pDNA-lipoplexes engrafted with flagellin-related peptide induce potent immunity and anti-tumour effects

Abstract

Complexes of cationic lipids and DNA (lipoplexes) are widely used for non-viral gene delivery and DNA vaccine development, but cationic lipids are toxic and promote non-specific interactions with cells, leading to poor efficacy. Near-neutral lipoplexes, on the other hand, can obviate toxicity, but a convenient means to target them to specific cells such as dendritic cells (DCs) has been lacking. Here, we show that a His-tagged flagellin-derived peptide (denoted 9Flg), previously reported to promote binding of liposomal antigen to TLR5-expressing cells, can be used to target near-neutral pDNA-lipoplexes incorporating the chelator lipid NTA(3)-DTDA (3(nitrilotriacetic acid)-ditetradecylamine) to DCs and other antigen-presenting cells (APCs). Thus, we show that pDNA-lipoplexes engrafted with 9Flg target pDNA to APCs in vitro and in vivo. Following i.v. administration, radiolabelled 9Flg-lipoplexes exhibited increased accumulation in spleen, lung and liver. Vaccination of C57BL/6 mice with 9Flg-lipoplexes containing either pcDNA3.1-SIIN (pSIIN) or a Kunjin virus replicon-based vector (pKUN), each encoding the epitope OVA(257-264) (SIINFEKL), induced Ag-specific T cell priming, and elicited strong cellular immunity as reflected by a marked increase in the number of Ag-responsive IFN-γ-producing CD8(+) T cells. Importantly, compared to i.m. injection of these SIINFEKL-encoding pDNAs in naked form, the i.v. administration of pSIIN or pKUN in 9Flg-lipoplexes to C57BL/6 mice induced a significantly more potent anti-tumour response in the B16-OVA melanoma tumour model. The targeting of near-neutral 9Flg-lipoplexes bearing pDNA encoding tumour antigens to TLR5 on APCs, therefore, is a powerful approach for developing more effective DNA vaccines and immunotherapies.

Recent Trends in Multifunctional Liposomal Nanocarriers for Enhanced Tumor Targeting

“…In other studies Altin's group reported on DC-targeted gene delivery in vivo and potent antitumor effects in the B16-OVA melanoma model after liposome functionalization with histidylated flagellin, the major constituent of the bacterial flagella, recognized by the Toll Like Receptor 5 that leads to their activation [221, 222]. LPR (Lipid-Polymer-RNA) mannosylated and histidylated lipopolyplexes loaded with MART1 (Melanoma Antigen Recognized by T cells 1) mRNA delayed the progression of B16F10 melanoma more effectively than untargeted LPR [223].…”

Incorporation of a truncated form of flagellin (TFlg) into porcine circovirus type 2 virus-like particles enhances immune responses in mice

“…Previous studies reported that Cap protein-based VLP vaccines induced protection against a PCV2 challenge [7,8,21,22]. In addition, two reports showed that a flagellin-related peptide, 9Flg, enhanced antigen-specific and antitumor immunity [18,23]. The previous work has confirmed that PCV2 virions surface displaying 27 aa peptide at C terminal of Cap could replicate as wildtype virions, which provided the clues that C terminal of Cap could display 27 aa peptide without influence the virions formation [24].…”

Application of DNA Replicons in Gene Therapy and Vaccine Development

“…In vivo applications showed that intranasal inoculation of KUN- β-gal DNA replicons resulted in expression of β-gal in the mouse lung epithelium for at least 8 weeks. KUN DNA replicons expressing the OVA(257–264)(SIINFEKL) epitope have been encapsulated in lipoplex formulations engrafted with a flagellin-derived peptide (9Flg) for antigen-presenting cell (APC) targeting [ 63 ]. Intravenous administration of KUN-SIINFEKL DNA-lipoplexes elicited strong antigen-specific T-cell responses and induced significantly enhanced antitumor responses in a B16-OVA melanoma mouse model compared to conventional DNA plasmids.…”