Aberrant claudin-4 transcript levels in eutopic endometrium of women with idiopathic infertility and minimal endometriosis

Introduction: Claudin-4 (CLDN4) is a transmembrane protein, responsible for cellular contact and organization. A different expression of claudin 4 in the endometrium, depending on the menstrual cycle and with peak at the aim of the 'implantation window', has been observed. CLDN4 is believed to play an important role in embryo implantation. The aim: The aim of the study was to compare the mRNA CLDN4 expression levels in two subgroups of infertile women (idiopathic infertility or minimal endometriosis) and compare them to fertile controls. Method: The study included 36 women with idiopathic infertility and 24 with minimal endometriosis. The control group comprised 26 women. Eutopic endometrium samples were collected with a Pipelle device during the implantation window. Firstly, mRNA was extracted from the endometrium and reverse transcribed into cDNA. Real time PCR was used for the assessment of relative expression levels. Results: The observed transcription level of CLDN4 did not differ statistically between the studied groups, but was significantly higher when compared to controls. Conclusions: Exceedingly high levels of CLDN4 might negatively influence fertility rates.