Browsing by Subject "TLR9"

Now showing 1 - 6 of 6

Open Access
Development of CpG ODN based vaccine adjuvant formulations
(Humana Press, New York, 2016) Gürsel, M.; Gürsel, İhsan; Thomas, S.
Open Access
Encapsulation of two different TLR ligands into liposomes confer protective immunity and prevent tumor development
(Elsevier B.V., 2017) Bayyurt, B.; Tincer, G.; Almacioglu, K.; Alpdundar, E.; Gursel, M.; Gursel, I.
Nucleic acid-based Toll-like receptor (TLR) ligands are promising adjuvants and immunotherapeutic agents. Combination of TLR ligands potentiates immune response by providing synergistic immune activity via triggering different signaling pathways and may impact antigen dependent T-cell immune memory. However, their short circulation time due to nuclease attack hampers their clinical performance. Liposomes offer inclusion of protein and nucleic acid-based drugs with high encapsulation efficiency and drug loading. Furthermore, they protect cargo from enzymatic cleavage while providing stability, and enhancing biological activity. Herein, we aimed to develop a liposomal carrier system co-encapsulating TLR3 (polyinosinic-polycytidylic acid; poly(I:C)) and TLR9 (oligodeoxynucleotides (ODN) expressing unmethylated CpG motifs; CpG ODN) ligands as immunoadjuvants together with protein antigen. To demonstrate that this depot system not only induce synergistic innate immune activation but also boost antigen-dependent immune response, we analyzed the potency of dual ligand encapsulated liposomes in long-term cancer protection assay. Data revealed that CpG ODN and poly(I:C) co-encapsulation significantly enhanced cytokine production from spleen cells. Activation and maturation of dendritic cells as well as bactericidal potency of macrophages along with internalization capacity of ligands were elevated upon incubation with liposomes co-encapsulating CpG ODN and poly(I:C). Immunization with co-encapsulated liposomes induced OVA-specific Th1-biased immunity which persisted for eight months post-booster injection. Subsequent challenge with OVA-expressing tumor cell line, E.G7, demonstrated that mice immunized with liposomes co-encapsulating dual ligands had significantly slower tumor progression. Tumor clearance was dependent on OVA-specific cytotoxic memory T-cells. These results suggest that liposomes co-encapsulating TLR3 and TLR9 ligands and a specific cancer antigen could be developed as a preventive cancer vaccine. ï¿½ 2017 Elsevier B.V.
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.
Open Access
Self-nanoparticle forming immunostimulatory DNA : structure-function relationship studies
(2009) Mammadov, Rashad
Toll-like receptors (TLRs) are one the most critical and widely studied members of the family of pattern recognition receptors expressed on innate immune cells. They recognize microbial signatures, such as bacterial/viral DNA, LPS, from gram negative bacteria, peptidoglycan from gram positive bacteria, zymosan from yeast, lipopeptides or profilin protein from parasites, and even single or double stranded RNA of viruses. Among several members of TLR family, TLR9, that recognizes microbial unmethylated dinucleotide motifs on DNA initiate a robust Th1- biased inflammatory response. Synthetic oligodeoxynucleotides expressing unmethylated CpG motifs, mimic bacterial DNA effect and can be harnessed for the treatment of health problems ranging from infectious diseases to cancer, or to allergy/asthma as well as stand alone immunoprotective agents and also as a vaccine adjuvants that improve protection against pathogens. To date, various classes of CpG ODNs have been identified and were shown to induce differential immune activation in mice and man. Distinct structure-function relationship analyses revealed that these single-stranded linear ODNs alter the immune milieu as they are formulated to form complex multimeric DNA aggregates. Recently, Guanosine-rich D type CpG ODNs has been reported to form complex aggregates, that are differentially regulating immune cells to mount an anti-viral immunity. However, the clinical trials of this type are hampered mainly due to batch to batch variation during large-scale synthesis. To the best of our knowledge, there is no report on self-nanoparticle forming DNA except G-rich sequences. This thesis project was designed to generate stable, selfnanoparticle forming, G-run free, CpG expressing ODNs. In this thesis, we designed a new generation CpG ODN, then characterized their structural and immunological properties. Our results suggest that dendrimeric structure confers higher immunostimulatory potential unparallel to conventional ODNs. Following four hours of in vivo ODN administration into mice indicated that nanoparticle-forming CpG ODNs initiated substantially high spleen and peritoneal exudate cell activation as evidenced by IFNγ and IL-12 production from culture medium. In order to shed light on the uptake and binding mechanisms, blocking experiments revealed that at least one type of scavenger receptor is critical for nanoparticle ODN internalization. Collectively, these data suggested that the improved stability to nucleases along with significantly higher binding to immune cells (no additional ODN formulation is required) seem to be the critical factors contributing to the nanoparticle CpG ODN mediated immune activation. The in vitro and in vivo performances implicated that these next generation immune stimulatory DNA molecules are promising candidates for various clinical applications.
Open Access
Structure, mechanism and therapeutic utility of immunosuppressive oligonucleotides
(Academic Press, 2016) Bayik D.; Gursel, I.; Klinman, D. M.
Synthetic oligodeoxynucleotides that can down-regulate cellular elements of the immune system have been developed and are being widely studied in preclinical models. These agents vary in sequence, mechanism of action, and cellular target(s) but share the ability to suppress a plethora of inflammatory responses. This work reviews the types of immunosuppressive oligodeoxynucleotide (Sup ODN) and compares their therapeutic activity against diseases characterized by pathologic levels of immune stimulation ranging from autoimmunity to septic shock to cancer (see graphical abstract). The mechanism(s) underlying the efficacy of Sup ODN and the influence size, sequence and nucleotide backbone on function are considered. © Published by Elsevier Ltd.
Open Access
TLR agonists on autoimmunity, cancer and M1/M2 macrophage polarization
(2019-07) Horuluoğlu, Begüm Han
Macrophages play an important role in the initiation of immune responses and the maintenance of immune homeostasis. Alterations in their phenotype, function and activation state have been implicated in the pathogenesis of autoimmune and inflammatory diseases. An increased M1:M2 ratio is associated with the development of several autoimmune diseases including Systematic Lupus Erythematosus (SLE), vasculitis and myositis. Previous work showed that the TLR2/1 agonist PAM3CSK4 (PAM3) could stimulate normal human monocytes to preferentially differentiate into immunosuppressive M2-like rather than inflammatory M1-like macrophages. This work seeks to investigate the ability of PAM3 to induce M2 macrophage differentiation from patient monocytes and evaluate the therapeutic efficacy of PAM3 in a murine model of lupus. Our findings revealed that patients with indicated autoimmune diseases have a significant increase in monocytes of the inflammatory subtypes coupled with a decrease in non-inflammatory classical monocytes compared to healthy controls. Additionally, in the absence of stimulant patient monocytes differentiated into more M1-like macrophages. Nevertheless, phenotypic analysis of in vitro generated macrophages revealed that, PAM3 stimulation induced M2-like macrophage differentiation without any difference from patient and healthy monocytes. Phenotypic analysis was further supported by the high endocytic abilities and secretion of anti-inflammatory cytokines instead of pro-inflammatory cytokines by PAM3 generated macrophages. Lupus-prone NZB x NZW F1 mice responded similarly to weekly PAM3 treatment. Upon PAM3 treatment the increased M1:M2 ratio, which was observed in PBS treated group, was decreased to normal levels. The increase in M2 macrophages was accompanied by decreased autoantibody and inflammatory cytokines along with an increase in anti-inflammatory cytokine production. Moreover, kidney damage was significantly suppressed and M2 macrophages were detected in the kidneys of PAM3 treated group. PAM3 treatment prolonged to survival of NZB/W significantly, at 45 weeks of age %60 of mice were still alive whereas in PBS group only %5 were. Our results indicate that, PAM3 induces immunosuppressive macrophages and thus could represent a novel approach to the therapy of autoimmune diseases. The second part of this thesis focused on enhancing the immunomodulatory effects of TLR9 ligands, CpG ODN upon encapsulation within liposomes as cancer vaccine adjuvants. Although both D and K ODN are strictly dependent on TLR9, K ODN trigger pDCs to mature and secrete TNFα while D ODN stimulate pDC to produce IFNα. When cells are incubated with a mixture of K and D ODN, K masks the activity of D. The use of both K and D ODN would be of benefit when preparing vaccine adjuvants and for immunotherapy. Our data indicate that simultaneous delivery of D ODN loaded into neutral liposomes plus K ODN loaded into cationic liposomes improved rather than masked IFNα production while continuing to support TNFα by PBMCs. Liposomal encapsulation did not alter the subcellular localization of either class of ODN, but internalization studies revealed that cationic liposome encapsulation slows and reduces the uptake of K ODN whereas neutral encapsulation of D increases their uptake by pDCs. The efficiency of K plus D liposome combinations was examined in a murine tumor vaccine model. The liposome combinations induced pronounced Th1-biased anti-OVA immunity and led to a significant reduction of B16-OVA tumors following inoculation. Our findings, demonstrate that the beneficial features of D and K ODN could be obtained simultaneously by appropriate liposomal formulation, further extending the breadth of CpG ODN-dependent immunotherapy.