Endocrine Abstracts

Background

One in 80 pregnancies is ectopic. Chlamydia trachomatis infection is the major risk factor for ectopic pregnancy yet knowledge of the pathogenic events that lead from Chlamydial infection to ectopic pregnancy is unclear. Furthermore, a blood test that can reliably differentiate an ectopic from an intra-uterine pregnancy is not available. The innate immune system is likely to offer protection against Chlamydia and the natural anti-microbial proteins, secretory leukocyte protease inhibitor (SLPI) and elafin, are key mediators of the innate immune system and are expressed throughout the genital tract, including the uterine decidua.

Objective

To compare elafin and SLPI expression in the decidua of women with ectopic to women with intra-uterine pregnancies.

Material and method

Local ethical approval was obtained to collect decidua from women undergoing surgical management of ectopic pregnancy (n=11), surgical management of miscarriage (n=5) and surgical termination of pregnancy (STOP) (n=5). Using RT-PCR and immunohistochemistry, the mRNA and protein expression pattern of SLPI and elafin were compared in the decidua from these groups.

Results

Elafin mRNA expression was significantly higher in the ectopic pregnancy decidua compared to the miscarriage and STOP groups. SLPI expression was also higher in this group. Elafin and SLPI protein expression were demonstrated in the decidual leukocyte populations and epithelium. Elafin and SLPI protein expression was compared in each group and appeared to reflect the mRNA pattern.

Conclusions

The demonstration of an altered expression pattern of elafin and SLPI in women with ectopic compared to intra-uterine pregnancies contributes further to our current knowledge of extra-uterine embryo implantation in the context of chlamydial infection. Furthermore, this difference could be exploited to provide the clinical pathologist with a means of diagnosing ectopic pregnancy in any woman with a failing early pregnancy in whom the diagnosis is uncertain, by simply examining a sample of the decidua.