccharide-induced secretion of TNFα. Our results suggested that GFPS could be applied to deliver therapeutic oligonucleotides for the treatment of diseases such as inflammation and cancers.

β-glucan as a new tool in vaccine development

Vaccination constitutes one of the major breakthroughs in human medicine. At the same time, development of more immunogenic vaccine alternatives to using aluminium-based adjuvants is one of the most important phases of vaccination development. Among different sources of carbohydrate polymers, including plants, microbes and synthetic sources tested, glucans were found to be the most promising vaccine adjuvant, as they alone stimulate various immune reactions including antibody production without any negative side effects. The use of glucan particles as a delivery system is a viable option based on the documented efficient antigen loading and receptor-targeted uptake in antigen-presenting cells. In addition to particles, soluble glucans can be used as novel hydrogels or as direct immunocyte-targeting delivery systems employing novel complexes with oligodeoxynucleotides. This review focuses on recent advances in glucan-based vaccine development from glucan-based conjugates to a glucan-based delivery and adjuvant platform.

Complex consisting of antisense DNA and β-glucan promotes internalization into cell through Dectin-1 and hybridizes with target mRNA in cytosol

Antisense oligonucleotides (AS-ODNs) hybridize with specific mRNAs, resulting in interference with the splicing mechanism or the regulation of protein translation. We previously demonstrated that the β-glucan schizophyllan (SPG) can form a complex with AS-ODNs with attached dA₄₀ (AS-ODNs/SPG), and this complex can be incorporated into cells, such as macrophages and dendritic cells, expressing the β-glucan receptor Dectin-1. We have achieved efficient gene silencing in animal models, but the uptake mechanism and intracellular distribution are unclear. In this study, we prepared the complex consisting of SPG and AS-ODNs (AS014) for Y-box binding protein-1 (YB-1). After treatment with endocytosis inhibitor Pitstop 2 and small interfering RNA targeting Dectin-1, we found that AS014/SPG complexes are incorporated into cells by Dectin-1-mediated endocytosis and inhibit cell growth in a Dectin-1 expression level-dependent manner. After treatment with AS014/SPG complexes, we separated the cell lysate into endosomal and cytoplasmic components by ultracentrifugation and directly determined the distribution of AS014 by reverse transcription PCR using AS014 ODNs as a template or a reverse transcription primer. In the cytoplasm, AS014 clearly hybridized with YB-1 mRNAs. This is the first demonstration of the distinct distribution of the complex in cells. These results could facilitate the clinical application of the complex.

Design of Mannose-Functionalized Curdlan Nanoparticles for Macrophage-Targeted siRNA Delivery

6-Amino-6-deoxy-curdlan is a promising nucleic acid carrier that efficiently delivers plasmid DNA as well as short interfering RNA (siRNA) to various cell lines. The highly reactive C6-NH₂ groups of 6-amino-6-deoxy-curdlan prompt conjugation of various side groups including tissue-targeting ligands to enhance cell-type-specific nucleic acid delivery to specific cell lines. Herein, to test the primary-cell-targeting efficiency of the curdlan derivative, we chemically conjugated a macrophage-targeting ligand, mannose, to 6-amino-6-deoxy-curdlan. The resulting curdlan derivative (denoted CMI) readily complexed with siRNA and formed nanoparticles with a diameter of 50-80 nm. The CMI nanoparticles successfully delivered a dye-labeled siRNA to mouse peritoneal macrophages. The delivery efficiency was blocked by mannan, a natural ligand for a macrophage surface mannose receptor (CD206), but not by zymosan, a ligand for the dectin-1 receptor, which is also present on the surface of macrophages. Moreover, CMI nanoparticles were internalized by macrophages only at 37 °C, suggesting that the cellular uptake of CMI nanoparticles was energy-dependent. Furthermore, CMI nanoparticle efficiently delivered siRNA against tumor necrosis factor α (TNFα) to lipopolysaccharide-stimulated primary mouse peritoneal macrophages. In vivo experiments demonstrated that CMI nanoparticles successfully delivered siTNFα to mouse peritoneal macrophages, liver, and lung and induced significant knockdown of the TNFα expression at both messenger RNA and protein levels. Therefore, our design of CMI may be a promising siRNA carrier for targeting CD206-expressing primary cells such as macrophage and dendritic cells.

Complex Consisting of β-Glucan and Antigenic Peptides with Cleavage Site for Glutathione and Aminopeptidases Induces Potent Cytotoxic T Lymphocytes

The efficient induction of antigen-specific immune responses requires not only promotion of the uptake of antigens and adjuvant molecules into antigen-presenting cells but also control of their intracellular behavior. We previously demonstrated that the β-glucan schizophyllan (SPG) can form complexes with CpG oligonucleotides with attached dA₄₀ (CpG-dA/SPG), which can accumulate in macrophages in the draining inguinal lymph nodes and induce strong immune responses. In this study, we prepared various conjugates composed of antigenic peptide (OVA_257-264) and dA₄₀ and made complexes with SPG. The conjugates with a disulfide bond between OVA_257-264 and dA₄₀ were easily cleaved by glutathione. The resultant peptides with a hydrophobic amino acid at the C-terminal end was recognized by puromycin-insensitive leucine aminopeptidase (PILS-AP), which trims antigenic peptide precursors and prepares peptides of eight or nine amino acids in length, which is the optimal length for binding to major histocompatibility complex (MHC)-I. The conjugate exposed to such enzymes induced a high antigen presentation level. The antigen presentation level was almost the same before and after the complexation with SPG. Immunization with a mixture of dA-OVA_257-264/SPG and CpG-dA/SPG induced high antigen-specific cytotoxic T-lymphocyte activity at a much lower peptide dose than in previous studies. These results can be strongly ascribed to not only the cell-specific delivery by SPG but also the control of the intracellular behavior by the introduction of cleavage sites. Therefore, peptide-dA/SPG complexes could be used as potent vaccine antigens for the treatment of cancers and infectious diseases.

Immunization with antigenic peptides complexed with β-glucan induces potent cytotoxic T-lymphocyte activity in combination with CpG-ODNs

The induction of antigen-specific immune responses requires immunization with not only antigens, but also adjuvants. CpG oligonucleotides (CpG-ODNs) are well-known ligands for Toll-like receptor 9 and a potent adjuvant that induces both Th1-type humoral and cellular immune responses including cytotoxic T-lymphocyte responses. We previously demonstrated that β-glucan schizophyllan (SPG) can form complexes with CpG-ODNs with attached dA40 (CpG-dA/SPG), which can accumulate in macrophages in the draining inguinal lymph nodes and induce strong immune responses by co-administration of antigenic proteins, namely ovalbumin (OVA). Immunization with antigenic peptides, OVA257-264, did not induce these antigen-specific immune responses even in combination with CpG-dA/SPG, indicating that peptides require a carrier to antigen presenting cells. In this study, we prepared conjugates comprising OVA257-264 and dA40, and made complexes with SPG. Immunization with OVA257-264-dA/SPG induced peptide-specific immune responses in combination with CpG-dA regardless of complexation with SPG both in vitro and in vivo. When splenocytes from immunized mice were incubated with E.G7-OVA tumor model cells presenting OVA peptides, the number of cells drastically decreased after 24h. Furthermore, mice pre-immunized with OVA257-264-dA/SPG and CpG-ODNs exhibited a long delay in tumor growth after tumor inoculation. Therefore, these peptide-dA/SPG and CpG-dA/SPG complexes could be used as a potent vaccine for the treatment of cancers and infectious diseases.

Drug Trafficking into Macrophages via the Endocytotic Receptor CD163

In inflammatory diseases, macrophages are a main producer of a range of cytokines regulating the inflammatory state. This also includes inflammation induced by tumor growth, which recruits so-called tumor-associated macrophages supporting tumor growth. Macrophages are therefore relevant targets for cytotoxic or phenotype-modulating drugs in the treatment of inflammatory and cancerous diseases. Such targeting of macrophages has been tried using the natural propensity of macrophages to non-specifically phagocytose circulating foreign particulate material. In addition, the specific targeting of macrophage-expressed receptors has been used in order to obtain a selective uptake in macrophages and reduce adverse effects of off-target delivery of drugs. CD163 is a highly expressed macrophage-specific endocytic receptor that has been studied for intracellular delivery of small molecule drugs to macrophages using targeted liposomes or antibody drug conjugates. This review will focus on the biology of CD163 and its potential role as a target for selective macrophage targeting compared with other macrophage targeting approaches.

Nanoengineering of vaccines using natural polysaccharides

Currently, there are over 70 licensed vaccines, which prevent the pathogenesis of around 30 viruses and bacteria. Nevertheless, there are still important challenges in this area, which include the development of more active, non-invasive, and thermo-resistant vaccines. Important biotechnological advances have led to safer subunit antigens, such as proteins, peptides, and nucleic acids. However, their limited immunogenicity has demanded potent adjuvants that can strengthen the immune response. Particulate nanocarriers hold a high potential as adjuvants in vaccination. Due to their pathogen-like size and structure, they can enhance immune responses by mimicking the natural infection process. Additionally, they can be tailored for non-invasive mucosal administration (needle-free vaccination), and control the delivery of the associated antigens to a specific location and for prolonged times, opening room for single-dose vaccination. Moreover, they allow co-association of immunostimulatory molecules to improve the overall adjuvant capacity.

The natural and ubiquitous character of polysaccharides, together with their intrinsic immunomodulating properties, their biocompatibility, and biodegradability, justify their interest in the engineering of nanovaccines. In this review, we aim to provide a state-of-the-art overview regarding the application of nanotechnology in vaccine delivery, with a focus on the most recent advances in the development and application of polysaccharide-based antigen nanocarriers.

Cytokine production by leukocytes in patients with periodontitis

In the present study, we investigated the relation between clinical parameters and levels of interleukin (IL) -4 and -5, and tumour necrosis factor-α (TNF-α) in the leukocyte incubation medium (LIM) obtained from 26 patients with chronic periodontitis (P) and 26 control group subjects (C). The levels of cytokines IL-4 and IL -5 produced by the LIM stimulated with non-opsonised E. coli were determined using the Enzyme-Linked Immunosorbent Assay (ELISA) method and the levels of TNF-α were evaluated by applying Enzyme Amplified Sensitivity Immunoassay (EASIA). TNF-α levels in stimulated LIM were strongly positively correlated with clinical parameters such as the pocket probing depths (PPD), the clinical attachment level (CAL), the bleeding on probing (BOP) and oral hygiene index (OHI), whereas the IL-4 and IL-5 levels in the analogous medium were strongly negatively correlated with the clinical parameters. IL-4 and IL-5 levels in stimulated LIM of P group patients were significantly lower, whereas TNF-α levels were significantly higher than that in analogous medium of C group subjects. These differences were associated with the severity of periodontal disease.

Preparation of novel curdlan nanoparticles for intracellular siRNA delivery

RNA interference (RNAi) down-regulates gene expression post-transcriptionally, which is a therapeutically significant phenomenon that could potentially reduce the level of disease related proteins that are undruggable by conventional small molecular approaches. However, clinical application of small interference RNAs (siRNAs) requires design of potent siRNA sequences and development of safe and efficient delivery systems. To create a biocompatible siRNA delivery agent, we chemically modified natural polysaccharide curdlan in a regioselective manner to introduce amino group in the glucose units. The resulting 6-amino-curdlan (6AC) is water soluble and forms nanoparticles upon complexing with siRNAs. The novel curdlan-based nanoparticles efficiently delivered siRNAs to human cancer cells and mouse primary cells, and reduced 70-90% of target mRNA level. Moreover, 6AC nanoparticles delivered siRNA targeting eGFP to mouse embryonic stem (mES) cells stably expressing eGFP, and produced substantial reductions of GFP protein level. The novel curdlan-based nanoparticle is a promising vehicle for delivery of short RNAs to knock down endogenous mRNAs.

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.

ssDNA-dsRNAs are cleaved at the next to its chimera-junction point by an unknown RNase activity

We found that there is an unknown aspect in serum RNases that cleaves ssDNA-dsRNA and ssRNA-dsRNA. In the first step, RNase cleaves the phosphodiester linkage between the first and second RNA, where the first one is connected to the single stranded RNA or DNA. In the second step, the ssRNA overhang attached siRNA is cleaved. When the 2' hydroxyl of the first RNA was replaced with methoxy, the cleavage did not occur. This RNase activity can be considered related to defense system against exogenous genetic materials.