O-28: New Insights into the Mechanisms UnderlyingChlamydia Trachomatis Infection InducedFemale Infertility

Background: Chlamydia (C.) trachomatis is an obligate intracellular gram-negative pathogen affecting over 600 million people worldwide with 92 million new cases occurring globally each year. Genital C. trachomatis infection has been recognized as the most common cause of pelvic inflammatory disease leading to severe tubal damage, ectopic pregnancy, hydrosalpinx and infertility. However, the mechanism underlying hydrosalpinx induced by C. trachomatis infection remains largely unknown. Materials and Methods: Real time – polymerase chain reaction, western blot analysis and immunoprecipitation, histology including Masson’s trichrome staining, immunostaining, electron microscopy, Chlamydia infection rodent models and Cystic fibrosis transmembraneconductance regulator (CFTR) mutant mice were used in this project. Sperm motility and acrosome reaction were determined using computer-aided sperm analysis (CASA) and acrobead assay respectively, and embryo development by mouse embryo development assay. Results: We first characterized hydrosalpinx of infertile patients seen on ultrasound scan. Inflammatory cells could be found in hydrosalpinx fluid (HF) in the lumen in areas with flattened to no epithelial cells, as well as dilated blood vessels and/or lymph vessels. Scanning electron microscopy revealed severe loss of both cilia and microvilli and for the first time stomatae exuding globular bodies on eroded ampullae surfaces providing explanation for HF formation, and thus for the detrimental effects of HF on reproductive processes and IVF outcome. Further investigation using Masson’s trichrome staining showed areas of epithelial transformation, focally attenuated and pseudostratified epithelium. Immunostaining showed enhanced CFTR immunoreactivity in the areas of transformed hydrosalpinx epithelium. Correlation with C. trachomatis infection was done by testing hydrosalpinx patients’ sera for C. trachomatis immunoglobulin G antibody titers using a Capita enzyme-linked immunosorbent assay (ELISA) based kit. We then determined CFTR involvement using a rodent C. trachomatis infection model and confirmed it using CFTR mutant (CFTR (tm1Unc)) mice. Increased CFTR expression and fluid accumulation was observed in the uterine horns infected with C. trachomatis elementary bodies. We further showed that upregulated CFTR expression and consequent fluid accumulation led to decreased implantation and infertility using a mouse model. For C. trachomatisto cause infection, it has to enter epithelial cells. However, the exact mechanism or receptor(s) for C. trachomatis reproductive tract epithelial entry is not well understood. Using human epithelial cell lines expressing functional and mutant Delta508 CFTR cells, CFTR mutant mice and wild type controls, we for the first time demonstrate that CFTR functions as a cell surface receptor for epithelial cell entry and internalization of C. trachomatis. Conclusion: The findings of this project may lead to the development of new treatment strategies to curtail the spread of Chlamydial infections, reduce hydrosalpinx formation and improve assisted reproduction treatment outcome in infertile patients.