Impact of Escherichia coli Outer Membrane Vesicles on Sperm Function

Area of Science:

• Reproductive biology
• Microbiology
• Andrology

Background:

• Reproductive tract infections cause about 15% of male infertility.
• Escherichia coli (E. coli) is the most common bacteria found in infertile men's semen.
• Gram-negative bacteria produce outer membrane vesicles (OMVs).

Purpose of the Study:

• To investigate the role of E. coli outer membrane vesicles (OMVs) in human sperm function.
• To determine the impact of OMVs on sperm vitality, motility, morphology, reactive oxygen species (ROS) levels, and DNA fragmentation.

Main Methods:

• Isolation and characterization of E. coli OMVs using ultracentrifugation, SDS-PAGE, TEM, and DLS.
• Exposure of human sperm to isolated OMVs (8 µg/mL) for varying durations (30, 45, 60, and 90 minutes).
• Evaluation of sperm vitality, motility, morphology, intracellular ROS, and DNA fragmentation.

Main Results:

• OMVs significantly reduced progressive sperm motility and increased immotile spermatozoa after 30 minutes.
• A significant increase in intracellular ROS and sperm DNA fragmentation was observed at all tested exposure times.
• OMVs were characterized and confirmed to be involved in altering sperm function.

Conclusions:

• Outer membrane vesicles (OMVs) from E. coli negatively impact human sperm function.
• OMVs contribute to male infertility by impairing sperm motility and causing DNA fragmentation.
• These findings highlight a novel mechanism by which bacterial infections can lead to male infertility.