Characterization of Apoptotic Activities During Chlamydia trachomatis Infection in Primary Cervical Epithelial Cells

Abstract

Chlamydiae are obligate intracellular bacteria that infect human epithelial cells. It has been reported that Chlamydia trachomatis, induces apoptosis in epithelial cells, however, the molecular mechanisms responsible for host cell death especially in primary epithelial cells remained largely unknown as most of the studies are in cell line like HeLa. In this study we demonstrated that C. trachomatis induces apoptosis signaling pathway and apoptosis in primary cervical epithelial cells in a time and dose dependent manner. Live cervical epithelial cells were isolated from endocervical cells and induction was done with chlamydial EBs. Our results demonstrated that apoptosis in infected epithelial cells was associated with an increased activity of caspase 8; however, caspase 9 was activated to a lesser extent. Analysis of apoptosis pathway revealed that expression level of McL-1, Bcl-2, CASP8, and TRADD genes were found to be significantly upregulated (P < 0.01), where as levels of Caspase 1, Caspase 10 and BRIC2 were found to be significantly downregulated (p < 0.01). Our results showed that Chlamydia induces apoptosis and caspase activation in epithelial cells through caspase 8, with an increased expression of the McL-1, which confers a block at the mitochondrial level.

Keywords:

• Chlamydia trachomatis
• Cervical epithelial cells
• Apoptosis
• Caspase activity
• Apoptosis signaling

ACKNOWLEDGMENTS

We specially thank Mrs. Madhu Badhwar, Mrs. Asha Rani and Mrs.Romamma Thomas, for providing technical assistance. We also acknowledge the Indian Council of Medical Research for providing financial assistance to Vikas Vats and Tanvi Agrawal in the form of a research fellowship.

Declaration of Interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.