Eutopic endometrium from patients with endometriosis modulates the expression of CD36 and SIRP-α in peritoneal macrophages

Abstract

Aim: This study aimed to investigate the in vitro alterations of the expression of signal regulatory protein-α (SIRP-α) and CD36 in macrophages in the endometriosis condition. Methods: The expression of SIRP-α and CD36 was measured in peritoneal macrophages and peripheral blood mononuclear cells of endometriosis patients and control participants. The expressions of SIRP-α and CD36 were measured in human acute monocytic leukemia (THP-1) cell-derived macrophages that were treated with interleukin-6 (IL-6)-induced conditioned medium, eutopic versus normal endometrial homogenate, or lipopolysaccharide in the presence or absence of nuclear factor kappa-B (NF-κB) or transforming growth factor (TGF-β) inhibitors, respectively. Results: Peritoneal macrophages that were isolated from women with endometriosis exhibited an enhanced expression of SIRP-α and a decreased expression of CD36 compared to control participants. Women with endometriosis had significantly higher levels of SIRP-α and CD36 in peripheral circulating mononuclear cells than in control participants. SIRP-α expression was significantly increased, whereas the CD36 expression was decreased in THP-1 cell-derived macrophages after treatment with eutopic endometrial homogenate. Intervention with IL-6-induced conditioned medium resulted in the downregulation of SIRP-α but the upregulation of CD36 in THP-1 cells. Incubation with the NF-κBp50 inhibitor decreased the expression of CD36 and SIRP-α in macrophages that were treated with normal endometrial homogenate, whereas the TGF-β inhibitor enhanced the CD36 expression of THP-1 cell-derived macrophages treated with eutopic endometrial homogenate. Conclusion: The eutopic endometrium could reduce the phagocytic ability of peritoneal macrophages in women with endometriosis through the modulation of SIRP-α and CD36 expression. Inhibition of the TGF-β signal pathway may be a potential therapeutic target for the treatment of endometriosis.