Engineering E. coli Nissle 1917 for Targeted Drug Delivery and Cancer Therapy
Engineering E. coli Nissle 1917 for Targeted Drug Delivery and Cancer Therapy
Probiotics, traditionally associated with promoting gut health, have evolved into sophisticated tools in biomedical applications. Among these, Escherichia coli Nissle 1917 (EcN) stands out due to its unique attributes and potential in targeted drug delivery and cancer therapy.
Introduction to E. coli Nissle 1917
E. coli Nissle 1917 (EcN) is a probiotic strain renowned for its unique attributes that distinguish it from other E. coli strains. Notably, EcN lacks pathogenic adhesion factors and does not produce enterotoxins, underscoring its non-pathogenic nature. This strain exhibits a remarkable ability to adhere to the intestinal mucosa and produce antimicrobial compounds, facilitating effective colonization of the human gut and providing a competitive advantage over pathogenic bacteria. Furthermore, EcN's genetic stability enhances its suitability for therapeutic applications. Additionally, EcN has been shown to modulate immune responses, which is beneficial in various therapeutic contexts.
EcN as an Innovative Drug Delivery Vector
Microbial Systems in Drug Delivery
The concept of using microbial systems as drug delivery vehicles has gained traction due to their ability to target specific tissues, particularly tumors. Bacteria can thrive in hypoxic and necrotic regions of tumors, areas often inaccessible to conventional therapies.
Advantages of EcN as a Therapeutic Vector
Advantage
Description
Safety Profile
EcN is a non-pathogenic strain that lacks virulence factors, making it safe for therapeutic use.
Tumor-Targeting Ability
EcN's facultative anaerobic nature allows it to selectively colonize hypoxic tumor regions, enhancing its potential as a targeted therapeutic delivery system.
Genetic Manipulability
EcN's genetic tractability facilitates the insertion of therapeutic genes, enabling the development of engineered strains for specific therapeutic applications.
Established Safety Record
EcN has a long history of safe use as a probiotic, supporting its potential for therapeutic applications.
Current Research Landscape
Recent studies have demonstrated EcN's potential in delivering therapeutic agents directly to tumor sites. For instance, EcN has been engineered to produce interleukin-2 (IL-2), a cytokine that stimulates immune responses against tumors. This approach has shown promise in preclinical models, highlighting EcN's potential as a drug delivery vector.
Genetic Engineering of EcN
Synthetic Biology Methods Applied to EcN
Plasmid-Based Genetic Engineering: Introduction of plasmids carrying therapeutic genes into EcN.
CRISPR/Cas9 Genome Editing: Precise modification of EcN's genome to enhance its therapeutic capabilities.
Bacteriophage Integration: Utilization of bacteriophages to insert genetic material into EcN's genome.
CRISPR/Cas9-Based Genome Editing
The application of CRISPR/Cas9 technology in EcN allows for precise genome modifications, enabling the insertion or deletion of specific genes to enhance its therapeutic functions. This method improves the strain's genetic stability and reduces the risk of horizontal gene transfer.
Phage Integration Technologies
Bacteriophage-based integration systems have been developed to introduce therapeutic genes into EcN's genome. This approach ensures stable gene expression and minimizes the potential for plasmid loss, enhancing the reliability of EcN-based therapies.
Bacteria like EcN can exploit the unique microenvironment of tumors, such as hypoxia and immunosuppression, to selectively colonize these tissues. Once localized within the tumor, they can deliver therapeutic agents directly to cancer cells.
Natural Tumor Colonization by EcN
Studies have shown that orally administered EcN can selectively colonize colorectal adenomas in murine models, demonstrating its natural tumor-targeting ability.
Enhancing Tumor Specificity Through Genetic Engineering
Genetic modifications can further enhance EcN's tumor specificity:
Anaerobic Promoter Systems: Engineering EcN to express therapeutic genes under anaerobic conditions prevalent in tumors.
Tumor-Specific Receptor Targeting: Modifying EcN to express receptors that recognize tumor-specific antigens, improving its targeting accuracy.
EcN-Mediated 5-ALA Production for Photodynamic Cancer Therapy
Overview of Photodynamic Therapy (PDT) and 5-ALA
Photodynamic therapy involves the administration of a photosensitizer, such as 5-aminolevulinic acid (5-ALA), which accumulates in tumor cells and, upon activation by specific wavelengths of light, induces cytotoxic effects leading to tumor cell death.
Engineering EcN to Synthesize and Deliver 5-ALA
EcN has been genetically engineered to synthesize 5-ALA, enabling localized production of the photosensitizer within the tumor microenvironment. This targeted delivery enhances the efficacy of PDT while minimizing systemic side effects.
Experimental Outcomes and Clinical Applications
Preclinical studies have demonstrated that EcN-mediated delivery of 5-ALA leads to significant tumor regression in mouse models, suggesting potential for clinical applications in photodynamic cancer therapy.
Fig.1 EcN mi-IL2 slows down the growth of CT26 tumors1
Probiotic-Based Cancer Immunotherapy
Concepts of Bacterial Cancer Immunotherapy
The utilization of bacteria in cancer immunotherapy leverages their inherent properties to stimulate and modulate the immune system. EcN, with its established safety profile and ability to colonize tumor tissues, serves as an effective vehicle for delivering immune-activating molecules directly to the tumor microenvironment.
EcN-Mediated Delivery of Immune-Activating Molecules
Genetically engineered EcN strains have been developed to produce and deliver immune-stimulating agents such as interleukin-2 (IL-2) and interferon-gamma (IFN-γ). For instance, EcN has been modified to secrete bioactive IL-2, leading to enhanced activation of immune cells within the tumor microenvironment. This approach has demonstrated a modest reduction in tumor growth rates in murine models, highlighting the potential of EcN as a delivery vector for cytokine-based cancer immunotherapies.
Similarly, EcN engineered to produce IFN-γ has shown promise in preclinical studies. The localized delivery of IFN-γ by EcN resulted in significant tumor regression in mouse models, suggesting potential clinical applications in enhancing anti-tumor immune responses.
Synergistic Effects with Existing Therapies
The combination of EcN-based therapies with existing immunotherapeutic agents or chemotherapy treatments holds promise for synergistic anti-cancer effects. For example, the concurrent use of EcN engineered to deliver IFN-γ with immune checkpoint inhibitors has been shown to enhance therapeutic efficacy in preclinical models. This combinatorial approach may potentiate immune responses against tumors, offering a multifaceted strategy for cancer treatment.
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Challenges and Future Prospects
Translational Challenges
Safety Concerns: Risks of host microbiota interactions and horizontal gene transfer.
Regulatory Hurdles: Need detailed safety and efficacy data for approval.
Stability and Efficacy: Maintaining stable gene expression and consistent outcomes.
Promising Research Avenues
Synthetic Regulatory Circuits: Circuits that activate in response to tumor-specific signals.
Creative Biolabs also offers comprehensive services for designing various other engineered therapeutic bacterial strains tailored for diverse biomedical applications, including:
EcN exploits the unique microenvironment of tumors, such as hypoxia and immunosuppression, to selectively colonize these tissues. Genetic modifications can further enhance its tumor-targeting specificity.
How does EcN-based therapy compare to traditional cancer treatments?
EcN-based therapy offers targeted delivery of therapeutic agents, potentially reducing systemic side effects associated with traditional treatments. However, further research is needed to fully understand its efficacy and safety compared to conventional therapies.
Tumas, Sarunas, et al. "Engineered E. coli Nissle 1917 for delivery of bioactive IL-2 for cancer immunotherapy." Scientific Reports 13.1 (2023): 12506. https://doi.org/10.1038/s41598-023-39365-2
Gurbatri, Candice R., et al. "Engineering tumor-colonizing E. coli Nissle 1917 for detection and treatment of colorectal neoplasia." Nature Communications 15.1 (2024): 646. https://doi.org/10.1038/s41467-024-44776-4
Distributed Under Open Access license CC BY 4.0, without modification.
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For Research Use Only. Not intended for use in
food manufacturing or medical procedures (diagnostics or therapeutics). Do Not Use in Humans.
Fig.1 EcN mi-IL2 slows down the growth of CT26 tumors1
