Engineered outer membrane vesicle is potent to elicit HPV16E7-specific cellular immunity in a mouse model of TC-1 graft tumor

Abstract

Purpose Currently, therapeutic tumor vaccines under development generally lack significant effects in human clinical trials. Exploring a powerful antigen delivery system is a potential approach to improve vaccine efficacy. We sought to explore engineered bacterial outer membrane vesicles (OMVs) as a new vaccine carrier for efficiently delivering tumor antigens and provoking robust antitumor immune responses. Materials and methods First, the tumoral antigen human papillomavirus type 16 early protein E7 (HPV16E7) was presented on Escherichia coli -derived OMVs by genetic engineering methods, acquiring the recombinant OMV vaccine. Second, the ability of recombinant OMVs delivering their components and the model antigen green fluorescent protein to antigen-presenting cells was investigated in the macrophage Raw264.7 cells and in bone marrow-derived dendritic cells in vitro. Third, it was evaluated in TC-1 graft tumor model in mice that the recombinant OMVs displaying HPV16E7 stimulated specific cellular immune response and intervened the growth of established tumor. Results E. coli DH5α-derived OMVs could be taken up rapidly by dendritic cells, for which vesicle structure has been proven to be important. OMVs significantly stimulated the expression of dendritic cellmaturation markers CD80, CD86, CD83 and CD40. The HPV16E7 was successfully embedded in engineered OMVs through gene recombinant techniques. Subcutaneous immunization with the engineered OMVs induced E7 antigen-specific cellular immune responses, as shown by the increased numbers of interferon-gamma-expressing splenocytes by enzyme-linked immunospot assay and interferon-gamma-expressing CD4 + and CD8 + cells by flow cytometry analyses. Furthermore, the growth of grafted TC-1 tumors in mice was significantly suppressed by therapeutic vaccination. The recombinant E7 proteins presented by OMVs were more potent than those mixed with wild-type OMVs or administered alone for inducing specific cellular immunity and suppressing tumor growth. Conclusion The results indicated that the nano-grade OMVs might be a useful vaccine platform for antigen delivery in cancer immunotherapy.

Peptidylarginine Deiminase Inhibitors Reduce Bacterial Membrane Vesicle Release and Sensitize Bacteria to Antibiotic Treatment

“…OMVs are released in greater abundance from Gram-negative than Gram-positive bacteria, are crucial for bacterial survival and form part of the stress response (McBroom and Kuehn, 2007; Macdonald and Kuehn, 2013; Jan, 2017). Research on bacterial OMVs has grown rapidly in recent years, including their use as bioengineered drug delivery vehicles (Gujrati et al, 2014; Bitto and Kaparakis-Liaskos, 2017) and in vaccine development (Gaillard et al, 2014; Choi et al, 2015; Alves et al, 2016; Raeven et al, 2016; Wang et al, 2017).…”

Bacterial Outer Membrane Vesicles (OMVs)-Based Dual Vaccine for Influenza A H1N1 Virus and MERS-CoV

“…LPS in the outer surface of OMVs acts as a self-adjuvant that induces humoral and cellular immunity. Therefore, OMVs vaccines may be used without extra adjuvant to increase the immunogenicity and produce antiviral innate immune responses against various influenza virus infections via activation of macrophages [42,43,44]. Despite that the exact role of LPS in the context of OMVs vaccines requires further investigations, high amounts of LPS could be a drawback due to its known endotoxicity and ability to induce excessive secretions of pro-inflammatory cytokines [45].…”

Nanovaccines for cancer immunotherapy

“…Furthermore, OMVs are 50–250 nm in diameters, making OMVs great carriers for efficient lymph node homing and intracellular delivery into APCs (Lin, Chattopadhyay, Lin, & Hu, ). Up to now, OMVs have been studied to develop bacterial vaccines (Lin et al, ) and more recently cancer therapeutic vaccines (Kim et al, ; Wang et al, ). For instance, OMVs were loaded with antitumor cytokines CXCL10 and interferon‐γ as therapeutic agents (Kim et al, ), which showed remarkable efficacy to induce long‐term antitumor immune responses that eradicated established tumors without notable adverse effects.…”

“…Further, engineered OMVs have been engineered to display Human Papillomavirus 16 (HPV16) E7 protein to induce E7‐specific cellular immunity. These OMVs showed significant therapeutic efficacy, thus demonstrating the potential of OMVs as cancer nanovaccines (Wang et al, ).…”