Disruption of gap junctions reduces biomarkers of decidualization and angiogenesis and increases inflammatory mediators in human endometrial stromal cell cultures

Uterine decidualization is critical to embryonic implantation and sustained pregnancy. Objective: To evaluate the role of gap junction intercellular communications and connexin (Cx) proteins in the morphological and biochemical differentiation of decidualized human endometrial stromal cell (ESC) cultures. Design: Translational cell biological study. Setting: Academic medical center. Patients: Endometrial tissue was provided by five healthy reproductive age women on no hormonal medication, undergoing laparoscopy in the early proliferative phase of the menstrual cycle. Interventions: Endometrial biopsy under general anesthesia, establishment and decidualization of ESC with 10. nM 17β-estradiol, 100. nM progesterone and 0.5. mM dibutyryl-cAMP (E/P/c), and manipulation of gap junctions in vitro via a combination of pharmacological or transgenic approaches. Main outcome measures: Decidualized ESC evaluated morphologically for epithelioid transformation, gap junctions by dye diffusion and Cx43, prolactin, VEGF and IL-6 expression by RT-PCR, Western and ELISA methods. Results: Cx43 accumulation and functional gap junctions between decidualized ESC increase concomitantly with morphological differentiation following E/P/c treatment. Disruption of gap junctions using pharmacological inhibitors or Cx43 shRNA prevents morphological differentiation and inhibits prolactin and VEGF secretion. By contrast, IL-6 secretion from decidualized ESC is augmented by both approaches. Conclusions: The findings suggest that decidualized ESC function as a coordinated secretory organ to regulate embryonic implantation via intercellular cooperation mediated by gap junctions. When adjacent cells can communicate through these junctions, decidual prolactin and VEGF secretion appears to be optimized for vascular development of the placental bed. Conversely, when intercellular communications are disrupted, angiogenesis is impaired and an inflammatory state is induced.