Polymyxin B treatment improves bactofection efficacy and reduces cytotoxicity

Area of Science:

• Biotechnology
• Gene Therapy
• Microbiology

Background:

• Bacterial vectors offer a promising nonviral approach for gene therapy, enabling efficient gene delivery.
• However, bacterial vectors can exhibit cytotoxicity and immunogenicity, necessitating strategies for attenuation.
• Optimizing bacterial vector performance requires balancing transfection efficiency with reduced adverse biological effects.

Purpose of the Study:

• To investigate the efficacy of polymyxin B (PLB) pretreatment in attenuating listeriolysin O (LLO)-producing Escherichia coli for enhanced gene delivery.
• To evaluate the impact of PLB treatment on bacterial gene and protein release, cytotoxicity, and transfection efficiency in a macrophage cell line.
• To determine if PLB pretreatment can improve the safety and effectiveness of bacterial vectors in gene therapy applications.

Main Methods:

• Escherichia coli BL21(DE3) strains producing listeriolysin O (LLO) were pretreated with polymyxin B (PLB).
• The treated bacterial strains were used as delivery vectors for gene transfer to murine RAW264.7 macrophage cells.
• A 96-well high-throughput assay was employed to assess gene delivery levels and cytotoxicity.

Main Results:

• Polymyxin B pretreatment significantly increased gene delivery levels compared to untreated controls.
• Cytotoxicity was significantly reduced in bacterial vectors treated with polymyxin B.
• A correlation was observed between bacterial cellular damage, enhanced gene/protein release, and improved gene delivery to mammalian cells.

Conclusions:

• Polymyxin B pretreatment is an effective strategy for enhancing the gene delivery capabilities of bacterial vectors.
• This approach successfully reduces unwanted biological outcomes, such as cytotoxicity, associated with bacterial gene therapy vectors.
• The findings suggest a viable method for optimizing bacterial vectors for safer and more efficient nonviral gene therapy.