Subpopulations of Macrophages within Eutopic Endometrium of Endometriosis Patients

Endometriosis is recognized as a chronic inflammatory disease and is related to immune response. There have been reports that revealed the different distribution of macrophage within the eutopic endometrium of women with endometriosis. Macrophages are functionally polarized into M1 and M2 cell lineages. We studied a difference in the subpopulations of M1 and M2 macrophages within the eutopic endometrium in patients with or without endometriosis to investigate how the eutopic endometrium is stimulated immunologically.Thirty-six patients with endometriosis (endometriosis group) and 37 without endometriosis (non-endometriosis group) were analyzed. Paraffin-embedded endometrial specimens were used for the study. Consecutive sections were used for immunostaining of CD68 (pan-macrophage marker) and CD163 (M2 macrophage marker). Cells positive for each marker were quantified, and the ratio of M2 macrophages in pan-macrophages was calculated.The endometriosis group had a significantly higher number of pan-macrophages than the control group in all phases (P < 0.05). The ratios of M2 macrophages in pan-macrophages were significantly lower in all phases in the endometriosis group (P < 0.05).The macrophage population slants toward M1 in the endometrium of endometriosis patients. The endometrium appeared to be stimulated by some organelles and/or substances that induce M1 in endometriosis patients.