Interview with Nie Guangjun of the National Center for Nanoscience: Genetic engineering of gut bacteria makes oral cancer vaccine possible

Written | Edited by Wang Cong | Typesetting by Wang Duoyu | Shui Chengwen On May 2, 2022, Nie Guangjun's team from the National Nanoscience Center published a paper in the journal Nature Biomedical Engineering, developing a genetically engineered bacteria by genetically engineering Escherichia coli source of outer membrane vesicle (OMV)-based oral tumor vaccines
.

To achieve oral effective activation of tumor antigen-specific immune response, play an anti-cancer effect
.

"Bioworld" interviewed researcher Nie Guangjun for the first time.
Through this interview, let's learn about the development and application prospects of tumor vaccines based on bacterial outer membrane vesicles (OMVs)
.

As personalized tumor immunotherapy, tumor vaccines activate specific cytotoxic T lymphocytes (CTLs) by using tumor antigens produced by genetic mutations, which then attack tumor cells
.

At present, there are many tumor vaccines in clinical trials all over the world, but the tumor vaccines in these clinical trials are basically administered by intramuscular or subcutaneous injection, and the immune stimulation is limited to a limited number of draining lymph nodes
.

Due to the limited distribution of antigen-presenting cells (APCs) in muscle tissue and subcutaneously, adjuvants are required to improve the immunogenicity of tumor vaccines administered by these routes
.

In fact, the gut is the largest immune organ in the human body, containing about 70% of human immune cells, so oral tumor vaccines are a promising alternative to elicit strong anti-tumor immune responses
.

Furthermore, oral administration is generally considered to have a better safety profile, better patient compliance, and lower medical costs than injection
.

However, oral tumor vaccines are greatly limited due to the complex gastrointestinal environment and the presence of the intestinal epithelial barrier
.

An ideal oral tumor vaccine must tolerate the gastrointestinal environment in order to reach the gut and overcome the intestinal epithelial barrier to interact with abundant immune cells
.

In recent years, liposomes, polymer nanoparticles, etc.
have been rapidly developed as vaccine delivery carriers, but their effectiveness as oral vaccine carriers is not ideal.
Therefore, a new oral vaccine technology paradigm is urgently needed
.

On May 2, 2022, the research team of Nie Guangjun and Zhao Xiao of the National Center for Nanoscience and Technology published a research titled: Antigen-bearing outer membrane vesicles as tumor vaccines produced in situ by ingested genetically engineered bacteria in Nature Biomedical Engineering, a sub-journal of Nature Paper [1]
.

In this study, a genetically engineered bacterial-derived outer membrane vesicle (OMV)-based oral tumor vaccine was established by genetically engineering Escherichia coli, which can control the production of OMVs carrying tumor antigens in situ after oral administration.
, OMV can carry tumor antigens together to effectively cross the intestinal epithelial barrier and be recognized by immune cells in the lamina propria, thereby effectively activating tumor antigen-specific immune responses, thereby significantly inhibiting tumor growth, limiting tumor metastasis, and playing a long-term protective effect
.

Researcher Nie Guangjun (left) and Zhao Xiao (right) Nie Guangjun graduated from the Institute of Biophysics, Chinese Academy of Sciences with a Ph.
D.
in 2002, and then worked as a postdoctoral researcher at McGill University in Canada
.

In 2008, he returned to China and established the "Nanobiology and Nanobiomaterials" laboratory in the National Nanoscience Center
.

The main research directions of the laboratory include smart nanomedicines regulated by tumor microenvironment, nanobiological effects and drug delivery of membrane vesicle systems, and novel therapeutic strategies based on nanotechnology
.

In these fields, Nie Guangjun's team has published more than 200 research papers and applied for more than 40 patents for related inventions such as anti-tumor applications
.

As early as 2013, Nie Guangjun's team published a research paper on the use of exosomes as a chemotherapy drug delivery platform to treat cancer in the journal Biomaterials
.

Google Scholar shows that the number of citations is as high as 1159, and it is also one of the earliest exosome research papers in China
.

Researcher Nie Guangjun told "Bioworld" that with the deepening of research, he has become more and more aware of the limitations of exosomes that are difficult to break through, such as low yield, difficult extraction, and complex components
.

At this time, another natural source of nanoparticles, bacterial-derived outer membrane vesicles (Outer Membrane Vesicles, OMV), has received its own attention
.

Gram-negative bacteria secrete a class of natural nanoparticles, outer membrane vesicles (OMVs), which can activate the host immune system due to the abundance of pathogen-associated molecular patterns (PAMPs)
.

Gut bacteria also secrete outer membrane vesicles (OMVs) and interact with the host immune system through OMVs
.

More importantly, OMVs secreted by gut bacteria are able to cross the intestinal epithelial barrier and interact with immune cells, especially dendritic cells (DCs) that play an antigen-presenting role, and exert immunomodulatory capabilities
.

Researcher Nie Guangjun said that tumor vaccines usually require adjuvants to improve immunogenicity, and OMV itself can be used as a natural adjuvant, thus realizing the integration of tumor vaccines and adjuvants
.

Intestinal bacteria such as Escherichia coli can be easily genetically engineered and easily fermented and scaled up to obtain OMVs in large quantities and quickly
.

In addition, some OMVs should be approved as an infectious disease treatment in New Zealand, Australia, etc.
, which also proves its safety and efficacy
.

Based on the advantages of OMV, Nie Guangjun's team and Zhao Xiao's team published a paper in the journal Nature Communications in April 2021 [2], proposing and developing a universal tumor vaccine platform based on OMV, combining tumor antigens with the ClyA protein on the surface of OMV.
Fusion to display tumor antigens on the surface of OMVs to induce tumor antigen-specific anti-tumor immune responses
.

This also lays the foundation for the development of subsequent oral tumor vaccines
.

On the basis of the above research, Nie Guangjun's team genetically engineered Escherichia coli, one of the most abundant symbiotic bacteria in the gut, to develop an oral tumor vaccine derived from genetically engineered bacteria
.

First, tumor antigen (Ag) and mouse immunoglobulin G Fc fragment (mFc) were fused to the C-terminus of ClyA protein, one of the most abundant proteins on the surface of OMVs
.

mFc will enhance OMV recognition and uptake by dendritic cells (DCs) through the interaction between Fc and the neonatal Fc receptor (FcRn)
.

Researcher Nie Guangjun said that although most genetically engineered bacteria were found to be cleared after 24 hours of oral administration, for safety, it is also necessary to control the production of OMVs carrying tumor antigens to avoid immune tolerance caused by long-term antigen stimulation
.

The research team introduced an arabinose (Ara) inducible promoter to control the expression of the fusion protein
.

Expression of the fusion protein is induced only in the presence of arabinose, otherwise expression is turned off
.

After oral administration of the above-mentioned genetically engineered bacteria and the inducer arabinose, the in situ and controllable production of tumor antigen-carrying outer membrane vesicles-OMV-Ag-mFc can be achieved in the intestinal tract
.

Experiments in mouse models showed that these OMV-Ag-mFc were able to efficiently cross the intestinal epithelial barrier and be taken up by dendritic cells (DCs) in the intestinal lamina propria, followed by the generation of draining lymph nodes and tumor antigen presentation
.

Tumor antigen-specific immune activation, and exerts antitumor effects in multiple mouse cancer models, significantly inhibiting tumor growth
.

In a mouse model of lung metastatic melanoma and a mouse model of subcutaneous colon tumor, OMV-Ag-mFc can significantly inhibit tumor growth, reduce tumor metastasis, and exert long-term protection against tumor recurrence and attack
.

Overall, this study established a genetically engineered bacteria-derived outer membrane vesicle (OMV)-based oral tumor vaccine by genetically engineering Escherichia coli, which can be controlled in situ in the gut after oral administration OMVs carrying tumor antigens, OMVs can carry tumor antigens together to effectively cross the intestinal epithelial barrier, and are recognized by immune cells in the lamina propria, thereby effectively activating tumor antigen-specific immune responses, thereby significantly inhibiting tumor growth, limiting tumor metastasis, and playing a long-term role.
protective effect
.

Researcher Nie Guangjun told Biology World that outer membrane vesicles (OMVs) have great potential as tumor vaccine carriers.
In addition to displaying and delivering tumor antigens, they can also deliver mRNA to develop mRNA tumor vaccines
.

In March 2022, Nie Guangjun's team and Zhao Xiao's team published a paper in the journal Advanced Materials [3], using outer membrane vesicles (OMVs) as mRNA delivery platforms, and genetically engineering them to RNA-binding protein L7Ae and lysosomal escape protein.
Surface modification of listeriolysin O - OMV-LL
.

OMV-LL can bind mRNA antigens via L7Ae and deliver them to dendritic cells, followed by cross-presentation via Listeriolysin O-mediated endosomal escape
.

Researcher Guangjun Nie said that this study is the first to explore OMV as an mRNA vaccine delivery vehicle, and has demonstrated impressive effects.
OMV-LL-mRNA can significantly inhibit the progression of melanoma in mice, resulting in 37.
5% of colorectal cancer in mice The tumor of the model completely regressed
.

OMV-LL-mRNA induces long-term immune memory and still protects mice from tumor challenge after 60 days
.

In July 2021, Nie Guangjun's team also published a research paper [4] that attracted widespread attention in the journal Science Translational Medicine
.

This study pioneered the integration of E.
coli cytoplasmic membrane and autologous tumor cell membrane into nanoparticles to develop a novel personalized cancer vaccine.
Animal experiments showed that these hybrid membrane nanoparticles induced a strong induction of a The tumor-specific immune response, which improved the survival rate of the mice, was able to protect the mice from tumor re-challenge in the long term
.

Researcher Guangjun Nie said that this study shows that a personalized autologous tumor antigen vaccine based on the effective activation of the innate immune system based on the bacterial cytoplasmic membrane has great potential in the personalized treatment of patients after cancer surgery
.

At present, it has begun to cooperate with several tertiary hospitals in Beijing to carry out investigator-initiated clinical trials (IIT), which will involve patients from non-small cell lung cancer to rare tumors
.

The follow-up will further develop a universal tumor vaccine based on this method
.

In recent years, the use of genetically engineered microorganisms to deliver therapeutic drugs or the use of genetically engineered microorganisms themselves as therapeutic agents has received increasing attention
.

A series of breakthrough studies by Nie Guangjun's team have opened up broader prospects for therapeutic applications based on genetically engineered microorganisms
.

Paper link: 1.
https:// https:// https://onlinelibrary .
wiley.
com/doi/abs/10.
1002/adma.
2021099844.
https://stm.
sciencemag.
org/content/13/601/eabc2816.
full is open for reprinting.
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