Downregulation of pattern recognition receptors on macrophages involved in aggravation of endometriosis

Abstract Problem In women of reproductive age, endometriosis may contribute to dysmenorrhea, chronic pelvic pain, dyspareunia, infertility, adenomyosis, and endometrial ovarian cyst (EOC). Recent studies have shown that chronic inflammation occurs in the pelvis of endometriosis patients and that this inflammation is exacerbated by immunosuppression, leading to survival endometrial debris. However, the detailed immunological mechanisms underlying the aggravation of inflammation and immunosuppression in endometriosis patients remain unclear. Method of Study We investigate the alarmins (high‐mobility group box‐1, IL‐33, IL‐1α, and S100B protein), proinflammatory cytokines (IL‐6 and IL‐1β), and immune cells (CD8 + T cells, CD4 + T cells, natural killer cells, natural killer T cells, dendritic cells, and macrophages) in peritoneal fluid of patients with EOC using enzyme‐linked immunosorbent assay, electrochemiluminescence, and flow cytometry. Then, we analyzed the correlation between these factors and the aggravating indicators of endometriosis, tumor size and revised American Society for Reproductive Medicine (r‐ASRM) score. Results Unexpectedly, there was no correlation between each alarmin level and aggravating indicators. However, the expression of pattern recognition receptors, toll‐like receptor 4, and receptor of advanced glycation end‐products on macrophages was inversely correlated with aggravating indicators. Conclusions The aggravation of endometriosis is associated with a decrease in alarmin receptors but not alarmin levels. Investigation of innate immune systems, such as alarmins and their receptors, may help elucidate new mechanisms of endometriosis.