Persistent Chlamydia trachomatis infections resist apoptotic stimuli.

Area of Science:

• Microbiology
• Cell Biology
• Immunology

Background:

• Microbial interactions with host cells are complex.
• Persistent infections can arise from apoptosis inhibition.
• Chlamydia trachomatis is a pathogen linked to diseases like trachoma.

Purpose of the Study:

• To investigate the role of apoptosis in Chlamydia trachomatis infection.
• To compare apoptotic responses in acute and persistent infections.
• To explore the mechanism behind Chlamydia-induced persistence.

Main Methods:

• HeLa 229 cells were infected with Chlamydia trachomatis serovar A/HAR-13.
• Persistence was induced using gamma interferon.
• Apoptosis was assessed via cell viability, DNA laddering, and cytochrome c translocation assays.
• Chlamydial hsp60 expression was measured using Western blot.

Main Results:

• Infected cells showed resistance to apoptosis-inducing agents (etoposide, staurosporine).
• Apoptosis inhibition was observed in both acute and persistent Chlamydia infections.
• Cytochrome c remained in mitochondria, suggesting caspase-9 was not activated.
• Chlamydial hsp60 expression increased in persistent infections, especially with apoptosis stimuli.

Conclusions:

• Chlamydia trachomatis actively inhibits host cell apoptosis, facilitating its persistence.
• This evasion of apoptosis, coupled with increased hsp60, may contribute to sustained inflammation and disease.
• The findings suggest a novel pathogenic mechanism for Chlamydia-related trachoma and infertility.