Browsing by Subject "CpG ODN"

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Open Access
Development & characterization of CpG adjuvanted SARS-CoV-2 Virus-Like Particle vaccine
(2022-06) Turay, Nilsu
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appeared in late 2019, led to countless cases and deaths and eventually regarded as one of the severe pandemics of modern times. To reduce hospitalization and mortality rates against COVID-19 an immediate need for effective vaccines has emerged. SARS-CoV-2 contains 4 structural proteins; Nucleocapsid (N), Envelope (E), Membrane (M) and Spike (S). Numerous vaccine platforms targeting Spike antigen were developed and tested on healthy volunteers. Among vaccine platforms, Virus-Like Particles (VLPs) capable of mimicking the structure, morphology and conformation of authentic and variant viruses offer a selective advantage for a better protection. VLPs, due to multivalent antigen display capabilities and ease of expressing different Spike variants can elicit cellular, as well as humoral immune responses and were expected to be superior to that of other COVID-19 vaccine platforms. Herein, we produced, purified and characterized the first mammalian derived, 4 structural protein containing SARS-CoV-2 VLP vaccine. Various animal models were used to assess the immunogenicity and immuno-protective potential of the candidate VLP vaccine that was formulated with two different CpG ODN adjuvants. Following cloning of four viral structural proteins to two separate dual expression plasmids and transiently transfecting them to adherent HEK293-FT cells, VLP yields were monitored daily from cell culture supernatant. Presence of SARS-CoV-2 structural proteins on VLPs were verified via immunoblotting. Furthermore, the size of VLPs was investigated and was shown to resemble to that of authentic SARS-CoV-2. To assess in vivo immunogenicity of the adjuvanted VLPs, BALB/c mice were subcutaneously (sc) immunized and end point titer ELISA was studied from sera. For the toxicity assay of the candidate VLP vaccine, the selected highest human dose was sc injected to female Sprague Dawley rats. Lastly, to show the immunoprotective effect of the VLP vaccine, challenge studies were conducted with transgenic K18-hACE2. Results demonstrated that VLPs induce robust antiviral humoral and Th1-biased cellular responses when adjuvanted with CpG ODNs. Furthermore, VLP immunization did not lead to any significant systemic effect during repeated dose toxicity studies on rats. A robust immuno-protection against the live SARS-CoV-2 virus was observed with the challenge experiments. Collectively, the results provide the rationale for using this vaccine candidate in human clinical trials. In the second part of the thesis, SARS-CoV-2 recombinant RBD and Nucleocapsid proteins were produced and purified via affinity chromatography. After 6X Histidinetagged RBD and N were produced in HEK293-FT cells, supernatant passed through the immobilized metal affinity chromatography (IMAC) column. Quality of the recombinant proteins was investigated using silver staining and western blotting. Afterward, immunized mice sera were used to find an optimal coating concentration of the purified recombinant proteins. Finally, purified recombinant proteins were used in in-house ELISA experiments.
Open Access
Development of CpG ODN based vaccine adjuvant formulations
(Humana Press, New York, 2016) Gürsel, M.; Gürsel, İhsan; Thomas, S.
Open Access
Dual-adjuvant effect of pH-sensitive liposomes loaded with STING and TLR9 agonists regress tumor development by enhancing Th1 immune response
(Elsevier, 2020) Bayyurt-Kocabaş, Banu; Almacıoğlu, Kübra; Alpdundar-Bulut, E.; Güçlüler, Gözde; Tincer, Gizem; Bayık, D.; Gürsel, M.; Gürsel, İhsan
Nucleic acid-based pattern recognition receptor agonists are effective adjuvants and immunotherapeutic agents. Rather than single applications, ligand combinations could synergistically potentiate immune responses by elevating cytokine and chemokine production via triggering multiple signaling pathways. However, short half-lives of such labile ligands due to nuclease attack and limited cellular uptake due to their structure significantly hamper their in vivo performances. More importantly, simultaneous delivery and activity presentation of protein antigen and nucleic acid ligands critically limit the clinical development of these constructs. In this work, we approached this problem by co-encapsulating a model antigen ovalbumin along with TLR9 and STING ligands within liposomes, a well-established drug delivery system that enables payload stability and enhanced cellular activity upon internalization. Moreover, by loading dual ligands we postulated to achieve heightened Th-1 immune response that would yield pronounced protective vaccine efficacy. We show that, pH-sensitive liposomes co-encapsulating CpG ODN and cGAMP induced synergistic innate immune response by elevating type I and type II interferon levels. Most importantly, this vaccine formulation led to ~70% regression of established melanoma tumor. pH-sensitive liposomal vaccine administration elevated IgG2c/IgG1 antibody ratio, indicative of augmented OVA-specific Th1-biased immunity. Importantly, while the frequency of tumor-specific IFN-γ producing CD8+ T-cells was significantly increased, the M2-type anti-inflammatory macrophage levels were decreased in the tumor bed. In conclusion, our strategy induces reversal of immunosuppressive tumor microenvironment, while enhancing effective anti-tumor immune-response. We propose that this could be coupled with standard therapies during combating tumor eradication.
Open Access
Elucidating immunomodulatory effects of telomeric repeat mimicking synthetic A151 oligodeoxynucleotide on immune cell transcriptome
(2019-09) Yazar, Volkan
Recent evidence revealed that DNA is beyond just the blueprint of life; it is also involved in immunomodulation. Unmethylated Cytosine-phosphate-Guanine (CpG) motifs of prokaryotic DNA stimulate immune response by interacting with Toll-like receptor 9 (TLR9). This interaction is mimicked using synthetic oligodeoxynucleotides (ODN) bearing similar DNA motifs to boost vaccinedriven immune response in human. Conversely, mammalian telomeric ends expressing TTAGGG repeats suppress immune response and contribute to fine-tuning of delicate immune balance. In this respect, suppressive ODN A151 with such G-rich telomeric repeats has proven useful in downregulating immune response; an overly active immune response is just as harmful to the host, as in the case of autoimmune disorders. Both CpG ODN and A151 are currently under preclinical/clinical trials with the aim of averting or medically treating a wide range of conditions from cancer to infectious disease or from autoimmune to autoinflammatory conditions. Contrary to CpG ODN, A151 literature is very limited and its modus operandi at gene level remains more of a mystery. Additionally, the degree, duration and breath of A151-induced alterations in immune transcriptome appear partially understood. Given the medical potential A151 holds for immunosuppressive therapy in human as a “self-molecule”, understanding the underlying molecular mechanisms via which A151 operates is invaluable. Toward this end, we attempted to uncover the unidentified features lying behind A151 ODNs immunosuppressive effects on immune cell transcriptome using a combined analysis approach of microarray data in this thesis. We demonstrated for the first time that A151 ODN deprives the cells energy by ceasing cellular uptake of fundamental molecules into the immune cells after derailing the entire intracellular trafficking. Putting it another way, A151 does not directly act on immune system cells but actually suffocates the cells by messing with intracellular trafficking, thereby blocking cellular uptake of fundamental molecules like glucose and glutamine. As such, immune suppression is just an indirect consequence of this larger cellular chaos. Our results indicated that this phenomenon occurs independent of CpG ODN stimulation of the cells and in a timely manner. Most, if not all, regulators of intracellular trafficking, vesicle signaling, and membrane protein transportation were found downregulated after incubation of cells with A151 at a physiologically relevant concentration, as well, implying full-blown entry to this intracellular turmoil at cellular level. The A151 effect on immune transcriptome was not just restricted to setting off a chaos for intracellular dynamics; novel long non-coding RNAs (lncRNAs) with immunometabolic activities were identified within the scope of this study among elements potentially regulated by A151, such as Lncpint, Malat1 and H2-T10 just to name a few. The involvement of lncRNAs in immune regulation is a well-documented phenomenon. Finally, our data showed that as an epiphenomenon of the intracellular turmoil mentioned above A151 has a deep impact in immune cells on mTOR network, the cardinal network of cellular energetics, growth, proliferation, and survival. A major shift in expression profile of relevant genes, i.e. downregulation of many activators of mTOR signaling along with core mTOR components, was validated on the benchtop after different layers of experimental validation using a wide range of marker genes and functional assays, reflecting A151’s ability to vastly shape dynamics of metabolism in favor of a metabolically inert state in macrophages and in B-cells. This knowledge will expand the breadth of A151 therapy in the clinics.
Open Access
Enhanced immunostimulatory activity of cyclic dinucleotides on mouse cells when complexed with a cell-penetrating peptide or combined with CpG
(Wiley - V C H Verlag GmbH & Co. KGaA, 2015) Yildiz, S.; Alpdundar, E.; Gungor, B.; Kahraman, T.; Bayyurt, B.; Gursel, I.; Gursel, M.
Recognition of pathogen-derived nucleic acids by immune cells is critical for the activation of protective innate immune responses. Bacterial cyclic dinucleotides (CDNs) are small nucleic acids that are directly recognized by the cytosolic DNA sensor STING (stimulator of IFN genes), initiating a response characterized by proinflammatory cytokine and type I IFN production. Strategies to improve the immune stimulatory activities of CDNs can further their potential for clinical development. Here, we demonstrate that a simple complex of cylic-di-GMP with a cell-penetrating peptide enhances both cellular delivery and biological activity of the cyclic-di-GMP in murine splenocytes. Furthermore, our findings establish that activation of the TLR-dependent and TLR-independent DNA recognition pathways through combined use of CpG oligonucleotide (ODN) and CDN results in synergistic activity, augmenting cytokine production (IFN-α/β, IL-6, TNF-α, IP-10), costimulatory molecule upregulation (MHC class II, CD86), and antigen-specific humoral and cellular immunity. Results presented herein indicate that 3′3′-cGAMP, a recently identified bacterial CDN, is a superior stimulator of IFN genes ligand than cyclic-di-GMP in human PBMCs. Collectively, these findings suggest that the immune-stimulatory properties of CDNs can be augmented through peptide complexation or synergistic use with CpG oligonucleotide and may be of interest for the development of CDN-based immunotherapeutic agents.
Open Access
In vivo applications of liposomal vaccines encapsulating single or dual pathogenassociated molecular patterns
(2017-03) Bayyurt Kocabaş, Banu
Nucleic acid-based pattern recognition receptor (PRR) agonists are promising adjuvants and immunotherapeutic agents. Combination of PRR ligands potentiates immune response by providing synergistic immune activity via triggering different signaling pathways and may impact antigen dependent T-cell immune memory. However, the duration of short circulation due to nuclease attacks is hampering their clinical performance. Liposomes enable protein and nucleic acid based compounds to have high encapsulation efficiency. Herein, we aimed to develop liposomal carrier systems that co-encapsulating single TLR9 or combinations with TLR3 or STING ligands and assess their potential as adjuvants and immunostimulatory agents in in vivo applications. Liposomal dual nucleic acid formulations induced synergistic innate immune activation, enhanced cytokine production along with internalization capacity of ligands. In anti-cancer vaccine study, CpG ODN and poly(I:C) coencapsulation significantly increased OVA-specific Th1-biased immune even after eight months post-booster injection. Challenge with OVA-expressing tumor cell line, E.G7, demonstrated that mice immunized with liposomes co-encapsulating CpG ODN and poly(I:C) had significantly slower tumor progression dependent on OVAspecific cytotoxic memory T-cells. In our second in vivo application, liposomal CDN and TLR9 therapy led to 80% remission of established melanoma tumor. Increased IgG2c/IgG1 ratio in mice treated with liposomal formulations indicating the development of antigen specific Th1-biased immunity was observed. Furthermore, along with the treatment, IFN-dual ligands into liposomes enhanced the anti-tumor activity of single ligands. In the third part, immunization with CpG ODN loaded liposomal formulations together with antigens increased antigen-specific humoral response against FMDV and Helicobacter. In addition, the liposomal CpG ODN reduced bacterial gastric colonization by antigen-dependent Th1 and Th17 immune responses after helicobacter challenging.
Open Access
Investigation of Pre-clinical and clinical results against SARS-COV-2 wild-type and Alpha variants combination of VLP-58-1023-AL-K3 vaccine
(2022-08) Bartan, Aslı Gülce
The SARS-CoV-2 virus, which first appeared in Wuhan, China and had a pandemic effect at the end of 2019, has urgently created need of suitable vaccine candidates’ development with its quick spread. Scientists in different laboratories from all over the world, including Turkey, have started the studies of vaccine development with different methods based on the basic proteins of the SARS-CoV-2 virus. Most of these vaccines are based on the Spike protein, which allows the virus to enter the host and survive. Although the Spike protein, which has high antigenic properties and contains the RBD region to bind ACE2 receptor in the host, is effective in the formation of neutralizing antibodies in the person, the virus essentially has 4 structural proteins, not only spike. Our vaccine strategy containing virus-like particles (VLP) was based on the self-assembly property of Spike, Membrane, Envelope and Nucleocapsid proteins, and these protein structures were transformed into plasmids with his-tag labels, and the products were collected in mammalian cells in vitro by the transfection method. VLPs were purified by affinity chromatography and formulated with 2 different adjuvants which are Alum and CpG. Since the virus, which has changed rapidly in the last 2 years, is open to new mutations over spreading, it is very important that our vaccine should be editable and adaptable to new virus variants. Due to the alpha variant effect in the world, which was first seen in the UK and has become widespread all over the world recent years, WT VLP formed with a more stable Spike protein containing a thermostable sub-proline (6p; HexaPro) mutation was used in the first dose of our vaccine, but UK VLP containing alpha variant mutations was used in the second dose. Alum and CpG adjuvants were used together for both injection formulations. Our vaccine has successfully completed Phase 2 studies. As a result of these studies, approximately 115 vaccinated volunteers were followed up for 90 days and immunological analyzes were performed with samples taken at certain day intervals (Day 21, Day 35, Day49 and Day90). As a result of these analyzes, moderate and high levels of neutralizing and non-neutralizing antibody responses were observed in many patients, and a humoral immune response was induced until day 90. In addition, it was observed that the cellular responses of the volunteers are progressed in tendency with the Th1 cell response.
Open Access
Investigation of Pre-clinical and Phase II clinical studies of VLP-58-1023- AL-K3-PII vaccine for Alpha variant
(2022-08) Saraydar, Berfu
In the late December of 2019, SARS-CoV-2, a new coronavirus, was discovered in Wuhan, China and described as the causative agent of Coronavirus Disease 2019 (COVID-19). The disease has spread rapidly across the world due to its high transmissibility and has been declared a pandemic by the World Health Organization (WHO). The development of an effective vaccine has become the most significant issue to constrain the pandemic. Several COVID-19 vaccines have been authorized for human use and others are in clinical trials. Although SARS-CoV-2 encodes four structural proteins, which are Spike (S), Nucleocapsid (N), Membrane (M) and Envelope (E), most of the current vaccines used only Spike as antigen in order to generate antibodies for preventing the virus entry and replication. However, concerns have raised about Spike-based vaccines with the emerging of variants as they can moderately escape from neutralizing antibodies. For these purposes, we developed Virus-like particle (VLP) vaccine which displays hexaproline prefusion-stabilized spike (S-6p), N, M, E proteins, and adjuvanted with Alum and K3-CpG ODN. Rather than using wild type, we preferred to use the sequence of Alpha variant because of its high mortality risk and selection advantages. At the beginning of the study, we designed three different vaccine formulations and based on the results of humoral immune response in mice we determined the optimal formulation and dosage for human use. Our pre-clinical studies revealed that the best vaccine combination was high dose antigen and low dose adjuvants. Next, we wondered whether a 3rd dose has an impact on long-lasting immunity or enhancing immunogenicity in mice so that its applicability to humans could be determined. It was found that 3rd dose injection increased the antibody levels much higher than 2nd dose administration and prevented humoral immunity from decreasing after a certain amount of time. Further, both humoral and cellular immunity were studied with serum and PBMC samples from 117 volunteers who participated in the Phase II clinical trial. All IgG ELISA experiments indicated that VLP-58-1023-AL-K3-PII vaccine induced great amount of humoral immune responses against S,N proteins and WT, Alpha, Delta RBDs. In terms of T cell responses, it is known that Alum-induced robust Th2 response can be redirected to the Th1 axis with the use of CpG ODN. So, we investigated whether Th1 or Th2 type of cell response was dominant after vaccination. All cytokine levels specific to SARS-CoV-2 peptides demonstrated that the vaccine elicited Th1-biased responses. Taken together, this study revealed that VLP-58-1023-AL-K3-PII vaccine for Alpha variant successfully elicited both humoral and cellular immune responses, its effectiveness against other variants was indicated and the efficiency of vaccine could be increased with the administration of 3rd dose, in terms of ensuring long-lasting immunity.
Open Access
Liposome encapsulation overcomes d-type and k-type CpG ODN dichotomy and induces synergistic immune activation = Lipozoma yüklenmiş D-tipi ve K-tipi ODN'lerin sinerjik immun aktivasyonu
(2014) Horuluoğlu, Begüm Han
Liposomes are one of the best candidates for the encapsulation of labile bioactive agents due to their safety and high entrapment efficiency. In human, two structurally distinct classes of CpG ODN are capable of activating different signaling pathways, leading to differential immune activation. While K-type ODN triggers plasmacytoid dendritic cells (pDCs) to mature and produce TNFα, D-type ODN leads to IRF-7 dependent IFNα secretion. Strikingly, when K-and D-type ODN are co-incubated in their free forms, K-ODN masks the D-ODN specific immune activation. Identifying proper delivery vehicles that provide both ODN types to display their superior features upon stimulation is of great clinical importance. In this study, first we investigated the synergistic effects of K- and D-ODN upon encapsulating them within five different liposome types. Then with the selected potential liposome combinations, we identified synergistic activation capacities both on human PBMCs and on mice splenocytes. In PBMC cytokine results revealed that D-ODN loaded in all five liposome types stimulated more IFNα than free D-ODN. Similarly, liposomal K-ODN triggered more TNFα than free K-ODN type. While incubation of free K and D- type ODN as expected, abrogated D-specific IFNα production from PBMC, simultaneous incubation with neutral or anionic D-ODN loaded liposomes plus cationic liposomes loaded with K-ODN significantly increased K-specific as well as D-specific effect rather than masking it (i.e. more production of TNFα and IFNα specific for K and D, respectively). This improved synergistic immune activity for both D and K ODN observed with ND+CK combination in 100% of individuals (TNFa) and 90% of individuals for IFNa. Additionally, intracellular cytokine staining findings supported improved TNFα and IFNα, from pDC population of PBMCs. Costimulatory molecule expressions and APC activation also significantly upregulated compared with free treatment. In mice contrary to ND+CK combination, sterically stabilized cationic liposome encapsulated K-ODN combined with i) neutral, ii) anionic, iii) cationic or iv) stealth encapsulated D-ODN increased IL6, IL12 and IFNγ levels, when stimulated simultaneously. Moreover, ex vivo experiments showed that cellular uptake and pro-inflammatory cytokine gene expressions significantly increased with combined liposomal formulations. This study established that by selecting proper liposome type(s) we reverse antagonistic action of K-ODN on DODN and induce a synergistic effect leading to a more robust immunostimulatory activity in both human and mice. This approach could broaden the immunotherapeutic application of these two important CpG ODN classes in clinic.