Structural, functional, and molecular mechanisms of endometrial transformation in habitual pregnancy failure

Abstract

Introduction. Habitual pregnancy failure (HPF) has long been a pressing problem of modern medicine and is characterized by multiple pathogenetic mechanisms of early pregnancy termination. The aim of the study was to examine the expression of estrogen, progesterone, progesterone-induced blocking factor and stromal cell factor-1 receptors in endometrial biopsy specimens from patients with HPF. Materials and methods. Histological and immunohistochemical studies were performed on 75 endometrial biopsies: 50 endometrial biopsies were taken from patients with HPF and chronic endometritis with no more than three pregnancies, and 25 endometrial biopsies were taken from conditionally healthy patients. Endometrial biopsy was performed on days 19 to 22 of the menstrual cycle. Histological examination of endometrial biopsy specimens was performed according to the standard technique with hematoxylin and eosin staining. The expression of estrogen receptor (ER), progesterone receptor (PR), progesterone-induced blocking factor (anti-PIBF), and stromal cell factor-1 (anti- SDF-1) was assessed by immunohistochemistry. Results. In patients with HPF, the endometrium corresponded to the middle stage of the secretion phase in 32 % of cases. Immunohistochemical study in patients with HPF verified multifocal decrease of estrogen and progesterone receptor expression in the stromal component in 82 % of cases. Assessment of PIBF and SDF-1 expression in the glands and stroma of the endometrial mid-stage secretion phase in patients with HPF revealed a statistically significant decrease compared to the control group. Discussion. The presence of chronic endometritis in patients with HPF leads to impaired endometrial secretory transformation, decreased expression of estrogen and progesterone receptors in the endometrial stroma, and decreased expression of PIBF and SDF-1 in the glands and endometrial stroma. The results of the study suggest the need for pathogenetic therapy of chronic endometritis and pregravidarial preparation in patients with HPF. Conclusion. Regardless of the completeness of endometrial transformation, desynchronosis of the receptor profile, altered expression of immunological markers (PIBF and SDF-1) against the background of chronic endometritis, and structural and molecular disturbances serve as factors of early pregnancy loss.