Drug-Loaded Liposomal Spherical Nucleic Acid as an Effective Cancer Nanovaccine

Background: Cancer nanovaccine has become a promising approach for cancer immunotherapy. The major challenge of cancer vaccines is limited efficacy caused by lack of desirable tumor specific antigens (TSA). Chemotherapeutics can trigger immunogenic cell death (ICD) and release TSAs, which initiate tumor-specific immune responses. However, ICD-triggered immune responses are usually not potent enough to eliminate the tumor cells. Herein, we developed liposomal spherical nucleic acids (SNA) that can simultaneously deliver and release doxorubicin (DOX) and CpG oligonucleotides upon biological stimuli in tumors to augment antitumor immune responses. Results: SNA nanoparticle increased DOX accumulation at the tumor tissue to induce tumor cells apoptosis and autophagy to activate both ICD-triggered and autophagy-mediated Th1-type immune responses. Meanwhile, CpG, which was co-delivered with DOX, functioned synergistically to potentiate the antitumor immune responses. These nanoparticles effectively inhibited tumor growth and extended animal survival of a mouse lymphoma model. Conclusions: This work provided a simple strategy of delivering chemotherapeutics and adjuvants to tumors to improve immunotherapeutic efficacy of nanovaccines.

The Recognition of and Reactions to Nucleic Acid Nanoparticles by Human Immune Cells

The relatively straightforward methods of designing and assembling various functional nucleic acids into nanoparticles offer advantages for applications in diverse diagnostic and therapeutic approaches. However, due to the novelty of this approach, nucleic acid nanoparticles (NANPs) are not yet used in the clinic. The immune recognition of NANPs is among the areas of preclinical investigation aimed at enabling the translation of these novel materials into clinical settings. NANPs’ interactions with the complement system, coagulation systems, and immune cells are essential components of their preclinical safety portfolio. It has been established that NANPs’ physicochemical properties—composition, shape, and size—determine their interactions with immune cells (primarily blood plasmacytoid dendritic cells and monocytes), enable recognition by pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs) and RIG-I-like receptors (RLRs), and mediate the subsequent cytokine response. However, unlike traditional therapeutic nucleic acids (e.g., CpG oligonucleotides), NANPs do not trigger a cytokine response unless they are delivered into the cells using a carrier. Recently, it was discovered that the type of carrier provides an additional tool for regulating both the spectrum and the magnitude of the cytokine response to NANPs. Herein, we review the current knowledge of NANPs’ interactions with various components of the immune system to emphasize the unique properties of these nanomaterials and highlight opportunities for their use in vaccines and immunotherapy.

Immunostimulatory CpG Oligonucleotides as an Adjuvant with Recombinant DNA Vaccine Encoding Hepatitis C Virus Core Protein

The immunogenicity and protective efficacy of DNA vaccines have been amply demonstrated in numerous animal models against infectious diseases. In order to increase the potency of DNA vaccines, we have compared the immune response of conventional adjuvants such as aluminum phosphates, Dendrosome, CpG motif and mixture of aluminum phosphate and CpG motif. Female BALB/c mice were immunized with 10, 25 and 50 microgram of HCV core pcDNA3 plasmid mixed with the adjuvants. Each dose of recombinant pcDNA3 and different adjuvant were used as an immunogen in three IM injection periods. Blood samples were collected at four different times. The data indicate that the antibody response achieved following DNA immunization can be enhanced by CpG motif as molecular adjuvant

A nucleic acid nanogel dually bears siRNA and CpG motifs for synergistic tumor immunotherapy

Immune system plays a key role in restraining the tumor progression. Therefore, enhancing immune functions using immune stimulants, such as unmethylated CpG oligonucleotides, have emerged as a promising strategy for...

The cryo-EM structure of the endocytic receptor DEC-205

DEC-205 (CD205), a member of the macrophage mannose receptor protein family, is the prototypic endocytic receptor of dendritic cells, whose ligands include phosphorothioated cytosine-guanosine (CpG) oligonucleotides, a motif often seen in bacterial or viral DNA. However, despite growing biological and clinical significance, little is known about the structural arrangement of this receptor or any of its family members. Here we describe the 3.2 Å cryo-EM structure of human DEC-205, thereby illuminating the structure of the mannose receptor protein family. The DEC-205 monomer forms a compact structure comprising two intercalated rings of C-type lectin-like domains, where the N-terminal cysteine-rich and fibronectin domains reside at the central intersection. We establish a pH dependant oligomerisation pathway forming tetrameric DEC-205 using solution-based techniques and ultimately solved the 4.9 Å cryo-EM structure of the DEC-205 tetramer to identify the unfurling of the second lectin ring which enables tetramer formation. Furthermore, we suggest the relevance of this oligomerisation pathway within a cellular setting, whereby CpG binding appeared to disrupt this cell-surface oligomer. Accordingly, we provide insight into the structure and oligomeric assembly of the DEC-205 receptor.

Biomaterial-based scaffold for in situ chemo-immunotherapy to treat poorly immunogenic tumors

Poorly immunogenic tumors, including triple negative breast cancers (TNBCs), remain resistant to current immunotherapies, due in part to the difficulty of reprogramming the highly immunosuppressive tumor microenvironment (TME). Here we show that peritumorally injected, macroporous alginate gels loaded with granulocyte-macrophage colony-stimulating factor (GM-CSF) for concentrating dendritic cells (DCs), CpG oligonucleotides, and a doxorubicin-iRGD conjugate enhance the immunogenic death of tumor cells, increase systemic tumor-specific CD8 + T cells, repolarize tumor-associated macrophages towards an inflammatory M1-like phenotype, and significantly improve antitumor efficacy against poorly immunogenic TNBCs. This system also prevents tumor recurrence after surgical resection and results in 100% metastasis-free survival upon re-challenge. This chemo-immunotherapy that concentrates DCs to present endogenous tumor antigens generated in situ may broadly serve as a facile platform to modulate the suppressive TME, and enable in situ personalized cancer vaccination.

Phosphate-modified CpG oligonucleotides induce in vitro maturation of human myeloid dendritic cells

Myeloid dendritic cells (DCs) play an important role in the immune response; therefore, the search for compounds that can effectively activate DCs is a needful goal. This study was aimed to investigate the effect of synthetic CpG oligodeoxynucleotides (CpG-ODN) on the maturation and allostimulatory activity of myeloid DCs in comparison with other PAMP and DAMP molecules. For the research, we synthesized known CpG-ODN class C (SD-101 and D-SL03) containing thiophosphate internucleotide groups, and their original phosphate-modified analogues (SD-101M and D-SL03M) with mesylphosphoramide internucleotide groups (M = μ-modification). The effects of CpG-ODN and other activators were evaluated on DCs generated from blood monocytes in the presence of GM-CSF and IFN-α (IFN-DC) or IL-4 (IL4-DC). Evaluation of the intracellular TLR-9 expression showed that both types of DCs (IFN-DC and IL4-DC) contained on average 52 and 80 % of TLR-9-positive cells, respectively. The CpG-ODNs studied enhanced the allostimulatory activity of IFN-DCs, and the effect of μ-modified CpG-ODNs was higher than that of CpG-ODNs with thiophosphate groups. The stimulating effect of CpG-ODN at a dose of 1.0 μg/ml was comparable (for D-SL03, D-SL03M, SD-101) with or exceeded (for SD-101M) the effect of LPS at a dose of 10 μg/ml. At the same time, IFN-DCs were characterized by greater sensitivity to the action of CpG-ODNs than IL4-DCs. The enhancement of DC allostimulatory activity in the presence of CpG-ODNs was associated with the induction of final DC maturation, which was confirmed by a significant decrease in the number of CD14+DC, an increase in mature CD83+DC and a trend towards an increase in CD86+DC. Interestingly, the characteristic ability of LPS to enhance the expression of the co-stimulatory molecule OX40L on DCs was revealed only for the μ-analogue SD-101M. In addition, CpG-ODNs (SD-101 and SD-101M) had a stimulatory effect on IFN-γ production comparable to the action of LPS. The data obtained indicate a stimulating effect of CpG-ODN on the maturation and allostimulatory activity of human myeloid DCs, which is more pronounced for μ-modified analogs.