Insights into penicillin-induced Chlamydia trachomatis persistence.

Area of Science:

• Microbiology
• Cell Biology
• Immunology

Background:

• Chlamydia trachomatis (CT) can enter a persistent, non-cultivable state within host cells.
• Persistence is induced by stressors like penicillin and alters the host-pathogen interaction.
• Understanding CT persistence is crucial for developing effective treatment strategies.

Purpose of the Study:

• To investigate host cell responses during CT persistence compared to normal infection.
• To analyze cell survival, phosphatidylserine externalization, and caspase activation.
• To quantify reactive oxygen species (ROS) production in persistent and normal CT infections.

Main Methods:

• In vitro infection of HeLa cells with CT serovars D and L2.
• Induction of persistence using penicillin treatment.
• Assessment of cell viability, phosphatidylserine exposure, and caspase activity (caspase 1, 3/7).
• Measurement of ROS production using flow cytometry.

Main Results:

• Penicillin-induced CT persistence abolished host cell cytotoxicity and phosphatidylserine externalization.
• Persistent CT strongly inhibited caspase 1 and caspase 3/7 activation.
• ROS production was significant in both normal and persistent infections, but higher in normal infection (serovar L > D, penicillin-free > penicillin-induced).

Conclusions:

• CT establishes a protected niche during persistence by downregulating host cell death and immune signaling pathways.
• Persistent CT still induces ROS production, potentially leading to chronic inflammation and tissue damage.
• These findings offer insights into the cellular dynamics of chlamydial persistence and its pathological implications.