CpG-PEG Conjugates and their Immune Modulating Effects after Systemic Administration
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Synthetic oligodeoxynucleotides (ODN) containing unmethylated CpG motifs were found to be able to target cells that express Toll-like receptor 9 to modulate innate and adaptive immune reactions. But their in vivo application in immunotherapy against cancer has not been successful. We attempted in this study to examine polyethylene-glycol (PEG) conjugated CpG ODNs and investigated their mechanism of immune modulation in anti-cancer therapy.
CpG-PEG conjugates with different PEG lengths were synthesized. In vitro activity as well as in vivo pharmacokinetics and pharmacodynamics properties were evaluated.
CpG-PEG20Ks were found to be able to persist longer in circulation and activate various downstream effector cells. After intravenous injection, they resulted in higher levels of IL-12p70 in the circulation and lower M-MDSC infiltrates in the tumor microenvironment. Such activities were different from those of CpG ODNs without PEGylation, suggesting different PK-PD profiles systemically and locally.
Our data support the development of CpG-PEGs as a new therapeutic agent that can be systemically administered to modulate immune responses and the microenvironment in tumor tissues.
Key WordsCpG-ODN PEG immune modulation systemic administation
PEG conjugated CpG ODNs
M type myeloid derived suppressor cells
Progression free survival
Toll-like receptor 9
CpG ODNs containing the sulfhydryl group
High performance liquid chromatography
Enzyme-linked immunosorbent assay
Bone-marrow-derived dendritic cells
A type I C-type lectin receptor that is expressed on various antigen presenting cell subsets
Quantitative- polymerase chain reaction
Enhanced permeability and retention
Triethylamine and acetic acid
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