Nasal delivery of Japanese cedar pollen Cryj1 by using self-gelling immunostimulatory DNA for effective induction of immune responses in mice

Intradermal delivery of Cryj1 loaded in CpG DNA hydrogel for inhibiting allergic reactions in mice

Immunotherapy for allergic rhinitis alleviates symptoms associated with antigen exposure by administering pathogenic antigens. However, many current immunotherapies fail to induce sufficient immune responses, resulting in frequent and prolonged hospital visits. Consequently, the development of more effective immunotherapies is necessary. In this study, we focused on the skin, which is rich in immune cells, as an administration site for inducing antigen-specific immune responses. To efficiently and sustainably deliver the cedar pollen antigen Cryj1 to immune cells, we attempted to load Cryj1 in an immunostimulatory CpG DNA hydrogel, prepared using self-gelatinizable nucleic acid technology. In this technology, the hydrogel became gelatinized by self-assembly of multiple predesigned DNA units containing potent CpG motifs. Cryj1 loaded in the CpG DNA hydrogel showed sustained release, was taken up by mouse macrophage-like RAW264.7 and mouse dendritic DC2.4 cells, and induced efficient production of interleukin-12 after intradermal injection into mice. Intradermal injection of Cryj1 loaded CpG DNA hydrogel into mice increased the production of Cryj1-specific IgG while suppressing the production of immunoglobulin E (IgE) antibodies. Furthermore, when Cryj1 was resensitized to mice, a stronger induction of IgG production and suppression of IgE production was observed. These results suggest that intradermal administration of Cryj1 loaded CpG DNA hydrogel is a novel immunotherapy for allergic symptoms caused by cedar pollen and can be used as a replacement for current immunotherapies.

Development of allergic rhinitis immunotherapy using antigen-loaded small extracellular vesicles

Allergic rhinitis is caused by a breakdown of the Th1/Th2 balance, in which the allergen-induced Th2 immune response predominates over the Th1 immune response, culminating in IgE-mediated anaphylaxis. In this study, we used small extracellular vesicles (sEVs), cell-derived membrane vesicles with a particle size of 100 nm, as simultaneous delivery carriers for allergens (ovalbumin, OVA) and CpG DNA, an adjuvant that can induce a Th1 immune response, for the treatment of allergic rhinitis. sEVs loaded with CpG DNA and OVA(CpG-OVA-sEVs) were successfully prepared. CpG-OVA-sEVs possessed an average particle size of 90 nm and average zeta potential of -30 mV. CpG DNA modification did not influence the uptake of sEVs by dendritic cells and CpG-OVA-sEV can activate dendritic cells. The CpG-OVA-sEVs were delivered to the nasopharynx-associated lymphoid tissue (NALT) of mice and were primarily taken up by the CD11c positive cells after intranasal administration. Intranasally administering CpG-OVA-sEVs significantly enhanced OVA-specific IgG antibody titers in mice models of allergic rhinitis, suggesting a transformed Th1/2 balance. Moreover, The CpG-OVA-sEV administration alleviated allergic symptoms compared to the control group. Further, the amount of IgE secreted in mouse serum decreased. Thus, CpG-OVA-sEVs could be a useful therapeutic method for treating allergic rhinitis.

Development of orally-deliverable DNA hydrogel by microemulsification and chitosan coating

Self-gelling DNA hydrogels with cytosine-phosphate-guanine (CpG) motifs have been shown to exhibit high potency as vaccine adjuvants. However, their oral use is limited because of their thermodynamic and chemical instability in the gastrointestinal tract. In this study, we aimed to develop DNA hydrogel microspheres (Dgel-MS) coated with chitosan to improve their stability. Chitosan-coated Dgel-MS (Cs-Dgel-MS) was prepared by emulsifying Dgel to obtain the D-gel core, followed by mixing with microemulsions of chitosan for electrostatic coating. Fluorescence imaging of Cs-Dgel-MS labeled with fluorescent dyes showed that Dgel-MS (approximately 30 μm) was coated with chitosan. The recovery efficiency of Alexa Fluor 488-DNA was 87.4 ± 7.5%. To load a phosphorothioate CpG oligodeoxynucleotide into Dgel, a modified Dgel (mDgel) was designed and fluorescein isothiocyanate (FITC)-dextran was loaded into Cs-mDgel-MS as a model compound. The recovery efficiency of Alexa Fluor 488-CpG1668 and FITC-dextran was 83.3 ± 3.8% and 67.8 ± 4.6%, respectively. The release of Alexa Fluor 488-CpG1668 from Cs-mDgel-MS was slower than that from mDgel under acidic or DNase conditions. Intra-duodenal administration of FITC-dextran/Cs-mDgel-MS showed prolonged intestinal transition of the encapsulated FITC-dextran. These results indicate that Cs-Dgel-MS can be useful for oral delivery of CpG DNA and other bioactive compounds.

CpG oligodeoxynucleotide nanomedicines for the prophylaxis or treatment of cancers, infectious diseases, and allergies

Unmethylated cytosine-guanine dinucleotide-containing oligodeoxynucleotides (CpG ODNs), which are synthetic agonists of Toll-like receptor 9 (TLR9), activate humoral and cellular immunity and are being developed as vaccine adjuvants to prevent or treat cancers, infectious diseases, and allergies. Free CpG ODNs have been used in many clinical trials implemented to verify their effects. However, recent research has reported that self-assembled CpG ODNs, protein/peptide–CpG ODN conjugates, and nanomaterial–CpG ODN complexes demonstrate higher adjuvant effects than free CpG ODNs, owing to their improved uptake efficiency into cells expressing TLR9. Moreover, protein/peptide–CpG ODN conjugates and nanomaterial–CpG ODN complexes are able to deliver CpG ODNs and antigens (or allergens) to the same types of cells, which enables a higher degree of prophylaxis or therapeutic effect. In this review, the author describes recent trends in the research and development of CpG ODN nanomedicines containing self-assembled CpG ODNs, protein/peptide–CpG ODN conjugates, and nanomaterial–CpG ODN complexes, focusing mainly on the results of preclinical and clinical studies.

Interaction between DNA and Drugs Having Protonable Basic Groups: Characterization through Affinity Constants, Drug Release Kinetics, and Conformational Changes

This paper reports the in vitro characterization of the interaction between the phosphate groups of DNA and the protonated species of drugs with basic groups through the determination of the affinity constants, the reversibility of the interaction, and the effect on the secondary structure of the macromolecule. Affinity constants of the counterionic condensation DNA–drug were in the order of 10⁶. The negative electrokinetic potential of DNA decreased with the increase of the proportion of loading drugs. The drugs were slowly released from the DNA–drug complexes and had release kinetics consistent with the high degree of counterionic condensation. The circular dichroism profile of DNA was not modified by complexation with atenolol, lidocaine, or timolol, but was significantly altered by the more lipophilic drugs benzydamine and propranolol, revealing modifications in the secondary structure of the DNA. The in vitro characterization of such interactions provides a physicochemical basis that would contribute to identify the effects of this kind of drugs in cellular cultures, as well as side effects observed under their clinical use. Moreover, this methodology could also be projected to the fields of intracellular DNA transfection and the use of DNA as a carrier of active drugs.

Intranasal administration of CpG oligodeoxynucleotides reduces lower airway inflammation in a murine model of combined allergic rhinitis and asthma syndrome

Given the relationship between allergic rhinitis (AR) and asthma, it can be hypothesized that reducing upper airway inflammation by targeting oligodeoxynucleotides with CpG motifs (CpG-ODN) specifically to the upper airway via intranasal administration in a small volume (10 μL) might improve lower airway (asthma) outcomes. The goal of this study was to investigate the therapeutic efficacy of 10 μL of intranasal versus intradermal administration of CpG-ODN in suppressing lower airway inflammation and methacholine-induced airway hyperreactivity (AHR) in mice subjected to ovalbumin (OVA)-induced combined allergic rhinitis and asthma syndrome (CARAS). OVA-sensitized BALB/c mice were subjected to upper-airway intranasal OVA exposure three times per week for 3 weeks. Then, CpG-ODN was administered to a subset of these mice 1h after intranasal OVA exposure, followed by five days of OVA aerosol challenges, thereby targeting OVA to the lower airways. Immunologic variables and nasal symptoms were evaluated. The results showed that the CARAS mice exhibited significant increases in bronchoalveolar lavage fluid (BALF) and splenocytes Th2-associated cytokine production, OVA-specific serum IgE, and AHR, as well as nose and lung pathologies. Intranasal administration of CpG-ODN significantly reduced Th2-associated cytokine production, the percentage of eosinophils in the BALF, the IL-4 and IL-5 concentrations in the supernatants of cultured OVA-challenged splenic lymphocytes, the serum OVA-specific IgE levels, the peribronchial inflammation score in the lungs, and the severity of nose pathology and nasal symptoms. However, intradermal administration of CpG-ODN did not significantly reduce the aforementioned parameters. In conclusion, intranasal treatment with CpG-ODN attenuated AR and significantly alleviated lower airway inflammation and AHR in the CARAS model. CpG-ODN therapy was more effective when administered intranasally than when administered intradermally. The current study supports the development of CpG-ODN nasal spray as a novel therapeutic agent for CARAS.