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Structures of cytosine-phosphate-guanosine (CpG) oligodeoxynucleotides (ODNs) consisting of entirely phosphodiester backbone. (A) Sequence and structure of CpG ODN with a dumbbell-like structure: the CpG ODN with a dumbbell-like structure has 30 nucleotides in both loops that contain three CpG dinucleotide motifs.a (B) Structure of dendrimer-like DNA: Y-shaped DNA consists of three single-stranded DNA with 30 nucleotides containing CpG dinucleotide motifs; G1, G2, and G3 dendrimer-like structures were synthesized by ligation of Y-shaped DNA; the sizes of CpG ODNs with G1, G2, and G3 dendrimer-like structures were about 12, 20, and 36 nm, respectively.b (C) Assembly of CpG bearing DNA tetrahedral nanostructure: the core tetrahedral nanostructure consists of assembly with four 55-mer ODNs. The CpG motif is linked to each ODN via a 7-mer oligothyamine spacer.c aReproduced with permission from Schmidt et al;⁵² breproduced with permission from Rattanakiat et al³⁰; creproduced with permission from Li et al.⁵⁵
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Unmethylated cytosine-phosphate-guanosine (CpG) oligodeoxynucleotides (ODNs) are recognized by Toll-like receptor 9 (TLR9) found in antigen-presenting cells and B cells and can activate the immune system. Using CpG ODNs as an adjuvant has been found to be effective for treating infectious diseases, cancers, and allergies. Because natural ODNs with...
Citations
... The ZIF-8/CpG ODNs complex exhibited good biocompatibility and high stability in a physiological environment but degraded in the acidic environment of endolysosomes to release CpG ODNs. CpG ODNs could activate the immune system and induce Th1 responses by stimulating Toll-like receptor 9 (TLR9) in the acidic endolysosomal compartment, thus enhancing their immunostimulatory activity (figure 11) [81,82]. ...
Zeolitic imidazolate framework-8 nanoparticles (ZIF-8 NPs) are emerging metal-organic framework nanomaterials composed of 2-methylimidazole and zinc ions, which are widely used in biomedical fields due to their distinctive features such as high porosity, bioresponsive degradation, and superior biocompatibility. Especially, the advanced research of ZIF-8 NPs in smart drug delivery systems is providing unique insights into the rational design of versatile nanomedicines for the treatment and diagnosis of serious diseases. This article provides a comprehensive review and outlook on ZIF-8 NPs-based smart drug delivery systems (SDDSs) including the synthesis methods, drug loading strategies, surface modification, and stimuli-responsive release. In particular, we focus on the advantages of ZIF-8 NPs-based drug loading strategies between the metal coordination-based active loading and the physical packaging-based passive loading. Finally, the opportunities and challenges of ZIF-8 NPs as smart drug delivery carriers are discussed.
... It is important to note that the CpG-ODN used in our experiments has natural phosphodiester bonds, in contrast to the typical phosphorothioate bonds used in commercial oligonucleotides to prevent possible DNAse degradation. Considering the higher cost and the reported toxicity of the latter, the use of phosphodiester CpG-ODN is advantageous [18,33]. To address the natural bonds susceptibility, other authors demonstrated that the formulation of phosphodiester CpG-ODN with liposomes provides protection to the DNA molecule [18,34]. ...
... Moreover, this discrepancy may arise from the inherent advantages of the G4 structure and non-viral vector carrier DOTAP [18]. The capacity to induce IFN-α production has been recognized to correlate with the potential to form extensive ODN structures [44].Moreover, the high-charge-ratio complexes with large sizes are taken into macrophages via micropinocytosis [45]. Besides B cells and pDCs, the high-chargeratio complexes might take up natural killer cells, monocytes/macrophages, and T cells in hPBMCs as well, leading to secreted IL-6 production. ...
Cationic liposomes, specifically 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) liposomes, serve as successful carriers for guanine-quadruplex (G4) structure-based cytosine-guanine oligodeoxynucleotides (CpG ODNs). The combined benefits of CpG ODNs forming a G4 structure and a non-viral vector carrier endow the ensuing complex with promising adjuvant properties. Although G4-CpG ODN-DOTAP complexes show a higher immunostimulatory effect than naked G4-CpG ODNs, the effects of the complex composition, especially charge ratios, on the production of the pro-inflammatory cytokines interleukin (IL)-6 and interferon (IFN)-α remain unclear. Here, we examined whether charge ratios drive the bifurcation of cytokine inductions in human peripheral blood mononuclear cells. Linear CpG ODN-DOTAP liposome complexes formed micrometer-sized positively charged agglomerates; G4-CpG ODN-DOTAP liposome complexes with low charge ratios (0.5 and 1.5) formed ~250 nm-sized negatively charged complexes. Notably, low-charge-ratio (0.5 and 1.5) complexes induced significantly higher IL-6 and IFN-α levels simultaneously than high-charge-ratio (2 and 2.5) complexes. Moreover, confocal microscopy indicated a positive correlation between the cellular uptake of the complex and amount of cytokine induced. The observed effects of charge ratios on complex size, surface charge, and affinity for factors that modify cellular-uptake, intracellular-activity, and cytokine-production efficiency highlight the importance of a rational complex design for delivering and controlling G4-CpG ODN activity.
... Considering the chemical backbone and sequence characteristics, CpG ODNs are classified into four categories: A/D-, B/K-, C-, and P-type ODNs [4][5][6]. Among them, A/D-type CpG-ODNs have a phosphodiester palindromic domain in the central region, which contains one or more CpG motifs in the palindrome [7,8]. ...
Among several types of CpG-ODNs, A/D-type CpG-ODNs have potent adjuvant activity to induce Th-1 immune responses, but exhibit a propensity to aggregate. For the clinical application of A/D-type CpG-ODNs, it is necessary to control such aggregation and obtain a comprehensive understanding of the relationship between their structure and the immune responses. This study revealed that a representative A/D-type CpG ODN, D35, adopted a single-stranded structure in water, while it assembled into aggregates in response to Na⁺ ions. From polyacrylamide gel electrophoresis and circular dichroism analyses, D35 adopted a homodimeric form (duplex) via palindromic sequences in low-Na⁺-concentration conditions (10–50 mM NaCl). After replacement of the solution with PBS, quadruplexes began to form in a manner coordinated by Na⁺, resulting in large aggregates. The duplexes and small aggregates prepared in 50 mM NaCl showed not only high cellular uptake but also high affinity to Toll-like receptor 9 (TLR9) proteins, leading to the production of a large amount of interferon-α for peripheral blood mononuclear cells. The much larger aggregates prepared in 100 mM NaCl were incorporated into cells at a high level, but showed a low ability to induce cytokine production. This suggests that the large aggregates have difficulty inducing TLR9 dimerization, resulting in loss of the stimulation of the cells. We thus succeeded in inducing adequate innate immunity in vitro by controlling and adjusting the formation of D35 aggregates. Therefore, the findings in this study for D35 ODNs could be a vital research foundation for in vivo applications.
... However, chemical modifications have raised concerns regarding their undesirable side effects. For example, repeated administration of backbone-modified ODNs has been shown to lead to reduced immune responses, lymphoid follicle destruction, and organ enlargement (Nobutaka, 2012). Recently, developing nanotechnology has provided a new strategy to solve the problem of ODN transmission. ...
... Hai'ao ® oral cavity repair film (Zhenghai, China) was cut at an average thickness of 0.7-1.0 mm into a circle with a diameter of 5 mm and was sterilized with ultraviolet radiation (254 nm, 70 μW/cm2) for 30 min for standby (Nobutaka, 2012). PEN was set at a concentration of 2 mg/mL, mixed with MT01 (1 mg/mL) at a mass ratio of 6.0, and allowed to stand for 30 min at a 37°C water bath. ...
Objective: This study aimed to investigate the regulatory effect of N-isopropylacrylamide-modified polyethyleneimine (PEN)-delivered oligodeoxynucleotide (ODN) MT01 on bone regeneration in vitro and in vivo.
Methods: A polyethylenimine (PEI) derivative, PEN, was constructed through Michael addition and employed as a carrier for ODN MT01 transfection. PEN/MT01 nanocomposites were characterized using agarose gel retardation assay, size distribution, zeta potential and transmission electron microscopy. The Cell Counting Kit-8 (CCK-8) assay was used to detect the effect of PEN on cell viability. Alkaline phosphatase (ALP) staining was used to detect the osteogenic differentiation ability of PEN/MT01 nanocomposite. Real-time quantitative PCR (q RT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to detect the regulatory effects of PEN/MT01 nanocomposite on osteogenic differentiation gene expression. Rat model was observed using the skull defect method and verified using micro-computed tomography (CT), serum biochemical indices, hematoxylin and eosin (H&E) staining and Immunohistochemistry (IHC).
Results: PEN had good biological properties and could deliver MT01 well to achieve efficient transmission of MT01. PEN/MT01 nanocomposites were effectively transfected into MC3T3-E1 cells at a ratio of 6.0. CCK-8 assay displayed that PEN had no cytotoxicity to MC3T3-E1 cells. Additionally, PEN/MT01 nanocomposites could promote the expression of osteogenic genes. In vivo results revealed that PEN/MT01 nanocomposites could promote bone regeneration more effectively than the other groups.
Conclusion: PEN has good biocompatibility and low toxicity, which is a good carrier for ODN MT01. PEN-delivered MT01 can be potentially employed as a useful approach to achieving bone regeneration.
... In this study, when compared with the control and allergy groups, the group treated with CpG ODN showed higher IFN-γ levels in the plasma, but the group also showed lower IFN-γ levels in the spleen. The problem with the application of CpG ODN is that it is easy for CpG ODN to degrade due to DNase (34). The use of chitosan nanoparticles in this study plays a role in the delivery system to increase the effectiveness of CpG ODN action. ...
... This study is in accordance with Kim et al., where the IL-13 concentration of both plasma and spleen in the CpG ODN treated group was higher than the allergic group. This finding may be caused by DNase degraded CpG ODN (34). Plasma and spleen IL-13 concentrations in the chitosan nanoparticles treated group were also higher than the allergy group. ...
Background:
This study aims to prepare high stability chitosan nanoparticles (CNP) and examine the ability of CNP in CpG-ODN delivery when treating allergic mice model.
Methods:
Preparation and characterization of CNP were performed by ionic gelation, dynamic light scattering, and zeta sizer. The CNP cytotoxicity and activation ability of CpG ODN delivered with CNP were tested using a cell counting kit-8 and Quanti blue method. Allergic mice were injected intraperitoneal with 10 ug ovalbumin on day 0 and 7, and then treated with intranasal CpG ODN/CpG ODN, delivered with CNP/CNP, on the third week three times per week for three weeks. The ELISA method measured cytokine and IgE profiles in the allergic mice's plasma and spleen.
Results:
CNP results have sizes 27.73 nm±3.67 dan 188.23 nm±53.47, spherical in shape and non-toxic, and did not alter the NF-κB activation of CpG ODN in RAW-blue cells. The application of CpG ODN delivered by chitosan nanoparticles shows no statistical difference between groups of IFN-γ, IL-10, and IL-13 in Balb/c mice's plasma and spleen, in contrast with IgE level.
Conclusions:
The results showed that using chitosan nanoparticles as a delivery system for CpG ODN has the potency to safely CpG ODN efficacy.
... Overall, it was shown that Class B CpG-ODNs induced IL-10 expression in both mammalian and avian macrophages. Additionally, Class C CpG-ODNs possess intermediate structural features between Class A CpG-ODNs, which have a CpG-containing palindromic motif, and Class B CpG-ODNs (Hanagata, 2012). Therefore, it was suggested that CpG-C 2395 , belonging to Class C CpG-ODN, may strongly induce IL-10 expression in HD11 cells because its structural features are similar to those of Class B CpG-ODN. ...
Unlabelled:
CpG-oligodeoxynucleotides (.
Cpg-odns:
) have been shown to possess immunostimulatory features in both mammals and birds. However, compared to their proinflammatory effects, little is known about the anti-inflammatory responses triggered by CpG-ODN in avian cells. Hence, in this study, the anti-inflammatory response in the chicken macrophage cell line HD11 was characterized under stimulation with five types of CpG-ODNs: CpG-A1585, CpG-AD35, CpG-B1555, CpG-BK3, and CpG-C2395. Single-stimulus of CpG-B1555, CpG-BK3, or CpG-C2395 induced interleukin (IL)-10 expression without causing cell injury. The effects of pretreatment with CpG-ODNs before subsequent lipopolysaccharide stimulation were also evaluated. Interestingly, pretreatment with only CpG-C2395 resulted in high expression levels of IL-10 mRNA in the presence of lipopolysaccharide. Finally, gene expression analysis of inflammation-related cytokines and receptors revealed that pre-treatment with CpG-C2395 significantly reduced the mRNA expression of tumor necrosis factor-α, IL-1β, IL-6, and Toll-like receptor 4. Overall, these results shed light on the anti-inflammatory responses triggered by CpG-C2395 stimulation through a comparative analysis of five types of CpG-ODNs in chicken macrophages. These results also offer insights into the use of CpG-ODNs to suppress the expression of proinflammatory cytokines, which may be valuable in the prevention of avian infectious diseases in the poultry industry.
... Oligodeoxynucleotides (ODNs) with cytosine-guanine dinucleotide (CpG) motifs have been considered potent immunostimulatory drugs (Klinman, 2004;Hanagata, 2012;Chuang et al., 2014). Nevertheless, ODNs have an unfavorable pharmacokinetic profile and adverse effects (Zhang et al., 2012;Zhang and Gao, 2017). ...
Virus-like nanoparticles (VLPs) are natural polymer-based nanomaterials that mimic viral structures through the hierarchical assembly of viral coat proteins, while lacking viral genomes. VLPs have received enormous attention in a wide range of nanotechnology-based medical diagnostics and therapies, including cancer therapy, imaging, and theranostics. VLPs are biocompatible and biodegradable and have a uniform structure and controllable assembly. They can encapsulate a wide range of therapeutic and diagnostic agents, and can be genetically or chemically modified. These properties have led to sophisticated multifunctional theranostic platforms. This article reviews the current progress in developing and applying engineered VLPs for molecular imaging, drug delivery, and multifunctional theranostics in cancer research.
... The phosphodiester backbone substituted by phosphorothioate can increase the enzymatic stability of CpG ODNs [21]. However, several side effects restrict the use of phosphorothioate-modified CpG ODNs, such as acute toxicity and nonspecific binding with proteins [22]. ...
Unmethylated cytosine-phosphate-guanosine oligodeoxynucleotides (CpG ODNs) induce inflammatory cytokines and type I interferons (IFNs) to activate the immune system. To apply CpG ODNs as vaccine adjuvants, the cellular uptake and stability of phosphodiester-based, non-modified ODNs require further improvement. Previously developed new CpG ODNs forming guanine-quadruplex (G4) structures showed higher nuclease resistance and cellular uptake than linear CpG ODNs; however, the complex formation of G4-CpG ODNs with antigen proteins is necessary for their application as vaccine adjuvants. In this study, we utilized a cationic polymer, ε-poly-L-lysine (ε-PLL), as a carrier for G4-CpG ODNs and antigen. The ε-PLL/G4-CpG ODN complex exhibited enhanced stability against nucleases. Cellular uptake of the ε-PLL/G4-CpG ODN complex positively correlated with the N/P ratio. In comparison to naked G4-CpG ODNs, the ε-PLL/G4-CpG ODN complex induced extremely high levels of interleukin (IL)-6, IL-12, and IFN-β. Relative immune cytokine production was successfully tuned by N/P ratio modification. Mice with the ε-PLL/G4-CpG ODN/ovalbumin (OVA) complex showed increased OVA-specific immunoglobulin (Ig)G, IgG1, and IgG2c levels, whereas total IgE levels did not increase and weight gain rates were not affected. Therefore, ε-PLL can serve as a safe and effective phosphodiester-based, non-modified CpG ODN delivery system, and the ε-PLL/G4-CpG ODN/antigen complex is a highly promising candidate for vaccine adjuvants and can be further used in clinical research.
... Based on how cfDNA affects the immune system, it is evident that many studies have been performed to find out what role the DNA-sensing pathway plays in inflammation, by generating and using synthetic ODN sequences. There are numerous subtypes of TLR9 activating/inhibitory synthetic ODNs [189,190]. Type-A CpG-ODNs frequently form large multimeric aggregates spontaneously and are consequently retained in the early endosomes of plasmacytoid dendritic cells (pDCs) for relatively long periods, resulting in the prolonged activation of the signal-transducing complex and the robust IFNα production. Type-B CpG-ODNs, in contrast, stay monomeric and are rapidly transported from early to late endosomes, making them potent B and NK cell stimulators. ...
The basic function of the immune system is the protection of the host against infections, along with the preservation of the individual antigenic identity. The process of self-tolerance covers the discrimination between self and foreign antigens, including proteins, nucleic acids, and larger molecules. Consequently, a broken immunological self-tolerance results in the development of autoimmune or autoinflammatory disorders. Immunocompetent cells express pattern-recognition receptors on their cell membrane and cytoplasm. The majority of endogenous DNA is located intracellularly within nuclei and mitochondria. However, extracellular, cell-free DNA (cfDNA) can also be detected in a variety of diseases, such as autoimmune disorders and malignancies, which has sparked interest in using cfDNA as a possible biomarker. In recent years, the widespread use of liquid biopsies and the increasing demand for screening, as well as monitoring disease activity and therapy response, have enabled the revival of cfDNA research. The majority of studies have mainly focused on the function of cfDNA as a biomarker. However, research regarding the immunological consequences of cfDNA, such as its potential immunomodulatory or therapeutic benefits, is still in its infancy. This article discusses the involvement of various DNA-sensing receptors (e.g., absent in melanoma-2; Toll-like receptor 9; cyclic GMP–AMP synthase/activator of interferon genes) in identifying host cfDNA as a potent danger-associated molecular pattern. Furthermore, we aim to summarize the results of the experimental studies that we recently performed and highlight the immunomodulatory capacity of cfDNA, and thus, the potential for possible therapeutic consideration.
