Dual-adjuvant effect of pH-sensitive liposomes loaded with STING and TLR9 agonists regress tumor development by enhancing Th1 immune response

Kocabas, Banu Bayyurt
Almacioglu, Kubra
Bulut, Esin Alpdundar
Gucluler, Gozde
Tincer, Gizem
Bayik, Defne
Gürsel, Mayda
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 similar 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-gamma 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.


Encapsulation of two different TLR ligands into liposomes confer protective immunity and prevent tumor development
Bayyurt, Banu; Tincer, Gizem; Almacioglu, Kubra; Alpdundar, Esin; Gürsel, Mayda; GÜRSEL, İHSAN (Elsevier BV, 2017-02-10)
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 load...
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The interactions of the nonsteroidal anti-inflammatory drug, celecoxib, with 1,2-distearoyl-sn-glycero-3-phosphocholine multilamellar vesicles were studied as a function of temperature and different drug concentrations, using Fourier transform infrared spectroscopy, differential scanning calorimetry, and turbidity technique at 440 nm. Our studies reveal that celecoxib lowers the main phase-transition temperature and decreases the fluidity of the membranes at all concentrations. Celecoxib induced opposing ef...
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Citation Formats
B. B. Kocabas et al., “Dual-adjuvant effect of pH-sensitive liposomes loaded with STING and TLR9 agonists regress tumor development by enhancing Th1 immune response,” JOURNAL OF CONTROLLED RELEASE, pp. 587–595, 2020, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/88500.