A54145 Factor D Is Not Less Susceptible to Inhibition by Lung Surfactant than Daptomycin

Area of Science:

• Microbiology
• Pharmacology
• Biochemistry

Background:

• A54145 factor D (A5D) is a lipopeptide antibiotic with similarities to daptomycin.
• Previous studies suggested A5D is not inhibited by lung surfactant, unlike daptomycin.
• This led to attempts to develop A5D analogs for community-acquired pneumonia (CAP).

Purpose of the Study:

• To investigate the interaction of A5D and daptomycin with lung surfactant components.
• To determine the specific stereoisomer of phosphatidylglycerol (PG) responsible for antibiotic antagonism.
• To clarify the susceptibility of A5D to lung surfactant inhibition compared to daptomycin.

Main Methods:

• Stereoisomer analysis of phosphatidylglycerol (PG) in lung surfactant.
• In vitro studies assessing antibiotic activity in the presence of specific PG stereoisomers.
• Comparative analysis of A5D and daptomycin activity in lung surfactant.

Main Results:

• A5D and daptomycin both show a strong preference for the 2R,2'S stereoisomer of PG.
• This specific PG stereoisomer is the only form present in lung surfactant.
• Both antibiotics are completely antagonized by this PG stereoisomer, and lung surfactant antagonism is primarily due to PG interaction.
• A5D is not significantly less susceptible to lung surfactant inhibition than daptomycin.

Conclusions:

• The antagonism of A5D and daptomycin by lung surfactant is mainly mediated by their interaction with the 2R,2'S stereoisomer of PG.
• Contrary to previous suggestions, A5D is significantly inhibited by lung surfactant.
• This finding has implications for the development of lipopeptide antibiotics targeting lung infections.