CpG Oligodeoxynucleotides Research Articles

Hybrid nanovesicles comprising induced pluripotent stem cells and dendritic cell-derived exosomes enhance antitumor immunity

Induced pluripotent stem cells (iPSCs) tailored to express tumor-specific antigens have emerged as a promising strategy for cancer immunoprevention. Despite the potential of this approach, a number of challenges remain to be addressed—such as ensuring that iPSCs are safely transported to immune-processing organs, mitigating the risk of oncogenesis, and increasing the degree of antitumor efficacy. To address these, we developed innovative vesicles that merge the antigenic repertoire of iPSCs with the lymph node homing and dendritic cell (DC)-targeting capabilities of DC-derived exosomes (DEXO), further boosted by the use of CpG oligodeoxynucleotides (CpG ODNs) as adjuvants. Our engineered vesicles are crafted to engage with immune system gatekeepers, streamlining the delivery of tumor antigens and priming T-cell responses. Laboratory analyses clarified their proficiency in terms of navigating to lymph nodes and initiating potent activation of both DCs and T-cells, thereby intensifying antitumor effects. Further tests in animal models corroborated their therapeutic potential, offering significant defense against tumor initiation, growth, spread, and recurrence, alongside significant enhancements in survival rates. Our findings indicate a promising pathway for innovative iPSC-based cancer vaccine therapies, laying a foundation for future clinical applications.

A laponite-based immunologically active gel delivery system for long-acting tumor vaccine

Traditional bolus vaccines typically require multiple doses, which complicates the vaccination process and may cause missed shots, leading to sub-optimal immunity and reduced vaccine effectiveness. Herein, a gel-based long-acting vaccine system with self-adjuvant properties based on laponite was constructed to simplify vaccination procedures and improve vaccine effectiveness. Firstly, the gel system could recruit multiple types of immune cells to form immune niches. Secondly, it could achieve sustained delivery of antigens to lymph nodes by active transport and passive drainage. Then, the gel system triggered the formation of a large number of germinal centers, which elicited enhanced and durable humoral immune responses, as well as strong cellular immune responses. As a result, it eventually showed good prophylactic and therapeutic effects in a variety of tumor models including melanoma, colorectal cancer and peritoneal metastasis models. By further combining the immunoadjuvant CpG ODN and cytokine IL-12, the effect of the gel-vaccine could be further enhanced. In a murine peritoneal metastasis model of colorectal carcinoma, a single administration of the gel-vaccine resulted in complete tumor eradication in 8/9 mice. In summary, this study developed an immunologically active gel-vaccine system. And as a robust and versatile vaccine platform, by loading different antigens and adjuvants, this gel-vaccine system is expected to realize its better therapeutic potential.

Bi-functional CpG-STAT3 decoy oligonucleotide triggers multilineage differentiation of acute myeloid leukemia in mice

Acute myeloid leukemia (AML) cells resist differentiation stimuli despite high expression of innate immune receptors, such as Toll-like receptor 9 (TLR9). We previously demonstrated that targeting Signal Transducer and Activator of Transcription 3 (STAT3) using TLR9-targeted decoy oligodeoxynucleotide (CpG-STAT3d) increases immunogenicity of human and mouse AML cells. Here, we elucidated molecular mechanisms of inv(16) AML reprogramming driven by STAT3-inhibition/TLR9-activation invivo. At the transcriptional levels, AML cells isolated from mice after intravenous administration of CpG-STAT3d or leukemia-targeted Stat3 silencing and TLR9 co-stimulation, displayed similar upregulation of myeloid cell differentiation (Irf8, Cebpa, Itgam) and antigen-presentation (Ciita, Il12a, B2m)-related genes with concomitant reduction of leukemia-promoting Runx1. Single-cell transcriptomics revealed that CpG-STAT3d induced multilineage differentiation of AML cells into monocytes/macrophages, erythroblastic and B cell subsets. As shown by an inducible Irf8 silencing invivo, IRF8 upregulation was critical for monocyte-macrophage differentiation of leukemic cells. TLR9-driven AML cell reprogramming was likely enabled by downregulation of STAT3-controlled methylation regulators, such as DNMT1 and DNMT3. In fact, the combination of DNA methyl transferase (DNMT) inhibition using azacitidine with CpG oligonucleotides alone mimicked CpG-STAT3d effects, resulting in AML cell differentiation, Tcell activation, and systemic leukemia regression. These findings highlight immunotherapeutic potential of bi-functional oligonucleotides to unleash TLR9-driven differentiation of leukemic cells by concurrent STAT3 and/or DNMT inhibition.

Additional use of α-IgM antibodies potentiates CpG ODN2006-induced B cell activation by targeting mainly naïve and marginal zone-like B cells

CpG ODN2006 is widely used as a potent B cell stimulant in vitro and in vivo. However, it shows a deficit in targeting naïve B cells in vitro. In this study, we investigated whether α-IgM can support ODN2006-induced effects on B cells to obtain enhanced activation with focus on different B cell subsets.Our results delineated robust B cell activation, shown by increased activation marker expression and cytokine secretion by each agent alone, and further augmented when used in combination. Interestingly, α-IgM targeted mainly naïve and marginal zone-like B cells, thus complementing the pronounced effects of ODN2006 on memory B cells and achieving optimal activation for all B cell subsets.Taken together, combining ODN2006 and α-IgM is beneficial for in vitro activation including all B cell subsets. Furthermore, our results suggest that α-IgM could enhance efficacy of ODN2006 in vivo with further need of investigation.

Antimetastatic effect of intratumoral Treg antagonists in mice with renal cancer.

The interplay of regulatory T cells (Tregs) within the tumour microenvironment presents a significant challenge in anticancer immunotherapy. This study investigates the potential of Treg blockade to enhance the efficiency of effector T cells. Two distinct treatment cocktails were examined: 3p-hpRNA (5' triphosphate hairpin RNA) combined with unmethylated CpG oligonucleotide (CpG); CpG in combination with OX40 receptor-specific monoclonal antibody (anti-OX40). Treatment efficacy was assessed using a murine model of kidney adenocarcinoma.Renca cells (renal cortical cells with adenocarcinoma) were subcutaneously engrafted in 30 BALB/c mice, then animals were allocated into three treatment groups: Group 1: CpG+anti-OX40, Group 2: CpG+3p-hpRNA, Group 3: untreated control. Treatment efficacy was evaluated based on tumour growth, the occurrence of metastases and overall survival.On day 28 post-implantation, experiments had to be terminated due to tumour progression. Although comparisons of survival times and primary tumour sizes thus became inconsequential, histological examinations provided valuable insights. We observed distinct variations in primary tumour characteristics among the different groups: Groups 1 and 2 displayed demarcations, while Group 3 exhibited diffuse tumours with necrosis. Lung metastases were evident in 70% of untreated mice, whereas none were observed in either of the treated groups.Our findings instil confidence in the potential efficacy of the treatments, thereby laying a solid foundation for future investigations.

Transcriptome and microRNAome elucidate the mechanism underlying the immunomodulatory effects of dietary CpG oligodeoxynucleotides (CpG ODNs) in Litopenaeus vannamei

Dietary supplementary of CpG oligodeoxynucleotides (CpG ODNs) could regulate the composition of gut microbiota and augment its immune function in Litopenaeus vannamei. However, the molecular mechanism of CpG ODNs remains poorly understood, particularly in the transcription level. In this study, transcriptome and microRNA sequencing were conducted to analyze the alterations of related genes and regulators in hepatopancreas of shrimp following the administration of CpG ODNs. The results revealed a total of 7820 differentially expressed genes (DEGs) and 573 differentially expressed miRNAs, indicating that the miRNAs targeted 1263 DEGs. These DEGs were found to be involved in the regulation of multiple immune-related signaling pathways, such as ubiquinone biosynthesis, folate biosynthesis, glutathione metabolism and alpha-linolenic acid metabolism, which were significantly enhanced upon stimulation with CpG ODNs. The pathway analysis of DEGs and differential miRNA target genes revealed significant alterations in the TGF-β signaling pathway, FoxO signaling pathway, mTOR signaling pathway, autophagy, lysosome function, ubiquitin-mediated proteolysis, and cytochrome P450 metabolism. It can be concluded that CpG ODNs induced activation of immune-related signaling pathways, thereby eliciting a robust immune response and augmenting overall immunity. These findings establish a robust theoretical framework for the practical implementation of CpG ODNs in the L. vannamei aquaculture industry.

Immune Responses and Protection Profiles in Mice Induced by Subunit Vaccine Candidates Based on the Extracellular Domain Antigen of Respiratory Syncytial Virus G Protein Combined with Different Adjuvants.

Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract disease of infants and older people. There is an urgent need for safe and effective vaccines against RSV infection. In this study, we analyzed the effects of the immune response and protection with the RSV recombinant G protein extracellular domain (Gecto) combined with various adjuvants as novel subunit vaccines in mice. All groups receiving RSV Gecto combined with adjuvants exhibited robust humoral and cellular immunity compared to those receiving an adjuvant alone or inactivated RSV vaccine. The greatest effect was observed in mice receiving Gecto combined with a CpG ODN + Alum salt adjuvant, resulting in the highest production of neutralizing antibodies against both RSV A and B subtypes, G-specific IgG and IFN-γ production in splenocytes, and interleukin-2 and interferon-γ expression in CD4+ T cells. Significant humoral and cellular immune responses were observed in mice immunized with Gecto combined with AddaS03™ or cyclosporin A adjuvants. The vaccine containing the AddaS03™ adjuvant showed significantly high expression of interleukin-4 in CD4+ T cells. Cross-protection against a challenge with either RSV A or B subtypes was observed in the Gecto plus adjuvant groups, resulting in a significant decrease in viral load and reduced pathological damage in the mouse lungs. These findings offer valuable insights into the development and application of recombinant RSV G-subunit vaccines with adjuvants.

Camptothecin-loaded mesoporous silica nanoparticles functionalized with CpG oligodeoxynucleotide as a new approach for skin cancer treatment

The therapeutic efficacy of camptothecin (CPT), a potent antitumor alkaloid, is hindered by its hydrophobic nature and instability, limiting its clinical use in treating cutaneous squamous cell carcinoma (SCC). This study introduces a novel nano drug delivery system (NDDS) utilizing functionalized mesoporous silica nanoparticles (FMSNs) for efficient CPT delivery. The FMSNs were loaded with CPT and subsequently coated with chitosan (CS) for enhanced stability and bioadhesion. Importantly, CpG oligodeoxynucleotide (CpG ODN) was attached onto the CS-coated FMSNs to leverage the immunostimulatory properties of CpG ODN, augmenting the chemotherapy’s efficacy. The final formulation FMSN-CPT-CS-CpG displayed an average size of 241 nm and PDI of 0.316 with an encapsulation efficiency of 95 %. Comprehensive in vitro and in vivo analyses, including B16F10 cells and DMBA/TPA-induced SCC murine model, demonstrated that the FMSN-CPT-CS-CpG formulation significantly enhanced cytotoxicity against B16F10 cells and induced complete regression in 40 % of the in vivo subjects, surpassing the efficacy of standard CPT and FMSN-CPT treatments. This study highlights the potential of combining chemotherapeutic and immunotherapeutic agents in an NDDS for targeted, efficient skin cancer treatment.

Oral biomimetic virus vaccine hydrogel for robust abscopal antitumour efficacy

Remarkable progress has been made in tumour immunotherapy in recent decades. However, the clinical outcomes of therapeutic interventions remain unpredictable, largely because of inefficient immune responses. To address this challenge and optimise immune stimulation, we present a novel administration route for enhancing the bioavailability of immunotherapeutic drugs. Our approach involves the development of an oral tumour vaccine utilising virus-like particles derived from the Hepatitis B virus core (HBc) antigen. The external surfaces of these particles are engineered to display the model tumour antigen OVA, whereas the interiors are loaded with cytosine phosphoguanosine oligodeoxynucleotide (CpG ODN), resulting in a construct called CpG@OVAHBc with enhanced antigenicity and immune response. For oral delivery, CpG@OVAHBc is encapsulated in a crosslinked dextran hydrogel called CpG@OVAHBc@Dex. The external hydrogel shield safeguards the biomimetic virus particles from degradation by gastric acid and proteases. Upon exposure to intestinal flora, the hydrogel disintegrates, releasing CpG@OVAHBc at the intestinal mucosal site. Owing to its virus-like structure, CpG@OVAHBc exhibits enhanced adhesion to the mucosal surface, facilitating uptake by microfold cells (M cells) and subsequent transmission to antigen-presenting cells. The enzyme-triggered release of this oral hydrogel ensures the integrity of the tumour vaccine within the digestive tract, allowing targeted release and significantly improving bioavailability. Beyond its efficacy, this oral hydrogel vaccine streamlines drug administration, alleviates patient discomfort, and enhances treatment compliance without the need for specialised injection methods. Consequently, our approach expands the horizons of vaccine development in the field of oral drug administration.

A rapid strategy to develop personalized cancer nanovaccines for different immunogenic tumors.

e14670 Background: Therapeutic cancer vaccines aim to train the immune system and elicit antitumor immune responses, which are expected to fill the unmet medical need of immune checkpoint inhibitors. Despite tremendous efforts over the past decades, it remains challenging to prepare personalized cancer vaccines using a facile and rapid approach due to tumor diversity. CpG-ODN is a promising immunoadjuvant in cancer immunotherapy, and many clinical trials have been performed or are ongoing. However, commonly used phosphorothioate-modified CpG ODN easily induces protein aggregation and its long-term side effects are concerned. Here, we designed hollow large-pore mesoporous organosilica with sulfide bond to simultaneously load unmodified CpG-ODN with guanine-quadruplex (G4) structures and different tumor antigens to prepare personalized cancer vaccines in a simple, fast, and effective way. Methods: High-immunogenicE.G7-OVA lymphoma or low-immunogenic Lewis lung carcinoma (LLC) cells were subcutaneously inoculated into the left flanks to establish tumor-bearing mice. On days 4, 7, and 10 post tumor inoculation, cancer vaccines prepared using model antigen (OVA) or autologous tumor antigen (LLC tumor cell lysate) were subcutaneously injected into the right flanks of mice, respectively. Saline group, free tumor antigen group, free tumor antigen + CpG-ODN group, tumor antigen + organosilica group were used as controls. The size of tumors was monitored. Results: Cancer vaccines against E.G7-OVA showed high loading efficiencies of >95% for both CpG-ODN and OVA, triggered antitumor immune response with high percentages of CD4+, CD8+, tetramer+CD8+ T cells in splenocytes, and effectively inhibited the growth of established tumor, compared with free OVA, free OVA + CpG-ODN, free OVA + organosilica groups. Cancer vaccines against LLC exhibited high loading efficiencies of >95% and >80% for CpG-ODN and LLC tumor cell lysate, activated antitumor immune response with high percentages of CD4+ and CD8+ T cells in splenocytes and CD8+ T, NK and M1 cells in tumor sites, and effectively inhibited the growth of established tumor, compared with control groups. Conclusions: Codelivery of CpG-ODN and different tumor antigens using hollow large-pore mesoporous organosilica elicits antitumor immunity against both high-immunogenic and low-immunogenic tumors.

An emerging antibacterial nanovaccine for enhanced chemotherapy by selectively eliminating tumor-colonizing bacteria

Fusobacterium nucleatum (F. nucleatum), an oral anaerobe, is prevalent in colorectal cancer and is closely related to increased cancer cell growth, metastasis, and poor treatment outcomes. Bacterial vaccines capable of selectively eliminating bacteria present a promising approach to targeting intratumor F. nucleatum, thereby enhancing cancer treatment. Although adjuvants have been employed to enhance the immune response, the vaccine’s effectiveness is constrained by inadequate T-cell activation necessary for eradicating intracellular pathogens. In this study, we developed a minimalistic, biomimetic nanovaccine by integrating highly immunostimulatory adjuvant cholesterol-modified CpG oligonucleotides into the autologously derived F. nucleatum membranes. Compared to the traditional vaccines consisting of inactivated bacteria and Alum adjuvant, the nanovaccine coupled with bacterial membranes and adjuvants could remarkably improve multiple antigens and adjuvant co-delivery to dendritic cells, maximizing their ability to achieve effective antigen presentation and strong downstream immune progress. Notably, the nanovaccine exhibits outstanding selective prophylactic and therapeutic effects, eliminating F. nucleatum without affecting intratumoral and gut microbiota. It significantly enhances chemotherapy efficacy and reduces cancer metastasis in F. nucleatum-infected colorectal cancer. Overall, this work represents the rational application of bacterial nanovaccine and provides a blueprint for future development in enhancing the antitumor effect against bacterial-infected cancer.

Gum Arabic Increases Phagocytosis of Escherichia coli by Blood Leukocytes of Young and Old Healthy Volunteers.

Gum arabic, a polysaccharide exudate from Acacia senegal (L.) Willdenow trees, has already been used by African native people in natural medicine. Using whole-blood samples from young (20-35 years) and older (>80 years) healthy volunteers (each group n = 10), the effect of an aqueous solution of GA on phagocytosis of Escherichia coli was examined with a gentamicin protection assay. Whole-blood samples of each volunteer were stimulated with GA and as a control with CpG oligodeoxynucleotides (Toll-like receptor -9 agonists) for 2 h, then co-incubated with E. coli for 30 min and thereafter treated with gentamicin for up to 240 min to kill extracellular bacteria. Then, whole-blood cells were lysed with distilled water, and colony-forming units were counted by quantitative plating. Cytokine enzyme-linked immunosorbent assay for the detection of TNF-α and IL-6 was performed using the blood supernatant. The GA concentration tested (20 mg/mL) did not affect the viability of eukaryotic cells. Phagocytosis of E. coli by whole-blood leukocytes derived from young (p = 0.008) and older (p = 0.004) healthy volunteers was increased by 120.8% (young) and 39.2% (old) after stimulation with GA. In contrast, CpG only stimulated the bacterial phagocytosis by cells derived from young volunteers (p = 0.004). Stimulation of whole blood with GA increased the intracellular killing of E. coli in young (p = 0.045) and older volunteers (p = 0.008) and induced a TNF-α release in whole blood collected from older volunteers but not from younger ones (p = 0.008). These data encourage the isolation of active compounds of GA and the initiation of clinical trials addressing the preventive effect of GA on bacterial infections.

Tumor-Targeted Codelivery of CpG and siRNA by a Dual-Ligand-Functionalized Curdlan Nanoparticle.

The simultaneous delivery of CpG oligonucleotide along with short interfering RNA (siRNA) has the potential to significantly boost the anticancer impact of siRNA medications. Our previous research demonstrated that Curdlan nanoparticles functionalized with adenosine are capable of selectively delivering therapeutic siRNA to cancerous cells through endocytosis mediated by adenosine receptors. Herein, we synthesized a dual-ligand-functionalized Curdlan polymer (denoted by CuMAN) to simultaneously target tumor cells and tumor-associated macrophages (TAMs). CuMAN nanoparticles containing CpG and siRNA demonstrated enhanced uptake by B16F10 tumor cells and bone marrow-derived macrophages, which are facilitated by AR on tumor cells and mannose receptor on macrophages. This led to increased release of pro-inflammatory cytokines in both in vitro and in vivo settings. The synergistic effect of CpG on TAMs and RNAi on tumor cells mediated by the CuMAN nanoparticle not only suppressed the tumor growth but also strongly inhibited the lung metastasis. Our findings indicate that the CuMAN nanoparticle has potential as an effective dual-targeting delivery system for nucleic acid therapeutics.

A Tumor Environment-Activated Photosensitized Biomimetic Nanoplatform for Precise Photodynamic Immunotherapy of Colon Cancer.

Aggressive nature of colon cancer and current imprecise therapeutic scenarios simulate the development of precise and effective treatment strategies. To achieve this, a tumor environment-activated photosensitized biomimetic nanoplatform (PEG2000-SiNcTI-Ph/CpG-ZIF-8@CM) is fabricated by encapsulating metal-organic framework loaded with developed photosensitizer PEG2000-SiNcTI-Ph and immunoadjuvant CpG oligodeoxynucleotide within fusion cell membrane expressing programmed death protein 1 (PD-1) and cluster of differentiation 47 (CD47). By stumbling across, systematic evaluation, and deciphering with quantum chemical calculations, a unique attribute of tumor environment (low pH plus high concentrations of adenosine 5'-triphosphate (ATP))-activated photodynamic effect sensitized by long-wavelength photons is validated for PEG2000-SiNcTI-Ph/CpG-ZIF-8@CM, advancing the precision of cancer therapy. Moreover, PEG2000-SiNcTI-Ph/CpG-ZIF-8@CM evades immune surveillance to target CT26 colon tumors in mice mediated by CD47/signal regulatory proteins α (SIRPα) interaction and PD-1/programmed death ligand 1 (PD-L1) interaction, respectively. Tumor environment-activated photodynamic therapy realized by PEG2000-SiNcTI-Ph/CpG-ZIF-8@CM induces immunogenic cell death (ICD) to elicit anti-tumor immune response, which is empowered by enhanced dendritic cells (DC) uptake of CpG and PD-L1 blockade contributed by the nanoplatform. The photodynamic immunotherapy efficiently combats primary and distant CT26 tumors, and additionally generates immune memory to inhibit tumor recurrence and metastasis. The nanoplatform developed here provides insights for the development of precise cancer therapeutic strategies.

Improvement of the Nuclease Resistance and Immunostimulatory Activity of CpG Oligodeoxynucleotides by Conjugation to Sugar-Immobilized Gold Nanoparticles.

Adjuvants are essential substances for vaccines and immunotherapies that enhance antigen-specific immune responses. Single-stranded oligodeoxynucleotides containing an unmethylated CpG motif (CpG ODNs) are agonistic ligands for toll-like receptor 9 that initiate an innate immune response. They represent promising adjuvants for antiviral and antitumor immunotherapies; however, CpG ODNs have some limitations, such as poor nuclease resistance and low cell membrane permeability. Therefore, an effective formulation is needed to improve the nuclease resistance and immunostimulatory effects of CpG ODNs. Previously, we demonstrated the selective delivery of a small molecule toll-like receptor 7 ligand to immune cells through sugar-binding receptors using sugar-immobilized gold nanoparticles (SGNPs), which significantly enhanced the potency of the ligand. In this study, we examined SGNPs as carriers for partially phosphorothioated A-type CpG ODN (D35) and an entirely phosphorothioated B-type CpG ODN (K3) and evaluated the functionality of the sugar moiety on SGNPs immobilized with CpG ODN. SGNPs immobilized with D35 (D35-SGNPs) exhibited improved nuclease resistance and the in vitro and in vivo potency was significantly higher compared with that of unconjugated D35. Furthermore, the sugar structure on the GNPs was a significant factor in enhancing the cell internalization ability, and enhanced intracellular delivery of D35 resulted in improving the potencies of the A-type CpG ODN, D35. SGNPs immobilized with K3 (K3-SGNPs) exhibited significantly higher induction activities for both humoral and cellular immunity compared with unconjugated K3 and D35-SGNPs. On the other hand, sugar structure on K3-SGNPs did not affect the immunostimulatory effects. These results indicate that the sugar moiety on K3-SGNPs primarily functions as a hydrophilic dispersant for GNPs and the formulation of K3 to SGNPs contributes to improving the immunostimulatory activity of K3. Because our CpG ODN-SGNPs have superior induction activities for antigen-specific T-cell mediated immune responses, they may be effective adjuvants for vaccines and immunotherapies.

A novel chimeric vaccine containing multiple epitopes for simulating robust immune activation against Klebsiella pneumoniae

BackgroundDue to antibiotic resistance, the Klebsiella genus is linked to morbidity and death, necessitating the development of a universally protective vaccine against Klebsiella pathogens.MethodsCore sequence analysis prioritized non-redundant host molecules and expected lipid bilayer peptides from fully sequenced Klebsiella genomes. These proteins were refined to identify epitopes, examining their immunogenicity, toxicity, solubility, and interaction with MHC alleles. Epitopes were linked to CPG ODN C274 via EAAAK, HEYGAEALERAG, and GGGS linkers to enhance immunological responses. The vaccine’s tertiary structure was modelled and docked with MHC-I and MHC-II.ResultsFifty-five proteins were recognized in the Vaxign collection as having remarkable features. Twenty-three proteins with potential pathogenicity were then identified. Eight options for vaccines emerged after the immunogenicity of proteins was examined. The best antigens were three proteins: MrkD, Iron-regulated lipid membrane polypeptides, and RmpA. These compounds were selected for their sensitivity. The structural protein sequences of K. pneumoniae were utilized to identify seven CTL epitopes, seven HTL epitopes, and seven LBL epitopes, respectively. The produced immunization displayed a stable contact with the receptors, based on molecular dynamic simulations lasting 250 nanoseconds. Intermolecular binding free energies also indicated the dominance of the van der Waals and electrostatic energies.ConclusionIn summary, the results of this study might help scientists develop a novel vaccine to prevent K. pneumoniae infections.

Co-administration of a Hepatitis B vaccine with CpG-ODN 2395 induces stronger immune response in BALB/c mice

Background Proof of effects of Cytosine Phosphoguanine Oligodeoxynucleotides (CpG ODNs), adjuvanted Hepatitis B Virus (HBV) vaccine on immune response is limited. This study aimed to assess the effect of five CpG ODNs in HBV Vaccine-immunized BALB/c mice and to identify the most effective CpG ODN adjuvant. Methods This laboratory-based experimental study was conducted using a total of 36 female BALB/c mice, which were clustered into 12 groups and immunized intramuscularly. Group 1 was immunized with CpG ODN 18281-1 alone, group 2 with vaccine plus CpG ODN 18281-1, group 3 with CpG ODN 18281-2 alone, group 4 with CpG ODN 18281-2 plus vaccine, group 5 CpG ODN 18289 alone, group 6 with CpG ODN 18289 plus vaccine, group 7 CpG ODN 1826 S alone, group 8 with CpG ODN 1826 S plus vaccine, group 9 CpG ODN 2395 alone, group 10 with CpG ODN 2395 plus vaccine, group 11 with vaccine alone and group 12 with Phosphate Buffer Saline (PBS). All the groups were observed for 14 and 28 days after immunization. Results In the vaccinated groups, those receiving supplementation with CpG 2395 exhibited a significant 4.4-fold elevation, resulting in a signal-to-noise ratio (S/N) value of 14.1 compared to the vaccine group only (S/N = 3.22) by day 28 (p-value < 0.0001). For mice immunized with the vaccine plus CpG ODNs, cytokine profiling using real-time quantitative polymerase chain reaction revealed increased IL-6 expression levels and decreased TNF-α levels compared to the untreated group, normalized with the housekeeping gene HPRT 1. However, the expression of IL-6 and TNF-α was not statistically significant between the treated groups (p-value ≥ 0.2). Parameters for toxicity were within the normal range in all treatment groups. Conclusion Based on these results the co-administration of the HBV vaccine with CpG ODN 2395 induces high immune responses in comparison to HBV vaccine alone.

Surface charge-dependent cytokine production using near-infrared emitting silicon quantum dots

Toll-like receptor 9 (TLR-9) is a protein that helps our immune system identify specific DNA types. Upon detection, CpG oligodeoxynucleotides signal the immune system to generate cytokines, essential proteins that contribute to the body’s defence against infectious diseases. Native phosphodiester type B CpG ODNs induce only Interleukin-6 with no effect on interferon-α. We prepared silicon quantum dots containing different surface charges, such as positive, negative, and neutral, using amine, acrylate-modified Plouronic F-127, and Plouronic F-127. Then, class B CpG ODNs are loaded on the surface of the prepared SiQDs. The uptake of ODNs varies based on the surface charge; positively charged SiQDs demonstrate higher adsorption compared to SiQDs with negative and neutral surface charges. The level of cytokine production in peripheral blood mononuclear cells was found to be associated with the surface charge of SiQDs prior to the binding of the CpG ODNs. Significantly higher levels of IL-6 and IFN-α induction were observed compared to neutral and negatively charged SiQDs loaded with CpG ODNs. This observation strongly supports the notion that the surface charge of SiQDs effectively regulates cytokine induction.

Core-shell nanomedicine based on multifunctional tetrahedral DNA nanostructures for synergistic enhancement of tumor chemodynamic/chemo-immunotherapy

Immune checkpoint blockade therapy has made great strides in cancer treatment, but conventional immune checkpoint blockade antibodies often lead to overactivation of the immune system and severe immune-related adverse effects. Herein, we report the design of a nanomedicine (denoted as CPD@M−TDN) based on multifunctional tetrahedral DNA nanostructures (M−TDN). In this system, a bimetallic metal–organic framework (Cu/ZIF-8) is synthesized as the core; doxorubicin-loaded polydopamine acts as a shell to reduce the immunogenicity of the nanomaterials in peripheral blood. Finally, the CpG oligodeoxynucleotides and PD-L1 aptamer-based M−TDN are coupled to the core–shell structure nanomedicine through the biotin-avidin-system. Under the acidic tumor microenvironment, the decomposition of Cu/ZIF-8 and the release of copper ions and doxorubicin can lead to immunogenic death of tumor cells through chemodynamic/chemotherapy. Furthermore, the M−TDN has the dual effects of weakening the immunosuppressive microenvironment with PD-L1 aptamer and promoting dendritic cell activation with the immunostimulant CpG. Overall, the developed CPD@M−TDN can effectively enhance the response rate to immunotherapy and has excellent potential in the field of integrated tumor treatment.

The orientation of CpG conjugation on aluminum oxyhydroxide nanoparticles determines the immunostimulatory effects of combination adjuvants

In subunit vaccines, aluminum salts (Alum) are commonly used as adjuvants, but with limited cellular immune responses. To overcome this limitation, CpG oligodeoxynucleotides (ODNs) have been used in combination with Alum. However, current combined usage of Alum and CpG is limited to linear mixtures, and the underlying interaction mechanism between CpG and Alum is not well understood. Thus, we propose to chemically conjugate Alum nanoparticles and CpG (with 5′ or 3′ end exposed) to design combination adjuvants. Our study demonstrates that compared to the 3′-end exposure, the 5′-end exposure of CpG in combination adjuvants (Al-CpG-5′) enhances the activation of bone-marrow derived dendritic cells (BMDCs) and promotes Th1 and Th2 cytokine secretion. We used the SARS-CoV-2 receptor binding domain (RBD) and hepatitis B surface antigen (HBsAg) as model antigens to demonstrate that Al-CpG-5′ enhanced antigen-specific antibody production and upregulated cytotoxic T lymphocyte markers. Additionally, Al-CpG-5′ allows for coordinated adaptive immune responses even at lower doses of both CpG ODNs and HBsAg antigens, and enhances lymph node transport of antigens and activation of dendritic cells, promoting Tfh cell differentiation and B cell activation. Our novel Alum-CPG strategy points the way towards broadening the use of nanoadjuvants for both prophylactic and therapeutic vaccines.