Iron overload-modulated nuclear factor kappa-B activation in human endometrial stromal cells as a mechanism postulated in endometriosis pathogenesis

Abstract

Objective: To evaluate the effect of iron overload on nuclear factor kappa-B (NF-kappa B) activation in human endometrial stromal cells (ESCs).

Design: Experimental study.

Setting: University hospital research laboratory.

Patient(s): Ten healthy women.

Intervention(s): Isolated ESCs from endometrial biopsies were incubated with 50 mu M FeSO4 or vehicle. The NF-kappa B inhibitor [5-(p-fluorophenyl)-2-ureido] thiophene-3-carboxamide (TPCA-1), which inhibits IKK beta, the kinase of I kappa B alpha (inhibitory protein of NF-kappa B), was used to prevent iron overload-stimulated NP-kappa B changes in ESCs.

Main Outcome Measure(s): NF-kappa B activation was assessed by p65:DNA-binding activity immunodetection assay. I kappa B alpha, p65, and intercellular adhesion molecule (ICAM)-1 proteins expression was evaluated by Western blots. ESC soluble ICAM (sICAM)-1 secretion was measured by ELISA using conditioned medium.

Result(s): Iron overload increased p65:DNA-binding activity and decreased I kappa B alpha and p65 cytoplasmic expression in ESCs after 30 minutes of incubation as compared with the basal condition. ESC ICAM-1 expression and sICAM-1 secretion were higher after 24 hours of iron overload treatment than in the absence of treatment. TPCA-1 prevented the iron overload-induced increase of p65:DNA binding and I kappa B alpha degradation.

Conclusion(s): Iron overload activates IKK beta in ESCs, stimulating the NF-kappa B pathway and increasing ICAM-1 expression and sICAM-1 secretion. These results suggest that iron overload induces a proendometriotic phenotype on healthy ESCs, which could participate in endometriosis pathogenesis and development.