Targeting Intracellular Pathogenic Bacteria Through N-Terminal Modification of Cationic Amphiphilic Polyproline...

Area of Science:

• Microbiology
• Biochemistry
• Drug Discovery

Background:

• Intracellular pathogens pose a significant challenge to antimicrobial therapies due to their protected location within host cells.
• Conventional antimicrobial agents often struggle to reach or effectively eliminate pathogens residing inside mammalian cells.
• Cationic amphiphilic polyproline helices (CAPHs) are a class of compounds with potential antimicrobial activity, but their efficacy can be limited by cell penetration.

Purpose of the Study:

• To develop novel CAPHs with improved cell-penetrating and antibacterial properties for targeting intracellular pathogens.
• To investigate the structure-activity relationship of CAPHs by modifying the hydrophobic moiety at the N-terminus.
• To evaluate the efficacy of modified CAPHs against intracellular bacterial infections in macrophage models.

Main Methods:

• Synthesis of modified cationic amphiphilic polyproline helices (CAPHs) with variations in the N-terminal hydrophobic group.
• Assessment of cell penetration efficiency of CAPHs in macrophage cell lines using fluorescence microscopy.
• Evaluation of antibacterial activity against various pathogenic bacterial strains, including intracellular pathogens.
• Cytotoxicity assays to determine the safety profile of the modified CAPHs.

Main Results:

• Modified CAPHs demonstrated enhanced penetration into macrophage cells compared to unmodified versions.
• Certain modified CAPHs exhibited potent antibacterial activity against multiple pathogenic bacterial strains.
• One specific CAPH, Pentyl-P14, showed significant efficacy in clearing intracellular *Shigella* infections within macrophages.
• Some modifications led to improved antibacterial properties with minimal observed cytotoxicity.

Conclusions:

• Modification of the N-terminal hydrophobic moiety is a viable strategy to enhance the cell-penetrating and antibacterial efficacy of CAPHs.
• Pentyl-P14 represents a promising candidate for developing novel therapeutics against intracellular bacterial infections.
• These findings open new avenues for designing advanced antimicrobial agents capable of targeting pathogens within host cells.