Neutrophils infiltrating the endometrium express vascular endothelial growth factor: potential role in endometrial angiogenesis

OBJECTIVE(S): To identify leukocytes within the human endometrium expressing vascular endothelial growth factor (VEGF). DESIGN(S): Prospective cohort study. SETTING(S): Healthy volunteers in an academic research environment. PATIENTS(S): Twenty-one normal cycling women without abnormal menstrual bleeding or infertility. INTERVENTION(S): Endometrial tissue collection by Pipelle de Cornier aspiration. MAIN OUTCOME MEASURES(S): Histologic, immunohistochemical (CD3, CD34, CD56, CD68, neutrophil elastase, estrogen and P receptors, VEGF), and simultaneous double immunoenzymatic labeling analysis of VEGF-positive cells within the human endometrium. RESULT(S): Ten endometrial samples were obtained in the proliferative (cycle days 5-10) and 11 samples in the secretory phase (cycle days 15-26). Immunohistochemical analyses showed the expected distribution of the different leukocyte cell types. Besides epithelial and stromal endometrial cells, the predominant cells that stained for VEGF were neutrophil granulocytes. Neutrophils were more abundant in the secretory phase but they expressed neither estrogen-a nor P receptors. CONCLUSION(S): Neutrophil granulocytes infiltrating the human endometrium express VEGF and regulate cyclical endometrial vascular proliferation. Ovarian steroids indirectly influence neutrophil migration.