Selective Bacterial Targeting and Infection-Triggered Release of Antibiotic Colistin Conjugates

Area of Science:

• Drug Delivery and Pharmacology
• Antimicrobial Peptides
• Bioconjugation Chemistry

Background:

• Potent antibiotics often exhibit significant toxicity, limiting their clinical application.
• Developing strategies for targeted drug delivery can enhance therapeutic efficacy and reduce side effects.
• Antimicrobial peptides show promise for bacterial targeting but require controlled release mechanisms.

Purpose of the Study:

• To design a novel conjugation strategy for selective antibiotic delivery.
• To enable infection-triggered release of potent but toxic antibiotics.
• To improve the safety and efficacy of antibiotic treatments.

Main Methods:

• Conjugation of the antibiotic colistin with a modified ubiquicidin peptide fragment for bacterial targeting.
• Incorporation of a neutrophil elastase (NE)-cleavable linker for infection-specific drug release.
• Synthesis and characterization of five regioisomeric colistin conjugates.
• In vitro testing using recombinant NE and co-cultures of human neutrophils and Escherichia coli.

Main Results:

• Antibacterial activity of colistin conjugates was masked until cleavage by NE.
• Cleavage and release of active colistin were observed when the linker was attached at specific positions (1- or 3-) of colistin.
• Proof-of-concept demonstrated NE secretion, colistin release, and potent antibacterial activity in a neutrophil-E. coli co-culture model.

Conclusions:

• The novel conjugation strategy successfully masked antibiotic activity until triggered by infection-specific enzymes.
• This approach allows for targeted delivery and release of colistin, enhancing its selectivity.
• The developed system holds potential for creating safer and more effective antibiotic therapies.